Acute effects of low-intensity resistance combined with blood flow restriction and high-intensity resistance exercise on lower extremity explosive strength, pennation angle and muscle-tendon stiffness in male sprinters

Acute effects of low-intensity resistance combined with blood flow restriction and high-intensity resistance exercise on lower extremity explosive strength, pennation angle and muscle-tendon stiffness in male sprinters | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Acute effects of low-intensity resistance combined with blood flow restriction and high-intensity resistance exercise on lower extremity explosive strength, pennation angle and muscle-tendon stiffness in male sprinters Junjie Zhang, Jun Ye, Haiyuan Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3952436/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The purpose of this study was to investigate the ecute effect of combining low-intensity resistance exercises with a blood flow restriction intervention and high-intensity resistance exercises on sprint ability, vertical jump performance, rectus femoris pennation angle, and lower extremity muscle-tendon stiffness in male sprinters. Methods: Seventeen male sprinters participated in the study and were randomly assigned to perform different interventions with 72-hour intervals. The interventions included 90% 1RM hip thrust (HT), 90% 1RM barbell half squat (HS), 30% 1RM HT + BFRT ( Blood Flow Restriction Training), and 30% 1RM HS + BFRT. Test content included 20-m sprint, vertical jump, rectus femoris pennation angle, and lower limb muscle-tendon stiffness. Descriptive statistics and Repeated measures ANOVA analysis were used for statistical analysis. Results: (1) The study found that the 10-20m sprint performance was significantly improved compared to the 90%1RM HT and 90%1RM HS after the 30%1RM HS + BFRT interventions. Additionally, the 0-20m sprint performance was significantly improved than 90%1RMHS after 30%1RM HT + BFRT interventions; (2) The CMJ vertical jump height was significantly higher than the 90%1RM HS after the 30%1RM HS + BFRT intervention; (3) Moreover, the CMJ relative peak power was significantly increased after the 90%1RMHT and 90%1RMHS interventions compared to the 30%1RM HT + BFRT; The CMJ (Countermovement Jump) relative rate force development was significantly expanded after the 90%1RM HS intervention compared to the 30%1RM HT + BFRT. Furthermore, the 90% SJ (Squat Jump) relative rate force development after the 90%1RMHT intervention was significantly higher than the 30% 1RM HT + BFRT and 30% 1RM HS + BFRT. The CMJ relative peak force after the 90% 1RMHS intervention was significantly higher than the 30% 1RM HT + BFRT. Similarly, the SJ relative peak force after the 90% 1RMHT intervention was significantly higher than the 30% 1RM HT + BFRT and 30% 1RM HS + BFRT; (4) The study also found that the rectus femoris pennation angle was significantly lower after the 30%1RM HS + BFRT and 90%1RMHS practice interventions compared to after the 30%1RM HT + BFRT; (5) Additionally, therectus femoris muscle stiffness was significantly improved after the 30%1RM HT + BFRT compared to after the 30%1RM HS + BFRT. Moreover, the biceps femoris muscle stiffness was significantly increased after the 90%1RM HS intervention compared to after the 30%1RM HS + BFRT. The 90% 1RMHS and 30% 1RM HS + BFRT had significantly higher post-intervention gastrocnemius lateral stiffness than the 90% 1RM HT, and 30% 1RM HS + BFRT had significantly higher post-intervention gastrocnemius medial stiffness than 90%1RMHS, 30%1RM HT + BFRT.Lastly, the 30%1RM HS + BFRT had significantly increased post-intervention tibialis anterior stiffness than the 90% 1RM HT, and higher tibialis anterior stiffness after the 30% 1RM HS + BFRT intervention than 30% 1RM HT + BFRT. Additionally, there was a significantly improved Achilles tendon stiffness after the 30% 1RM HS + BFRT intervention compared to the 30% 1RM HT + BFRT. Conclusions: (1) The study found that male sprinters experienced significant improvement in sprint performance after low-intensity barbell hip thrust resistance combined with blood flow restriction intervention compared to high-intensity barbell half-squat; (2) The positive effect of barbell half-squat exercise was significantly better than that barbell hip thrust on vertical jump performance; (3) Barbell half-squat exercise was found to have a significantly stronger positive effect than barbell hip thrust in decreasing the pennation angle of the rectus femoris muscle; (4) Both low-intensity barbell half squat and hip thrust exercises, when accompanied by blood flow restriction training intervention, were found to significantly improve lower extremity muscle-tendon stiffness. Biological sciences/Physiology Health sciences/Anatomy blood flow restriction resistance exercise post-activation potentiation pennation angle stiffness vertical jump sprint Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Post-activation Potentiation (PAP) is a phenomenon wherein an acute increase in muscle performance occurs due to voluntary muscle contraction. Scholars hold differing viewpoints regarding PAP, with some suggesting it is caused by voluntary muscle contraction 1 , while others argue it results from an acute increase in explosive force following preload stimulation 2 . Although there is no standardized definition for PAP, it is widely acknowledged that the post-activation enhancement effect benefits explosive performance 3 . The potential mechanisms behind this effect include increased recruitment capacity of high-threshold motor units, phosphorylation of myosin regulatory light chain, and changes in myofiber pennation angle 4 . While the mechanism of enhanced phosphorylation has been confirmed by numerous studies, the identification of other explanatory mechanisms, such as enhanced recruitment of higher-order motor neurons and changes in the pennation angle, remains incomplete. In anatomy, the angle between the tendon and the muscle fibers is often referred to as the pennation angle, reflecting the relationship between the orientation of the muscle fibers and the tendon. In their study, Mahlfeld et al. (2004) 5 conducted ultrasonographic examinations on the lateral femoral muscle and observed changes in the pennation angle in three sets of examinations. They investigated the effect of pennation on PAP using ultrasonography and found that immediately after three sets of 3 s of static MVC-induced stimulation of the lateral femoral muscle, the pennation angle decreased by 0.5° (15.7° vs 16.2°). Furthermore, after 3-6 minutes of MVC practice, the pennation angle decreased significantly by 1.8° (14.4° vs 16.2°). However, increased pennation has been found to reduce the overall muscle contraction under equal force conditions 6 . This allows the muscle to work in a more optimal region of the force-velocity curve and prolongs the time it operates within the optimal region of the length-tension curve. Earp et al. (2011) 7 demonstrated that subjects with greater pennation had better early RFD (rate of force development) during the deep jump, attributed to their muscles greater ability to cope with centrifugal loading. Therefore, the interpretation of the post-activation enhancement effect of increased or decreased muscle pennation angle remains controversial. New potential explanatory mechanisms for the post-activation enhancement effect have been proposed 8 , particularly the enhancement of lower limb muscle-tendon stiffness, Brughelli et al.(2008) 9 found higher stiffness promotes the stretch-shortening cycle (SSC) and higher-velocity explosive movements. Wu et al. (2010) 10 found a significant correlation between the increase in tendon stiffness induced by SSC exercise and enhancement in countermovement jump (CMJ) performance. Other studies also support the idea that high stiffness is beneficial for stretch-shortening cycle (SSC) performance and muscle force generation 11 . Various methods have been used to measure stiffness in the human body, providing valuable information for understanding muscle-tendon stiffness and its impact on performance. However, most of these methods focus on specific segments of the lower extremity and do not thoroughly investigate the individual contributions of muscle and tendon stiffness to performance. Therefore, further research is needed to explore the relationship between individual muscle stiffness, tendon stiffness, and performance to enhance our understanding of muscle-tendon interactions 12 . The Myoton pro Digital Muscle Function Tester is a reliable and valid tool for measuring the stiffness of individual muscles, providing accurate and objective data for research and clinical applications. To date, there is no study investigating the acute effect of post-activation potentiation (PAP) on lower limb muscle-tendon stiffness specifically in sprinters. Understanding the detailed impact of lower limb muscle-Achilles tendon stiffness on PAP regulation is crucial for optimizing training strategies and injury prevention in athletes. The magnitude of the enhancement effect depends on various factors, including the level of exercise, type of muscle fiber, type of muscle contraction, duration, and amount of induced load 4 . Hamada et al. (2003) 13 found that post-activation enhancement effects appear to require high-intensity resistance exercises for induction; however, fatigue induced by such exercises also increases the risk of injury and subjective discomfort. Blood flow restriction training (BFRT) has garnered significant attention from sports researchers, competitive coaches, and athletes in recent years. BFRT involves applying pressure during training to inhibit venous blood flow and partially restrict arterial blood flow. This leads to inadequate oxygen transport in adjacent joints or localized areas, disrupting internal environment homeostasis, resulting in a rapid increase in blood lactate levels and free radicals 14 . Consequently, there is an increase in the recruitment capacity of high-threshold motor units, facilitating improved muscle hypertrophy and strength 15 . Several studies have demonstrated that combining low-intensity resistance with blood flow restriction training (BFRT) yields comparable effects to high-intensity resistance exercise in promoting muscle hypertrophy and strength, benefiting both elite athletes and the general population 16,17 . This presents an alternative approach for athletes unable to engage in high-intensity resistance exercise during rehabilitation. However, current research on low-intensity resistance combined with BFRT has primarily focused on its long-term training adaptations, neglecting to elucidate the acute effects of low-intensity resistance combined with BFRT on athletic performance. Previous studies have shown that low-intensity resistance combined with blood flow restriction training can significantly enhance sprinting ability in sprinters 16 . However, whether it produces effects similar to those of high-intensity resistance exercise interventions requires further verification. Accordingly, this study aimed to investigate the acute effects of combining low-intensity resistance with blood flow restriction training and high-intensity resistance exercise on sprinting ability, explosive jumping performance, muscle pennation angle, and lower limb muscle-tendon stiffness in male sprinters. Materials and Methods Subjects The sample size required for the study was pre-estimated using G*Power3.1 software (Dusseldorf, Germany), effect size, alpha and test efficacy (1-β) were set at 0.40, 0.05 and 0.80, respectively, in reference to the findings of Seitz L B et al 18 . and Faul F et al 19 . The results of the estimation showed that the minimum sample size required to carry out the present study is 12 individuals. Considering a potential sample dropout rate of 20%, a minimum of 15 participants were recruited for this study. Accordingly, 18 male sprinters were recruited and one withdrew due to an ankle sprain during the intervention. The final 17 participants [age (22.88 ± 1.13) years, height (178.46 ± 3.24) cm, weight (72.12 ± 3.74) kg, thigh circumference (56.67 ± 1.77) cm, blood flow restriction pressure values (271.26 ± 28.85) mmHg, years of training (4.31 ± 1.29), and 1RM hip thrust ( 196.41 ± 35.28) kg, 1RM barbell half squat (150.19 ± 19.92) kg] completed all the tests. All of the above participants were free of injury, sleep disorders, and non-smokers, volunteered to participate, and signed an informed consent form after being informed of the testing process and potential risks. Research have been performed in accordance with the Declaration of Helsinki. Approval for this study was obtained from the Ethics Committee of Beijing Sport University(2023215H) and informed consent was obtained from all participants, all of them signed a consent form. Procedures This study utilizes a randomized crossover control trial design. During the familiarization session, participants are required to familiarize themselves with the evaluation process of all test tasks and indicators to mitigate the influence of learning effects and physical discomfort on the formal experiment. During the familiarization session, participants underwent the following: 1) Introduction to testing procedures, encompassing methods for 20m sprint run, explosive vertical jump, feather angle, and lower limb muscle-tendon stiffness, during which testing tools could be briefly examined; 2) Collection and recording of subjects' age, height, weight, thigh circumference, years of training, and best performance in the 100m sprint; 3) Assessment of maximal force in barbell hip thrust and barbell half-squat, and establishment of baseline kinematic and kinetic parameters for 20m sprint and vertical jump on the force platform. Additionally, participants were briefed on test precautions: 1) Avoid high-intensity physical exercise, consumption of caffeine- or alcohol-containing beverages for 24 hours prior to the experiment, and ensure at least 8 hours of sleep 20 ; 2) Hydrate appropriately and refrain from eating for 2 hours before the test 21 ; 3) Attempt to schedule tests at the same time each time, ideally within a deviation of 1 hour; 4) Maintain consistent or similar training attire; 5) Ensure uniformity in dressing and attire; 6) Refrain from engaging in high-intensity training activities during the washout period. Participants followed the same procedure during the formal experimental session. Participants completed interventions in a randomized order, including 90% 1RM HT, 90% 1RM HS, 30% 1RM HT + BFRT, and 30% 1RM HS + BFRT. For the formal experimental intervention, participants engaged in an 8–10 minute standardized warm-up, involving jogging, glute activation, dynamic stretching, and marching movement integration 22 . Following a 3–5 minute rest at the end of the warm-up, participants underwent task interventions. These interventions included a low-intensity resistance combined with blood flow restriction training protocol of 30% 1RM (HT/HS) × 15 repetitions/set × 3 sets with a 30-second interval between sets, as referenced in studies by Abe et al. (2005) 23 , Patterson et al.(2019) 24 . Additionally, a high-intensity resistance exercise protocol of 90% 1RM (HT/HS) × 3 repetitions 25 . It is noteworthy that studies have confirmed, for collegiate male sprinters, the optimal window for enhancing sprint running and jumping performance is between minutes 4 and 8 post-intervention, with the majority of studies indicating peak efficacy at the fifth minute 26,27 . Therefore, the 20-m sprint run, the force platform vertical jump test (including CMJ, SJ, and DJ completed in one session), the rectus femoris pennation angle, and the lower extremity muscle-tendon stiffness test were all conducted at minute 5 post-intervention, with only one of these tests being completed in each experiment. To minimize the potential for interaction between interventions, participants were explicitly instructed to refrain from engaging in high-intensity training activities during the washout period and to ensure their readiness for each training session (ensuring physiological recovery from fatigue and maintaining psychological anticipation of the training). Additionally, based on the studies of Mina et al. (2019) 28 and Dello et al. (2016) 29 , a 72-hour interval was maintained between each pair of training interventions. The room temperature during the testing period ranged from 23.2°C to 26.3°C, with humidity between 67% and 85%. Selection of blood flow restriction training equipment model, operation method and training pressure The blood flow restriction training equipment used is the B STRONG pressurized training belt (B STRONG, Utah, USA), featuring an adjustable design and employing a distributed airbag pressure filling method. This design effectively alleviates compression pain and ensures safe, convenient operation. Specifically, participants assumed a standing position and wrapped the pressurized training belt around the vertical longitudinal axis of the thigh, targeting the gluteus transversus muscle on both sides. Considering gradual adaptation of blood vessels to changes in pressure induced by blood flow restriction, inflation pressure was incrementally increased until reaching the target pressure value. In this study, we employed personalized blood flow restriction pressure, determined by the relative pressure value selected according to the individual subject's thigh circumference. Research by Loenneke et al. (2012) 30 , and Natsume et al. (2015) 31 supports the superiority of personalized pressure over fixed values. Specifically, pressure selection was based on thigh circumference: 200 mmHg for 60 cm. The mean blood flow restriction training pressure for subjects in this study was 271.26 ± 28.85 mmHg. Barbell hip thrust and barbell half squat 1RM test The 1RM test included the Smith barbell half squat and barbell hip thrust tests, adhering to the 1RM test requirements outlined by the American Physical Fitness Association. During the Smith barbell half squat 1RM test, subjects positioned their feet slightly wider than shoulder width, rotated their toes outward, and descended until their thighs were parallel to the floor 32 . During the hip thrust test, a soft cushion was positioned at the subject's anterior superior iliac spine, and the upper back was placed on a training bench. The feet were positioned slightly wider than shoulder width, with toes externally rotated. The movement involved lowering the barbell until it touched the ground, while maintaining a neutral spine and pelvis position on the ascent 20 . During the formal test, subjects initially attempted a weight they could easily lift for 5–10 repetitions, followed by a 2-minute rest. Subsequent attempts increased the weight by 10–20% each time, with a 2-4-minute rest between sets. The subject's 1RM was determined within 3–5 attempts. 20m sprint test Participants conducted the 20m sprint run test on the track using portable Smart Speed timing gates (Smart Speed Pro, Fusion Sport, Australia), positioned at 0m, 10m, and 20m, and configured in running application mode. To prevent interference with the timing system, athletes assumed a three-point pre-sprint position 30 cm behind the starting line, ensuring their bodies did not cross the starting infrared beam 20 . The test was conducted three times with 2–3 minute intervals between attempts, and the best performance was selected for statistical analysis. Vertical jump test Jump tests comprised the counter movement jump (CMJ), squat jump (SJ), and drop jump (DJ), all conducted on the KISTLER Quattro Jump (2822A1-1, Winterthur, Switzerland). Participants sequentially completed three attempts of CMJ, SJ, and DJ, with 1–2 minute intervals between each attempt 33 . The best score from each test was recorded. During CMJ jumps, subjects stood on a force platform with hands on hips, maintaining an upright position, squatted to 90 degrees of knee flexion, and exerted maximal effort to jump vertically upwards.SJ jumps involve initiating a vertical jump from a half-squat position, followed by a forceful vertical upward movement to maintain continuity. The SJ also assesses peak force, peak power, and peak rate of force development (RFD= \(\frac{\text{Fmax}-\text{Fstart}}{\varDelta \text{T}}\) ) ) at the optimal jump height 34 .Weight normalization was conducted to derive relative peak force, relative peak power, and relative peak rate of force generation. During DJ jumps, subjects stood on a 30 cm high jump box 35 , with hands placed at the waist, took a small step forward, dropped vertically with feet together, then quickly jumped upward upon contacting the force measuring platform. The reactive strength index (RSI) was calculated using the time in the air and the time of ground contact during the DJ. Reactive Strength Index ( \(\text{R}\text{S}\text{I}=\frac{\text{Flight time}}{\text{C}\text{o}\text{n}\text{t}\text{a}\text{c}\text{t} \text{t}\text{i}\text{m}\text{e}}\) ) 34 . Rectus femoris pennation angle test The pennation angle of the rectus femoris muscle in athletes was measured using a GE-LOGIQ-E9 color ultrasound diagnostic device (GE LOGIQ-E9, Wauwatosa, WI, USA), known for its high clarity, resolution, and absence of radiation exposure 36 . Following the guidelines of the American Institute of Ultrasound Medicine, athletes were instructed to wear shorts, relax their legs, and assume a supine position with the femur neutrally positioned for the pennation angle ultrasound examination. An experienced evaluator obtained all images using consistent techniques, applied ultrasound gel uniformly to the ultrasound probe, and positioned it along the long axis of the anterior thigh. The pennation angle measurements were taken in the muscle bellies of the lateral femoral and rectus femoris muscles of the athlete's dominant leg. A custom-made ultrasound probe fixation device ensured the probe was aligned parallel to the muscle fibers' direction. Markers were drawn on the subject's legs to ensure reproducibility of image locations during subsequent ultrasound assessments. A 12 MHz linear probe scanning head was selected to enhance spatial resolution. Water-soluble transmission gel was applied to the location of the rectus femoris muscle belly for longitudinal imaging of the pennation angle. Subjects underwent pre-testing of the rectus femoris pennation angle 3 minutes before the formal warm-up and post-testing at the 5th minute after the various exercise-induced interventions. Ultrasound testing was conducted by a physician experienced in operating GE ultrasound equipment. Lower extremity muscle-tendon stiffness test Higher stiffness facilitates the stretch-shortening cycle (SSC) and higher velocity explosive movements. Therefore, testing the stiffness of lower limb muscles and tendons is crucial for assessing the effectiveness of preparatory activities. The Myoton PRO (Myoton AS, Tallinn, Estonia) portable diagnostic equipment for muscle function utilizes parameters and measurements referenced from the study conducted by Papla M et al.(2023) 37 The device's accelerometer was set to 3200 Hz, and the average value was calculated from 3 consecutive measurements, each monitored with a 3% error margin. Pre-measurements were conducted 3 minutes before the official warm-up, During testing, the Myoton PRO probe was perpendicular to the surface of each measurement point (duration: 15 ms; force: 0.58 N) 38 .while post-measurements were taken at the 5th minute following the warm-up. Muscle measurements were taken at the muscle belly of each muscle, while Achilles tendon measurements were positioned 5 cm directly above the calcaneus. Subjects were instructed to fully relax their muscles during the measurement process to standardize muscle activity. Statistical analysis Data were analyzed using SPSS 22.0. Normal distribution was confirmed via the Shapiro-Wilk method, and results were uniformly reported as mean ± standard deviation (M ± SD). Repeated measures ANOVA was utilized to examine differences in sprint ability, explosive jumping performance, rectus femoris pennation angle, and lower limb muscle-tendon stiffness among male sprinters following the task intervention. For ANOVA results not meeting the assumption of sphericity by Mauchly's test, corrections were applied using the Greenhouse-Geisser method. Post-hoc comparisons were conducted using the Bonferroni method. Cohen's d-value was employed to assess Effect Size (ES), with effect size interpreted as medium (0.50) or large (0.80) 39 . The significance level was set at P < 0.05. Results 20m sprint As shown in Fig. 1 , the effects of different interventions on 10-20m (F = 4.632, P < 0.05) and 0-20m (F = 12.58, P < 0.05) sprint ability reached significant difference. Upon further testing, 10-20m sprint ability was significantly higher after 30% 1RMHS + BFRT intervention than 90% 1RMHT (1.21 ± 0.06s vs. 1.24 ± 0.05s), 90% 1RMHS (1.21 ± 0.06s vs. 1.23 ± 0.06s) (P 0.50), 30% 1RMHT + BFRT intervention had significantly improved 0-20m sprint ability than 90% 1RMHS (2.89 ± 0.12s VS 2.93 ± 0.10s) (P 0.50). Vertical jump As indicated in Fig. 2 , the effects of different interventions on CMJ jump height (F = 22.20, P < 0.05), CMJ relative peak power (F = 3.76, P < 0.05), CMJ rate of force development (F = 7.025, P < 0.05), CMJ relative peak force (F = 13.28, P < 0.05), and CMJ concentric phase impulse (F = 4.66, P < 0.05) reached significant differences in their effects. Upon further examination, CMJ jump height was significantly higher after 30% 1RMHS + BFRT intervention than 90% 1RMHS (60.12 ± 4.07 cm vs. 58.35 ± 4.11 cm) (P = 0.0015, ES > 0.50); CMJ relative peak power was significantly higher after 90% 1RMHS intervention than 30% 1RMHT + BFRT (63.32 ± 4.69 W/kg vs. 60.21 ± 3.25 W/kg) (P = 0.02, ES > 0.50), and CMJ relative peak power was significantly higher after 30%1RMHS + BFRT intervention than 90%1RMHT (61.73 ± 3.83 W/kg vs. 59.70 ± 6.11 W/kg) (P = 0.04, ES > 0.50); CMJ rate of force development was significantly higher after 90% 1RMHS intervention than 30% 1RMHT + BFRT (17.58 ± 4.51N- kg − 1 -s − 1 vs. 12.48 ± 2.95N- kg − 1 -s − 1 ) (P = 0.0002, ES > 0.50); The relative peak force of CMJ was significantly higher after 30% 1RMHS + BFRT intervention than 90% 1RMHT (P = 0.01, ES > 0.50); the relative peak force of CMJ was significantly higher after 90% 1RMHS intervention than 30% 1RMHT + BFRT (11.73 ± 2.53N- kg − 1 vs. 9.78 ± 2.55N- kg − 1 ) (P = 0.002, ES > 0.50); CMJ concentric phase impulse was significantly higher after 30%1RMHS + BFRT intervention than 90%1RMHT (235.40 ± 19.37 Ns vs. 230.9 ± 17.98 Ns) (P = 0.0013, ES > 0.50). The effects of different interventions on SJ relative peak power (F = 6.586, P < 0.05), SJ rate of force development (F = 5.694, P < 0.05), and SJ relative peak force (F = 8.594, P < 0.05) reached significant difference. Upon further examination, SJ relative peak power was significantly higher after 30% 1RMHS + BFRT intervention than 90% 1RMHT (63.06 ± 5.12W/kg vs. 60.47 ± 3.38W/kg) (P = 0.0012, ES > 0.50); SJ rate of force development after 90% 1RMHT intervention (17.81 ± 3.37N- kg − 1 -s − 1 vs. 15.91 ± 2.90N- kg − 1 -s − 1 ) (P = 0.007, ES > 0.50), and SJ relative peak force were significantly higher than those of 30% 1RMHS + BFRT (11.57 ± 2.16N- kg − 1 vs. 10.05 ± 1.67N- kg − 1 ) (P = 0.005, ES > 0.50); SJ relative peak force was significantly higher after 30%1RMHT + BFRT intervention than 90%1RMHS (10.57 ± 1.91N- kg − 1 vs 9.63 ± 2.30N- kg − 1 ) (P = 0.04, ES > 0.50); SJ concentric phase impulse was significantly higher after 30%1RMHS + BFRT intervention than 30%1RMHT + BFRT (274.60 ± 32.27 Ns vs. 254.40 ± 39.05Ns) (p = 0.04, ES > 0.50). Reactive strength index did not reach significance between intervention tasks (F = 2.813, P = 0.074), 90% 1RMHS (1.39 ± 0.40 vs. 1.14 ± 0.41) (P = 0.014, ES > 0.50), and 30% 1RMHS + BFRT (1.38 ± 0.37 vs. 1.14 ± 0.41) practice interventions were significantly higher than baseline after (P = 0.018, ES > 0.50). Rectus Femoris pennation angle As demonstrated in Fig. 3 , the effect of different interventions on the change in rectus femoris pennation angle (F = 13.91, P < 0.0001) reached significant variability as revealed by repeated measures ANOVA. Upon further testing, 30% 1RMHS + BFRT (11.15 ± 0.27° vs. 11.44 ± 0.25°) (P = 0.043 0.50), 90% 1RMHS (11.13 ± 0.36° vs. 11.44 ± 0.25°) (P = 0.039, ES > 0.50) intervention Rectus femoris pinna angle was significantly lower than 30%1RMHT + BFRT; the difference between the effects of 30%1RMHS + BFRT and 90%1RMHS on the change of rectus femoris pennation angle after intervention was not statistically significant (P > 0.05, ES 0.05, ES > 0.50). Lower limb muscle-tendon stiffness As illustrated in Fig. 4 , the effects of different interventions on rectus femoris muscle stiffness (F = 3.43, P = 0.01), biceps femoris muscle stiffness (F = 5.85, P = 0.02), lateral gastrocnemius head stiffness (F = 4.038, P = 0.007), medial gastrocnemius head stiffness (F = 5.668, P = 0.004), tibialis anterior muscle stiffness (F = 13.37, P = 0.04), and Achilles tendon stiffness (F = 6.013, P = 0.003) reached significant variability. Upon further examination, the muscle stiffness of the rectus femoris muscle was significantly higher after the intervention of 30% 1RMHT + BFRT (289.80 ± 52.74 N/m vs. 239.30 ± 39.03 N/m) compared to the baseline (P = 0.026, ES > 0.05); the rectus femoris muscle stiffness after the intervention of 30% 1RMHT + BFRT was significantly higher than the stiffness of the rectus femoris muscle after the intervention of 30% 1RMHS + BFRT (289.80 ± 52.74 N/m vs. 242.70 ± 25.80 N/m) (P = 0.04, ES > 0.05). Compared with baseline, 90%1RMHT (310.0 ± 53.41 N/m vs. 273.30 ± 39.57 N/m) (P = 0.02, ES > 0.05) and 90%1RMHS (320.10 ± 43.91 N/m vs. 273.30 ± 39.57 N/m) (P = 0.001, ES > 0.05) interventions resulted in significant increases in femoral Biceps stiffness was significantly higher; biceps femoris stiffness was significantly higher after 90% 1RMHS intervention than 30% 1RMHS + BFRT (320.10 ± 43.91N/m vs. 287.10 ± 24.93N/m) (P = 0.03, ES > 0.05). Compared with baseline, 90% 1RMHS (346.90 ± 57.91N/m vs. 274.10 ± 26.61N/m) (P = 0.02, ES > 0.05) and 30% 1RMHS + BFRT (342.90 ± 41.70N/m vs. 274.10 ± 26.61N/m) (P = 0.03, ES > 0.05) Post-intervention lateral gastrocnemius head stiffness was significantly higher; compared to 90% 1RMHT post-intervention, 90% 1RMHS (346.90 ± 57.91N/m vs. 299.70 ± 27.16N/m) (P = 0.03, ES > 0.05) and 30% 1RMHS + BFRT (342.90 ± 41.70N/m vs. 299.70 ± 27.16N/m) post-intervention lateral gastrocnemius head Stiffness was significantly improved (P = 0.05, ES > 0.05). Medial gastrocnemius head stiffness was significantly higher (315.50 ± 54.51N/m vs. 260.20 ± 2.60N/m) after 30% 1RMHS + BFRT intervention compared to baseline (P = 0.0003, ES > 0.05); medial gastrocnemius head stiffness was significantly higher (P = 0.0003, ES > 0.05) after 30% 1RMHS + BFRT intervention than 90% 1RMHS (315.50 ± 54.51N/m vs. 273.60 ± 48.39N/m) (P = 0.01, ES > 0.05), and 30%1RMHT + BFRT (315.50 ± 54.51N/m vs. 271.10 ± 11.31N/m) (P = 0.006, ES > 0.05). Compared with baseline, 90% 1RMHS (408.80 ± 47.95 N/m vs. 363.70 ± 29.65 N/m) (P = 0.006, ES > 0.05), 30% 1RMHT + BFRT (388.0 ± 21.26 N/m vs. 363.70 ± 29.65 N/m) (P = 0.041, ES > 0.05) and a significant increase in Tibialis Anterior muscle stiffness after 30% 1RMHS + BFRT (419.80 ± 56.10 N/m vs. 363.70 ± 29.65N/m) (P = 0.003, ES > 0.05) intervention. Tibialis Anterior muscle stiffness was increased after intervention with 30% 1RMHS + BFRT (387.0 ± 31.15 N/m vs. 419.80 ± 56.10 N/m) compared to 90% 1RMHT (P = 0.02, ES > 0.05), and after intervention with 30% 1RMHT + BFRT (388.0 ± 21.26 N/ m vs. 419.80 ± 56.10 N/m) intervention improved tibialis anterior muscle stiffness (P = 0.027, ES > 0.05). Compared with baseline, 90% 1RMHS (1230.22 ± 154.80 N/m vs. 1093.10 ± 134.30 N/m) (P = 0.01, ES > 0.05), 30% 1RMHS + BFRT (1275.05 ± 120.30 N/m vs. 1093.10 ± 134.30 N/m) (P = 0.0004, ES > 0.05) Achilles tendon stiffness was significantly increased after the intervention. Achilles tendon stiffness was significantly higher after intervention with 30% 1RMHS + BFRT (1275.05 ± 120.30 N/m vs. 1134.16 ± 66.36 N/m) compared to 30% 1RMHT + BFRT (P = 0.012, ES > 0.05). Discussion Few studies have investigated the acute effects of post-activation potentiation (PAP) on lower limb muscle-tendon stiffness in sprinters. It is crucial to understand how lower limb muscle-Achilles tendon stiffness regulation of PAP. This study suggest that examine the acute effects of low-intensity resistance combined with blood flow restriction training and high-intensity resistance exercises on lower limb muscle-tendon stiffness sprint ability, explosive jumping athletic performance, rectus femoris pennation angle, and rectus femoris muscle in male sprinters. Additionally, the study tried to explore the possible mechanisms influencing PAP. The findings of this study can be applied to improve sprinters' performance in competitions and identify the optimal pre-competition warm-up program. Furthermore, The results of this study can serve as a theoretical basis and provide data support for implementing PAP in sprinters' actual competitions to determine the most effective pre-competition warm-up program. Effects of sprint ability The ability to sprint 20m is crucial for sprinters to win races. Based on significant changes in gait characteristics during the 0-20m sprinting process, this ability can be further divided into start-up speed (0-10m) and acceleration (0-20m). The results showed that after 30% 1RMHT + BFRT exercise intervention, the 0-20m sprint ability significantly improved compared to 90% 1RMHS and the 0-10m sprint ability also significantly improved compared to the baseline. This suggests that combining low-intensity hip thrust resistance exercise with blood flow restriction training acutely enhances speed performance (start-up speed and acceleration) and it has a significantly better acute augmentation effect on acceleration capacity compared to high-intensity resistance intervention, which is a key finding of this study. Similarly, Fernández et al. (2022) 4 noted that a significant improvement in 0-5m sprint ability in tennis players after an intervention using 60% 1RMHT exercises. In this study, we investigated the performance differences between hip thrust and weighted half squat-induced PAP and its impact on athletes' explosive performance in sprinters. The research not only supported the findings of previous studies but also provided empirical scientific data supporting lower limb explosive training in sprinters, considering different loading intensities and induced movement patterns. Specifically, different loading intensities of hip thrust resistance were able to enhance the 0-20m sprint running post-enhancement effect. Research reports on the effects of hip thrust induction activation on enhancement have garnered significant attention from coaches, athletes, and sport researchers. Atalağ et al.(2020) 40 discovered that subjects' sprinting abilities in the 0–20 yards and 0–40 yards range were significantly improved after 90% 1RMHS and 90% 1RMHT exercise interventions. Similarly, Dello et al. (2018) 20 utilized barbell hip thrust exercises with loading intensities of 50% 1RM and 85% 1RM to induce a significant reduction in sprint times for distances of 0-10m and 0-15m in high-level handball players at the 4th and 8th min after 85% 1RM accompanied by barbell hip thrust exercises. Dello et al. (2018) 41 conducted a study with 18 soccer players as subjects and found that using 85% 1RM loading intensity accompanied by barbell hip thrust exercise as an induction method led to significant improvements in the sprinting abilities of soccer players for distances of 0-5m, 0-10m, and 0-20m at 4minutes and 8minutes after the intervention. These research demonstrate that the barbell hip thrust lifting mode successfully induces a post-activation enhancement effect, particularly evident in the significant improvement of short-distance sprint ability in the subjects. Some scholars attribute the enhancement of sprint running performance to the barbell hip thrust's its significant increase in horizontal vector forces during sprint running 42 . This study suggests that the enhancement may also be attributed to the activation and mobilization of hip-extensor muscle groups such as the gluteus maximus and hamstrings through the hip thrust mode of action, which aligns with the forward hip extension in sprint running, and may have a positive ransfer effect. The results of the study demonstrated that combining low-intensity weight-bearing half-squats blood flow restriction training resulted in a significant augmentation effect on sprint performance. Specifically, the activation after the intervention was significantly higher than the baseline for 0-10m sprint performance. Additionally, the 10-20m sprint ability was significantly better than when performing exercises at 90% of 1RM for both half-squats and hamstring curls. These findings align with a study by Abe et al. (2005) 23 , which showed that combining 20% of 1RM hamstring curls with blood flow restriction (160–240 mmHg) led to a was significant improved in university sprinters after the intervention, this study also found that start-up speed (0-10m) was similarly significantly improvement in acceleration (0-30m) in university sprinters. The present study also found a similar improvement in start-up speed (0-10m) after the intervention. Similarly, Manimmanakorn et al.(2013) 43 found that combining 20% of 1RM with blood flow restriction (160–230 mmHg) and lower extremity seated isometric exercise significantly enhanced 0-5m and 0-10m sprint ability in female netball players. These studies collectively demonstrate that the acute augmentation effect of low-intensity resistance exercises combined with blood flow restriction can significantly improve start-up speed and acceleration in athletes. Short-distance acceleration capacity involves rapidly accelerating from a stationary or slow state to maximal velocity, requiring explosive strength and maximal strength capacity. Therefore, the significant improvements in acceleration performance observed with low-intensity resistance exercises combined with blood flow restriction interventions may be attributed to acute increases in strength. The main physiological mechanism through which blood flow restriction training can effectively increase muscle strength is by activating the growth hormone-insulin-like growth factor axis.This axis induces expansion of muscle cells by applying pressurizing the limb and restricting venous blood flow to cause a pooling effect in the distal veins of the limb. The swelling of the cells inhibits proteolysis, accelerates lipolysis, and positively influences protein synthesis. Additionally, this study found that low intensity resistance combined with blood flow restriction, significantly improves explosive performance, providing empirical support for training practice. Effects of jump performance Vertical jump height is a commonly used measure to evaluate vertical jump performance. Rate of force development (RFD) peak power are mechanistic factors that explain the enhancement in jump height. The results of this study demonstrated that CMJ vertical jump height was significantly higher after a 30% 1RMHS + BFRT intervention compared to 90% 1RMHS intervention. Gaviglio et al.(2015) 44 also found that athletes' vertical jump height and peak power were significantly higher after 20% 1RMHS + BFRT exercise intervention. Furthermore, this study found that CMJ relative peak power was significantly higher after a 90% 1RMHT and 90% 1RMHS practice intervention, compared to 30% 1RMHT intervention, and CMJ and SJ relative peak power were significantly higher after 30% 1RMHS + BFRT intervention compared to 90%1RMHT intervention. In addition, other research noted that CMJ relative peak power was significantly higher after 90% 1RMHS intervention. These studies suggest that low-intensity resistance raining with blood flow restriction can improve jumping performance similar to high-intensity resistance exercise intervention. This may be due to the selection of sprinters from athletic colleges and universities with a high level of competitiveness and an average of 4.47 years of training experience in this study. The application of blood flow restriction training to individuals with training experience in explosive events offers the potential for selective recruitment of fast muscle fibers and mobilization of high-threshold motor units during subsequent explosive movements under conditions of limb ischemia and hypoxia. Katz et al. (1987) 45 shown that high-threshold motor units are associated not only with the force and velocity of muscle contraction, but also with the exercise oxygen concentration. Blood flow restriction can alter body oxygen concentration, creating conditions for the recruitment of high threshold motor units. Skeletal muscle is an excitable tissue that generates action potentials when stimulated PAP can enhance excitation transmission at the nerve-muscle junction, resulting in increased excitation in the myocyte membrane. This leads to an increase in neurotransmitters and improved transmission efficiency. As a result, there is a rapid recruitment of high-threshold motor units. Vertical jump-like movements consist of centrifugal, buffer, and centripetal phases. The centrifugal phase strongly stimulates the muscle spindle, activating the active muscle group, and increases the number of motor units. In the buffer phase α-motor neuron transmits signals to the acting muscle group, while in the centripetal phase α-motor neuron stimulates the acting muscle group. Simultaneously, the tandem elastic tissue releases elastic energy and accelerates the stretch-contraction cycle. In conclusion, combining low-intensity resistance training with blood flow restriction was found to enhance lower limb explosive jump performance. Overall, the positive effects of high-intensity resistance exercises on explosive jumping were superior to those of low-intensity resistance combined with blood flow restriction training. The study results demonstrated that the reaction strength index of male sprinters significantly increased after both 90% 1RMHS and 30% 1RMHS + BFRT exercises. However, there was no significant difference between the two indicated that high-intensity resistance exercises and low-intensity resistance combined with blood flow restriction training were equally effective in improving the reaction strength index. Further research is needed to determine if there is a correlation between the reaction strength index and sprint ability. The reaction force index, also known as the ratio of the time to vacate or the height of vacating to the time of foot contact with the ergometer 33 , represents the force generated during the transition from centrifugal lengthening to centripetal contraction of the muscle. This force utilizes the storage and re-release of elastic energy in the muscle, as well as neural reflexive modulation. Barr et al.(2011) 46 discovered a significant positive correlation between the reaction force index of rugby players during the jumping deep maneuver. However, Healy et al. (2019) 47 reported no significant correlation between the reaction force index and short distance sprint ability. The existence of a significant correlation between the reaction force index and explosive performance is still a topic of debate in the academic community. Some scholars have suggested that the variations in study results may be attributed to factors 34 , such as the level of the subject, the intervention environment, the height of the depth of the jump, the data processing method the findings of the present experimental study align with these observations . Effect of muscle pennation angle In anatomy, the angle between the tendon and the muscle fibers is commonly known as the "pennation angle". This angle indicates the orientation of the muscle fibers in relation to the tendon 48 . When skeletal muscle contract total the force transmitted to the tendons and bones from all individual muscle fibers increases as the pennation angle decreases. Folland et al. (2007) 49 discovered that the size of the pennation angle impacts the efficiency of force transmission from muscle to tendon and bone. The size of the pennation angle also affects the relationship between influence and velocity curves, with smaller angles favoring force transfer and consequently affecting power output.Therefore, as the pennation angle decreases, muscle contraction force increases. The study's results demonstrated that both the 90% 1RMHS and 30% 1RMHS + BFRT exercise intervention programs significantly reduced the pennation angle of the rectus femoris muscle. Similarly, Mahlfeld et al.(2004) 5 found that the pennation angle immediately after MVIC exercise was slightly smaller than before, but not significantly. However, 3–6 min later, the pennation angle was significantly reduced. Although this change only increased muscle energy transfer by 0.9%, it may have had an augmentation effect, and the decrease in pennation angle could be responsible for the augmentation effect of PAP. Considering that the reduction of the pennation angle in skeletal muscle can enhance muscle force generation, the study's findings suggest that pennation angle reduction cloud be a potential mechanism to explain PAP. Effects of lower limb muscle-tendon stiffness The MyotonPRO Digital Muscle Function Testing System is a portable device, that offers a new method for evaluating lower limb muscle-tendon stiffness in high-level athletes. Numerous studies have demonstrated a positive correlation between tendon stiffness and jumping performance, where higher stiffness is advantageous for activities involving stretch-shortening cycles (SSC) and sports with higher speeds 11,50 . Subjects with higher stiffness levels exhibited better locomotor performance during SSC activities.Bojsen-Müller et al.(2005) 12 discovered that higher stiffness not only aids in the storage and release of rate of force development(RFD)and elastic energy, but also plays crucial role in muscle force generation. The results of this study indicate that the stiffness of the rectus femoris muscle was significantly higher than 30% 1RMHT + BFRT after the 30% 1RMHS + BFRT intervention. Similarly, the biceps femoris muscle stiffness was significantly higher than 30% 1RMHS + BFRT after 90% 1RMHS intervention, and gastrocnemius muscle lateral head stiffness was significantly higher than 90% 1RMHT after 90% 1RMHS and 30% 1RMHS + BFRT interventions. Furthermore, the medial head stiffness of the gastrocnemius was significantly higher after the 30%1RMHS + BFRT interventions. The intervention than 90%1RMHS, 30%1RMHT + BFRT, tibialis anterior muscle stiffness was higher after the 30%1RMHS + BFRT intervention compared to the 90%1RMHT, tibialis anterior muscle stiffness was higher after intervention, and it was also higher compared to the 30%1RMHS + BFRT intervention than 30%1RMHT + BFRT, 30%1RMHS + BFRT intervention resulted in significantly higher Achilles tendon stiffness compared to the 30% 1RMHT + BFRT intervention. Similarly, Byrne et al.(2020) 51 demonstrated that completion of drop jump exercises led to shorter countermovement jump (CMJ) touchdown times and increased reactive strength index (RSI) and muscle-tendon unit stiffness properties. This indicates that the SSC(stretch-shortening cycle) was enhanced during CMJ, resulting in significant increases in CMJ height. Therefore, increased stiffness of the primary force-generating muscles and tendons in the lower limb may contribute to the phenomenon of PAP. Limitations of the study This study focused on male university sprinters, and further research is needed to determine if the conclusions can be applied to female sprinters and higher level athletes. The study only evaluated the test indexes of sprinting time, jumping performance, muscle pennation angle, and lower limb muscle-tendon stiffness, but did not analyze physiological indexes such as EMG signals, electroencephalography, and blood lactate concentration. It is important to note that attaching EMG patches may cause discomfort to the subjects and affect their sprinting technique, which could impact their all-out sprinting acceleration. Finding ways to address these issues will be the main focus of the next phase of this study. Conclusions Our study revealed several significant findings. Firstly, we found that incorporating a blood flow restriction intervention along with low intensity barbell hip thrust resistance led to a significant improvement in sprint ability when compared to high-intensity barbell half-squats. Additionally, we observed that barbell half squat exercises resulted in a significant enhancement in vertical jump performance as well as a notable reduction in rectus femoris pennation angle when compared to barbell hip thrust. Lastly, both low-intensity barbell half squat and hip thrust exercises, when combined with a blood flow restriction training intervention, led to a significant improvement in lower extremity muscle-tendon stiffness. Declarations Data availability The datasets used and analysed during the current study are available from the corresponding author on reasonable request. Author contributions J.J.Z. designed the protocol, collected the data, organized the database, and wrote the main manuscript text; Y.J. designed the research study and performed the research; H.Y.L collected the data, provided help and advice on the critically reviewed the contents of the manuscript. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. Funding This research received no external funding. Competing interests The authors declare no competing interests. Additional information Correspondence and requests for materials should be addressed to Y.J. Reprints and permissions information is available at www.nature.com/reprints. References Tillin, N. A. & Bishop, D. Factors modulating post-activation potentiation and its effect on performance of subsequent explosive activities. Sports Med 39 , 147-166, doi:10.2165/00007256-200939020-00004 (2009). Gołaś, A., Maszczyk, A., Zajac, A., Mikołajec, K. & Stastny, P. Optimizing post activation potentiation for explosive activities in competitive sports. J Hum Kinet 52 , 95-106, doi:10.1515/hukin-2015-0197 (2016). Aagaard, P. Training-induced changes in neural function. Exerc Sport Sci Rev 31 , 61-67, doi:10.1097/00003677-200304000-00002 (2003). Fernández-Galván, L. M., Prieto-González, P., Sánchez-Infante, J., Jiménez-Reyes, P. & Casado, A. The Post-Activation Potentiation Effects on Sprinting Abilities in Junior Tennis Players. Int J Environ Res Public Health 19 , 2080, doi:10.3390/ijerph19042080 (2022). Mahlfed K, F. J., Awiszus F. post contraction changes of muscle architecture in human quadriceps muscle. muscle Nerve 29 , 597-600 (2004). Wakeling, J. M., Blake, O. M., Wong, I., Rana, M. & Lee, S. S. Movement mechanics as a determinate of muscle structure, recruitment and coordination. Philos Trans R Soc Lond B Biol Sci 366 , 1554-1564, doi:10.1098/rstb.2010.0294 (2011). Earp, J. E. et al. Influence of muscle-tendon unit structure on rate of force development during the squat, countermovement, and drop jumps. J Strength Cond Res 25 , 340-347, doi:10.1519/jsc.0b013e3182052d78 (2011). Herzog, W., Schappacher, G., DuVall, M., Leonard, T. R. & Herzog, J. A. Residual Force Enhancement Following Eccentric Contractions: A New Mechanism Involving Titin. Physiology (Bethesda) 31 , 300-312, doi:10.1152/physiol.00049.2014 (2016). Brughelli, M. & Cronin, J. A review of research on the mechanical stiffness in running and jumping: methodology and implications. Scand J Med Sci Sports 18 , 417-426, doi:10.1111/j.1600-0838.2008.00769.x (2008). Wu, Y. K. et al. Relationships between three potentiation effects of plyometric training and performance. Scand J Med Sci Sports 20 , e80-86, doi:10.1111/j.1600-0838.2009.00908.x (2010). Burgess, K. E., Connick, M. J., Graham-Smith, P. & Pearson, S. J. Plyometric vs. isometric training influences on tendon properties and muscle output. J Strength Cond Res 21 , 986-989, doi:10.1519/r-20235.1 (2007). Bojsen-Møller, J., Magnusson, S. P., Rasmussen, L. R., Kjaer, M. & Aagaard, P. Muscle performance during maximal isometric and dynamic contractions is influenced by the stiffness of the tendinous structures. J Appl Physiol (1985) 99 , 986-994, doi:10.1152/japplphysiol.01305.2004 (2005). Hamada, T., Sale, D. G., MacDougall, J. D. & Tarnopolsky, M. A. Interaction of fibre type, potentiation and fatigue in human knee extensor muscles. Acta Physiol Scand 178 , 165-173, doi:10.1046/j.1365-201X.2003.01121.x (2003). Wei, J. L. B. Application effect and mechanism of blood flow restriction training. Sports Science 39 , 71-80 (2019). Sumide, T., Sakuraba, K., Sawaki, K., Ohmura, H. & Tamura, Y. Effect of resistance exercise training combined with relatively low vascular occlusion. J Sci Med Sport 12 , 107-112, doi:10.1016/j.jsams.2007.09.009 (2009). Luebbers, P. E., Witte, E. V., Oshel, J. Q. & Butler, M. S. Effects of Practical Blood Flow Restriction Training on Adolescent Lower-Body Strength. J Strength Cond Res 33 , 2674-2683, doi:10.1519/jsc.0000000000002302 (2019). Yasuda, T., Fukumura, K., Tomaru, T. & Nakajima, T. Thigh muscle size and vascular function after blood flow-restricted elastic band training in older women. Oncotarget 7 , 33595-33607, doi:10.18632/oncotarget.9564 (2016). Seitz, L. B. & Haff, G. G. Factors Modulating Post-Activation Potentiation of Jump, Sprint, Throw, and Upper-Body Ballistic Performances: A Systematic Review with Meta-Analysis. Sports Med 46 , 231-240, doi:10.1007/s40279-015-0415-7 (2016). Faul, F., Erdfelder, E., Buchner, A. & Lang, A. G. Statistical power analyses using G*Power 3.1: tests for correlation and regression analyses. Behav Res Methods 41 , 1149-1160, doi:10.3758/brm.41.4.1149 (2009). Dello Iacono, A., Padulo, J. & Seitz, L. D. Loaded hip thrust-based PAP protocol effects on acceleration and sprint performance of handball players. J Sports Sci 36 , 1269-1276, doi:10.1080/02640414.2017.1374657 (2018). Carbone, L. et al. Effects of heavy barbell hip thrust vs back squat on subsequent sprint performance in rugby players. Biol Sport 37 , 325-331, doi:10.5114/biolsport.2020.96316 (2020). Seitz, L. B. et al. Relationships between maximal strength, muscle size, and myosin heavy chain isoform composition and postactivation potentiation. Appl Physiol Nutr Metab 41 , 491-497, doi:10.1139/apnm-2015-0403 (2016). ABE T, K. K., YASUDA T, et al. Eight Days KAATSU-Resistance Training Improved Sprint but Not Jump Performance in Collegiate Male Track and Field Athletes. Int J KAATSU Training Res 36 , 1269-1276 (2005). Patterson, S. D. et al. Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety. Front Physiol 10 , 533, doi:10.3389/fphys.2019.00533 (2019). Seitz, L. B., de Villarreal, E. S. & Haff, G. G. The temporal profile of postactivation potentiation is related to strength level. J Strength Cond Res 28 , 706-715, doi:10.1519/JSC.0b013e3182a73ea3 (2014). Fletcher, I. M. An investigation into the effect of a pre-performance strategy on jump performance. J Strength Cond Res 27 , 107-115, doi:10.1519/JSC.0b013e3182517ffb (2013). Khamoui, A. V. et al. Effect of potentiating exercise volume on vertical jump parameters in recreationally trained men. J Strength Cond Res 23 , 1465-1469, doi:10.1519/JSC.0b013e3181a5bcdd (2009). Mina, M. A. et al. Variable, but not free-weight, resistance back squat exercise potentiates jump performance following a comprehensive task-specific warm-up. Scand J Med Sci Sports 29 , 380-392, doi:10.1111/sms.13341 (2019). Dello Iacono, A., Martone, D. & Padulo, J. Acute Effects of Drop-Jump Protocols on Explosive Performances of Elite Handball Players. J Strength Cond Res 30 , 3122-3133, doi:10.1519/jsc.0000000000001393 (2016). Loenneke, J. P. et al. Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. Eur J Appl Physiol 112 , 2903-2912, doi:10.1007/s00421-011-2266-8 (2012). Natsume, T., Ozaki, H., Saito, A. I., Abe, T. & Naito, H. Effects of Electrostimulation with Blood Flow Restriction on Muscle Size and Strength. Med Sci Sports Exerc 47 , 2621-2627, doi:10.1249/mss.0000000000000722 (2015). Dello Iacono, A., Martone, D., Milic, M. & Padulo, J. Vertical- vs. Horizontal-Oriented Drop Jump Training: Chronic Effects on Explosive Performances of Elite Handball Players. J Strength Cond Res 31 , 921-931, doi:10.1519/jsc.0000000000001555 (2017). Zhiquan Lu, Y., Liu. Neurobiomechanical basis and diagnosis of muscle strength. Shanghai University of Sport 43 , 113-120. (2019). Yu Zang, Y. X., Fei Yin, et al. . Effect of landing height on lower limb biomechanics and reactive strength of high-level sprinters in deep jump. Sports and Science, 40 , 101-110 (2019). Newton, R. u., Eric Dugan. Application of Strength Diagnosis. Strength Cond J 24 , 50-59. (2002). Thomaes, T. et al. Reliability and validity of the ultrasound technique to measure the rectus femoris muscle diameter in older CAD-patients. BMC Med Imaging 12 , 7, doi:10.1186/1471-2342-12-7 (2012). Papla, M., Ewertowska, P. & Krzysztofik, M. Acute Effects of Complex Conditioning Activities on Athletic Performance and Achilles Tendon Stiffness in Male Basketball Players. J Sports Sci Med 22 , 281-287, doi:10.52082/jssm.2023.281 (2023). Krzysztofik, M. et al. Acute Effects of High-Load vs. Plyometric Conditioning Activity on Jumping Performance and the Muscle-Tendon Mechanical Properties. J Strength Cond Res 37 , 1397-1403, doi:10.1519/jsc.0000000000004398 (2023). Mei fu Liang, W. x. G. Research progress on the enhancement effect of skeletal muscle after activation[J].Sports Science,2019,39(5):70-80.). Sports Science 39 , 70-80. (2019). Atalağ, O., Kurt, C., Solyomvari, E., Sands, J. & Cline, C. Postactivation potentiation effects of Back Squat and Barbell Hip Thrust exercise on vertical jump and sprinting performance. J Sports Med Phys Fitness 60 , 1223-1230, doi:10.23736/s0022-4707.20.10888-0 (2020). Dello Iacono, A. & Seitz, L. B. Hip thrust-based PAP effects on sprint performance of soccer players: heavy-loaded versus optimum-power development protocols. J Sports Sci 36 , 2375-2382, doi:10.1080/02640414.2018.1458400 (2018). Neto, W. K., Vieira, T. L. & Gama, E. F. Barbell Hip Thrust, Muscular Activation and Performance: A Systematic Review. J Sports Sci Med 18 , 198-206 (2019). Manimmanakorn, A., Hamlin, M. J., Ross, J. J., Taylor, R. & Manimmanakorn, N. Effects of low-load resistance training combined with blood flow restriction or hypoxia on muscle function and performance in netball athletes. J Sci Med Sport 16 , 337-342, doi:10.1016/j.jsams.2012.08.009 (2013). GAVIGLIO C M, B. W. Blood Flow Restriction Training as A Novel Approach to Improve Jumping Performance. J Aus Strength Cond 12 , 54-59. (2015). Katz, A. & Sahlin, K. Effect of decreased oxygen availability on NADH and lactate contents in human skeletal muscle during exercise. Acta Physiol Scand 131 , 119-127, doi:10.1111/j.1748-1716.1987.tb08213.x (1987). Barr, M. J. & Nolte, V. W. Which measure of drop jump performance best predicts sprinting speed? J Strength Cond Res 25 , 1976-1982, doi:10.1519/JSC.0b013e3181e4f7ba (2011). Healy, R., Smyth, C., Kenny, I. C. & Harrison, A. J. Influence of Reactive and Maximum Strength Indicators on Sprint Performance. J Strength Cond Res 33 , 3039-3048, doi:10.1519/jsc.0000000000002635 (2019). Ledoux, W. R., Hirsch, B. E., Church, T. & Caunin, M. Pennation angles of the intrinsic muscles of the foot. J Biomech 34 , 399-403, doi:10.1016/s0021-9290(00)00194-9 (2001). Folland, J. P. & Williams, A. G. The adaptations to strength training : morphological and neurological contributions to increased strength. Sports Med 37 , 145-168, doi:10.2165/00007256-200737020-00004 (2007). Kubo, K. et al. Influences of tendon stiffness, joint stiffness, and electromyographic activity on jump performances using single joint. Eur J Appl Physiol 99 , 235-243, doi:10.1007/s00421-006-0338-y (2007). Byrne, P. J., Moody, J. A., Cooper, S. M., Callanan, D. & Kinsella, S. Potentiating Response to Drop-Jump Protocols on Sprint Acceleration: Drop-Jump Volume and Intrarepetition Recovery Duration. J Strength Cond Res 34 , 717-727, doi:10.1519/jsc.0000000000002720 (2020). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3952436","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":274594977,"identity":"3c133abc-9740-432b-ba8e-a8aff4fa079f","order_by":0,"name":"Junjie Zhang","email":"","orcid":"","institution":"Graduate School, Capital University of Physical Education and Sports","correspondingAuthor":false,"prefix":"","firstName":"Junjie","middleName":"","lastName":"Zhang","suffix":""},{"id":274594978,"identity":"b23fef03-93f9-4528-a8c5-8eb9287e357a","order_by":1,"name":"Jun Ye","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxElEQVRIiWNgGAWjYBACNvbmAwc+GNTI8bM3EKmFj+dY4sEZBceMJXsOEKlFTiLH+DDHB+ZEgxsJxDpMIsHgMIMBW4LkzMcbbzDU2EQT1sLzIOFwgYFMHr90WrEFw7G03AaCWtgTDhyeYcBWLDk7x0yCseEwEVoYEhsO8xgwJ264eYZYLRzJDBAtN3iI1cJzjOHgDANQIAP9kkCMX+Tb+z9/+PAHFJWHN974UGNDWAsyMJBIIEU5RAupOkbBKBgFo2BkAABLtUHTZ7OlvQAAAABJRU5ErkJggg==","orcid":"","institution":"Huaibei Normal University","correspondingAuthor":true,"prefix":"","firstName":"Jun","middleName":"","lastName":"Ye","suffix":""},{"id":274594979,"identity":"829ba7de-a115-4f76-9142-ad4836cc403a","order_by":2,"name":"Haiyuan Liu","email":"","orcid":"","institution":"Graduate School, Capital University of Physical Education and Sports","correspondingAuthor":false,"prefix":"","firstName":"Haiyuan","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2024-02-13 02:24:45","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3952436/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3952436/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51645440,"identity":"4fabddd7-8f3d-43a3-a81a-8cf0041597b0","added_by":"auto","created_at":"2024-02-26 14:06:59","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":95177,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of different exercise interventions on the sprint time of 20m segments\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3952436/v1/08ef9bdd94b0689d92b00a34.jpg"},{"id":51645441,"identity":"637668ab-7282-4911-947f-af809d0b8950","added_by":"auto","created_at":"2024-02-26 14:07:00","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":144475,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of different exercise interventions on the change of jumping performance parameters\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3952436/v1/db2d0a61f7c4d87ddf103088.jpg"},{"id":51645438,"identity":"14b6cc34-587b-4677-9c37-9afa74d10923","added_by":"auto","created_at":"2024-02-26 14:06:58","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":55431,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of different exercise interventions on the plume angle of rectus femoris muscle\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3952436/v1/6e49c931fec3392e023672fc.jpg"},{"id":51645443,"identity":"a0c4875a-f522-4455-a7f7-a130ab14e753","added_by":"auto","created_at":"2024-02-26 14:07:01","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":123612,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of different exercise interventions on lower limb muscle-tendon stiffness\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3952436/v1/ddc0f94d645f900f33286749.jpg"},{"id":71477495,"identity":"630b96be-ff62-4f75-8d8c-f3966fa3aed8","added_by":"auto","created_at":"2024-12-16 05:26:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1070906,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3952436/v1/6dd6dd26-7882-42bc-80dc-25e9eda2215d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Acute effects of low-intensity resistance combined with blood flow restriction and high-intensity resistance exercise on lower extremity explosive strength, pennation angle and muscle-tendon stiffness in male sprinters","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePost-activation Potentiation (PAP) is a phenomenon wherein an acute increase in muscle performance occurs due to voluntary muscle contraction. Scholars hold differing viewpoints regarding PAP, with some suggesting it is caused by voluntary muscle contraction\u003csup\u003e1\u003c/sup\u003e, while others argue it results from an acute increase in explosive force following preload stimulation\u003csup\u003e2\u003c/sup\u003e. Although there is no standardized definition for PAP, it is widely acknowledged that the post-activation enhancement effect benefits explosive performance\u003csup\u003e3\u003c/sup\u003e. The potential mechanisms behind this effect include increased recruitment capacity of high-threshold motor units, phosphorylation of myosin regulatory light chain, and changes in myofiber pennation angle\u003csup\u003e4\u003c/sup\u003e. While the mechanism of enhanced phosphorylation has been confirmed by numerous studies, the identification of other explanatory mechanisms, such as enhanced recruitment of higher-order motor neurons and changes in the pennation angle, remains incomplete. In anatomy, the angle between the tendon and the muscle fibers is often referred to as the pennation angle, reflecting the relationship between the orientation of the muscle fibers and the tendon. In their study, Mahlfeld et al. (2004)\u0026nbsp;\u003csup\u003e5\u003c/sup\u003econducted ultrasonographic examinations on the lateral femoral muscle and observed changes in the pennation angle in three sets of examinations. They investigated the effect of pennation on PAP using ultrasonography and found that immediately after three sets of 3 s of static MVC-induced stimulation of the lateral femoral muscle, the pennation angle decreased by 0.5° (15.7° vs 16.2°). Furthermore, after 3-6 minutes of MVC practice, the pennation angle decreased significantly by 1.8° (14.4° vs 16.2°). However, increased pennation has been found to reduce the overall muscle contraction under equal force conditions\u003csup\u003e6\u003c/sup\u003e. This allows the muscle to work in a more optimal region of the force-velocity curve and prolongs the time it operates within the optimal region of the length-tension curve. Earp et al. (2011)\u0026nbsp;\u003csup\u003e7\u003c/sup\u003edemonstrated that subjects with greater pennation had better early RFD (rate of force development) during the deep jump, attributed to their muscles greater ability to cope with centrifugal loading. Therefore, the interpretation of the post-activation enhancement effect of increased or decreased muscle pennation angle remains controversial.\u003c/p\u003e\n\u003cp\u003eNew potential explanatory mechanisms for the post-activation enhancement effect have been proposed\u003csup\u003e8\u003c/sup\u003e, particularly the enhancement of lower limb muscle-tendon stiffness, Brughelli et al.(2008)\u003csup\u003e9\u003c/sup\u003efound higher stiffness promotes the stretch-shortening cycle (SSC) and higher-velocity explosive movements. Wu et al. (2010)\u003csup\u003e10\u003c/sup\u003e found a significant correlation between the increase in tendon stiffness induced by SSC exercise and enhancement in countermovement jump (CMJ) performance. Other studies also support the idea that high stiffness is beneficial for stretch-shortening cycle (SSC) performance and muscle force generation\u003csup\u003e11\u003c/sup\u003e. Various methods have been used to measure stiffness in the human body, providing valuable information for understanding muscle-tendon stiffness and its impact on performance. However, most of these methods focus on specific segments of the lower extremity and do not thoroughly investigate the individual contributions of muscle and tendon stiffness to performance. Therefore, further research is needed to explore the relationship between individual muscle stiffness, tendon stiffness, and performance to enhance our understanding of muscle-tendon interactions\u003csup\u003e12\u003c/sup\u003e. The Myoton pro Digital Muscle Function Tester is a reliable and valid tool for measuring the stiffness of individual muscles, providing accurate and objective data for research and clinical applications. To date, there is no study investigating the acute effect of post-activation potentiation (PAP) on lower limb muscle-tendon stiffness specifically in sprinters. Understanding the detailed impact of lower limb muscle-Achilles tendon stiffness on PAP regulation is crucial for optimizing training strategies and injury prevention in athletes. The magnitude of the enhancement effect depends on various factors, including the level of exercise, type of muscle fiber, type of muscle contraction, duration, and amount of induced load\u003csup\u003e4\u003c/sup\u003e. Hamada et al. (2003)\u003csup\u003e13\u003c/sup\u003efound that post-activation enhancement effects appear to require high-intensity resistance exercises for induction; however, fatigue induced by such exercises also increases the risk of injury and subjective discomfort.\u003c/p\u003e\n\u003cp\u003eBlood flow restriction training (BFRT) has garnered significant attention from sports researchers, competitive coaches, and athletes in recent years. BFRT involves applying pressure during training to inhibit venous blood flow and partially restrict arterial blood flow. This leads to inadequate oxygen transport in adjacent joints or localized areas, disrupting internal environment homeostasis, resulting in a rapid increase in blood lactate levels and free radicals\u003csup\u003e14\u003c/sup\u003e. Consequently, there is an increase in the recruitment capacity of high-threshold motor units, facilitating improved muscle hypertrophy and strength\u003csup\u003e15\u003c/sup\u003e. Several studies have demonstrated that combining low-intensity resistance with blood flow restriction training (BFRT) yields comparable effects to high-intensity resistance exercise in promoting muscle hypertrophy and strength, benefiting both elite athletes and the general population\u003csup\u003e16,17\u003c/sup\u003e. This presents an alternative approach for athletes unable to engage in high-intensity resistance exercise during rehabilitation. However, current research on low-intensity resistance combined with BFRT has primarily focused on its long-term training adaptations, neglecting to elucidate the acute effects of low-intensity resistance combined with BFRT on athletic performance. Previous studies have shown that low-intensity resistance combined with blood flow restriction training can significantly enhance sprinting ability in sprinters\u003csup\u003e16\u003c/sup\u003e. However, whether it produces effects similar to those of high-intensity resistance exercise interventions requires further verification. Accordingly, this study aimed to investigate the acute effects of combining low-intensity resistance with blood flow restriction training and high-intensity resistance exercise on sprinting ability, explosive jumping performance, muscle pennation angle, and lower limb muscle-tendon stiffness in male sprinters.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eSubjects\u003c/h2\u003e \u003cp\u003eThe sample size required for the study was pre-estimated using G*Power3.1 software (Dusseldorf, Germany), effect size, alpha and test efficacy (1-β) were set at 0.40, 0.05 and 0.80, respectively, in reference to the findings of Seitz L B et al\u003csup\u003e18\u003c/sup\u003e. and Faul F et al\u003csup\u003e19\u003c/sup\u003e. The results of the estimation showed that the minimum sample size required to carry out the present study is 12 individuals. Considering a potential sample dropout rate of 20%, a minimum of 15 participants were recruited for this study. Accordingly, 18 male sprinters were recruited and one withdrew due to an ankle sprain during the intervention. The final 17 participants [age (22.88\u0026thinsp;\u0026plusmn;\u0026thinsp;1.13) years, height (178.46\u0026thinsp;\u0026plusmn;\u0026thinsp;3.24) cm, weight (72.12\u0026thinsp;\u0026plusmn;\u0026thinsp;3.74) kg, thigh circumference (56.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77) cm, blood flow restriction pressure values (271.26\u0026thinsp;\u0026plusmn;\u0026thinsp;28.85) mmHg, years of training (4.31\u0026thinsp;\u0026plusmn;\u0026thinsp;1.29), and 1RM hip thrust ( 196.41\u0026thinsp;\u0026plusmn;\u0026thinsp;35.28) kg, 1RM barbell half squat (150.19\u0026thinsp;\u0026plusmn;\u0026thinsp;19.92) kg] completed all the tests. All of the above participants were free of injury, sleep disorders, and non-smokers, volunteered to participate, and signed an informed consent form after being informed of the testing process and potential risks. Research have been performed in accordance with the Declaration of Helsinki. Approval for this study was obtained from the Ethics Committee of Beijing Sport University(2023215H) and informed consent was obtained from all participants, all of them signed a consent form.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eProcedures\u003c/h2\u003e \u003cp\u003eThis study utilizes a randomized crossover control trial design. During the familiarization session, participants are required to familiarize themselves with the evaluation process of all test tasks and indicators to mitigate the influence of learning effects and physical discomfort on the formal experiment. During the familiarization session, participants underwent the following: 1) Introduction to testing procedures, encompassing methods for 20m sprint run, explosive vertical jump, feather angle, and lower limb muscle-tendon stiffness, during which testing tools could be briefly examined; 2) Collection and recording of subjects' age, height, weight, thigh circumference, years of training, and best performance in the 100m sprint; 3) Assessment of maximal force in barbell hip thrust and barbell half-squat, and establishment of baseline kinematic and kinetic parameters for 20m sprint and vertical jump on the force platform. Additionally, participants were briefed on test precautions: 1) Avoid high-intensity physical exercise, consumption of caffeine- or alcohol-containing beverages for 24 hours prior to the experiment, and ensure at least 8 hours of sleep\u003csup\u003e20\u003c/sup\u003e; 2) Hydrate appropriately and refrain from eating for 2 hours before the test \u003csup\u003e21\u003c/sup\u003e; 3) Attempt to schedule tests at the same time each time, ideally within a deviation of 1 hour; 4) Maintain consistent or similar training attire; 5) Ensure uniformity in dressing and attire; 6) Refrain from engaging in high-intensity training activities during the washout period.\u003c/p\u003e \u003cp\u003eParticipants followed the same procedure during the formal experimental session. Participants completed interventions in a randomized order, including 90% 1RM HT, 90% 1RM HS, 30% 1RM HT\u0026thinsp;+\u0026thinsp;BFRT, and 30% 1RM HS\u0026thinsp;+\u0026thinsp;BFRT. For the formal experimental intervention, participants engaged in an 8\u0026ndash;10 minute standardized warm-up, involving jogging, glute activation, dynamic stretching, and marching movement integration\u003csup\u003e22\u003c/sup\u003e. Following a 3\u0026ndash;5 minute rest at the end of the warm-up, participants underwent task interventions. These interventions included a low-intensity resistance combined with blood flow restriction training protocol of 30% 1RM (HT/HS) \u0026times; 15 repetitions/set \u0026times; 3 sets with a 30-second interval between sets, as referenced in studies by Abe et al. (2005)\u003csup\u003e23\u003c/sup\u003e, Patterson et al.(2019)\u003csup\u003e24\u003c/sup\u003e. Additionally, a high-intensity resistance exercise protocol of 90% 1RM (HT/HS) \u0026times; 3 repetitions\u003csup\u003e25\u003c/sup\u003e. It is noteworthy that studies have confirmed, for collegiate male sprinters, the optimal window for enhancing sprint running and jumping performance is between minutes 4 and 8 post-intervention, with the majority of studies indicating peak efficacy at the fifth minute\u003csup\u003e26,27\u003c/sup\u003e. Therefore, the 20-m sprint run, the force platform vertical jump test (including CMJ, SJ, and DJ completed in one session), the rectus femoris pennation angle, and the lower extremity muscle-tendon stiffness test were all conducted at minute 5 post-intervention, with only one of these tests being completed in each experiment. To minimize the potential for interaction between interventions, participants were explicitly instructed to refrain from engaging in high-intensity training activities during the washout period and to ensure their readiness for each training session (ensuring physiological recovery from fatigue and maintaining psychological anticipation of the training). Additionally, based on the studies of Mina et al. (2019)\u003csup\u003e28\u003c/sup\u003e and Dello et al. (2016)\u003csup\u003e29\u003c/sup\u003e, a 72-hour interval was maintained between each pair of training interventions. The room temperature during the testing period ranged from 23.2\u0026deg;C to 26.3\u0026deg;C, with humidity between 67% and 85%.\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section3\"\u003e \u003ch2\u003eSelection of blood flow restriction training equipment model, operation method and training pressure\u003c/h2\u003e \u003cp\u003eThe blood flow restriction training equipment used is the B STRONG pressurized training belt (B STRONG, Utah, USA), featuring an adjustable design and employing a distributed airbag pressure filling method. This design effectively alleviates compression pain and ensures safe, convenient operation. Specifically, participants assumed a standing position and wrapped the pressurized training belt around the vertical longitudinal axis of the thigh, targeting the gluteus transversus muscle on both sides. Considering gradual adaptation of blood vessels to changes in pressure induced by blood flow restriction, inflation pressure was incrementally increased until reaching the target pressure value. In this study, we employed personalized blood flow restriction pressure, determined by the relative pressure value selected according to the individual subject's thigh circumference. Research by Loenneke et al. (2012) \u003csup\u003e30\u003c/sup\u003e, and Natsume et al. (2015) \u003csup\u003e31\u003c/sup\u003esupports the superiority of personalized pressure over fixed values. Specifically, pressure selection was based on thigh circumference: 200 mmHg for \u0026lt;\u0026thinsp;45\u0026ndash;50 cm, 250 mmHg for 51\u0026ndash;55 cm, 300 mmHg for 56\u0026ndash;59 cm, and 350 mmHg for \u0026gt;\u0026thinsp;60 cm. The mean blood flow restriction training pressure for subjects in this study was 271.26\u0026thinsp;\u0026plusmn;\u0026thinsp;28.85 mmHg.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eBarbell hip thrust and barbell half squat 1RM test\u003c/h2\u003e \u003cp\u003eThe 1RM test included the Smith barbell half squat and barbell hip thrust tests, adhering to the 1RM test requirements outlined by the American Physical Fitness Association. During the Smith barbell half squat 1RM test, subjects positioned their feet slightly wider than shoulder width, rotated their toes outward, and descended until their thighs were parallel to the floor\u003csup\u003e32\u003c/sup\u003e. During the hip thrust test, a soft cushion was positioned at the subject's anterior superior iliac spine, and the upper back was placed on a training bench. The feet were positioned slightly wider than shoulder width, with toes externally rotated. The movement involved lowering the barbell until it touched the ground, while maintaining a neutral spine and pelvis position on the ascent\u003csup\u003e20\u003c/sup\u003e. During the formal test, subjects initially attempted a weight they could easily lift for 5\u0026ndash;10 repetitions, followed by a 2-minute rest. Subsequent attempts increased the weight by 10\u0026ndash;20% each time, with a 2-4-minute rest between sets. The subject's 1RM was determined within 3\u0026ndash;5 attempts.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e20m sprint test\u003c/h2\u003e \u003cp\u003eParticipants conducted the 20m sprint run test on the track using portable Smart Speed timing gates (Smart Speed Pro, Fusion Sport, Australia), positioned at 0m, 10m, and 20m, and configured in running application mode. To prevent interference with the timing system, athletes assumed a three-point pre-sprint position 30 cm behind the starting line, ensuring their bodies did not cross the starting infrared beam \u003csup\u003e20\u003c/sup\u003e. The test was conducted three times with 2\u0026ndash;3 minute intervals between attempts, and the best performance was selected for statistical analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eVertical jump test\u003c/h2\u003e \u003cp\u003eJump tests comprised the counter movement jump (CMJ), squat jump (SJ), and drop jump (DJ), all conducted on the KISTLER Quattro Jump (2822A1-1, Winterthur, Switzerland). Participants sequentially completed three attempts of CMJ, SJ, and DJ, with 1\u0026ndash;2 minute intervals between each attempt\u003csup\u003e33\u003c/sup\u003e. The best score from each test was recorded. During CMJ jumps, subjects stood on a force platform with hands on hips, maintaining an upright position, squatted to 90 degrees of knee flexion, and exerted maximal effort to jump vertically upwards.SJ jumps involve initiating a vertical jump from a half-squat position, followed by a forceful vertical upward movement to maintain continuity. The SJ also assesses peak force, peak power, and peak rate of force development (RFD= \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\frac{\\text{Fmax}-\\text{Fstart}}{\\varDelta \\text{T}}\\)\u003c/span\u003e\u003c/span\u003e) ) at the optimal jump height\u003csup\u003e34\u003c/sup\u003e.Weight normalization was conducted to derive relative peak force, relative peak power, and relative peak rate of force generation. During DJ jumps, subjects stood on a 30 cm high jump box\u003csup\u003e35\u003c/sup\u003e, with hands placed at the waist, took a small step forward, dropped vertically with feet together, then quickly jumped upward upon contacting the force measuring platform. The reactive strength index (RSI) was calculated using the time in the air and the time of ground contact during the DJ. Reactive Strength Index (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\text{R}\\text{S}\\text{I}=\\frac{\\text{Flight time}}{\\text{C}\\text{o}\\text{n}\\text{t}\\text{a}\\text{c}\\text{t} \\text{t}\\text{i}\\text{m}\\text{e}}\\)\u003c/span\u003e\u003c/span\u003e)\u003csup\u003e34\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eRectus femoris pennation angle test\u003c/h2\u003e \u003cp\u003eThe pennation angle of the rectus femoris muscle in athletes was measured using a GE-LOGIQ-E9 color ultrasound diagnostic device (GE LOGIQ-E9, Wauwatosa, WI, USA), known for its high clarity, resolution, and absence of radiation exposure\u003csup\u003e36\u003c/sup\u003e. Following the guidelines of the American Institute of Ultrasound Medicine, athletes were instructed to wear shorts, relax their legs, and assume a supine position with the femur neutrally positioned for the pennation angle ultrasound examination. An experienced evaluator obtained all images using consistent techniques, applied ultrasound gel uniformly to the ultrasound probe, and positioned it along the long axis of the anterior thigh. The pennation angle measurements were taken in the muscle bellies of the lateral femoral and rectus femoris muscles of the athlete's dominant leg. A custom-made ultrasound probe fixation device ensured the probe was aligned parallel to the muscle fibers' direction. Markers were drawn on the subject's legs to ensure reproducibility of image locations during subsequent ultrasound assessments. A 12 MHz linear probe scanning head was selected to enhance spatial resolution. Water-soluble transmission gel was applied to the location of the rectus femoris muscle belly for longitudinal imaging of the pennation angle. Subjects underwent pre-testing of the rectus femoris pennation angle 3 minutes before the formal warm-up and post-testing at the 5th minute after the various exercise-induced interventions. Ultrasound testing was conducted by a physician experienced in operating GE ultrasound equipment.\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003eLower extremity muscle-tendon stiffness test\u003c/h2\u003e \u003cp\u003eHigher stiffness facilitates the stretch-shortening cycle (SSC) and higher velocity explosive movements. Therefore, testing the stiffness of lower limb muscles and tendons is crucial for assessing the effectiveness of preparatory activities. The Myoton PRO (Myoton AS, Tallinn, Estonia) portable diagnostic equipment for muscle function utilizes parameters and measurements referenced from the study conducted by Papla M et al.(2023)\u003csup\u003e37\u003c/sup\u003e The device's accelerometer was set to 3200 Hz, and the average value was calculated from 3 consecutive measurements, each monitored with a 3% error margin. Pre-measurements were conducted 3 minutes before the official warm-up, During testing, the Myoton PRO probe was perpendicular to the surface of each measurement point (duration: 15 ms; force: 0.58 N)\u003csup\u003e38\u003c/sup\u003e.while post-measurements were taken at the 5th minute following the warm-up. Muscle measurements were taken at the muscle belly of each muscle, while Achilles tendon measurements were positioned 5 cm directly above the calcaneus. Subjects were instructed to fully relax their muscles during the measurement process to standardize muscle activity.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using SPSS 22.0. Normal distribution was confirmed via the Shapiro-Wilk method, and results were uniformly reported as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (M\u0026thinsp;\u0026plusmn;\u0026thinsp;SD). Repeated measures ANOVA was utilized to examine differences in sprint ability, explosive jumping performance, rectus femoris pennation angle, and lower limb muscle-tendon stiffness among male sprinters following the task intervention. For ANOVA results not meeting the assumption of sphericity by Mauchly's test, corrections were applied using the Greenhouse-Geisser method. Post-hoc comparisons were conducted using the Bonferroni method. Cohen's d-value was employed to assess Effect Size (ES), with effect size interpreted as medium (0.50) or large (0.80) \u003csup\u003e39\u003c/sup\u003e. The significance level was set at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e20m sprint\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the effects of different interventions on 10-20m (F\u0026thinsp;=\u0026thinsp;4.632, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) and 0-20m (F\u0026thinsp;=\u0026thinsp;12.58, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) sprint ability reached significant difference. Upon further testing, 10-20m sprint ability was significantly higher after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90% 1RMHT (1.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06s vs. 1.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05s), 90% 1RMHS (1.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06s vs. 1.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06s) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50), 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT intervention had significantly improved 0-20m sprint ability than 90% 1RMHS (2.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12s VS 2.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10s) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eVertical jump\u003c/h2\u003e \u003cp\u003eAs indicated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the effects of different interventions on CMJ jump height (F\u0026thinsp;=\u0026thinsp;22.20, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), CMJ relative peak power (F\u0026thinsp;=\u0026thinsp;3.76, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), CMJ rate of force development (F\u0026thinsp;=\u0026thinsp;7.025, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), CMJ relative peak force (F\u0026thinsp;=\u0026thinsp;13.28, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), and CMJ concentric phase impulse (F\u0026thinsp;=\u0026thinsp;4.66, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) reached significant differences in their effects. Upon further examination, CMJ jump height was significantly higher after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90% 1RMHS (60.12\u0026thinsp;\u0026plusmn;\u0026thinsp;4.07 cm vs. 58.35\u0026thinsp;\u0026plusmn;\u0026thinsp;4.11 cm) (P\u0026thinsp;=\u0026thinsp;0.0015, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); CMJ relative peak power was significantly higher after 90% 1RMHS intervention than 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (63.32\u0026thinsp;\u0026plusmn;\u0026thinsp;4.69 W/kg vs. 60.21\u0026thinsp;\u0026plusmn;\u0026thinsp;3.25 W/kg) (P\u0026thinsp;=\u0026thinsp;0.02, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50), and CMJ relative peak power was significantly higher after 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90%1RMHT (61.73\u0026thinsp;\u0026plusmn;\u0026thinsp;3.83 W/kg vs. 59.70\u0026thinsp;\u0026plusmn;\u0026thinsp;6.11 W/kg) (P\u0026thinsp;=\u0026thinsp;0.04, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); CMJ rate of force development was significantly higher after 90% 1RMHS intervention than 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (17.58\u0026thinsp;\u0026plusmn;\u0026thinsp;4.51N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e-s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e vs. 12.48\u0026thinsp;\u0026plusmn;\u0026thinsp;2.95N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e-s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) (P\u0026thinsp;=\u0026thinsp;0.0002, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); The relative peak force of CMJ was significantly higher after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90% 1RMHT (P\u0026thinsp;=\u0026thinsp;0.01, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); the relative peak force of CMJ was significantly higher after 90% 1RMHS intervention than 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (11.73\u0026thinsp;\u0026plusmn;\u0026thinsp;2.53N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e vs. 9.78\u0026thinsp;\u0026plusmn;\u0026thinsp;2.55N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e ) (P\u0026thinsp;=\u0026thinsp;0.002, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); CMJ concentric phase impulse was significantly higher after 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90%1RMHT (235.40\u0026thinsp;\u0026plusmn;\u0026thinsp;19.37 Ns vs. 230.9\u0026thinsp;\u0026plusmn;\u0026thinsp;17.98 Ns) (P\u0026thinsp;=\u0026thinsp;0.0013, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50).\u003c/p\u003e \u003cp\u003eThe effects of different interventions on SJ relative peak power (F\u0026thinsp;=\u0026thinsp;6.586, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), SJ rate of force development (F\u0026thinsp;=\u0026thinsp;5.694, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), and SJ relative peak force (F\u0026thinsp;=\u0026thinsp;8.594, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) reached significant difference. Upon further examination, SJ relative peak power was significantly higher after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90% 1RMHT (63.06\u0026thinsp;\u0026plusmn;\u0026thinsp;5.12W/kg vs. 60.47\u0026thinsp;\u0026plusmn;\u0026thinsp;3.38W/kg) (P\u0026thinsp;=\u0026thinsp;0.0012, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); SJ rate of force development after 90% 1RMHT intervention (17.81\u0026thinsp;\u0026plusmn;\u0026thinsp;3.37N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e-s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e vs. 15.91\u0026thinsp;\u0026plusmn;\u0026thinsp;2.90N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e-s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) (P\u0026thinsp;=\u0026thinsp;0.007, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50), and SJ relative peak force were significantly higher than those of 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (11.57\u0026thinsp;\u0026plusmn;\u0026thinsp;2.16N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e vs. 10.05\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e ) (P\u0026thinsp;=\u0026thinsp;0.005, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); SJ relative peak force was significantly higher after 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT intervention than 90%1RMHS (10.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e vs 9.63\u0026thinsp;\u0026plusmn;\u0026thinsp;2.30N- kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e ) (P\u0026thinsp;=\u0026thinsp;0.04, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50); SJ concentric phase impulse was significantly higher after 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT (274.60\u0026thinsp;\u0026plusmn;\u0026thinsp;32.27 Ns vs. 254.40\u0026thinsp;\u0026plusmn;\u0026thinsp;39.05Ns) (p\u0026thinsp;=\u0026thinsp;0.04, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50).\u003c/p\u003e \u003cp\u003eReactive strength index did not reach significance between intervention tasks (F\u0026thinsp;=\u0026thinsp;2.813, P\u0026thinsp;=\u0026thinsp;0.074), 90% 1RMHS (1.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40 vs. 1.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41) (P\u0026thinsp;=\u0026thinsp;0.014, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50), and 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (1.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 vs. 1.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41) practice interventions were significantly higher than baseline after (P\u0026thinsp;=\u0026thinsp;0.018, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eRectus Femoris pennation angle\u003c/h2\u003e \u003cp\u003eAs demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the effect of different interventions on the change in rectus femoris pennation angle (F\u0026thinsp;=\u0026thinsp;13.91, P\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) reached significant variability as revealed by repeated measures ANOVA. Upon further testing, 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (11.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u0026deg; vs. 11.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u0026deg;) (P\u0026thinsp;=\u0026thinsp;0.043\u0026thinsp;\u0026lt;\u0026thinsp;0.05, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50), 90% 1RMHS (11.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u0026deg; vs. 11.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u0026deg;) (P\u0026thinsp;=\u0026thinsp;0.039, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50) intervention Rectus femoris pinna angle was significantly lower than 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT; the difference between the effects of 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT and 90%1RMHS on the change of rectus femoris pennation angle after intervention was not statistically significant (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05, ES\u0026thinsp;\u0026lt;\u0026thinsp;0.50), and the difference between 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT and 90%1RMHT on the change of rectus femoris pennation angle after intervention was not statistically significant (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.50).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eLower limb muscle-tendon stiffness\u003c/h2\u003e \u003cp\u003eAs illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the effects of different interventions on rectus femoris muscle stiffness (F\u0026thinsp;=\u0026thinsp;3.43, P\u0026thinsp;=\u0026thinsp;0.01), biceps femoris muscle stiffness (F\u0026thinsp;=\u0026thinsp;5.85, P\u0026thinsp;=\u0026thinsp;0.02), lateral gastrocnemius head stiffness (F\u0026thinsp;=\u0026thinsp;4.038, P\u0026thinsp;=\u0026thinsp;0.007), medial gastrocnemius head stiffness (F\u0026thinsp;=\u0026thinsp;5.668, P\u0026thinsp;=\u0026thinsp;0.004), tibialis anterior muscle stiffness (F\u0026thinsp;=\u0026thinsp;13.37, P\u0026thinsp;=\u0026thinsp;0.04), and Achilles tendon stiffness (F\u0026thinsp;=\u0026thinsp;6.013, P\u0026thinsp;=\u0026thinsp;0.003) reached significant variability.\u003c/p\u003e \u003cp\u003eUpon further examination, the muscle stiffness of the rectus femoris muscle was significantly higher after the intervention of 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (289.80\u0026thinsp;\u0026plusmn;\u0026thinsp;52.74 N/m vs. 239.30\u0026thinsp;\u0026plusmn;\u0026thinsp;39.03 N/m) compared to the baseline (P\u0026thinsp;=\u0026thinsp;0.026, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05); the rectus femoris muscle stiffness after the intervention of 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT was significantly higher than the stiffness of the rectus femoris muscle after the intervention of 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (289.80\u0026thinsp;\u0026plusmn;\u0026thinsp;52.74 N/m vs. 242.70\u0026thinsp;\u0026plusmn;\u0026thinsp;25.80 N/m) (P\u0026thinsp;=\u0026thinsp;0.04, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Compared with baseline, 90%1RMHT (310.0\u0026thinsp;\u0026plusmn;\u0026thinsp;53.41 N/m vs. 273.30\u0026thinsp;\u0026plusmn;\u0026thinsp;39.57 N/m) (P\u0026thinsp;=\u0026thinsp;0.02, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) and 90%1RMHS (320.10\u0026thinsp;\u0026plusmn;\u0026thinsp;43.91 N/m vs. 273.30\u0026thinsp;\u0026plusmn;\u0026thinsp;39.57 N/m) (P\u0026thinsp;=\u0026thinsp;0.001, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) interventions resulted in significant increases in femoral Biceps stiffness was significantly higher; biceps femoris stiffness was significantly higher after 90% 1RMHS intervention than 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (320.10\u0026thinsp;\u0026plusmn;\u0026thinsp;43.91N/m vs. 287.10\u0026thinsp;\u0026plusmn;\u0026thinsp;24.93N/m) (P\u0026thinsp;=\u0026thinsp;0.03, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Compared with baseline, 90% 1RMHS (346.90\u0026thinsp;\u0026plusmn;\u0026thinsp;57.91N/m vs. 274.10\u0026thinsp;\u0026plusmn;\u0026thinsp;26.61N/m) (P\u0026thinsp;=\u0026thinsp;0.02, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) and 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (342.90\u0026thinsp;\u0026plusmn;\u0026thinsp;41.70N/m vs. 274.10\u0026thinsp;\u0026plusmn;\u0026thinsp;26.61N/m) (P\u0026thinsp;=\u0026thinsp;0.03, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) Post-intervention lateral gastrocnemius head stiffness was significantly higher; compared to 90% 1RMHT post-intervention, 90% 1RMHS (346.90\u0026thinsp;\u0026plusmn;\u0026thinsp;57.91N/m vs. 299.70\u0026thinsp;\u0026plusmn;\u0026thinsp;27.16N/m) (P\u0026thinsp;=\u0026thinsp;0.03, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) and 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (342.90\u0026thinsp;\u0026plusmn;\u0026thinsp;41.70N/m vs. 299.70\u0026thinsp;\u0026plusmn;\u0026thinsp;27.16N/m) post-intervention lateral gastrocnemius head Stiffness was significantly improved (P\u0026thinsp;=\u0026thinsp;0.05, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Medial gastrocnemius head stiffness was significantly higher (315.50\u0026thinsp;\u0026plusmn;\u0026thinsp;54.51N/m vs. 260.20\u0026thinsp;\u0026plusmn;\u0026thinsp;2.60N/m) after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention compared to baseline (P\u0026thinsp;=\u0026thinsp;0.0003, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05); medial gastrocnemius head stiffness was significantly higher (P\u0026thinsp;=\u0026thinsp;0.0003, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 90% 1RMHS (315.50\u0026thinsp;\u0026plusmn;\u0026thinsp;54.51N/m vs. 273.60\u0026thinsp;\u0026plusmn;\u0026thinsp;48.39N/m) (P\u0026thinsp;=\u0026thinsp;0.01, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05), and 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT (315.50\u0026thinsp;\u0026plusmn;\u0026thinsp;54.51N/m vs. 271.10\u0026thinsp;\u0026plusmn;\u0026thinsp;11.31N/m) (P\u0026thinsp;=\u0026thinsp;0.006, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eCompared with baseline, 90% 1RMHS (408.80\u0026thinsp;\u0026plusmn;\u0026thinsp;47.95 N/m vs. 363.70\u0026thinsp;\u0026plusmn;\u0026thinsp;29.65 N/m) (P\u0026thinsp;=\u0026thinsp;0.006, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05), 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (388.0\u0026thinsp;\u0026plusmn;\u0026thinsp;21.26 N/m vs. 363.70\u0026thinsp;\u0026plusmn;\u0026thinsp;29.65 N/m) (P\u0026thinsp;=\u0026thinsp;0.041, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) and a significant increase in Tibialis Anterior muscle stiffness after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (419.80\u0026thinsp;\u0026plusmn;\u0026thinsp;56.10 N/m vs. 363.70\u0026thinsp;\u0026plusmn;\u0026thinsp;29.65N/m) (P\u0026thinsp;=\u0026thinsp;0.003, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) intervention. Tibialis Anterior muscle stiffness was increased after intervention with 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (387.0\u0026thinsp;\u0026plusmn;\u0026thinsp;31.15 N/m vs. 419.80\u0026thinsp;\u0026plusmn;\u0026thinsp;56.10 N/m) compared to 90% 1RMHT (P\u0026thinsp;=\u0026thinsp;0.02, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05), and after intervention with 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (388.0\u0026thinsp;\u0026plusmn;\u0026thinsp;21.26 N/ m vs. 419.80\u0026thinsp;\u0026plusmn;\u0026thinsp;56.10 N/m) intervention improved tibialis anterior muscle stiffness (P\u0026thinsp;=\u0026thinsp;0.027, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Compared with baseline, 90% 1RMHS (1230.22\u0026thinsp;\u0026plusmn;\u0026thinsp;154.80 N/m vs. 1093.10\u0026thinsp;\u0026plusmn;\u0026thinsp;134.30 N/m) (P\u0026thinsp;=\u0026thinsp;0.01, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05), 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (1275.05\u0026thinsp;\u0026plusmn;\u0026thinsp;120.30 N/m vs. 1093.10\u0026thinsp;\u0026plusmn;\u0026thinsp;134.30 N/m) (P\u0026thinsp;=\u0026thinsp;0.0004, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05) Achilles tendon stiffness was significantly increased after the intervention. Achilles tendon stiffness was significantly higher after intervention with 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT (1275.05\u0026thinsp;\u0026plusmn;\u0026thinsp;120.30 N/m vs. 1134.16\u0026thinsp;\u0026plusmn;\u0026thinsp;66.36 N/m) compared to 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT (P\u0026thinsp;=\u0026thinsp;0.012, ES\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eFew studies have investigated the acute effects of post-activation potentiation (PAP) on lower limb muscle-tendon stiffness in sprinters. It is crucial to understand how lower limb muscle-Achilles tendon stiffness regulation of PAP. This study suggest that examine the acute effects of low-intensity resistance combined with blood flow restriction training and high-intensity resistance exercises on lower limb muscle-tendon stiffness sprint ability, explosive jumping athletic performance, rectus femoris pennation angle, and rectus femoris muscle in male sprinters. Additionally, the study tried to explore the possible mechanisms influencing PAP. The findings of this study can be applied to improve sprinters' performance in competitions and identify the optimal pre-competition warm-up program. Furthermore, The results of this study can serve as a theoretical basis and provide data support for implementing PAP in sprinters' actual competitions to determine the most effective pre-competition warm-up program.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eEffects of sprint ability\u003c/h2\u003e \u003cp\u003eThe ability to sprint 20m is crucial for sprinters to win races. Based on significant changes in gait characteristics during the 0-20m sprinting process, this ability can be further divided into start-up speed (0-10m) and acceleration (0-20m). The results showed that after 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT exercise intervention, the 0-20m sprint ability significantly improved compared to 90% 1RMHS and the 0-10m sprint ability also significantly improved compared to the baseline. This suggests that combining low-intensity hip thrust resistance exercise with blood flow restriction training acutely enhances speed performance (start-up speed and acceleration) and it has a significantly better acute augmentation effect on acceleration capacity compared to high-intensity resistance intervention, which is a key finding of this study. Similarly, Fern\u0026aacute;ndez et al. (2022) \u003csup\u003e4\u003c/sup\u003enoted that a significant improvement in 0-5m sprint ability in tennis players after an intervention using 60% 1RMHT exercises. In this study, we investigated the performance differences between hip thrust and weighted half squat-induced PAP and its impact on athletes' explosive performance in sprinters. The research not only supported the findings of previous studies but also provided empirical scientific data supporting lower limb explosive training in sprinters, considering different loading intensities and induced movement patterns. Specifically, different loading intensities of hip thrust resistance were able to enhance the 0-20m sprint running post-enhancement effect.\u003c/p\u003e \u003cp\u003eResearch reports on the effects of hip thrust induction activation on enhancement have garnered significant attention from coaches, athletes, and sport researchers. Atalağ et al.(2020) \u003csup\u003e40\u003c/sup\u003ediscovered that subjects' sprinting abilities in the 0\u0026ndash;20 yards and 0\u0026ndash;40 yards range were significantly improved after 90% 1RMHS and 90% 1RMHT exercise interventions. Similarly, Dello et al. (2018) \u003csup\u003e20\u003c/sup\u003eutilized barbell hip thrust exercises with loading intensities of 50% 1RM and 85% 1RM to induce a significant reduction in sprint times for distances of 0-10m and 0-15m in high-level handball players at the 4th and 8th min after 85% 1RM accompanied by barbell hip thrust exercises. Dello et al. (2018)\u003csup\u003e41\u003c/sup\u003e conducted a study with 18 soccer players as subjects and found that using 85% 1RM loading intensity accompanied by barbell hip thrust exercise as an induction method led to significant improvements in the sprinting abilities of soccer players for distances of 0-5m, 0-10m, and 0-20m at 4minutes and 8minutes after the intervention. These research demonstrate that the barbell hip thrust lifting mode successfully induces a post-activation enhancement effect, particularly evident in the significant improvement of short-distance sprint ability in the subjects. Some scholars attribute the enhancement of sprint running performance to the barbell hip thrust's its significant increase in horizontal vector forces during sprint running\u003csup\u003e42\u003c/sup\u003e. This study suggests that the enhancement may also be attributed to the activation and mobilization of hip-extensor muscle groups such as the gluteus maximus and hamstrings through the hip thrust mode of action, which aligns with the forward hip extension in sprint running, and may have a positive ransfer effect.\u003c/p\u003e \u003cp\u003eThe results of the study demonstrated that combining low-intensity weight-bearing half-squats blood flow restriction training resulted in a significant augmentation effect on sprint performance. Specifically, the activation after the intervention was significantly higher than the baseline for 0-10m sprint performance. Additionally, the 10-20m sprint ability was significantly better than when performing exercises at 90% of 1RM for both half-squats and hamstring curls. These findings align with a study by Abe et al. (2005)\u003csup\u003e23\u003c/sup\u003e, which showed that combining 20% of 1RM hamstring curls with blood flow restriction (160\u0026ndash;240 mmHg) led to a was significant improved in university sprinters after the intervention, this study also found that start-up speed (0-10m) was similarly significantly improvement in acceleration (0-30m) in university sprinters. The present study also found a similar improvement in start-up speed (0-10m) after the intervention. Similarly, Manimmanakorn et al.(2013)\u003csup\u003e43\u003c/sup\u003e found that combining 20% of 1RM with blood flow restriction (160\u0026ndash;230 mmHg) and lower extremity seated isometric exercise significantly enhanced 0-5m and 0-10m sprint ability in female netball players. These studies collectively demonstrate that the acute augmentation effect of low-intensity resistance exercises combined with blood flow restriction can significantly improve start-up speed and acceleration in athletes. Short-distance acceleration capacity involves rapidly accelerating from a stationary or slow state to maximal velocity, requiring explosive strength and maximal strength capacity. Therefore, the significant improvements in acceleration performance observed with low-intensity resistance exercises combined with blood flow restriction interventions may be attributed to acute increases in strength. The main physiological mechanism through which blood flow restriction training can effectively increase muscle strength is by activating the growth hormone-insulin-like growth factor axis.This axis induces expansion of muscle cells by applying pressurizing the limb and restricting venous blood flow to cause a pooling effect in the distal veins of the limb. The swelling of the cells inhibits proteolysis, accelerates lipolysis, and positively influences protein synthesis. Additionally, this study found that low intensity resistance combined with blood flow restriction, significantly improves explosive performance, providing empirical support for training practice.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eEffects of jump performance\u003c/h2\u003e \u003cp\u003eVertical jump height is a commonly used measure to evaluate vertical jump performance. Rate of force development (RFD) peak power are mechanistic factors that explain the enhancement in jump height. The results of this study demonstrated that CMJ vertical jump height was significantly higher after a 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention compared to 90% 1RMHS intervention. Gaviglio et al.(2015)\u003csup\u003e44\u003c/sup\u003e also found that athletes' vertical jump height and peak power were significantly higher after 20% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT exercise intervention. Furthermore, this study found that CMJ relative peak power was significantly higher after a 90% 1RMHT and 90% 1RMHS practice intervention, compared to 30% 1RMHT intervention, and CMJ and SJ relative peak power were significantly higher after 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention compared to 90%1RMHT intervention. In addition, other research noted that CMJ relative peak power was significantly higher after 90% 1RMHS intervention. These studies suggest that low-intensity resistance raining with blood flow restriction can improve jumping performance similar to high-intensity resistance exercise intervention. This may be due to the selection of sprinters from athletic colleges and universities with a high level of competitiveness and an average of 4.47 years of training experience in this study. The application of blood flow restriction training to individuals with training experience in explosive events offers the potential for selective recruitment of fast muscle fibers and mobilization of high-threshold motor units during subsequent explosive movements under conditions of limb ischemia and hypoxia. Katz et al. (1987) \u003csup\u003e45\u003c/sup\u003eshown that high-threshold motor units are associated not only with the force and velocity of muscle contraction, but also with the exercise oxygen concentration. Blood flow restriction can alter body oxygen concentration, creating conditions for the recruitment of high threshold motor units. Skeletal muscle is an excitable tissue that generates action potentials when stimulated PAP can enhance excitation transmission at the nerve-muscle junction, resulting in increased excitation in the myocyte membrane. This leads to an increase in neurotransmitters and improved transmission efficiency. As a result, there is a rapid recruitment of high-threshold motor units. Vertical jump-like movements consist of centrifugal, buffer, and centripetal phases. The centrifugal phase strongly stimulates the muscle spindle, activating the active muscle group, and increases the number of motor units. In the buffer phase α-motor neuron transmits signals to the acting muscle group, while in the centripetal phase α-motor neuron stimulates the acting muscle group. Simultaneously, the tandem elastic tissue releases elastic energy and accelerates the stretch-contraction cycle. In conclusion, combining low-intensity resistance training with blood flow restriction was found to enhance lower limb explosive jump performance. Overall, the positive effects of high-intensity resistance exercises on explosive jumping were superior to those of low-intensity resistance combined with blood flow restriction training.\u003c/p\u003e \u003cp\u003eThe study results demonstrated that the reaction strength index of male sprinters significantly increased after both 90% 1RMHS and 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT exercises. However, there was no significant difference between the two indicated that high-intensity resistance exercises and low-intensity resistance combined with blood flow restriction training were equally effective in improving the reaction strength index. Further research is needed to determine if there is a correlation between the reaction strength index and sprint ability. The reaction force index, also known as the ratio of the time to vacate or the height of vacating to the time of foot contact with the ergometer\u003csup\u003e33\u003c/sup\u003e, represents the force generated during the transition from centrifugal lengthening to centripetal contraction of the muscle. This force utilizes the storage and re-release of elastic energy in the muscle, as well as neural reflexive modulation. Barr et al.(2011)\u003csup\u003e46\u003c/sup\u003e discovered a significant positive correlation between the reaction force index of rugby players during the jumping deep maneuver. However, Healy et al. (2019)\u003csup\u003e47\u003c/sup\u003ereported no significant correlation between the reaction force index and short distance sprint ability. The existence of a significant correlation between the reaction force index and explosive performance is still a topic of debate in the academic community. Some scholars have suggested that the variations in study results may be attributed to factors\u003csup\u003e34\u003c/sup\u003e, such as the level of the subject, the intervention environment, the height of the depth of the jump, the data processing method the findings of the present experimental study align with these observations .\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eEffect of muscle pennation angle\u003c/h2\u003e \u003cp\u003eIn anatomy, the angle between the tendon and the muscle fibers is commonly known as the \"pennation angle\". This angle indicates the orientation of the muscle fibers in relation to the tendon\u003csup\u003e48\u003c/sup\u003e. When skeletal muscle contract total the force transmitted to the tendons and bones from all individual muscle fibers increases as the pennation angle decreases. Folland et al. (2007) \u003csup\u003e49\u003c/sup\u003ediscovered that the size of the pennation angle impacts the efficiency of force transmission from muscle to tendon and bone. The size of the pennation angle also affects the relationship between influence and velocity curves, with smaller angles favoring force transfer and consequently affecting power output.Therefore, as the pennation angle decreases, muscle contraction force increases. The study's results demonstrated that both the 90% 1RMHS and 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT exercise intervention programs significantly reduced the pennation angle of the rectus femoris muscle. Similarly, Mahlfeld et al.(2004)\u003csup\u003e5\u003c/sup\u003e found that the pennation angle immediately after MVIC exercise was slightly smaller than before, but not significantly. However, 3\u0026ndash;6 min later, the pennation angle was significantly reduced. Although this change only increased muscle energy transfer by 0.9%, it may have had an augmentation effect, and the decrease in pennation angle could be responsible for the augmentation effect of PAP. Considering that the reduction of the pennation angle in skeletal muscle can enhance muscle force generation, the study's findings suggest that pennation angle reduction cloud be a potential mechanism to explain PAP.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eEffects of lower limb muscle-tendon stiffness\u003c/h2\u003e \u003cp\u003eThe MyotonPRO Digital Muscle Function Testing System is a portable device, that offers a new method for evaluating lower limb muscle-tendon stiffness in high-level athletes. Numerous studies have demonstrated a positive correlation between tendon stiffness and jumping performance, where higher stiffness is advantageous for activities involving stretch-shortening cycles (SSC) and sports with higher speeds\u003csup\u003e11,50\u003c/sup\u003e. Subjects with higher stiffness levels exhibited better locomotor performance during SSC activities.Bojsen-M\u0026uuml;ller et al.(2005)\u003csup\u003e12\u003c/sup\u003e discovered that higher stiffness not only aids in the storage and release of rate of force development(RFD)and elastic energy, but also plays crucial role in muscle force generation. The results of this study indicate that the stiffness of the rectus femoris muscle was significantly higher than 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT after the 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention. Similarly, the biceps femoris muscle stiffness was significantly higher than 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT after 90% 1RMHS intervention, and gastrocnemius muscle lateral head stiffness was significantly higher than 90% 1RMHT after 90% 1RMHS and 30% 1RMHS\u0026thinsp;+\u0026thinsp;BFRT interventions. Furthermore, the medial head stiffness of the gastrocnemius was significantly higher after the 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT interventions. The intervention than 90%1RMHS, 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT, tibialis anterior muscle stiffness was higher after the 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention compared to the 90%1RMHT, tibialis anterior muscle stiffness was higher after intervention, and it was also higher compared to the 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention than 30%1RMHT\u0026thinsp;+\u0026thinsp;BFRT, 30%1RMHS\u0026thinsp;+\u0026thinsp;BFRT intervention resulted in significantly higher Achilles tendon stiffness compared to the 30% 1RMHT\u0026thinsp;+\u0026thinsp;BFRT intervention. Similarly, Byrne et al.(2020)\u003csup\u003e51\u003c/sup\u003e demonstrated that completion of drop jump exercises led to shorter countermovement jump (CMJ) touchdown times and increased reactive strength index (RSI) and muscle-tendon unit stiffness properties. This indicates that the SSC(stretch-shortening cycle) was enhanced during CMJ, resulting in significant increases in CMJ height. Therefore, increased stiffness of the primary force-generating muscles and tendons in the lower limb may contribute to the phenomenon of PAP.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eLimitations of the study\u003c/h2\u003e \u003cp\u003eThis study focused on male university sprinters, and further research is needed to determine if the conclusions can be applied to female sprinters and higher level athletes. The study only evaluated the test indexes of sprinting time, jumping performance, muscle pennation angle, and lower limb muscle-tendon stiffness, but did not analyze physiological indexes such as EMG signals, electroencephalography, and blood lactate concentration. It is important to note that attaching EMG patches may cause discomfort to the subjects and affect their sprinting technique, which could impact their all-out sprinting acceleration. Finding ways to address these issues will be the main focus of the next phase of this study.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eOur study revealed several significant findings. Firstly, we found that incorporating a blood flow restriction intervention along with low intensity barbell hip thrust resistance led to a significant improvement in sprint ability when compared to high-intensity barbell half-squats. Additionally, we observed that barbell half squat exercises resulted in a significant enhancement in vertical jump performance as well as a notable reduction in rectus femoris pennation angle when compared to barbell hip thrust. Lastly, both low-intensity barbell half squat and hip thrust exercises, when combined with a blood flow restriction training intervention, led to a significant improvement in lower extremity muscle-tendon stiffness.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJ.J.Z. designed the protocol, collected the data, organized the database, and wrote the main manuscript text; Y.J. designed the research study and performed the research; H.Y.L collected the data, provided help and advice on the critically reviewed the contents of the manuscript. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondence and requests for materials should be addressed to Y.J.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eReprints and permissions information\u0026nbsp;\u003c/strong\u003eis available at www.nature.com/reprints.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTillin, N. A. \u0026amp; Bishop, D. Factors modulating post-activation potentiation and its effect on performance of subsequent explosive activities. \u003cem\u003eSports Med\u003c/em\u003e \u003cstrong\u003e39\u003c/strong\u003e, 147-166, doi:10.2165/00007256-200939020-00004 (2009).\u003c/li\u003e\n\u003cli\u003eGołaś, A., Maszczyk, A., Zajac, A., Mikołajec, K. \u0026amp; Stastny, P. Optimizing post activation potentiation for explosive activities in competitive sports. \u003cem\u003eJ Hum Kinet\u003c/em\u003e \u003cstrong\u003e52\u003c/strong\u003e, 95-106, doi:10.1515/hukin-2015-0197 (2016).\u003c/li\u003e\n\u003cli\u003eAagaard, P. Training-induced changes in neural function. \u003cem\u003eExerc Sport Sci Rev\u003c/em\u003e \u003cstrong\u003e31\u003c/strong\u003e, 61-67, doi:10.1097/00003677-200304000-00002 (2003).\u003c/li\u003e\n\u003cli\u003eFern\u0026aacute;ndez-Galv\u0026aacute;n, L. M., Prieto-Gonz\u0026aacute;lez, P., S\u0026aacute;nchez-Infante, J., Jim\u0026eacute;nez-Reyes, P. \u0026amp; Casado, A. The Post-Activation Potentiation Effects on Sprinting Abilities in Junior Tennis Players. \u003cem\u003eInt J Environ Res Public Health\u003c/em\u003e \u003cstrong\u003e19\u003c/strong\u003e, 2080, doi:10.3390/ijerph19042080 (2022).\u003c/li\u003e\n\u003cli\u003eMahlfed K, F. J., Awiszus F. post contraction changes of muscle architecture in human quadriceps muscle. \u003cem\u003emuscle Nerve\u003c/em\u003e \u003cstrong\u003e29\u003c/strong\u003e, 597-600 (2004).\u003c/li\u003e\n\u003cli\u003eWakeling, J. M., Blake, O. M., Wong, I., Rana, M. \u0026amp; Lee, S. S. Movement mechanics as a determinate of muscle structure, recruitment and coordination. \u003cem\u003ePhilos Trans R Soc Lond B Biol Sci\u003c/em\u003e \u003cstrong\u003e366\u003c/strong\u003e, 1554-1564, doi:10.1098/rstb.2010.0294 (2011).\u003c/li\u003e\n\u003cli\u003eEarp, J. E.\u003cem\u003e et al.\u003c/em\u003e Influence of muscle-tendon unit structure on rate of force development during the squat, countermovement, and drop jumps. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, 340-347, doi:10.1519/jsc.0b013e3182052d78 (2011).\u003c/li\u003e\n\u003cli\u003eHerzog, W., Schappacher, G., DuVall, M., Leonard, T. R. \u0026amp; Herzog, J. A. Residual Force Enhancement Following Eccentric Contractions: A New Mechanism Involving Titin. \u003cem\u003ePhysiology (Bethesda)\u003c/em\u003e \u003cstrong\u003e31\u003c/strong\u003e, 300-312, doi:10.1152/physiol.00049.2014 (2016).\u003c/li\u003e\n\u003cli\u003eBrughelli, M. \u0026amp; Cronin, J. A review of research on the mechanical stiffness in running and jumping: methodology and implications. \u003cem\u003eScand J Med Sci Sports\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, 417-426, doi:10.1111/j.1600-0838.2008.00769.x (2008).\u003c/li\u003e\n\u003cli\u003eWu, Y. K.\u003cem\u003e et al.\u003c/em\u003e Relationships between three potentiation effects of plyometric training and performance. \u003cem\u003eScand J Med Sci Sports\u003c/em\u003e \u003cstrong\u003e20\u003c/strong\u003e, e80-86, doi:10.1111/j.1600-0838.2009.00908.x (2010).\u003c/li\u003e\n\u003cli\u003eBurgess, K. E., Connick, M. J., Graham-Smith, P. \u0026amp; Pearson, S. J. Plyometric vs. isometric training influences on tendon properties and muscle output. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 986-989, doi:10.1519/r-20235.1 (2007).\u003c/li\u003e\n\u003cli\u003eBojsen-M\u0026oslash;ller, J., Magnusson, S. P., Rasmussen, L. R., Kjaer, M. \u0026amp; Aagaard, P. Muscle performance during maximal isometric and dynamic contractions is influenced by the stiffness of the tendinous structures. \u003cem\u003eJ Appl Physiol (1985)\u003c/em\u003e \u003cstrong\u003e99\u003c/strong\u003e, 986-994, doi:10.1152/japplphysiol.01305.2004 (2005).\u003c/li\u003e\n\u003cli\u003eHamada, T., Sale, D. G., MacDougall, J. D. \u0026amp; Tarnopolsky, M. A. Interaction of fibre type, potentiation and fatigue in human knee extensor muscles. \u003cem\u003eActa Physiol Scand\u003c/em\u003e \u003cstrong\u003e178\u003c/strong\u003e, 165-173, doi:10.1046/j.1365-201X.2003.01121.x (2003).\u003c/li\u003e\n\u003cli\u003eWei, J. L. B. Application effect and mechanism of blood flow restriction training. \u003cem\u003eSports Science\u003c/em\u003e \u003cstrong\u003e39\u003c/strong\u003e, 71-80 (2019).\u003c/li\u003e\n\u003cli\u003eSumide, T., Sakuraba, K., Sawaki, K., Ohmura, H. \u0026amp; Tamura, Y. Effect of resistance exercise training combined with relatively low vascular occlusion. \u003cem\u003eJ Sci Med Sport\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 107-112, doi:10.1016/j.jsams.2007.09.009 (2009).\u003c/li\u003e\n\u003cli\u003eLuebbers, P. E., Witte, E. V., Oshel, J. Q. \u0026amp; Butler, M. S. Effects of Practical Blood Flow Restriction Training on Adolescent Lower-Body Strength. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e33\u003c/strong\u003e, 2674-2683, doi:10.1519/jsc.0000000000002302 (2019).\u003c/li\u003e\n\u003cli\u003eYasuda, T., Fukumura, K., Tomaru, T. \u0026amp; Nakajima, T. Thigh muscle size and vascular function after blood flow-restricted elastic band training in older women. \u003cem\u003eOncotarget\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, 33595-33607, doi:10.18632/oncotarget.9564 (2016).\u003c/li\u003e\n\u003cli\u003eSeitz, L. B. \u0026amp; Haff, G. G. Factors Modulating Post-Activation Potentiation of Jump, Sprint, Throw, and Upper-Body Ballistic Performances: A Systematic Review with Meta-Analysis. \u003cem\u003eSports Med\u003c/em\u003e \u003cstrong\u003e46\u003c/strong\u003e, 231-240, doi:10.1007/s40279-015-0415-7 (2016).\u003c/li\u003e\n\u003cli\u003eFaul, F., Erdfelder, E., Buchner, A. \u0026amp; Lang, A. G. Statistical power analyses using G*Power 3.1: tests for correlation and regression analyses. \u003cem\u003eBehav Res Methods\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 1149-1160, doi:10.3758/brm.41.4.1149 (2009).\u003c/li\u003e\n\u003cli\u003eDello Iacono, A., Padulo, J. \u0026amp; Seitz, L. D. Loaded hip thrust-based PAP protocol effects on acceleration and sprint performance of handball players. \u003cem\u003eJ Sports Sci\u003c/em\u003e \u003cstrong\u003e36\u003c/strong\u003e, 1269-1276, doi:10.1080/02640414.2017.1374657 (2018).\u003c/li\u003e\n\u003cli\u003eCarbone, L.\u003cem\u003e et al.\u003c/em\u003e Effects of heavy barbell hip thrust vs back squat on subsequent sprint performance in rugby players. \u003cem\u003eBiol Sport\u003c/em\u003e \u003cstrong\u003e37\u003c/strong\u003e, 325-331, doi:10.5114/biolsport.2020.96316 (2020).\u003c/li\u003e\n\u003cli\u003eSeitz, L. B.\u003cem\u003e et al.\u003c/em\u003e Relationships between maximal strength, muscle size, and myosin heavy chain isoform composition and postactivation potentiation. \u003cem\u003eAppl Physiol Nutr Metab\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 491-497, doi:10.1139/apnm-2015-0403 (2016).\u003c/li\u003e\n\u003cli\u003eABE T, K. K., YASUDA T, et al. Eight Days KAATSU-Resistance Training Improved Sprint but Not Jump Performance in Collegiate Male Track and Field Athletes. \u003cem\u003eInt J KAATSU Training Res\u003c/em\u003e \u003cstrong\u003e36\u003c/strong\u003e, 1269-1276 (2005).\u003c/li\u003e\n\u003cli\u003ePatterson, S. D.\u003cem\u003e et al.\u003c/em\u003e Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety. \u003cem\u003eFront Physiol\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, 533, doi:10.3389/fphys.2019.00533 (2019).\u003c/li\u003e\n\u003cli\u003eSeitz, L. B., de Villarreal, E. S. \u0026amp; Haff, G. G. The temporal profile of postactivation potentiation is related to strength level. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e28\u003c/strong\u003e, 706-715, doi:10.1519/JSC.0b013e3182a73ea3 (2014).\u003c/li\u003e\n\u003cli\u003eFletcher, I. M. An investigation into the effect of a pre-performance strategy on jump performance. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, 107-115, doi:10.1519/JSC.0b013e3182517ffb (2013).\u003c/li\u003e\n\u003cli\u003eKhamoui, A. V.\u003cem\u003e et al.\u003c/em\u003e Effect of potentiating exercise volume on vertical jump parameters in recreationally trained men. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 1465-1469, doi:10.1519/JSC.0b013e3181a5bcdd (2009).\u003c/li\u003e\n\u003cli\u003eMina, M. A.\u003cem\u003e et al.\u003c/em\u003e Variable, but not free-weight, resistance back squat exercise potentiates jump performance following a comprehensive task-specific warm-up. \u003cem\u003eScand J Med Sci Sports\u003c/em\u003e \u003cstrong\u003e29\u003c/strong\u003e, 380-392, doi:10.1111/sms.13341 (2019).\u003c/li\u003e\n\u003cli\u003eDello Iacono, A., Martone, D. \u0026amp; Padulo, J. Acute Effects of Drop-Jump Protocols on Explosive Performances of Elite Handball Players. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e30\u003c/strong\u003e, 3122-3133, doi:10.1519/jsc.0000000000001393 (2016).\u003c/li\u003e\n\u003cli\u003eLoenneke, J. P.\u003cem\u003e et al.\u003c/em\u003e Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. \u003cem\u003eEur J Appl Physiol\u003c/em\u003e \u003cstrong\u003e112\u003c/strong\u003e, 2903-2912, doi:10.1007/s00421-011-2266-8 (2012).\u003c/li\u003e\n\u003cli\u003eNatsume, T., Ozaki, H., Saito, A. I., Abe, T. \u0026amp; Naito, H. Effects of Electrostimulation with Blood Flow Restriction on Muscle Size and Strength. \u003cem\u003eMed Sci Sports Exerc\u003c/em\u003e \u003cstrong\u003e47\u003c/strong\u003e, 2621-2627, doi:10.1249/mss.0000000000000722 (2015).\u003c/li\u003e\n\u003cli\u003eDello Iacono, A., Martone, D., Milic, M. \u0026amp; Padulo, J. Vertical- vs. Horizontal-Oriented Drop Jump Training: Chronic Effects on Explosive Performances of Elite Handball Players. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e31\u003c/strong\u003e, 921-931, doi:10.1519/jsc.0000000000001555 (2017).\u003c/li\u003e\n\u003cli\u003eZhiquan Lu, Y., Liu. Neurobiomechanical basis and diagnosis of muscle strength. \u003cem\u003eShanghai University of Sport\u003c/em\u003e \u003cstrong\u003e43\u003c/strong\u003e, 113-120. (2019).\u003c/li\u003e\n\u003cli\u003eYu Zang, Y. X., Fei Yin, et al. . Effect of landing height on lower limb biomechanics and reactive strength of high-level sprinters in deep jump. \u003cem\u003eSports and Science,\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 101-110 (2019).\u003c/li\u003e\n\u003cli\u003eNewton, R. u., Eric Dugan. Application of Strength Diagnosis. \u003cem\u003eStrength Cond J\u003c/em\u003e \u003cstrong\u003e24\u003c/strong\u003e, 50-59. (2002).\u003c/li\u003e\n\u003cli\u003eThomaes, T.\u003cem\u003e et al.\u003c/em\u003e Reliability and validity of the ultrasound technique to measure the rectus femoris muscle diameter in older CAD-patients. \u003cem\u003eBMC Med Imaging\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 7, doi:10.1186/1471-2342-12-7 (2012).\u003c/li\u003e\n\u003cli\u003ePapla, M., Ewertowska, P. \u0026amp; Krzysztofik, M. Acute Effects of Complex Conditioning Activities on Athletic Performance and Achilles Tendon Stiffness in Male Basketball Players. \u003cem\u003eJ Sports Sci Med\u003c/em\u003e \u003cstrong\u003e22\u003c/strong\u003e, 281-287, doi:10.52082/jssm.2023.281 (2023).\u003c/li\u003e\n\u003cli\u003eKrzysztofik, M.\u003cem\u003e et al.\u003c/em\u003e Acute Effects of High-Load vs. Plyometric Conditioning Activity on Jumping Performance and the Muscle-Tendon Mechanical Properties. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e37\u003c/strong\u003e, 1397-1403, doi:10.1519/jsc.0000000000004398 (2023).\u003c/li\u003e\n\u003cli\u003eMei fu Liang, W. x. G. Research progress on the enhancement effect of skeletal muscle after activation[J].Sports Science,2019,39(5):70-80.). \u003cem\u003eSports Science\u003c/em\u003e \u003cstrong\u003e39\u003c/strong\u003e, 70-80. (2019).\u003c/li\u003e\n\u003cli\u003eAtalağ, O., Kurt, C., Solyomvari, E., Sands, J. \u0026amp; Cline, C. Postactivation potentiation effects of Back Squat and Barbell Hip Thrust exercise on vertical jump and sprinting performance. \u003cem\u003eJ Sports Med Phys Fitness\u003c/em\u003e \u003cstrong\u003e60\u003c/strong\u003e, 1223-1230, doi:10.23736/s0022-4707.20.10888-0 (2020).\u003c/li\u003e\n\u003cli\u003eDello Iacono, A. \u0026amp; Seitz, L. B. Hip thrust-based PAP effects on sprint performance of soccer players: heavy-loaded versus optimum-power development protocols. \u003cem\u003eJ Sports Sci\u003c/em\u003e \u003cstrong\u003e36\u003c/strong\u003e, 2375-2382, doi:10.1080/02640414.2018.1458400 (2018).\u003c/li\u003e\n\u003cli\u003eNeto, W. K., Vieira, T. L. \u0026amp; Gama, E. F. Barbell Hip Thrust, Muscular Activation and Performance: A Systematic Review. \u003cem\u003eJ Sports Sci Med\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, 198-206 (2019).\u003c/li\u003e\n\u003cli\u003eManimmanakorn, A., Hamlin, M. J., Ross, J. J., Taylor, R. \u0026amp; Manimmanakorn, N. Effects of low-load resistance training combined with blood flow restriction or hypoxia on muscle function and performance in netball athletes. \u003cem\u003eJ Sci Med Sport\u003c/em\u003e \u003cstrong\u003e16\u003c/strong\u003e, 337-342, doi:10.1016/j.jsams.2012.08.009 (2013).\u003c/li\u003e\n\u003cli\u003eGAVIGLIO C M, B. W. Blood Flow Restriction Training as A Novel Approach to Improve Jumping Performance. \u003cem\u003eJ Aus Strength Cond\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 54-59. (2015).\u003c/li\u003e\n\u003cli\u003eKatz, A. \u0026amp; Sahlin, K. Effect of decreased oxygen availability on NADH and lactate contents in human skeletal muscle during exercise. \u003cem\u003eActa Physiol Scand\u003c/em\u003e \u003cstrong\u003e131\u003c/strong\u003e, 119-127, doi:10.1111/j.1748-1716.1987.tb08213.x (1987).\u003c/li\u003e\n\u003cli\u003eBarr, M. J. \u0026amp; Nolte, V. W. Which measure of drop jump performance best predicts sprinting speed? \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, 1976-1982, doi:10.1519/JSC.0b013e3181e4f7ba (2011).\u003c/li\u003e\n\u003cli\u003eHealy, R., Smyth, C., Kenny, I. C. \u0026amp; Harrison, A. J. Influence of Reactive and Maximum Strength Indicators on Sprint Performance. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e33\u003c/strong\u003e, 3039-3048, doi:10.1519/jsc.0000000000002635 (2019).\u003c/li\u003e\n\u003cli\u003eLedoux, W. R., Hirsch, B. E., Church, T. \u0026amp; Caunin, M. Pennation angles of the intrinsic muscles of the foot. \u003cem\u003eJ Biomech\u003c/em\u003e \u003cstrong\u003e34\u003c/strong\u003e, 399-403, doi:10.1016/s0021-9290(00)00194-9 (2001).\u003c/li\u003e\n\u003cli\u003eFolland, J. P. \u0026amp; Williams, A. G. The adaptations to strength training : morphological and neurological contributions to increased strength. \u003cem\u003eSports Med\u003c/em\u003e \u003cstrong\u003e37\u003c/strong\u003e, 145-168, doi:10.2165/00007256-200737020-00004 (2007).\u003c/li\u003e\n\u003cli\u003eKubo, K.\u003cem\u003e et al.\u003c/em\u003e Influences of tendon stiffness, joint stiffness, and electromyographic activity on jump performances using single joint. \u003cem\u003eEur J Appl Physiol\u003c/em\u003e \u003cstrong\u003e99\u003c/strong\u003e, 235-243, doi:10.1007/s00421-006-0338-y (2007).\u003c/li\u003e\n\u003cli\u003eByrne, P. J., Moody, J. A., Cooper, S. M., Callanan, D. \u0026amp; Kinsella, S. Potentiating Response to Drop-Jump Protocols on Sprint Acceleration: Drop-Jump Volume and Intrarepetition Recovery Duration. \u003cem\u003eJ Strength Cond Res\u003c/em\u003e \u003cstrong\u003e34\u003c/strong\u003e, 717-727, doi:10.1519/jsc.0000000000002720 (2020).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"blood flow restriction, resistance exercise, post-activation potentiation, pennation angle, stiffness, vertical jump, sprint","lastPublishedDoi":"10.21203/rs.3.rs-3952436/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3952436/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe purpose of this study was to investigate the ecute effect of combining low-intensity resistance exercises with a blood flow restriction intervention and high-intensity resistance exercises on sprint ability, vertical jump performance, rectus femoris pennation angle, and lower extremity muscle-tendon stiffness in male sprinters.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eSeventeen male sprinters participated in the study and were randomly assigned to perform different interventions with 72-hour intervals. The interventions included \u0026nbsp;90% 1RM hip thrust (HT), 90% 1RM barbell half squat (HS), 30% 1RM HT + BFRT ( Blood Flow Restriction Training), and 30% 1RM HS + BFRT. Test content included 20-m sprint, vertical jump, rectus femoris pennation angle, and lower limb muscle-tendon stiffness. Descriptive statistics and Repeated measures ANOVA analysis were used for statistical analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e (1) The study found that the 10-20m sprint performance was significantly improved compared to the 90%1RM HT and 90%1RM HS after the 30%1RM HS + BFRT interventions. Additionally, the 0-20m sprint performance was significantly improved than 90%1RMHS after 30%1RM HT + BFRT interventions; (2) The CMJ vertical jump height was significantly higher than the 90%1RM HS after the 30%1RM HS + BFRT intervention; (3) Moreover, the CMJ relative peak power was significantly increased after the 90%1RMHT and 90%1RMHS interventions compared to the 30%1RM HT + BFRT; The CMJ (Countermovement Jump) relative rate force development was significantly expanded after the 90%1RM HS intervention compared to the 30%1RM HT + BFRT. Furthermore, the 90% SJ (Squat Jump) relative rate force development after the 90%1RMHT intervention was significantly higher than the 30% 1RM HT + BFRT and 30% 1RM HS + BFRT. The CMJ relative peak force after the 90% 1RMHS intervention was significantly higher than the 30% 1RM HT + BFRT. Similarly, the SJ relative peak force after the 90% 1RMHT intervention was significantly higher than the 30% 1RM HT + BFRT and 30% 1RM HS + BFRT; (4) The study also found that the rectus femoris pennation angle was significantly lower after the 30%1RM HS + BFRT and 90%1RMHS practice interventions compared to after the 30%1RM HT + BFRT; (5) Additionally, therectus femoris muscle stiffness was significantly improved after the 30%1RM HT + BFRT compared to after the 30%1RM HS + BFRT. Moreover, the biceps femoris muscle stiffness was significantly increased after the 90%1RM HS intervention compared to after the 30%1RM HS + BFRT. The 90% 1RMHS and 30% 1RM HS + BFRT had significantly higher post-intervention gastrocnemius lateral stiffness than the 90% 1RM HT, and 30% 1RM HS + BFRT had significantly higher post-intervention gastrocnemius medial stiffness than 90%1RMHS, 30%1RM HT + BFRT.Lastly, the 30%1RM HS + BFRT had significantly increased post-intervention tibialis anterior stiffness than the 90% 1RM HT, and higher tibialis anterior stiffness after the 30% 1RM HS + BFRT intervention than 30% 1RM HT + BFRT. Additionally, there was a significantly improved Achilles tendon stiffness after the 30% 1RM HS + BFRT intervention compared to the 30% 1RM HT + BFRT.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e (1) The study found that male sprinters experienced significant improvement in sprint performance after low-intensity barbell hip thrust resistance combined with blood flow restriction intervention compared to high-intensity barbell half-squat; (2) The positive effect of barbell half-squat exercise was significantly better than that barbell hip thrust on vertical jump performance; (3) Barbell half-squat exercise was found to have a significantly stronger positive effect than barbell hip thrust in decreasing the pennation angle of the rectus femoris muscle; (4) Both low-intensity barbell half squat and hip thrust exercises, when accompanied by blood flow restriction training intervention, were found to significantly improve lower extremity muscle-tendon stiffness.\u003c/p\u003e","manuscriptTitle":"Acute effects of low-intensity resistance combined with blood flow restriction and high-intensity resistance exercise on lower extremity explosive strength, pennation angle and muscle-tendon stiffness in male sprinters","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-26 14:06:49","doi":"10.21203/rs.3.rs-3952436/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"99eb3968-52d1-4b18-a263-216058b9cc0f","owner":[],"postedDate":"February 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":28947968,"name":"Biological sciences/Physiology"},{"id":28947969,"name":"Health sciences/Anatomy"}],"tags":[],"updatedAt":"2024-12-16T05:25:07+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-26 14:06:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3952436","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3952436","identity":"rs-3952436","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}