Investigation of pitching performance and physical changes associated with fatigue

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Pitching performance and physical changes were assessed across six cycles of 15 pitches with 10-minute rest intervals. The visual analogue scale was used to measure fatigue levels, while the active shoulder range of motion was also measured before and after each pitching cycle. The Rapsodo Pitching system was used to measure ball velocity, release point height, spin rate, and strike rate to evaluate pitching performance. Fatigue levels significantly increased after pitching cycle (p < 0.01), coupled with decreases in shoulder flexion on the throwing side (p = 0.02) as well as flexion and abduction on the non-throwing side (p = 0.03 and 0.02, respectively). The ball velocity decreased in the last cycle (p = 0.03), while no significant changes were observed in release point height, ball spin rate, or strike rate. Active shoulder flexion on the throwing side emerged as a more sensitive indicator of pitching-related fatigue than overall pitching form. These findings underscore the importance of post-game recovery for both the throwing and non-throwing sides to mitigate the effects of pitching fatigue on shoulder performance. Health sciences/Signs and symptoms/Fatigue Health sciences/Biomarkers/Predictive markers Baseball pitching Performance Fatigue Shoulder flexion Early indicator INTRODUCTION Pitching in baseball is a demanding activity associated with a risk of injury. Over recent years, there has been a marked escalation in the prevalence of shoulder and elbow ailments among young pitchers. Relative to the 1990s, the frequency of cases necessitating surgical intervention surged more than fourfold during the 2000s [ 1 , 2 ]. Fatigue associated with pitching is one cause of shoulder and elbow disorders in baseball players [ 1 , 2 ]. Shoulder and elbow disorders in young pitchers are not only a problem for the future of elite athletes but also a major issue in terms of athletic safety. Therefore, establishing measured for preventing shoulder and elbow disorders in pitchers is necessary. The stress caused by pitching leads to increased torque at the shoulder and elbow, which can lead to injury [ 3 – 7 ]. In addition, fatigue may disrupt the kinetic chain and further increase the risk of injury [ 2 , 8 ]. Overuse, high ball speed, and short rest times have been identified as predictors or risk factors for fatigue that are linked to kinematics, performance, tissue stress, and injury [ 1 , 2 , 9 – 13 ]. However, little has been elucidated about the physical changes in pitching behaviour associated with fatigue, especially during games. The purpose of this study was to investigate the changes in throwing performance as well as physical parameters induced by throwing fatigue. This study highlights physical changes and performance deteriorations associated with fatigue in baseball pitchers and emphasizes the importance of monitoring fatigue levels and maintaining proper shoulder function to prevent injury and optimize performance. METHODS Experimental Approach To investigate the effects of pitching-induced fatigue on physical parameters and performance, a descriptive laboratory study design was employed. This design allowed for the evaluation of pitching behaviour before and after repeated pitching cycles. By comparing pre- and post-pitching measurements, this study aimed to examine changes in pitching performance, fatigue levels, and active range of motion (ROM) of the shoulder. Participants Approval for this study was obtained from the ethics committee of Kitasato University School of Medicine (IRB No. C21-075, 01/07/2021), and the study was registered with Clinical Research registration number UMIN000044406. And all our methods were performed in accordance with the relevant guidelines and regulations. The study enrolled 21 healthy adult males who were active members of baseball clubs at universities or companies and engaged in daily baseball activities. Prior to participation, written informed consent was obtained from all players in accordance with the study institution’s institutional review board. The participants met the following inclusion criteria: regular pitching practice, 18 years or older, and voluntarily provided written informed consent. The exclusion criteria comprised participants experiencing shoulder pain that required anti-inflammatory analgesics, those who had recently undergone shoulder/elbow surgery, or those with pain in the shoulder/elbow on the evaluation day. Procedure Participants underwent a standardized protocol for pitching assessment. This involved pitching five warm-up throws from the mound followed by pitching fifteen consecutive throws. Between each pitching cycle, a 10-minute rest period was incorporated. The selection of a 10-minute interval was based on the average time taken for innings in baseball games ending in the ninth inning, as per data from the Nippon Professional Baseball Organization [ 14 ]. To consider the safety and established guidelines for pitch counts, a protocol of 15 pitches per cycle and six cycles was adopted. This approach aimed to simulate the fatigue and performance changes experienced by pitchers during a game while ensuring the well-being of participants. A comprehensive set of parameters was measured, including fatigue levels assessed using a 10-cm visual analogue scale (VAS), active ROM of the shoulder, ball velocity, spin rate, strike rate, and release point height. Active shoulder ROM was assessed using a goniometer, covering flexion, abduction, external rotation in the drooping position, internal rotation at 90° abduction, and internal rotation at 90° flexion. Ball-related metrics were measured using the Rapsodo Pitching 2.0 system (Rapsodo Inc., Singapore) Visual analogue scale Each pitcher completed a questionnaire rating subjective measures of fatigue and rated the degree of fatigue felt at the beginning and end of the game. Fatigue was quantified using a 10-point VAS, with the player marking his level of energy on a 10-cm line between ‘completely fatigued’ and ‘fully rested’. Active Shoulder ROM Shoulder ROM was measured for all participants. The active shoulder ROM was measured in the standing position in both the dominant and nondominant shoulders before and after measurement. All measurements were taken by one of two examiners, while a third examiner held the player in position. Shoulder flexion, abduction, external rotation, and internal rotation ROM were measured with the player in the standing position. Shoulder joint rotation angles were measured by three positions. First, the angle of external rotation of the shoulder was measured in the drooped position. Second, external and internal rotation of the shoulder were measured at 90° of shoulder abduction. Third, external and internal rotation at 90 degrees of shoulder flexion were measured. All measurements were performed at 90 degrees flexion of the elbow joint. Ball-related metrics The Rapsodo Pitching measurement technology has been widely adopted by Major League Baseball. Validation studies have previously shown that this system is useful for evaluating ball velocity, pitching motion, spin axis, and spin rate [ 15 – 17 ]. The Rapsodo Pitching unit was set up according to the manufacturer’s instructions and was not moved or changed during the measurement of each participant. In this study, we assessed the ball velocity, spin rate, height of the release point, and strike rate using the Rapsodo Pitching system. The release speed (km/h) was measured as the ball left the pitcher’s hand, and the spin rate was also measured in revolutions per minute (RPM). The release point height was measured as the vertical distance, in meter, between home plate and the pitcher’s vertical release point. The strike rate was evaluated by the strike zone analysis determine by Rapsodo Pitching system. Statistical Analysis Statistical analysis was performed using JMP® Pro 16.1.0 software (SAS Institute, Cary, NC, USA). The mean and standard deviation were calculated for relevant variables. Paired t-tests were employed to compare the first and last inning measurements of the height of the release point, ball velocity, and spin rate (rpm). Additionally, Wilcoxon signed-rank tests were utilized to analyse VAS scores, active shoulder ROM, and strike rates. Significance was set at 5% (α ≤ .05) for all tests. The use of traditional statistical methods and reporting of effect sizes and confidence intervals adhered to the study’s analytical approach. RESULTS The study included a diverse group of participants, with an average age of 23.1 years, a mean height of 175.7 ± 8.59 cm, and an average weight of 75.9 ± 10.46 kg. The majority of participants (n = 19) were right-handed, while two were left-handed. The VAS for fatigue levels showed a significant increase from (mean ± standard deviation) 2.8 ± 2.1 before pitching to 7.01 ± 1.45 after all six cycles of pitching (p < 0.01). In the evaluation of pitching performance, the pitch velocity significantly decreased from 117.1 ± 14.6 km/h in the first cycle to 114.6 ± 11.9 km/h in the last cycle (p = 0.03). In contrast, the number of ball rotations in the first (1,836.7 ± 309.5) and last cycle (1,827.9 ± 242.6) were not significantly different (p = 0.39). Similarly, no differences were observed in release point height (first cycle, 1.48 ± 0.23 m; last cycle, 1.46 ± 0.23 m; p = 0.44) or strike rate (first cycle, 28 ± 21%; last cycle, 34 ± 22%; p = 0.24; Table 1 ). Table 1 Evaluation of pitching performancea Inning Measurement 1st Last p-value Ball velocity, km/h 117.1 (14.6) 114.6 (11.9) 0.03 Number of rotations, r/s 1,836.7 (309.5) 1,827.9 (242.6) 0.39 Height of the release point, m 1.48 (0.23) 1.46 (0.23) 0.44 Strike rate, % 28 (21) 34 (22) 0.24 a Values are presented as mean (standard deviation); p < 0.05. In the assessment of shoulder ROM on the throwing side, flexion was 162.5 ± 7.5° and 156.6 ± 11.8° before and after pitching, respectively, with a statistically significant difference (p = 0.02). Conversely, abduction (p = 0.40) and external rotation (p = 0.49) were not significantly different before and after throwing. In the 90° abduction position, external rotation was 117.0 ± 12.7° and 120.0 ± 12.5° (p = 0.38), while internal rotation was 46.6 ± 14.7° and 37.6 ± 15.9° (p = 0.03), before and after throwing, respectively; differences were only observed for the internal rotation angle. In contrast, no significant difference was observed in the angles of external rotation at 90° flexion (p = 0.69) and internal rotation at 90° flexion (p = 0.09; Table 2 ). Table 2 Assessment of shoulder range of motion (ROM) on the throwing sidea Pretest Post-test p-value Flexion, ° 162.5 (7.5) 156.6 (11.8) 0.02 Abduction, ° 161.0 (12.3) 159.2 (13.4) 0.40 External rotation, ° 65.3 (14.4) 63.9 (15.2) 0.49 External rotation at 90° abduction, ° 117.0 (12.7) 120.0 (12.5) 0.38 External rotation at 90° flexion, ° 115.1 (14.8) 114.0 (15.2) 0.69 Internal rotation at 90° abduction, ° 46.6 (14.7) 37.6 (15.9) 0.03 Internal rotation at 90° flexion, ° 23 (18.1) 18.8 (13.1) 0.09 a Values are presented as mean (standard deviation); p < 0.05. In the assessment of shoulder ROM on the non-throwing side, significant differences before and after pitching were found in flexion (161.4 ± 8.4° and 155.3 ± 14.6°, respectively; p = 0.03) and abduction (165.2 ± 11.9° and 161.8 ± 9.4°, respectively; p = 0.02). However, external rotation did not significantly differ before and after pitching (p = 0.96). Upon evaluation in the 90° abduction position, external rotation was not significantly different (p = 0.80), while internal rotation significantly decreased from 52.3 ± 16.9° before pitching to 42.6 ± 23.2° after pitching (p = 0.02). Additionally, at 90° flexion, no significant differences were found in both the external (p = 0.05) and internal rotations (p = 0.96; Table 3 ). Table 3 Assessment of shoulder ROM on the non-throwing sidea Pretest Post-test p-value Flexion, ° 161.4 (8.4) 155.3 (14.6) 0.03 Abduction, ° 165.2 (11.9) 161.8 (9.4) 0.02 External rotation, ° 66.7 (14.9) 66.8 (15.2) 0.96 External rotation at 90° abduction, ° 108.7 (26.9) 110.1 (13.5) 0.80 External rotation at 90° flexion, ° 114.3 (14.9) 107.3 (16.8) 0.05 Internal rotation at 90° abduction, ° 52.3 (16.9) 42.6 (23.2) 0.02 Internal rotation at 90° flexion, ° 26.6 (17.9) 26.3 (17.7) 0.96 a Values are presented as mean (standard deviation); p < 0.05. DISCUSSION In a report on the physical changes induced by throwing fatigue, college students pitching in one simulated game showed changes in ball velocity only throughout each inning, with no significant differences in the maximum shoulder abduction angle during the cocking phase, the maximum horizontal abduction angle during the acceleration phase, or the maximum horizontal abduction angle during the acceleration phase, despite fatigue [ 18 ]. Another study reported that external rotation and the total ROM in the pitching shoulder significantly increased after pitching among adolescent pitchers [ 19 ]. In the present study, active flexion angles on the throwing side and ball velocity were significantly lower after 90 pitches, although the release point height, spin rate, and strike rate were not changed. These findings suggest that active flexion is more reliable than throwing form for the assessment of throwing fatigue. The prevalence of shoulder and elbow injuries among baseball players has become a significant concern in recent years [ 1 , 2 ]. In an effort to mitigate these injuries, various studies have observed that high school and college students with shoulder and elbow injuries threw an average of 88 pitches per game over six innings, compared to an average of 66 pitches per game over four innings in a group of uninjured pitchers [ 1 ]. Furthermore, evidence suggests that exceeding a pitch count of 80 pitches in a game significantly elevates the risk of injury necessitating surgical intervention [ 1 ]. In addition, another report showed a 35% increased risk of elbow pain and a 52% increased risk of shoulder pain by the 75-to-99 pitches per game level for youth baseball players [ 20 ]. In the present study, ball velocity and active shoulder elevation significantly decreased and VAS scores for fatigue significantly increased after six cycles of 15 pitches each. Therefore, this protocol, consisting of 90 pitches over six cycles, can serve as reliable method for evaluating physical alterations associated with pitching. Decrements in athletic performance and the incidence of injuries in athletes have been linked to muscular fatigue and compromised joint control [ 6 ]. Investigations examining the repercussions of fatigue accumulation in pitchers have documented notable decrease in maximum shoulder external rotation during the cocking phase [ 18 , 22 , 23 ], the knee angle at ball release [ 23 ], and hip-to-shoulder separation [ 19 ]. The present study demonstrated substantial fatigue after pitching, evaluated using VAS ratings. Concerning the performance decreases attributed to fatigue, no statistically significant differences were observed between the initial and final pitching cycles in the release point height. However, significant reductions in active shoulder flexion were noted on both the throwing and non-throwing sides following six cycles. Prior research has indicated increased deltoid muscle activity during the early cocking phase and after ball release, in addition to increased activity of the trapezius and serratus anterior muscles, correlated with shoulder flexion, from the early cocking phase to the acceleration phase [ 24 ]. Consequently, these muscles, associated with shoulder flexion, demonstrate indications of fatigue induced by pitching. Although the velocity of pitches notably decreased with increasing fatigue, the pitching motion remained largely consistent [ 18 ]. In a preceding study, 10 college baseball pitchers participated in simulated games from the 7th to the 9th inning, each allotted 15 pitches per inning. Despite the onset of fatigue, the biomechanical patterns exhibited by the pitchers during pitching remained largely consistent, leading to a decline solely in ball velocity [ 18 ]. Other reports have corroborated this finding, indicating a significant reduction in ball velocity with increasing fatigue accumulation, while pitching form remains relatively unchanged [ 9 , 21 ]. The present findings align with these prior investigations, suggesting that the impact of fatigue on pitching performance initially manifests as a decrease in ball velocity before alterations in pitching form occur. Consequently, these collective results indicate that pitching form may not serve as a reliable indicator of fatigue during pitching. Conversely, ball velocity may offer insights into pitching fatigue. However, the dynamic nature of this parameter, influenced by pitcher control and strategic considerations for each hitter, means that the ball is not consistently thrown at maximum speed. Therefore, ball velocity presents challenges when being used as an indicator of fatigue during games. Fatigue on the non-throwing side has been less frequently reported [ 22 ]. The present results revealed a significant decrease in both flexion and abduction angles on the non-throwing side, whereas a significant decrease was observed solely in flexion on the throwing side. These findings imply that the non-throwing side may exhibit comparable or even greater reductions in rotator cuff function compared to the throwing side. Consequently, our findings suggest the presence of fatigue on the non-throwing side as well. In a previous report, pitchers showed muscle weakness not only on the throwing side but also in the non-throwing shoulder before and after an average of 99 pitches [ 22 ]. Taken together, these findings confirm that comprehensive post-game care should encompass both the throwing and non-throwing sides. Additionally, training to enhance rotator cuff function on the non-throwing side may contribute to enhanced pitching performance. Nonetheless, further investigation is warranted to confirm improvements in throwing performance following enhancement of rotator cuff function on the non-throwing side. The active shoulder flexion angle on the throwing side emerged as a sensitive indicator of fatigue, outperforming pitching form evaluation. Coaches can utilize this metric to assess player fatigue during games and training sessions, enabling timely interventions to optimize performance and mitigate injury risks. Furthermore, our results highlight the necessity of paying equal attention to both the throwing and non-throwing shoulder sides. Post-game care encompassing both sides can lead to better overall shoulder health, potentially enhancing pitching longevity and sustained performance. An understanding of the intricate manifestations of fatigue-induced alterations in pitching behaviour enables coaches to tailor training protocols with greater precision. Targeted interventions aimed at preserving shoulder function bilaterally, particularly through specialized exercises, may serve as a preventive measure against injuries and foster enhanced pitching outcomes. These insights hold potential for shaping the formulation of evidence-based training methodologies that bridge the gap between theoretical findings and practical coaching implementations. This study furnishes valuable insights pertinent to coaches and practitioners within the realm of baseball. the present findings underscore the influence of fatigue on pitching performance and physiological parameters as well as the importance of vigilance in monitoring and managing fatigue levels among pitchers. Notably, a decline in active shoulder flexion can serve as an early indicator of pitching fatigue, offering pivotal information for in-game decision-making and player rotation strategies. This study has several limitations. First, the sample size was small, potentially limiting the generalizability of the findings. Given that pitching fatigue may vary according to factors such as age, sex, baseball experience, pitch count, and pitch characteristics (e.g., variation in pitch types), further investigations encompassing more diverse conditions are warranted. Second, the study participants ranged from collegiate baseball players to adult amateur team members, resulting in a wide disparity in skill levels. Consequently, additional research across different competitive levels and age groups is necessary to provide a comprehensive understanding of pitching fatigue. Nonetheless, it is noteworthy that elite athletes are relatively scarce, and the majority of individuals targeted for preventive measures are student or recreational level pitchers. Hence, we posit that the outcomes of this study hold relevance for a broad spectrum of baseball players. Thirdly, the evaluation exclusively focused on straight pitches, overlooking the varied repertoire of pitches encountered in actual gameplay, such as fastballs and breaking balls. Consequently, the potential impact of different pitch types warrants consideration in future investigations. Nevertheless, irrespective of demanding to investigate additional factors such as breaking balls, our findings underscore the utility of active shoulder flexion as an informative metric for assessing pitch fatigue in real-world scenarios. Finally, the absence of three-dimensional motion capture for the pitching motion limited the detail in the data on fatigue-induced changes assessed in this study. Thus, future research should employ comprehensive motion measurement techniques to facilitate a more nuanced evaluation of fatigue-related changes. In summary, this study offers actionable takeaways for coaches and practitioners working with baseball pitchers. The identified indicators of fatigue and their implications for performance and injury risk serve as essential tools for strategic decision-making, player development, and injury prevention. By integrating these findings into coaching strategies, practitioners can enhance player well-being and optimize their overall pitching performance. Declarations Competing Interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution DI measured pitching performance and physical changes and was involved in the writing all sections of this manuscript. TK was responsible for the integrity of this study, and he submitted an application for the research ethics review and revised the manuscript. RT provided logistic support for statistical analyses and revised the manuscript. KI, MM and RH measured pitching performance and physical changes. MK and HW managed the subjects and analyzed the data. NT provided administrative and logistic support during the study. GI and MT contributed to the data interpretation and critical revision of this manuscript. All authors approved the final version of the manuscript. Acknowledgement The authors thank Tetsu Youhu (Roots Baseball Academy) for lending us the use of his baseball field. Data Availability Data are available on request, due to privacy and ethical restrictions.The data that support the findings of this study are available on request to the corresponding author. The data are not publicly available because the information could compromise the privacy of the research participants. 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Upper and lower extremity muscle fatigue after a baseball pitching performance. Am. J. Sports Med. 33, 108–113 (2005). Murray, T. A., Cook, T. D., Werner, S. L., Schlegel, T. F., & Hawkins, R. J. The effects of extended play on professional baseball pitchers. Am. J. Sports Med. 29, 137–142 (2001). Escamilla, R. F., & Andrews, J. R. Shoulder muscle recruitment patterns and related biomechanics during upper extremity sports. Sports Med. 39, 569–590 (2009). 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-4231884","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":296902549,"identity":"99dd9810-598d-4202-8220-e5a8ab50e080","order_by":0,"name":"Daisuke Ishii","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Daisuke","middleName":"","lastName":"Ishii","suffix":""},{"id":296902551,"identity":"423b1fd2-a66e-491f-973a-a6c8736da1c5","order_by":1,"name":"Tomonori Kenmoku","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYLACHgYLBvYGBsYHCQY2QC5j4wEitEgw8BxjYDZ4UJAG0tJAtBY2yQcfDoMF8Gox5z98TOJNhYQcj3yPsUGCwXm7te2HgbbU2ETj0mI5Iy1Ncs4ZCWMeNh5DoF9uJ287kwjUciwttwGHFoMbPGbSvG0SifvZeEC23E42OwDUwthwGLeW8+e/gbTU97DxmEkkGJxLNjv/kICWAzlsIC0JPBAtB+zMbhCwBegXY0ugXwx72NKKgQ5LTjC7AbQlAY9fgCH28MabCht5HubDGx/++GNnb3Y+/eGDDzU2uB2GYHKA2YlglQk4lKNpYX8AIu3xKB4Fo2AUjIIRCgDzHGASb3gZ9gAAAABJRU5ErkJggg==","orcid":"","institution":"Kitasato University","correspondingAuthor":true,"prefix":"","firstName":"Tomonori","middleName":"","lastName":"Kenmoku","suffix":""},{"id":296902552,"identity":"d1fce144-4980-475c-afe1-b849048395ce","order_by":2,"name":"Ryo Tazawa","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Ryo","middleName":"","lastName":"Tazawa","suffix":""},{"id":296902554,"identity":"a3e962c6-2a75-4e65-a381-2e28df06da87","order_by":3,"name":"Kosuke Inoue","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Kosuke","middleName":"","lastName":"Inoue","suffix":""},{"id":296902556,"identity":"0d86531e-5e57-4d1c-a2fe-baba7ee42583","order_by":4,"name":"Mitsuyoshi Matsumoto","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Mitsuyoshi","middleName":"","lastName":"Matsumoto","suffix":""},{"id":296902558,"identity":"43a6dba2-4a04-4506-be93-30470dccb7d1","order_by":5,"name":"Masashi Kawabata","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Masashi","middleName":"","lastName":"Kawabata","suffix":""},{"id":296902560,"identity":"8dcad263-9907-4e2a-bddf-aa5e3e11054b","order_by":6,"name":"Hiroyuki Watanabe","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Hiroyuki","middleName":"","lastName":"Watanabe","suffix":""},{"id":296902562,"identity":"13aa219d-0e7b-4e63-b9a7-7c8b06cce5c8","order_by":7,"name":"Naonobu Takahira","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Naonobu","middleName":"","lastName":"Takahira","suffix":""},{"id":296902564,"identity":"80c795eb-0877-43f2-a8d8-6adc80c03246","order_by":8,"name":"Gen Inoue","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Gen","middleName":"","lastName":"Inoue","suffix":""},{"id":296902566,"identity":"d1e16faf-a36a-431f-ba70-6d04053348fb","order_by":9,"name":"Masashi Takaso","email":"","orcid":"","institution":"Kitasato University","correspondingAuthor":false,"prefix":"","firstName":"Masashi","middleName":"","lastName":"Takaso","suffix":""}],"badges":[],"createdAt":"2024-04-07 14:44:46","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4231884/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4231884/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":59856026,"identity":"11998e20-7d9a-4ea4-b23f-2d15de1a20d7","added_by":"auto","created_at":"2024-07-08 13:24:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":360978,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4231884/v1/e18f3dff-8d4f-43e6-9273-213b6fd14032.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Investigation of pitching performance and physical changes associated with fatigue","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003ePitching in baseball is a demanding activity associated with a risk of injury. Over recent years, there has been a marked escalation in the prevalence of shoulder and elbow ailments among young pitchers. Relative to the 1990s, the frequency of cases necessitating surgical intervention surged more than fourfold during the 2000s [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Fatigue associated with pitching is one cause of shoulder and elbow disorders in baseball players [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Shoulder and elbow disorders in young pitchers are not only a problem for the future of elite athletes but also a major issue in terms of athletic safety. Therefore, establishing measured for preventing shoulder and elbow disorders in pitchers is necessary.\u003c/p\u003e \u003cp\u003eThe stress caused by pitching leads to increased torque at the shoulder and elbow, which can lead to injury [\u003cspan additionalcitationids=\"CR4 CR5 CR6\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In addition, fatigue may disrupt the kinetic chain and further increase the risk of injury [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Overuse, high ball speed, and short rest times have been identified as predictors or risk factors for fatigue that are linked to kinematics, performance, tissue stress, and injury [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan additionalcitationids=\"CR10 CR11 CR12\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, little has been elucidated about the physical changes in pitching behaviour associated with fatigue, especially during games.\u003c/p\u003e \u003cp\u003eThe purpose of this study was to investigate the changes in throwing performance as well as physical parameters induced by throwing fatigue. This study highlights physical changes and performance deteriorations associated with fatigue in baseball pitchers and emphasizes the importance of monitoring fatigue levels and maintaining proper shoulder function to prevent injury and optimize performance.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eExperimental Approach\u003c/h2\u003e \u003cp\u003eTo investigate the effects of pitching-induced fatigue on physical parameters and performance, a descriptive laboratory study design was employed. This design allowed for the evaluation of pitching behaviour before and after repeated pitching cycles. By comparing pre- and post-pitching measurements, this study aimed to examine changes in pitching performance, fatigue levels, and active range of motion (ROM) of the shoulder.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eApproval for this study was obtained from the ethics committee of Kitasato University School of Medicine (IRB No. C21-075, 01/07/2021), and the study was registered with Clinical Research registration number UMIN000044406. And all our methods were performed in accordance with the relevant guidelines and regulations.\u003c/p\u003e \u003cp\u003eThe study enrolled 21 healthy adult males who were active members of baseball clubs at universities or companies and engaged in daily baseball activities. Prior to participation, written informed consent was obtained from all players in accordance with the study institution\u0026rsquo;s institutional review board.\u003c/p\u003e \u003cp\u003eThe participants met the following inclusion criteria: regular pitching practice, 18 years or older, and voluntarily provided written informed consent. The exclusion criteria comprised participants experiencing shoulder pain that required anti-inflammatory analgesics, those who had recently undergone shoulder/elbow surgery, or those with pain in the shoulder/elbow on the evaluation day.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eProcedure\u003c/h2\u003e \u003cp\u003eParticipants underwent a standardized protocol for pitching assessment. This involved pitching five warm-up throws from the mound followed by pitching fifteen consecutive throws. Between each pitching cycle, a 10-minute rest period was incorporated. The selection of a 10-minute interval was based on the average time taken for innings in baseball games ending in the ninth inning, as per data from the Nippon Professional Baseball Organization [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e To consider the safety and established guidelines for pitch counts, a protocol of 15 pitches per cycle and six cycles was adopted. This approach aimed to simulate the fatigue and performance changes experienced by pitchers during a game while ensuring the well-being of participants.\u003c/p\u003e \u003cp\u003eA comprehensive set of parameters was measured, including fatigue levels assessed using a 10-cm visual analogue scale (VAS), active ROM of the shoulder, ball velocity, spin rate, strike rate, and release point height. Active shoulder ROM was assessed using a goniometer, covering flexion, abduction, external rotation in the drooping position, internal rotation at 90\u0026deg; abduction, and internal rotation at 90\u0026deg; flexion.\u003c/p\u003e \u003cp\u003eBall-related metrics were measured using the Rapsodo Pitching 2.0 system (Rapsodo Inc., Singapore)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eVisual analogue scale\u003c/h2\u003e \u003cp\u003eEach pitcher completed a questionnaire rating subjective measures of fatigue and rated the degree of fatigue felt at the beginning and end of the game. Fatigue was quantified using a 10-point VAS, with the player marking his level of energy on a 10-cm line between \u0026lsquo;completely fatigued\u0026rsquo; and \u0026lsquo;fully rested\u0026rsquo;.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eActive Shoulder ROM\u003c/h2\u003e \u003cp\u003eShoulder ROM was measured for all participants. The active shoulder ROM was measured in the standing position in both the dominant and nondominant shoulders before and after measurement. All measurements were taken by one of two examiners, while a third examiner held the player in position. Shoulder flexion, abduction, external rotation, and internal rotation ROM were measured with the player in the standing position. Shoulder joint rotation angles were measured by three positions. First, the angle of external rotation of the shoulder was measured in the drooped position. Second, external and internal rotation of the shoulder were measured at 90\u0026deg; of shoulder abduction. Third, external and internal rotation at 90 degrees of shoulder flexion were measured. All measurements were performed at 90 degrees flexion of the elbow joint.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eBall-related metrics\u003c/h2\u003e \u003cp\u003eThe Rapsodo Pitching measurement technology has been widely adopted by Major League Baseball. Validation studies have previously shown that this system is useful for evaluating ball velocity, pitching motion, spin axis, and spin rate [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The Rapsodo Pitching unit was set up according to the manufacturer\u0026rsquo;s instructions and was not moved or changed during the measurement of each participant. In this study, we assessed the ball velocity, spin rate, height of the release point, and strike rate using the Rapsodo Pitching system. The release speed (km/h) was measured as the ball left the pitcher\u0026rsquo;s hand, and the spin rate was also measured in revolutions per minute (RPM). The release point height was measured as the vertical distance, in meter, between home plate and the pitcher\u0026rsquo;s vertical release point. The strike rate was evaluated by the strike zone analysis determine by Rapsodo Pitching system.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using JMP\u0026reg; Pro 16.1.0 software (SAS Institute, Cary, NC, USA). The mean and standard deviation were calculated for relevant variables. Paired t-tests were employed to compare the first and last inning measurements of the height of the release point, ball velocity, and spin rate (rpm). Additionally, Wilcoxon signed-rank tests were utilized to analyse VAS scores, active shoulder ROM, and strike rates. Significance was set at 5% (α\u0026thinsp;\u0026le;\u0026thinsp;.05) for all tests. The use of traditional statistical methods and reporting of effect sizes and confidence intervals adhered to the study\u0026rsquo;s analytical approach.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThe study included a diverse group of participants, with an average age of 23.1 years, a mean height of 175.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.59 cm, and an average weight of 75.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.46 kg. The majority of participants (n\u0026thinsp;=\u0026thinsp;19) were right-handed, while two were left-handed.\u003c/p\u003e \u003cp\u003eThe VAS for fatigue levels showed a significant increase from (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation) 2.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 before pitching to 7.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.45 after all six cycles of pitching (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). In the evaluation of pitching performance, the pitch velocity significantly decreased from 117.1\u0026thinsp;\u0026plusmn;\u0026thinsp;14.6 km/h in the first cycle to 114.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.9 km/h in the last cycle (p\u0026thinsp;=\u0026thinsp;0.03). In contrast, the number of ball rotations in the first (1,836.7 \u0026plusmn; 309.5) and last cycle (1,827.9 \u0026plusmn; 242.6) were not significantly different (p\u0026thinsp;=\u0026thinsp;0.39). Similarly, no differences were observed in release point height (first cycle, 1.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23 m; last cycle, 1.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23 m; p\u0026thinsp;=\u0026thinsp;0.44) or strike rate (first cycle, 28\u0026thinsp;\u0026plusmn;\u0026thinsp;21%; last cycle, 34\u0026thinsp;\u0026plusmn;\u0026thinsp;22%; p\u0026thinsp;=\u0026thinsp;0.24; Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEvaluation of pitching performancea\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eInning\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMeasurement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1st\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLast\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBall velocity, km/h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e117.1 (14.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e114.6 (11.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of rotations, r/s\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1,836.7 (309.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,827.9 (242.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.39\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight of the release point, m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.48 (0.23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.46 (0.23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStrike rate, %\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28 (21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34 (22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003eValues are presented as mean (standard deviation); p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the assessment of shoulder ROM on the throwing side, flexion was 162.5\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5\u0026deg; and 156.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.8\u0026deg; before and after pitching, respectively, with a statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.02). Conversely, abduction (p\u0026thinsp;=\u0026thinsp;0.40) and external rotation (p\u0026thinsp;=\u0026thinsp;0.49) were not significantly different before and after throwing. In the 90\u0026deg; abduction position, external rotation was 117.0\u0026thinsp;\u0026plusmn;\u0026thinsp;12.7\u0026deg; and 120.0\u0026thinsp;\u0026plusmn;\u0026thinsp;12.5\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.38), while internal rotation was 46.6\u0026thinsp;\u0026plusmn;\u0026thinsp;14.7\u0026deg; and 37.6\u0026thinsp;\u0026plusmn;\u0026thinsp;15.9\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.03), before and after throwing, respectively; differences were only observed for the internal rotation angle. In contrast, no significant difference was observed in the angles of external rotation at 90\u0026deg; flexion (p\u0026thinsp;=\u0026thinsp;0.69) and internal rotation at 90\u0026deg; flexion (p\u0026thinsp;=\u0026thinsp;0.09; Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssessment of shoulder range of motion (ROM) on the throwing sidea\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePretest\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePost-test\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFlexion, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e162.5 (7.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e156.6 (11.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbduction, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e161.0 (12.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e159.2 (13.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExternal rotation, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65.3 (14.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63.9 (15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExternal rotation at 90\u0026deg; abduction, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e117.0 (12.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120.0 (12.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExternal rotation at 90\u0026deg; flexion, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e115.1 (14.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e114.0 (15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.69\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInternal rotation at 90\u0026deg; abduction, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46.6 (14.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.6 (15.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInternal rotation at 90\u0026deg; flexion, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23 (18.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.8 (13.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003eValues are presented as mean (standard deviation); p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the assessment of shoulder ROM on the non-throwing side, significant differences before and after pitching were found in flexion (161.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u0026deg; and 155.3\u0026thinsp;\u0026plusmn;\u0026thinsp;14.6\u0026deg;, respectively; p\u0026thinsp;=\u0026thinsp;0.03) and abduction (165.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.9\u0026deg; and 161.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u0026deg;, respectively; p\u0026thinsp;=\u0026thinsp;0.02). However, external rotation did not significantly differ before and after pitching (p\u0026thinsp;=\u0026thinsp;0.96). Upon evaluation in the 90\u0026deg; abduction position, external rotation was not significantly different (p\u0026thinsp;=\u0026thinsp;0.80), while internal rotation significantly decreased from 52.3\u0026thinsp;\u0026plusmn;\u0026thinsp;16.9\u0026deg; before pitching to 42.6\u0026thinsp;\u0026plusmn;\u0026thinsp;23.2\u0026deg; after pitching (p\u0026thinsp;=\u0026thinsp;0.02). Additionally, at 90\u0026deg; flexion, no significant differences were found in both the external (p\u0026thinsp;=\u0026thinsp;0.05) and internal rotations (p\u0026thinsp;=\u0026thinsp;0.96; Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssessment of shoulder ROM on the non-throwing sidea\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePretest\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePost-test\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFlexion, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e161.4 (8.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e155.3 (14.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbduction, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e165.2 (11.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e161.8 (9.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExternal rotation, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66.7 (14.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66.8 (15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExternal rotation at 90\u0026deg; abduction, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e108.7 (26.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e110.1 (13.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExternal rotation at 90\u0026deg; flexion, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e114.3 (14.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e107.3 (16.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInternal rotation at 90\u0026deg; abduction, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52.3 (16.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.6 (23.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInternal rotation at 90\u0026deg; flexion, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.6 (17.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.3 (17.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003eValues are presented as mean (standard deviation); p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eIn a report on the physical changes induced by throwing fatigue, college students pitching in one simulated game showed changes in ball velocity only throughout each inning, with no significant differences in the maximum shoulder abduction angle during the cocking phase, the maximum horizontal abduction angle during the acceleration phase, or the maximum horizontal abduction angle during the acceleration phase, despite fatigue [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Another study reported that external rotation and the total ROM in the pitching shoulder significantly increased after pitching among adolescent pitchers [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In the present study, active flexion angles on the throwing side and ball velocity were significantly lower after 90 pitches, although the release point height, spin rate, and strike rate were not changed. These findings suggest that active flexion is more reliable than throwing form for the assessment of throwing fatigue.\u003c/p\u003e \u003cp\u003eThe prevalence of shoulder and elbow injuries among baseball players has become a significant concern in recent years [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In an effort to mitigate these injuries, various studies have observed that high school and college students with shoulder and elbow injuries threw an average of 88 pitches per game over six innings, compared to an average of 66 pitches per game over four innings in a group of uninjured pitchers [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Furthermore, evidence suggests that exceeding a pitch count of 80 pitches in a game significantly elevates the risk of injury necessitating surgical intervention [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In addition, another report showed a 35% increased risk of elbow pain and a 52% increased risk of shoulder pain by the 75-to-99 pitches per game level for youth baseball players [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In the present study, ball velocity and active shoulder elevation significantly decreased and VAS scores for fatigue significantly increased after six cycles of 15 pitches each. Therefore, this protocol, consisting of 90 pitches over six cycles, can serve as reliable method for evaluating physical alterations associated with pitching.\u003c/p\u003e \u003cp\u003eDecrements in athletic performance and the incidence of injuries in athletes have been linked to muscular fatigue and compromised joint control [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Investigations examining the repercussions of fatigue accumulation in pitchers have documented notable decrease in maximum shoulder external rotation during the cocking phase [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], the knee angle at ball release [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], and hip-to-shoulder separation [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The present study demonstrated substantial fatigue after pitching, evaluated using VAS ratings. Concerning the performance decreases attributed to fatigue, no statistically significant differences were observed between the initial and final pitching cycles in the release point height. However, significant reductions in active shoulder flexion were noted on both the throwing and non-throwing sides following six cycles. Prior research has indicated increased deltoid muscle activity during the early cocking phase and after ball release, in addition to increased activity of the trapezius and serratus anterior muscles, correlated with shoulder flexion, from the early cocking phase to the acceleration phase [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Consequently, these muscles, associated with shoulder flexion, demonstrate indications of fatigue induced by pitching. Although the velocity of pitches notably decreased with increasing fatigue, the pitching motion remained largely consistent [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In a preceding study, 10 college baseball pitchers participated in simulated games from the 7th to the 9th inning, each allotted 15 pitches per inning. Despite the onset of fatigue, the biomechanical patterns exhibited by the pitchers during pitching remained largely consistent, leading to a decline solely in ball velocity [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Other reports have corroborated this finding, indicating a significant reduction in ball velocity with increasing fatigue accumulation, while pitching form remains relatively unchanged [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The present findings align with these prior investigations, suggesting that the impact of fatigue on pitching performance initially manifests as a decrease in ball velocity before alterations in pitching form occur. Consequently, these collective results indicate that pitching form may not serve as a reliable indicator of fatigue during pitching. Conversely, ball velocity may offer insights into pitching fatigue. However, the dynamic nature of this parameter, influenced by pitcher control and strategic considerations for each hitter, means that the ball is not consistently thrown at maximum speed. Therefore, ball velocity presents challenges when being used as an indicator of fatigue during games.\u003c/p\u003e \u003cp\u003eFatigue on the non-throwing side has been less frequently reported [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The present results revealed a significant decrease in both flexion and abduction angles on the non-throwing side, whereas a significant decrease was observed solely in flexion on the throwing side. These findings imply that the non-throwing side may exhibit comparable or even greater reductions in rotator cuff function compared to the throwing side. Consequently, our findings suggest the presence of fatigue on the non-throwing side as well. In a previous report, pitchers showed muscle weakness not only on the throwing side but also in the non-throwing shoulder before and after an average of 99 pitches [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTaken together, these findings confirm that comprehensive post-game care should encompass both the throwing and non-throwing sides. Additionally, training to enhance rotator cuff function on the non-throwing side may contribute to enhanced pitching performance. Nonetheless, further investigation is warranted to confirm improvements in throwing performance following enhancement of rotator cuff function on the non-throwing side. The active shoulder flexion angle on the throwing side emerged as a sensitive indicator of fatigue, outperforming pitching form evaluation. Coaches can utilize this metric to assess player fatigue during games and training sessions, enabling timely interventions to optimize performance and mitigate injury risks. Furthermore, our results highlight the necessity of paying equal attention to both the throwing and non-throwing shoulder sides. Post-game care encompassing both sides can lead to better overall shoulder health, potentially enhancing pitching longevity and sustained performance.\u003c/p\u003e \u003cp\u003eAn understanding of the intricate manifestations of fatigue-induced alterations in pitching behaviour enables coaches to tailor training protocols with greater precision. Targeted interventions aimed at preserving shoulder function bilaterally, particularly through specialized exercises, may serve as a preventive measure against injuries and foster enhanced pitching outcomes. These insights hold potential for shaping the formulation of evidence-based training methodologies that bridge the gap between theoretical findings and practical coaching implementations. This study furnishes valuable insights pertinent to coaches and practitioners within the realm of baseball. the present findings underscore the influence of fatigue on pitching performance and physiological parameters as well as the importance of vigilance in monitoring and managing fatigue levels among pitchers. Notably, a decline in active shoulder flexion can serve as an early indicator of pitching fatigue, offering pivotal information for in-game decision-making and player rotation strategies.\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, the sample size was small, potentially limiting the generalizability of the findings. Given that pitching fatigue may vary according to factors such as age, sex, baseball experience, pitch count, and pitch characteristics (e.g., variation in pitch types), further investigations encompassing more diverse conditions are warranted. Second, the study participants ranged from collegiate baseball players to adult amateur team members, resulting in a wide disparity in skill levels. Consequently, additional research across different competitive levels and age groups is necessary to provide a comprehensive understanding of pitching fatigue. Nonetheless, it is noteworthy that elite athletes are relatively scarce, and the majority of individuals targeted for preventive measures are student or recreational level pitchers. Hence, we posit that the outcomes of this study hold relevance for a broad spectrum of baseball players. Thirdly, the evaluation exclusively focused on straight pitches, overlooking the varied repertoire of pitches encountered in actual gameplay, such as fastballs and breaking balls. Consequently, the potential impact of different pitch types warrants consideration in future investigations. Nevertheless, irrespective of demanding to investigate additional factors such as breaking balls, our findings underscore the utility of active shoulder flexion as an informative metric for assessing pitch fatigue in real-world scenarios. Finally, the absence of three-dimensional motion capture for the pitching motion limited the detail in the data on fatigue-induced changes assessed in this study. Thus, future research should employ comprehensive motion measurement techniques to facilitate a more nuanced evaluation of fatigue-related changes.\u003c/p\u003e \u003cp\u003eIn summary, this study offers actionable takeaways for coaches and practitioners working with baseball pitchers. The identified indicators of fatigue and their implications for performance and injury risk serve as essential tools for strategic decision-making, player development, and injury prevention. By integrating these findings into coaching strategies, practitioners can enhance player well-being and optimize their overall pitching performance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting Interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDI measured pitching performance and physical changes and was involved in the writing all sections of this manuscript. TK was responsible for the integrity of this study, and he submitted an application for the research ethics review and revised the manuscript. RT provided logistic support for statistical analyses and revised the manuscript. KI, MM and RH measured pitching performance and physical changes. MK and HW managed the subjects and analyzed the data. NT provided administrative and logistic support during the study. GI and MT contributed to the data interpretation and critical revision of this manuscript. All authors approved the final version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors thank Tetsu Youhu (Roots Baseball Academy) for lending us the use of his baseball field.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData are available on request, due to privacy and ethical restrictions.The data that support the findings of this study are available on request to the corresponding author. The data are not publicly available because the information could compromise the privacy of the research participants.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eOlsen, S. J., Fleisig, G. S., Dun, S., Loftice, J., \u0026amp; Andrews, J. R. Risk factors for shoulder and elbow injuries in adolescent baseball pitchers. Am. J. Sports Med. 34, 905\u0026ndash;912 (2006).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLyman, S., et al. Longitudinal study of elbow and shoulder pain in youth baseball pitchers. Med. Sci. Sports Exerc. 33, 1803\u0026ndash;1810 (2001).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAguinaldo, A. L., \u0026amp; Chambers, H. Correlation of throwing mechanics with elbow valgus load in adult baseball pitchers. Am. J. Sports Med. 37, 2043\u0026ndash;2048 (2009).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnz, A. W., Bushnell, B. D., Griffin, L. P., Noonan, T. 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Sports Med. 39, 569\u0026ndash;590 (2009).\u003c/span\u003e\u003c/li\u003e\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":"Baseball pitching, Performance, Fatigue, Shoulder flexion, Early indicator","lastPublishedDoi":"10.21203/rs.3.rs-4231884/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4231884/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this study, the impact of repeated pitching on the shoulder performance and physical parameters was examined in 21 male baseball players, averaging 23.1 years old. Pitching performance and physical changes were assessed across six cycles of 15 pitches with 10-minute rest intervals. The visual analogue scale was used to measure fatigue levels, while the active shoulder range of motion was also measured before and after each pitching cycle. The Rapsodo Pitching system was used to measure ball velocity, release point height, spin rate, and strike rate to evaluate pitching performance. Fatigue levels significantly increased after pitching cycle (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), coupled with decreases in shoulder flexion on the throwing side (p\u0026thinsp;=\u0026thinsp;0.02) as well as flexion and abduction on the non-throwing side (p\u0026thinsp;=\u0026thinsp;0.03 and 0.02, respectively). The ball velocity decreased in the last cycle (p\u0026thinsp;=\u0026thinsp;0.03), while no significant changes were observed in release point height, ball spin rate, or strike rate. Active shoulder flexion on the throwing side emerged as a more sensitive indicator of pitching-related fatigue than overall pitching form. These findings underscore the importance of post-game recovery for both the throwing and non-throwing sides to mitigate the effects of pitching fatigue on shoulder performance.\u003c/p\u003e","manuscriptTitle":"Investigation of pitching performance and physical changes associated with fatigue","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-30 18:33:02","doi":"10.21203/rs.3.rs-4231884/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":"2303ccf3-e513-4c93-a10e-cf6305e7d076","owner":[],"postedDate":"April 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":31317206,"name":"Health sciences/Signs and symptoms/Fatigue"},{"id":31317208,"name":"Health sciences/Biomarkers/Predictive markers"}],"tags":[],"updatedAt":"2024-07-08T13:16:17+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-30 18:33:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4231884","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4231884","identity":"rs-4231884","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}