In vivo biomechanical quantification and individual factor analysis of lever positioning manipulation under different thrust modes：a cross-sectional study

In vivo biomechanical quantification and individual factor analysis of lever positioning manipulation under different thrust modes：a cross-sectional study | 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 Research Article In vivo biomechanical quantification and individual factor analysis of lever positioning manipulation under different thrust modes：a cross-sectional study Qiong Xia, Longhao Chen, Kaizheng Wang, Binghao Wang, Ziyu Zhang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7723433/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 Background Lever Positioning Manipulation (LPM), an innovative manual therapy derived from traditional lumbar extension manipulation in Traditional Chinese Medicine, has been clinically proven to be effective in treating Lumbar Disc Herniation (LDH). However, clinical observations indicate significant individual variations in patients' responses to LPM treatment, with therapeutic outcomes closely related to the applied manipulation force and individual patient characteristics. Therefore, conducting quantitative research on the mechanical parameters of different LPM manipulation modes and analyzing individual factors hold significant clinical importance. Methods A total of 107 volunteers were recruited from the Department of Tuina, The Third Affiliated Hospital of Zhejiang Chinese Medical University. Biomechanical data of unilateral and bilateral LPM were collected using wearable gloves and elbow sleeves, including hand preload force (HPF), hand maximum pulling force (HMPF), hand instantaneous pulling force (HIPF), elbow preload force (EPF), elbow maximum pressing force (EMPF), and elbow instantaneous pressing force (EIPF). Individual characteristic parameters recorded included waist circumference (WC), femur length (FL), lumbosacral angle (LA), lumbar curvature (LC), and lumbar lordosis angle (LLA). Quantitative and correlation analyses were conducted. Results No significant differences were found between left- and right-sided unilateral manipulations (p > 0.05). Compared with LDH patients, healthy participants showed significant differences in EPF-A (p < 0.05), but not in other parameters. In unilateral LPM, EMPF-U correlated strongly with EIPF-U (p < 0.01), HMPF-U with both HIPF-U and HPF-U (p < 0.01), and EPF-U with EMPF-U (p < 0.05). In bilateral LPM, HMPF-A correlated with HIPF-A (p < 0.01); EPF-A correlated positively with EMPF-A (p < 0.05) but negatively with EIPF-A (p < 0.05). EMPF-A and EIPF-A were positively correlated (p < 0.01). Regarding individual characteristics, EPF-U negatively correlated with LC (p < 0.05); in bilateral LPM, HMPF-A correlated positively with WC (p < 0.05), and EPF-A negatively with FL (p < 0.05). Conclusion This study quantitatively defined biomechanical profiles of unilateral and bilateral LPM and clarified inter-parameter correlations and their associations with individual characteristic parameters. Findings support tailoring manipulation strategies based on lumbar curvature, waist circumference, and femur length to optimize individualized, precision treatment for LDH. Trial registration The study protocol was registered at ClinicalTrials.gov (ClinicalTrials.gov Registration Number and Date: NCT06872918, Initial Release: 10/03/2025). Lever positioning manipulation (LPM) Lumbar disc herniation (LDH) Lumbar disc degeneration Biomechanics Individual characteristics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1 Introduction LDH is a prevalent degenerative spinal disorder, affecting approximately 2%–3% of the global population [ 1 ] . In recent years, lifestyle changes have contributed to an increasing incidence and a trend toward younger onset, making LDH an important public health concern [ 2 , 3 ] . Although surgical intervention is a commonly used treatment option, it carries a 2.7% complication rate and a 2.1% reoperation rate within 90 days postoperatively [ 4 ] . In contrast, non-surgical management remains the first-line approach for most patients, alleviating symptoms in 80%–90% of cases [ 5 , 6 ] . In traditional Chinese medicine (TCM), LDH is categorized under the concepts of Bi syndrome and tendon disorders . Among various TCM modalities, spinal manipulation—particularly Tuina therapy—has been widely employed due to its minimal adverse effects and high safety profile [ 7 , 8 ] . LPM is a specialized manual therapy derived from conventional lumbar extension manipulation and refined by incorporating modern anatomical and biomechanical principles. Clinical evidence has demonstrated its efficacy in managing LDH and facet joint subluxation [ 9 ] . This technique applies a “high-velocity, low-amplitude” force based on an energy-efficient lever principle, delivering targeted mechanical input to specific lumbar segments to correct joint misalignment, relieve nerve root compression, and restore the balance of spinal alignment and soft tissue tension [ 10 ] .As a biomechanically demanding intervention, the therapeutic effectiveness of LPM is closely related to both the magnitude and pattern of applied forces, as well as the patient’s individual anatomical characteristics. Building upon previous research [ 11 ] , our team has modified LPM into two distinct patterns: bilateral manipulation (cross-legged) and unilateral manipulation (affected-side leg). Using a biomechanical acquisition system, this study aims to quantify the force parameters of both patterns to elucidate their underlying mechanisms of action. Such quantitative biomechanical profiling not only provides objective evidence for clinical practice and facilitates visualized training but also enables the development of individualized force application strategies tailored to patient-specific characteristics [ 12 ] . Furthermore, investigating the correlation between manipulation forces and patient anatomical parameters (e.g., structural features and imaging metrics) may help refine operational protocols, thereby enhancing both the safety and effectiveness of treatment [ 13 ] . 2 Materials and Methods 2.1 Participants From June 2024 to March 2025, a total of 107 volunteers were recruited from the Department of Tuina, The Third Affiliated Hospital of Zhejiang Chinese Medical University. Prior to participation, all individuals were informed of the study objectives, procedures, precautions, and potential risks. Written informed consent was obtained from each participant. The study flowchart is presented in Fig. 1 . The study protocol was approved by the Ethics Committee of the Third Affiliated Hospital of Zhejiang Chinese Medical University (Approval No.: ZSLL-KY-2024-080-01).Additionally, the study protocol was registered on ClinicalTrials.gov (Registration No.: NCT06872918). 2.2 Study Design and Grouping This investigation was designed as a biomechanical parameter quantification study of LPM, aiming to obtain standardized mechanical data. To minimize the influence of inter-individual variability among LDH patients on force measurements, a case–control design was adopted, with healthy volunteers serving as the control group to reduce confounding bias. A total of 107 participants were enrolled: 57 patients with LDH (25 central type, 32 paracentral type) and 50 healthy controls (25 central type, 25 paracentral type). Intervention assignment was determined according to anatomical subtype: participants with central-type LDH received the bilateral LPM pattern, whereas those with paracentral-type LDH received the unilateral LPM pattern. All manipulations were performed using a standardized LPM protocol previously validated for safety, with no adverse effects observed in healthy volunteers during preliminary testing. 2.3 Diagnostic Criteria The diagnosis of LDH was established according to the Guidelines for the Diagnosis and Treatment of Lumbar Disc Herniation (2020 Edition) issued by the Spine Surgery Group of the Orthopedic Branch of the Chinese Medical Association [ 14 ] . Diagnostic confirmation required both imaging evidence—lumbar MRI or CT demonstrating disc herniation consistent with the clinical level of nerve compression—and clinical manifestations meeting at least three of the following five criteria: (1) radiating lower limb pain within the distribution of the affected nerve root; (2) sensory disturbance in the corresponding dermatome (e.g., hypoesthesia or hyperesthesia); (3) positive nerve root tension signs, such as the straight leg raise test, Bragard’s test, crossed straight leg raise test, or femoral nerve stretch test; (4) diminished deep tendon reflexes compared with the contralateral side; and (5) muscle weakness in the relevant myotomal distribution. 2.4 Inclusion and Exclusion Criteria 2.4.1 Inclusion Criteria For the LDH group: (1) meeting the diagnostic criteria for LDH (central, paracentral, or far-lateral type) with imaging findings consistent with neurological localization signs; (2) age between 18 and 35 years, regardless of sex; (3) non-acute stage, presenting with mild-to-moderate pain and functional impairment, with symptom duration ≥ 2 weeks; (4) willingness to provide written informed consent. For the healthy control group: (1) age between 18 and 35 years, regardless of sex; (2) no history of low back pain or spinal disorders; (3) normal physical examination findings and a body mass index (BMI) of 18.5–24.9 kg/m²; (4) willingness to provide written informed consent. 2.4.2 Exclusion Criteria Participants were excluded if they had any of the following: (1) structural lumbar pathology, such as fracture, dislocation, tumor, tuberculosis, fused vertebrae, or paravertebral bony bridging; (2) history of lumbar surgery or severe trauma; (3) local dermatological lesions, such as lumbar skin inflammation or open wounds; (4) severe systemic diseases, including primary disorders of the cardiovascular, hepatic, renal, or hematopoietic systems, psychiatric disorders, or severe osteoporosis (T-score ≤ − 2.5); (5) special conditions, including pregnancy or extreme frailty; (6) neuropathic conditions, such as primary or dry sciatica; (7) factors interfering with study integrity, such as concurrent participation in other manual therapy trials that could influence outcomes, or the occurrence of intolerable adverse reactions. 2.5 Withdrawal Criteria Participants were withdrawn if: (1) data acquisition failed due to force majeure (e.g., equipment malfunction, natural disasters); or (2) they failed to comply with the study protocol requirements or voluntarily withdrew from the study. 2.6 Termination Criteria Intervention was immediately terminated if: (1) an adverse event occurred during manipulation; or (2) the participant developed discomfort during intervention and requested cessation. 3 Experimental Equipment and Methods 3.1 Experimental Equipment A wearable biomechanical measurement system, developed by the Institute of Orthopaedics and Traumatology, China Academy of Chinese Medical Sciences (Utility Model Patent No. 201620427405.8), was employed in this study. The system’s core components included specially designed biomechanical measurement gloves and elbow sleeves, with evenly distributed dot-type pressure sensors on the glove surface that directly contacted the participant’s skin for measurement (Fig.2A, Fig.2B). The sensor assembly consisted of resistive strain gauges and elastic elements, integrated with a dual-axis accelerometer to convert detected pressure into real-time voltage output. Data acquisition was performed at a continuous sampling frequency of 100 Hz to ensure temporal accuracy (Fig. 2C). Data were transmitted in real time via a wireless transmission system based on a CSR Bluetooth chip (V5.0 protocol) with dual-channel transmitters for the left and right sides, supporting 5 V/3.3 V logic-level interfaces, maintaining stable transmission within 10 m, and achieving a tested latency of < 50 ms. Data collection and analysis were conducted using self-developed intelligent biomechanical acquisition software, programmed in C language, compatible with Windows 10 or later. The software included four main modules—device configuration, connection control, data acquisition, and real-time display—supporting synchronous multi-channel sensor data processing with 16-bit resolution, and offering storage and export functions (Fig. 2D). 3.2 Experimental Methods 3.2.1 LPM Treatment Procedure All LPM manipulations were performed by the same expert (Professor Lv Lijiang) with 33 years of clinical experience in Tuina therapy. A stratified intervention protocol was adopted: patients with central-type LDH received bilateral manipulation mode, whereas those with para-central-type LDH received unilateral manipulation mode. Each participant underwent three standardized treatments with at least 48 hours between sessions, and the average of the three biomechanical measurements was used for analysis. Healthy volunteers receiving the unilateral manipulation mode underwent symmetrical operations on both sides (one on each side) to ensure data comparability. Before treatment, a standardized 15-minute Tuina session was performed to relax the lumbar soft tissues, including the one-finger meditation pushing method (focusing on the erector spinae), rolling method (applied to the lumbosacral region), pressing-kneading method (targeting paraspinal tender points), and plucking method (to separate adhesions). Participants were placed in a prone position with the mouth open, muscles relaxed, and breathing naturally throughout the treatment. (1) Unilateral Manipulation Mode (e.g., left para-central protrusion) The practitioner stood on the patient’s right side, placing the olecranon of the right ulna precisely against the targeted vertebra (approximately 1 cm lateral to the affected segment). The practitioner firmly held the patient’s left ankle, flexing the leg backward and upward using leverage. When resistance was encountered during hyperextension, the ankle joint was rapidly pulled upward while the right elbow simultaneously pressed downward on the targeted vertebra until the protrusion loosened or a “click” was felt (Fig.3A). (2) Bilateral Manipulation Mode The patient’s legs were crossed and fixed. After lumbar positioning, the practitioner placed the olecranon of the right ulna precisely against the targeted vertebra (approximately 1 cm lateral to the affected segment). Both ankles were held, and the legs were hyperextended upward using leverage. Upon encountering resistance, the practitioner applied a rapid pulling force while pressing downward with the right elbow, producing loosening or a “click” at the protrusion site(Fig.3B). 3.2.2 In Vivo Biomechanical Measurement and Parameters Following the operational characteristics of LPM, this study quantified the key biomechanical parameters of the practitioner’s hands and elbows. Measurements were performed using the wearable biomechanical sensor system (gloves and elbow sleeves) with a 100 Hz sampling frequency. All devices were calibrated and zero-adjusted before operation to ensure accuracy. Six biomechanical parameters were recorded: Hand Preload Force (HPF), Hand Maximum Pulling Force (HMPF), Hand Instantaneous Pulling Force (HIPF), Elbow Preload Force (EPF), Elbow Maximum Pressing Force (EMPF), and Elbow Instantaneous Pressing Force (EIPF), with definitions provided in Table 1. Data were wirelessly transmitted in real time to a computer system, and force–time curves were plotted to analyze manipulation characteristics. In the unilateral manipulation mode (para-central LDH), only the affected side was recorded for LDH patients, whereas both sides were recorded for healthy volunteers to allow symmetry comparison. In the bilateral manipulation mode (central LDH), operations were uniformly performed on the participant’s right side without bilateral comparison. All parameters were recorded continuously throughout the procedure, with particular attention to the preload phase, maximum pulling phase, and instantaneous pulling phase. Table 1. Biomechanical parameters of manipulation measured by pressure sensors Parameter Description Hand Preload Force,HPF(N) Positioning pressure applied by the hand during the preparation phase (HPF-U for unilateral, HPF-B for bilateral) Hand Maximum Pulling Force,HMPF(N) Peak hand force during the pulling phase (HMPF-U for unilateral, HMPF-B for bilateral) Hand Instantaneous Pulling Force,HIPF(N) Dynamic increase in hand force during rapid pulling, calculated as HIPF = HMPF − HPF (HIPF-U for unilateral, HIPF-B for bilateral) Elbow Preload Force,EPF(N) Positioning pressure applied by the elbow during the preparation phase (EPF-U for unilateral, EPF-B for bilateral) Elbow Maximum Pressing Force ,EMPF(N) Peak elbow force during the pressing phase (EMPF-U for unilateral, EMPF-B for bilateral) Elbow Instantaneous Pressing Force,EIPF(N) Dynamic increase in elbow force during rapid pressing, calculated as EIPF = EMPF − EPF (EIPF-U for unilateral, EIPF-B for bilateral) Note: (1) All parameters were measured in triplicate to ensure data reliability. (2) For patients with LDH, only affected-side parameters were collected. Healthy volunteers in the unilateral manipulation group underwent bilateral parameter acquisition (both left and right sides) to enable comparative analysis. 3.2.3 Measurement of Individual Characteristics (1) Baseline Information Two trained researchers jointly collected participant data, including age (years), sex (male/female), height (cm), and weight (kg), using standardized procedures. Each parameter was measured twice independently by both assessors, and the average was used as the final result. All values were rounded to one decimal place to improve data accuracy. (2) Individual Characteristics The parameters included in Table 2 are Lumbar Curvature (LC), Lumbosacral Angle (LA), Lumbar Lordosis Angle (LLA), Femur Length (FL), and Waist Circumference (WC). All measurements were independently performed by two researchers in a double-blind manner, with the mean of the two measurements used as the final result. Table 2. Measurement methods for individual characteristics Parameter Description Lumbar curvature,LC(mm) Measured using Seze’s method [15] on lateral CT scans of L3–S1. The posterior–inferior corner of T12 (Point A) and the posterior–superior corner of S1 (Point B) were identified, and an arc was drawn along the posterior edges of the lumbar vertebrae connecting A and B. The perpendicular distance from the arc apex (Point O) to the chord AB was recorded as LC. Lumbosacral angle ,LA(°) Measured using Ferguson’s method [16] on lateral CT scans of L3–S1. The tangent to the superior endplate of S1 was drawn, and the angle between this tangent and the horizontal line was recorded as LA. Lumbar lordosis angle ,LLA(°) Measured on lateral CT scans of L3–S1 as the angle between the superior endplates of L1 and S1. Femur length,FL(cm) Distance from the greater trochanter to the lateral femoral condyle. Waist circumference,WC(cm) Measured at the midpoint between the lower rib margin and the iliac crest. 3.3 Statistical Analysis Statistical analyses were performed using SPSS 25.0. The significance level was set at α = 0.05 (two-tailed). Normality was assessed using the Shapiro–Wilk test combined with histograms and Q–Q plots. Normally distributed data were expressed as mean ± standard deviation (Mean ± SD) and analyzed with parametric tests; non-normally distributed data were expressed as median (interquartile range) [Median (IQR)] and analyzed with non-parametric tests.For within-group comparisons (e.g., left vs. right side), paired t-tests were used for normally distributed data, and Wilcoxon signed-rank tests for non-normal data. For between-group comparisons, independent t-tests were used when data were normally distributed with homogeneity of variance, and Mann–Whitney U tests were used otherwise. Categorical variables were compared using χ² tests or Fisher’s exact tests (when expected frequencies <5). For correlation analysis, Pearson’s correlation was applied for bivariate normal data, and Spearman’s rank correlation for non-normal data. Test statistics were reported as t-values, Z-values, or correlation coefficients (r) with corresponding 95% confidence intervals. Analyses focused on the quantitative relationship between individual characteristics and biomechanical parameters of manipulation. 4 Experimental Results 4.1 Baseline Characteristics of Participants A total of 107 participants meeting the inclusion and exclusion criteria were enrolled in this study, including 57 patients with LDH and 50 healthy volunteers. Baseline demographic characteristics were comparable between the two groups, as detailed in Table 3. Table 3 General characteristics of the volunteers Characteristic Healthy Volunteers（n=50） LDH Patients（n=57） P1 P2 P3 Unilateral manipulation group（n=25） Bilateral manipulation group（n=25） Unilateral manipulation group（n=32） Bilateral manipulation group（n=25） Male（%） 11（44） 10（40） 16（50） 13（52） 0.653 0.395 0.358 Female（%） 14（56） 15（60） 16（50） 12（48） Age（years） 24（4） 22（5） 24（4） 20（4） 0.817 0.126 0.332 Height（cm） 167.36（7.05） 168.02（9.39） 170.31 （7.37） 168.60（7.41） 0.132 0.809 0.217 Weight(Kg) 57（22） 61（19） 60（20） 60（19） 0.398 0.587 0.314 Note: (1) According to the Shapiro–Wilk test, height followed a normal distribution and is presented as mean (SD), whereas age and weight did not follow a normal distribution and are presented as median (IQR) using the rank-sum test. (2) p1:unilateral group comparison; p2:bilateral group comparison; P3:overall group comparison. 4.2 Biomechanical Loading Curves of LPM Figure 4 illustrates the biomechanical trajectories: 4.3 Quantitative Comparison of Biomechanical Parameters under Different LPM Manipulation Modes Biomechanical parameters were extracted for both the preloading and thrust phases of the lumbar posterior manipulation (LPM) under two manipulation modes. As shown in Table 4, no significant differences in biomechanical parameters between the left and right sides were found in the unilateral manipulation group of healthy volunteers (p > 0.05). As shown in Table 5, in the unilateral manipulation mode, the mean values of HPF, HMPF, HIPF, EPF, EMPF, and EIPF were 62.55 N, 106.91 N, 43.54 N, 151.74 N, 249.99 N, and 94.06 N, respectively, with no significant between-group differences between healthy volunteers and LDH patients (p > 0.05). In the bilateral manipulation mode, the mean values of HPF, HMPF, HIPF, EPF, EMPF, and EIPF were 91.15 N, 151.12 N, 59.36 N, 199.74 N, 309.02 N, and 110.80 N, respectively. A significant between-group difference was observed in EPF-A between healthy volunteers and LDH patients (p = 0.032 0.05). Table 4. Comparison of biomechanical parameters between left and right sides in the LPM unilateral manipulation mode among healthy volunteers(n = 25) Parameter Mean （ SD ） t/Z p Left Right HPF-U（N） 62.33（5.79） 61.79（6.98） -1.388 0.178 HMPF-U（N） 105.48（10.55） 105.48（12.49） -0.003 0.998 HIPF-U（N） 43.15（9.41） 43.68（10.48） 1.427 0.167 EPF-U（N） 150.07（14.33） 151.55（18.54） 1.684 0.105 EMPF-U（N） 248.53（16.82） 249.74（20.46） 1.599 0.123 EIPF-U（N） 98.47（17.84） 98.19（21.93） -0.304 0.763 Note:In the LPM unilateral manipulation mode among healthy volunteers, the biomechanical parameters of both the left and right sides conformed to a normal distribution. Table 5.Comparison of LPM biomechanical parameters between healthy volunteers and LDH patients Manipulation Mode Parameter Healthy LDH t/Z p Unilateral mode（Healthy=25，LDH=32） HPF-U（N） 62.06 （6.34） 63.04（8.28） -0.908 0.368 HMPF-U（N） 105.48（11.51） 108.33（10.62） -0.852 0.394 HIPF-U（N） 43.42 （9.92） 43.66（9.90） 0.274 0.785 EPF-U（N） 150.81（16.42） 152.66（21.10） -0.012 0.990 EMPF-U（N） 249.14（18.63） 250.83（16.73） -0.370 0.711 EIPF-U（N） 98.33（19.86） 89.79（31.97） 1.153 0.254 Bilateral mode（Healthy=25，LDH=25） HPF-A（N） 91.03 （7.81） 91.27（5.54） -0.572 0.567 HMPF-A（N） 150.37（14.37） 151.87（14.03） -0.375 0.710 HIPF-A（N） 59.33 （14.50） 59.39（13.10） -0.014 0.989 EPF-A（N） 196.48（19.56） 203.00（19.51） -2.145 0.032 EMPF-A（N） 306.36（25.43） 311.68（28.45） -0.697 0.489 EIPF-A（N） 112.91（28.25） 108.68（26.70） 0.544 0.589 Note: (1) According to the Shapiro–Wilk test, HMPF-U, EMPF-U, HPF-A, and EPF-A did not follow a normal distribution; results are therefore presented as median (IQR) and analyzed using the Mann–Whitney U test to obtain Z and p values. The remaining parameters followed a normal distribution, presented as mean (SD), and analyzed using the independent-samples t-test to obtain t and p values. 4.4 Correlation Analysis Among LPM Biomechanical Parameters Correlation analysis was performed for all LPM biomechanical parameters. As shown in Table 6、Table 7, in the unilateral manipulation mode, EMPF-U and EIPF-U demonstrated a highly significant positive correlation (rs = 0.738, p < 0.01). HMPF-U was significantly positively correlated with HIPF-U and HPF-U (rs = 0.718 and rs = 0.411, respectively; p < 0.01). EPF-U showed a positive correlation with EMPF-U (rs = 0.311, p < 0.05). In the bilateral manipulation mode, HMPF-A and HIPF-A exhibited a highly significant positive correlation (rs = 0.837, p < 0.01). EPF-A was positively correlated with EMPF-A (rs = 0.329, p < 0.05) and negatively correlated with EIPF-A (rs = –0.302, p < 0.05). EMPF-A and EIPF-A were significantly positively correlated (rs = 0.767, p < 0.01)(Figure 5). Table 6 Correlation between biomechanical parameters in the LPM unilateral manipulation mode. Parameter HPF-U HMPF-U HIPF-U EPF-U EMPF-U EIPF-U HPF-U 1 HMPF-U 0.411** 1 HIPF-U -0.196 0.718** 1 EPF-U 0.155 0.023 -0.085 1 EMPF-U 0.059 -0.012 0.003 0.311* 1 EIPF-U -0.084 -0.075 0.080 -0.246 0.738** 1 Note: (1) For certain biomechanical data in the LPM unilateral manipulation mode that did not follow a normal distribution, Spearman’s rank correlation was used for correlation analysis. (2) *Correlation is significant at the 0.01 level (two-tailed); correlation is significant at the 0.05 level (two-tailed). Table 7 Correlation between biomechanical parameters in the LPM bilateral manipulation mode. Parameter HPF-A HMPF-A HIPF-A EPF-A EMPF-A EIPF-A HPF-A 1 HMPF-A 0.260 1 HIPF-A -0.211 0.837** 1 EPF-A 0.090 -0.093 -0.138 1 EMPF-A 0.190 0.034 -0.069 0.329* 1 EIPF-A 0.120 0.078 0.002 -0.302* 0.767** 1 Note: (1) For certain biomechanical data in the LPM bilateral manipulation mode that did not conform to a normal distribution, Spearman’s rank correlation was used for the correlation analysis. (2) *Correlation is significant at the 0.01 level (two-tailed); correlation is significant at the 0.05 level (two-tailed). 4.5 Correlation Analysis Between In Vivo LPM Biomechanical Parameters and Individual Factors A correlation analysis was conducted between LPM biomechanical parameters and individual characteristics, with the results presented as a heatmap (Figure 6). In the LPM unilateral manipulation mode, elbow preloading force (EPF-U) showed a negative correlation with lumbar curvature (LC) (p < 0.05). In the LPM bilateral manipulation mode, maximum hand pulling force (HMPF-A) was positively correlated with waist circumference (WC) (p < 0.05), while elbow preloading force (EPF-A) was negatively correlated with femur length (FL) (p < 0.05). No significant correlations were found among the remaining parameters. 5 Discussions The biomechanical characteristics of manual manipulation are key indicators for evaluating the quality of clinical procedures and serve as an important basis for optimizing therapeutic protocols [ 17 ] . In this study, we analyzed the biomechanical profiles of Lever-Positioning Manipulation (LPM) under different thrust modes, aiming to establish a precision-oriented treatment approach tailored to individual patient needs. As illustrated in Fig. 4 , the LPM procedure is a complex three-dimensional composite motion involving multidirectional forces and displacements. We employed a novel wearable biomechanical measurement system equipped with a high-precision pressure sensor array, enabling real-time, dynamic acquisition of three-dimensional biomechanical parameters during manipulation. This system synchronously recorded both the practitioner’s operational forces and the subject’s mechanical responses, including key parameters such as force magnitude and application time. The primary objective of this study was to systematically compare the biomechanical differences between two distinct thrust modes of LPM, analyze the correlations among parameters and their clinical implications, and investigate the influence of individual subject characteristics on these parameters. The findings provide objective, quantitative metrics for clinical manual therapy, which may facilitate the development of evidence-based, individualized treatment plans, thereby improving therapeutic efficacy and reducing procedural risks. This study further performed a detailed biomechanical characterization of different thrust modes in LPM. The results revealed that the two operational modes not only demonstrated significant biomechanical differences but also exhibited specific interrelationships. Force–time trajectory analysis (Fig. 4 ) identified three characteristic biomechanical phases: the preload phase, the instantaneous thrust phase, and the dissipation phase, consistent with the spinal manipulation force–time curves described by Gyer et al. [ 18 ] . During the preload phase, the practitioner applied targeted force via the elbow to a point 1 cm lateral to the paraspinal spinous process, producing a smooth and progressive rise in the force curve. Biomechanically, this gradual loading guided the subject’s lower limbs into extension, rotating the lumbar spine to its maximal physiological angle; the slow preload increase facilitated adaptive contraction of the paraspinal musculature, induced deformation of the intervertebral disc, and achieved graded stress transmission—preparing the tissues for the subsequent rapid thrust [ 19 , 20 ] .In the instantaneous thrust phase, the force curve exhibited a typical “high-explosive” profile. This rapid thrust generated a pulse-like mechanical stimulus capable of overcoming the facet joint’s elastic barrier, producing multiple therapeutic effects: correction of subtle facet joint misalignments, promotion of herniated nucleus pulposus retraction through transient negative pressure, and activation of the disc’s hydrodynamic regulation mechanisms [ 21 , 22 ] . Statistical analysis using the Shapiro–Wilk test indicated that certain biomechanical parameters did not conform to normal distribution, potentially due to altered tactile feedback from wearing the measurement apparatus and the limited statistical power of the 107-case sample. Comparative analysis of left- and right-side manipulations in healthy volunteers showed no statistically significant differences (p > 0.05), confirming that LPM possesses strong operational symmetry and clinical reproducibility.Regarding safety, all procedures strictly adhered to established clinical safety protocols, and no adverse events were observed during the study period. These findings confirm that, under standardized conditions, the biomechanical parameters generated by LPM remain within a safe and effective range. The safety mechanism appears to be attributable to three main factors: (1) the stress-buffering effect of the preload phase, which protects against excessive force during thrust; (2) precise control of the instantaneous thrust, ensuring accuracy of the mechanical stimulus; and (3) directional force application consistent with lumbar spine biomechanics, minimizing the risk of tissue injury. Collectively, these results provide robust evidence supporting the standardization and clinical application of LPM. This study focused on the unilateral and bilateral thrust modes of the Lever Positioning Manipulation (LPM), utilizing a novel wearable biomechanical measurement system to capture and analyze six key biomechanical parameters—HPF, HMPF, HIPF, EPF, EMPF, and EIPF—in real time. The mechanical differences between the two modes were systematically compared, the correlations among the parameters were explored, and the influence of individual anthropometric and structural characteristics on the practitioner’s force application strategy was analyzed. The results showed that, in the unilateral mode of LPM, EMPF-U was highly positively correlated with EIPF-U, suggesting a synergistic enhancement effect between the peak thrust force and the instantaneous impulse generated by the ipsilateral elbow. This may reflect the synchronous contraction and force transmission of the deep lumbar and dorsal muscle groups at the moment of thrust [ 23 ] . Similar synergistic effects have been reported in high-velocity low-amplitude (HVLA) manipulations—Nougarou et al. [ 24 ] observed a consistent dynamic linkage between preload force and peak force, indicating that the mechanical characteristics of different force application phases can jointly influence treatment outcomes. The significant positive correlations of HMPF-U with HIPF-U and HPF-U suggest the formation of a stable kinetic chain linking hand peak thrust force, instantaneous impulse, and preload force, which facilitates smooth and efficient force output. This finding aligns with the peak–impulse coupling phenomenon observed by Choi et al. [ 25 ] under different manipulation strategies.In the bilateral mode, HMPF-A was highly positively correlated with HIPF-A (rs = 0.837, p < 0.01), indicating strong synchronization between the two hands during both peak thrust and instantaneous loading phases. Nyirô et al. [ 26 ] similarly reported a strong correlation between peak force and loading rate under simultaneous bilateral loading, reflecting the balanced activation of bilateral lumbar extensors and abdominal muscles. The significant positive correlation between EIPF-A and EMPF-A indicates coordinated force generation by both elbows, whereas the negative correlation between EIPF-A and EPF-A suggests the presence of a dynamic modulation mechanism between preload and instantaneous force, possibly to maintain lumbar segmental stability and safety during high-speed thrusting. Reed et al. [ 27 ] noted that changes in peak force at a constant loading rate can markedly influence spinal kinematics and muscle activation patterns, implying that practitioners may dynamically adjust the balance between preload and explosive force according to the soft tissue and joint structural status of the patient. With respect to individual factors, the study found that in the unilateral mode, elbow preload force (EPF-U) was negatively correlated with lumbar curvature (LC), indicating that individuals with greater LC required less vertical elbow support force during the preload phase. This may be explained by the shortening of the posterior facet joint lever arm relative to the practitioner’s force direction, along with reduced initial tension of the posterior ligaments and joint capsule, thereby lowering the vertical pressure required to achieve the same degree of joint distraction [ 28 , 29 ] . In the bilateral mode, hand peak thrust force (HMPF-A) was positively correlated with waist circumference (WC), supporting the notion that central obesity increases both external and internal lumbar loading [ 30 ] . Existing computational modeling and epidemiological studies have shown that increased body weight and WC significantly raise L5–S1 compressive and shear forces, while greater soft tissue thickness and viscoelastic resistance increase the peak traction force needed to overcome passive tissue resistance—consistent with our observation that HMPF-A increased with WC [ 31 , 32 ] . Additionally, EPF-A was negatively correlated with femur length (FL) in the bilateral mode, suggesting that FL may influence force transmission efficiency through the pelvic–lumbar biomechanical linkage. Prior research on lumbopelvic–hip coordination has indicated that FL, along with its positional relationship to the pelvis, affects load transfer between the hip and lumbar spine [ 33 ] ; when the lower limb lever arm is longer, practitioners can utilize a more advantageous force transmission pathway, thereby reducing dependence on sustained elbow pressure—providing a plausible biomechanical explanation for the observed relationship of “longer FL, lower EPF” [ 34 ] . 6 Limitations This study has certain limitations. First, all participants exhibited varying degrees of lumbar muscle tension. Although thorough lumbar relaxation was performed prior to manipulation to minimize variability from local muscle tone differences, this factor could not be entirely eliminated. Second, the range of quantified parameters was relatively limited, particularly regarding associations between biomechanical variables and individual characteristics, as only a small set of anthropometric variables was considered. Future studies should include clinical variables such as disease duration, pain scores, and lumbar muscle tension, as well as operator-related factors such as manual therapy experience, to establish a more comprehensive and clinically relevant multivariate regression model. Additionally, kinematic parameters such as lumbar angular displacement during manipulation should be incorporated into the evaluation framework to further refine the in vivo biomechanical profile of LPM. Future research could integrate motion capture technology, AnyBody modeling, and three-dimensional finite element analysis to investigate the deeper biomechanical mechanisms of LPM from multiple dimensions, thereby providing a stronger theoretical basis for its optimization and clinical application. 7 Conclusion This study employed a wearable biomechanical measurement system to perform an in vivo quantitative analysis of the unilateral and bilateral thrust modes of LPM. The results indicated that differences between LPM modes were associated with LDH subtypes, supporting the biomechanical rationale for subtype-based manipulation selection. Both modes demonstrated characteristic preload, instantaneous thrust, and dissipation phases. The preload phase exhibited a gradual force increase, facilitating progressive lumbar rotation and soft tissue stress adaptation, whereas the instantaneous thrust phase showed a “high-explosiveness” profile characteristic of HVLA manipulations. Healthy participants exhibited no significant left–right differences in unilateral mode parameters, suggesting good operational symmetry and reproducibility. Individual factor analysis revealed that in the unilateral mode, EPF-U was negatively correlated with LC, indicating reduced elbow vertical support requirements in individuals with greater lumbar lordosis; in the bilateral mode, WC was positively correlated with HMPF-A, suggesting that individuals with larger WC require greater peak hand thrust to overcome soft tissue resistance; and FL was negatively correlated with EPF-A, likely due to the influence of lower limb length on force transmission efficiency via the lumbopelvic kinetic chain. These findings highlight the importance of incorporating patient-specific anatomical and anthropometric characteristics into LPM strategies to optimize efficacy and safety. Abbreviations LPM: Lever positioning manipulation; LDH: Lumbar disc herniation; HPF: Hand preload force; HMPF: Hand maximum pulling force; HIPF: Hand instantaneous pulling force; EPF: Elbow preload force; EMPF: Elbow maximum pressing force; EIPF: Elbow instantaneous pressing force; WC: Waist circumference; FL: Femur length; LA: Lumbosacral angle; LC: Lumbar curvature; LLA: Lumbar lordosis angle; TCM: Traditional Chinese medicine; BMI: Body mass index Declarations Data availability statement The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding authors. Ethics statement The studies involving humans were approved by the Institutional Review Board of The Third Affiliated Hospital of Zhejiang Chinese Medical University.The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article. Author Contributions QX, LC, ZL, and LL contributed to the conception and design of the work and drafted the manuscript.KW and BW were responsible for data acquisition.ZZ and YT performed statistical analysis.All authors contributed to the analysis and interpretation of data, and critically reviewed the manuscript for important intellectual content.All authors read and approved the final manuscript.All authors had full access to all the data and take responsibility for the integrity of the data and the accuracy of the data analysis. Funding The author(s) declare that financial support was received for the research and/or publication of this article. This study received support from the General Program of the National Natural Science Foundation of China (No. 82474668), the National TCM Advantageous Specialty Construction Unit (State Administration of TCM Medical Policy Document No. 2024-90), the Lv Lijiang Famous Traditional Chinese Medicine Expert Inheritance Studio (No. GZS2021026), and the Key Discipline Project of High-level TCM of the National Administration of Traditional Chinese Medicine (No. GJXK2023-85). Acknowledgements The cooperation of all study participants is appreciated. Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Publisher’s note All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. 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Bibrowicz K, Szurmik T, Kurzeja P, Bibrowicz B, Ogrodzka-Ciechanowicz K. (2024).Pelvic tilt and stiffness of the muscles stabilising the lumbo-pelvic-hip (LPH) complex in tensiomyography examination. PLoS One. 2024;19(10):e0312480. doi: 10.1371/journal.pone.0312480. Additional Declarations No competing interests reported. Supplementary Files ClinicalTrials.govProtocolRegistrationandResultsSystemPRSReceipt.pdf 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. We do this by developing innovative software and high quality services for the global research community. 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15:16:21","extension":"xml","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":131666,"visible":true,"origin":"","legend":"","description":"","filename":"00d70dff88f746b38edeb2ba1e0323ce1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/0453e70269e819018155a718.xml"},{"id":95443883,"identity":"7fc69ed4-da54-4f12-8777-e1e9bd703fd6","added_by":"auto","created_at":"2025-11-08 15:16:21","extension":"html","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":144715,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/2b6bfd2d6894b18c528c1ba7.html"},{"id":95443862,"identity":"15e63aff-4498-48de-a159-d231f77fa21b","added_by":"auto","created_at":"2025-11-08 15:16:21","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":74835,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart of the study. This figure shows the sequence of experimental steps including recruitment, intervention, and analysis.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/3ed069d74087bab8a44c84b5.jpg"},{"id":95527157,"identity":"d7d4769c-8e6e-4e42-b668-f37f0c073fbd","added_by":"auto","created_at":"2025-11-10 10:11:13","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":101647,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWearable biomechanical measurement device.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNotes: A, wearable biomechanical measurement glove; B, wearable biomechanical measurement elbow sleeve; C, schematic diagram of manipulative operation while wearing the device; D, user interface of the intelligent biomechanical acquisition software.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/b43befe4b74b59d9b164faa1.jpg"},{"id":95443864,"identity":"29be6c9e-f596-4acf-8a4c-7fe0c109dd95","added_by":"auto","created_at":"2025-11-08 15:16:21","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":52352,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic illustration of the LPM technique in different manipulation modes.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) Unilateral manipulation mode of LPM; (B) Bilateral manipulation mode of LPM.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/477f48db4d57a79b6427a8c4.jpg"},{"id":95527119,"identity":"fe9fb086-3c4a-421c-96cf-be5aa5d03277","added_by":"auto","created_at":"2025-11-10 10:11:03","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":84209,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic diagram of LPM mechanical trajectory\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNote: (A) Unilateral LPM mode；(B) Bilateral LPM mode\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/e2a734271b33a2ffd137038b.jpg"},{"id":95443881,"identity":"d3b92a24-b460-4bcf-9428-ee4abbf0c211","added_by":"auto","created_at":"2025-11-08 15:16:21","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":62502,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCorrelations among LPM biomechanical parameters\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNote: (A)unilateral manipulation mode; (B)bilateral manipulation mode. In the figure, connecting lines indicate correlations between the two parameters, with color intensity representing the strength of the association; red indicates a positive correlation, and blue indicates a negative correlation.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/55adbc92a984929dfea39ef9.jpg"},{"id":95443870,"identity":"517dd42f-cc7f-4899-9978-1297c04c4f71","added_by":"auto","created_at":"2025-11-08 15:16:21","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":72275,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHeatmap of the correlation analysis between biomechanical parameters and individual factors in the two LPM manipulation modes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNote: Left panel: LPM unilateral manipulation mode; Right panel: LPM bilateral manipulation mode. Red indicates a positive correlation, blue indicates a negative correlation, and the color intensity reflects the strength of the correlation.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/61cb0a8aa92e4872d6642536.jpg"},{"id":95887004,"identity":"f1ac2098-6166-401c-a192-08aeb3dc5f3a","added_by":"auto","created_at":"2025-11-14 05:08:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1889605,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/3f350871-e62c-40d4-adba-24ad459d33b0.pdf"},{"id":95527392,"identity":"ff61cc6f-c97f-4f73-9376-28b1a04cc4f0","added_by":"auto","created_at":"2025-11-10 10:13:31","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":86580,"visible":true,"origin":"","legend":"","description":"","filename":"ClinicalTrials.govProtocolRegistrationandResultsSystemPRSReceipt.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7723433/v1/f1433bda5ed6a620ea367d69.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"In vivo biomechanical quantification and individual factor analysis of lever positioning manipulation under different thrust modes：a cross-sectional study","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eLDH is a prevalent degenerative spinal disorder, affecting approximately 2%\u0026ndash;3% of the global population\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. In recent years, lifestyle changes have contributed to an increasing incidence and a trend toward younger onset, making LDH an important public health concern\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Although surgical intervention is a commonly used treatment option, it carries a 2.7% complication rate and a 2.1% reoperation rate within 90 days postoperatively\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. In contrast, non-surgical management remains the first-line approach for most patients, alleviating symptoms in 80%\u0026ndash;90% of cases\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn traditional Chinese medicine (TCM), LDH is categorized under the concepts of \u003cem\u003eBi syndrome\u003c/em\u003e and \u003cem\u003etendon disorders\u003c/em\u003e. Among various TCM modalities, spinal manipulation\u0026mdash;particularly Tuina therapy\u0026mdash;has been widely employed due to its minimal adverse effects and high safety profile\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. LPM is a specialized manual therapy derived from conventional lumbar extension manipulation and refined by incorporating modern anatomical and biomechanical principles. Clinical evidence has demonstrated its efficacy in managing LDH and facet joint subluxation\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. This technique applies a \u0026ldquo;high-velocity, low-amplitude\u0026rdquo; force based on an energy-efficient lever principle, delivering targeted mechanical input to specific lumbar segments to correct joint misalignment, relieve nerve root compression, and restore the balance of spinal alignment and soft tissue tension\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e.As a biomechanically demanding intervention, the therapeutic effectiveness of LPM is closely related to both the magnitude and pattern of applied forces, as well as the patient\u0026rsquo;s individual anatomical characteristics. Building upon previous research\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e, our team has modified LPM into two distinct patterns: bilateral manipulation (cross-legged) and unilateral manipulation (affected-side leg). Using a biomechanical acquisition system, this study aims to quantify the force parameters of both patterns to elucidate their underlying mechanisms of action. Such quantitative biomechanical profiling not only provides objective evidence for clinical practice and facilitates visualized training but also enables the development of individualized force application strategies tailored to patient-specific characteristics\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. Furthermore, investigating the correlation between manipulation forces and patient anatomical parameters (e.g., structural features and imaging metrics) may help refine operational protocols, thereby enhancing both the safety and effectiveness of treatment\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e"},{"header":"2 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Participants\u003c/h2\u003e\u003cp\u003eFrom June 2024 to March 2025, a total of 107 volunteers were recruited from the Department of Tuina, The Third Affiliated Hospital of Zhejiang Chinese Medical University. Prior to participation, all individuals were informed of the study objectives, procedures, precautions, and potential risks. Written informed consent was obtained from each participant. The study flowchart is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The study protocol was approved by the Ethics Committee of the Third Affiliated Hospital of Zhejiang Chinese Medical University (Approval No.: ZSLL-KY-2024-080-01).Additionally, the study protocol was registered on ClinicalTrials.gov (Registration No.: NCT06872918).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Study Design and Grouping\u003c/h2\u003e\u003cp\u003eThis investigation was designed as a biomechanical parameter quantification study of LPM, aiming to obtain standardized mechanical data. To minimize the influence of inter-individual variability among LDH patients on force measurements, a case\u0026ndash;control design was adopted, with healthy volunteers serving as the control group to reduce confounding bias.\u003c/p\u003e\u003cp\u003eA total of 107 participants were enrolled: 57 patients with LDH (25 central type, 32 paracentral type) and 50 healthy controls (25 central type, 25 paracentral type). Intervention assignment was determined according to anatomical subtype: participants with central-type LDH received the bilateral LPM pattern, whereas those with paracentral-type LDH received the unilateral LPM pattern. All manipulations were performed using a standardized LPM protocol previously validated for safety, with no adverse effects observed in healthy volunteers during preliminary testing.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Diagnostic Criteria\u003c/h2\u003e\u003cp\u003eThe diagnosis of LDH was established according to the Guidelines for the Diagnosis and Treatment of Lumbar Disc Herniation (2020 Edition) issued by the Spine Surgery Group of the Orthopedic Branch of the Chinese Medical Association\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. Diagnostic confirmation required both imaging evidence\u0026mdash;lumbar MRI or CT demonstrating disc herniation consistent with the clinical level of nerve compression\u0026mdash;and clinical manifestations meeting at least three of the following five criteria: (1) radiating lower limb pain within the distribution of the affected nerve root; (2) sensory disturbance in the corresponding dermatome (e.g., hypoesthesia or hyperesthesia); (3) positive nerve root tension signs, such as the straight leg raise test, Bragard\u0026rsquo;s test, crossed straight leg raise test, or femoral nerve stretch test; (4) diminished deep tendon reflexes compared with the contralateral side; and (5) muscle weakness in the relevant myotomal distribution.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Inclusion and Exclusion Criteria\u003c/h2\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e2.4.1 Inclusion Criteria\u003c/h2\u003e\u003cp\u003eFor the LDH group: (1) meeting the diagnostic criteria for LDH (central, paracentral, or far-lateral type) with imaging findings consistent with neurological localization signs; (2) age between 18 and 35 years, regardless of sex; (3) non-acute stage, presenting with mild-to-moderate pain and functional impairment, with symptom duration\u0026thinsp;\u0026ge;\u0026thinsp;2 weeks; (4) willingness to provide written informed consent.\u003c/p\u003e\u003cp\u003e For the healthy control group: (1) age between 18 and 35 years, regardless of sex; (2) no history of low back pain or spinal disorders; (3) normal physical examination findings and a body mass index (BMI) of 18.5\u0026ndash;24.9 kg/m\u0026sup2;; (4) willingness to provide written informed consent.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\u003ch2\u003e2.4.2 Exclusion Criteria\u003c/h2\u003e\u003cp\u003eParticipants were excluded if they had any of the following: (1) structural lumbar pathology, such as fracture, dislocation, tumor, tuberculosis, fused vertebrae, or paravertebral bony bridging; (2) history of lumbar surgery or severe trauma; (3) local dermatological lesions, such as lumbar skin inflammation or open wounds; (4) severe systemic diseases, including primary disorders of the cardiovascular, hepatic, renal, or hematopoietic systems, psychiatric disorders, or severe osteoporosis (T-score \u0026le; \u0026minus;\u0026thinsp;2.5); (5) special conditions, including pregnancy or extreme frailty; (6) neuropathic conditions, such as primary or dry sciatica; (7) factors interfering with study integrity, such as concurrent participation in other manual therapy trials that could influence outcomes, or the occurrence of intolerable adverse reactions.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Withdrawal Criteria\u003c/h2\u003e\u003cp\u003eParticipants were withdrawn if: (1) data acquisition failed due to force majeure (e.g., equipment malfunction, natural disasters); or (2) they failed to comply with the study protocol requirements or voluntarily withdrew from the study.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Termination Criteria\u003c/h2\u003e\u003cp\u003eIntervention was immediately terminated if: (1) an adverse event occurred during manipulation; or (2) the participant developed discomfort during intervention and requested cessation.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"3 Experimental Equipment and Methods","content":"\u003cp\u003e\u003cstrong\u003e3.1 Experimental Equipment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA wearable biomechanical measurement system, developed by the Institute of Orthopaedics and Traumatology, China Academy of Chinese Medical Sciences (Utility Model Patent No. 201620427405.8), was employed in this study. The system\u0026rsquo;s core components included specially designed biomechanical measurement gloves and elbow sleeves, with evenly distributed dot-type pressure sensors on the glove surface that directly contacted the participant\u0026rsquo;s skin for measurement (Fig.2A, Fig.2B). The sensor assembly consisted of resistive strain gauges and elastic elements, integrated with a dual-axis accelerometer to convert detected pressure into real-time voltage output. Data acquisition was performed at a continuous sampling frequency of 100 Hz to ensure temporal accuracy (Fig. 2C). Data were transmitted in real time via a wireless transmission system based on a CSR Bluetooth chip (V5.0 protocol) with dual-channel transmitters for the left and right sides, supporting 5 V/3.3 V logic-level interfaces, maintaining stable transmission within 10 m, and achieving a tested latency of \u0026lt; 50 ms. Data collection and analysis were conducted using self-developed intelligent biomechanical acquisition software, programmed in C language, compatible with Windows 10 or later. The software included four main modules\u0026mdash;device configuration, connection control, data acquisition, and real-time display\u0026mdash;supporting synchronous multi-channel sensor data processing with 16-bit resolution, and offering storage and export functions (Fig. 2D).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Experimental Methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.1\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eLPM Treatment Procedure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll LPM manipulations were performed by the same expert (Professor Lv Lijiang) with 33 years of clinical experience in Tuina therapy. A stratified intervention protocol was adopted: patients with central-type LDH received bilateral manipulation mode, whereas those with para-central-type LDH received unilateral manipulation mode. Each participant underwent three standardized treatments with at least 48 hours between sessions, and the average of the three biomechanical measurements was used for analysis. Healthy volunteers receiving the unilateral manipulation mode underwent symmetrical operations on both sides (one on each side) to ensure data comparability.\u003c/p\u003e\n\u003cp\u003eBefore treatment, a standardized 15-minute Tuina session was performed to relax the lumbar soft tissues, including the one-finger meditation pushing method (focusing on the erector spinae), rolling method (applied to the lumbosacral region), pressing-kneading method (targeting paraspinal tender points), and plucking method (to separate adhesions). Participants were placed in a prone position with the mouth open, muscles relaxed, and breathing naturally throughout the treatment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(1) Unilateral Manipulation Mode (e.g., left para-central protrusion)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe practitioner stood on the patient\u0026rsquo;s right side, placing the olecranon of the right ulna precisely against the targeted vertebra (approximately 1 cm lateral to the affected segment). The practitioner firmly held the patient\u0026rsquo;s left ankle, flexing the leg backward and upward using leverage. When resistance was encountered during hyperextension, the ankle joint was rapidly pulled upward while the right elbow simultaneously pressed downward on the targeted vertebra until the protrusion loosened or a \u0026ldquo;click\u0026rdquo; was felt (Fig.3A).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(2) Bilateral Manipulation Mode\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patient\u0026rsquo;s legs were crossed and fixed. After lumbar positioning, the practitioner placed the olecranon of the right ulna precisely against the targeted vertebra (approximately 1 cm lateral to the affected segment). Both ankles were held, and the legs were hyperextended upward using leverage. Upon encountering resistance, the practitioner applied a rapid pulling force while pressing downward with the right elbow, producing loosening or a \u0026ldquo;click\u0026rdquo; at the protrusion site(Fig.3B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.2 In Vivo Biomechanical Measurement and Parameters\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFollowing the operational characteristics of LPM, this study quantified the key biomechanical parameters of the practitioner\u0026rsquo;s hands and elbows. Measurements were performed using the wearable biomechanical sensor system (gloves and elbow sleeves) with a 100 Hz sampling frequency. All devices were calibrated and zero-adjusted before operation to ensure accuracy.\u003c/p\u003e\n\u003cp\u003eSix biomechanical parameters were recorded: Hand Preload Force (HPF), Hand Maximum Pulling Force (HMPF), Hand Instantaneous Pulling Force (HIPF), Elbow Preload Force (EPF), Elbow Maximum Pressing Force (EMPF), and Elbow Instantaneous Pressing Force (EIPF), with definitions provided in Table 1. Data were wirelessly transmitted in real time to a computer system, and force\u0026ndash;time curves were plotted to analyze manipulation characteristics.\u003c/p\u003e\n\u003cp\u003eIn the unilateral manipulation mode (para-central LDH), only the affected side was recorded for LDH patients, whereas both sides were recorded for healthy volunteers to allow symmetry comparison. In the bilateral manipulation mode (central LDH), operations were uniformly performed on the participant\u0026rsquo;s right side without bilateral comparison. All parameters were recorded continuously throughout the procedure, with particular attention to the preload phase, maximum pulling phase, and instantaneous pulling phase.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1. Biomechanical parameters of manipulation measured by pressure sensors\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003eHand Preload Force,HPF(N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003ePositioning pressure applied by the hand during the preparation phase (HPF-U for unilateral, HPF-B for bilateral)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003eHand Maximum Pulling Force,HMPF(N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003ePeak hand force during the pulling phase (HMPF-U for unilateral, HMPF-B for bilateral)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003eHand Instantaneous Pulling Force,HIPF(N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003eDynamic increase in hand force during rapid pulling, calculated as HIPF = HMPF \u0026minus; HPF (HIPF-U for unilateral, HIPF-B for bilateral)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003eElbow Preload Force,EPF(N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003ePositioning pressure applied by the elbow during the preparation phase (EPF-U for unilateral, EPF-B for bilateral)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003eElbow Maximum Pressing Force ,EMPF(N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003ePeak elbow force during the pressing phase (EMPF-U for unilateral, EMPF-B for bilateral)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 312px;\"\u003e\n \u003cp\u003eElbow Instantaneous Pressing Force,EIPF(N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 256px;\"\u003e\n \u003cp\u003eDynamic increase in elbow force during rapid pressing, calculated as EIPF = EMPF \u0026minus; EPF (EIPF-U for unilateral, EIPF-B for bilateral)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNote: (1) All parameters were measured in triplicate to ensure data reliability. (2) For patients with LDH, only affected-side parameters were collected. Healthy volunteers in the unilateral manipulation group underwent bilateral parameter acquisition (both left and right sides) to enable comparative analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.3 Measurement of Individual Characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(1) Baseline Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTwo trained researchers jointly collected participant data, including age (years), sex (male/female), height (cm), and weight (kg), using standardized procedures. Each parameter was measured twice independently by both assessors, and the average was used as the final result. All values were rounded to one decimal place to improve data accuracy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(2) Individual Characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe parameters included in Table 2 are Lumbar Curvature (LC), Lumbosacral Angle (LA), Lumbar Lordosis Angle (LLA), Femur Length (FL), and Waist Circumference (WC). All measurements were independently performed by two researchers in a double-blind manner, with the mean of the two measurements used as the final result.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Measurement methods for individual characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eLumbar curvature,LC(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eMeasured using Seze\u0026rsquo;s method\u003csup\u003e[15]\u003c/sup\u003eon lateral CT scans of L3\u0026ndash;S1. The posterior\u0026ndash;inferior corner of T12 (Point A) and the posterior\u0026ndash;superior corner of S1 (Point B) were identified, and an arc was drawn along the posterior edges of the lumbar vertebrae connecting A and B. The perpendicular distance from the arc apex (Point O) to the chord AB was recorded as LC.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eLumbosacral angle ,LA(\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eMeasured using Ferguson\u0026rsquo;s method\u003csup\u003e[16]\u003c/sup\u003eon lateral CT scans of L3\u0026ndash;S1. The tangent to the superior endplate of S1 was drawn, and the angle between this tangent and the horizontal line was recorded as LA.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eLumbar lordosis angle ,LLA(\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eMeasured on lateral CT scans of L3\u0026ndash;S1 as the angle between the superior endplates of L1 and S1.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eFemur length,FL(cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eDistance from the greater trochanter to the lateral femoral condyle.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eWaist circumference,WC(cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eMeasured at the midpoint between the lower rib margin and the iliac crest.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e3.3 Statistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using SPSS 25.0. The significance level was set at \u0026alpha; = 0.05 (two-tailed). Normality was assessed using the Shapiro\u0026ndash;Wilk test combined with histograms and Q\u0026ndash;Q plots. Normally distributed data were expressed as mean \u0026plusmn; standard deviation (Mean \u0026plusmn; SD) and analyzed with parametric tests; non-normally distributed data were expressed as median (interquartile range) [Median (IQR)] and analyzed with non-parametric tests.For within-group comparisons (e.g., left vs. right side), paired t-tests were used for normally distributed data, and Wilcoxon signed-rank tests for non-normal data. For between-group comparisons, independent t-tests were used when data were normally distributed with homogeneity of variance, and Mann\u0026ndash;Whitney U tests were used otherwise. Categorical variables were compared using \u0026chi;\u0026sup2; tests or Fisher\u0026rsquo;s exact tests (when expected frequencies \u0026lt;5).\u003c/p\u003e\n\u003cp\u003eFor correlation analysis, Pearson\u0026rsquo;s correlation was applied for bivariate normal data, and Spearman\u0026rsquo;s rank correlation for non-normal data. Test statistics were reported as t-values, Z-values, or correlation coefficients (r) with corresponding 95% confidence intervals. Analyses focused on the quantitative relationship between individual characteristics and biomechanical parameters of manipulation.\u003c/p\u003e"},{"header":"4 Experimental Results","content":"\u003cp\u003e\u003cstrong\u003e4.1 Baseline Characteristics of Participants\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 107 participants meeting the inclusion and exclusion criteria were enrolled in this study, including 57 patients with LDH and 50 healthy volunteers. Baseline demographic characteristics were comparable between the two groups, as detailed in Table 3.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3 General characteristics of the volunteers\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003eCharacteristic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\"\u003e\n \u003cp\u003eHealthy Volunteers（n=50）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\"\u003e\n \u003cp\u003eLDH Patients（n=57）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003eP1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003eP2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003eP3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eUnilateral manipulation group（n=25）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eBilateral manipulation group（n=25）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eUnilateral manipulation group（n=32）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eBilateral manipulation group（n=25）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMale（%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e11（44）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10（40）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e16（50）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e13（52）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003e0.653\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003e0.395\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\"\u003e\n \u003cp\u003e0.358\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFemale（%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e14（56）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e15（60）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e16（50）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12（48）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eAge（years）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e24（4）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e22（5）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e24（4）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e20（4）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.817\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.126\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.332\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eHeight（cm）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e167.36（7.05）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e168.02（9.39）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e170.31\u003c/p\u003e\n \u003cp\u003e（7.37）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e168.60（7.41）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.809\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.217\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eWeight(Kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e57（22）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e61（19）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e60（20）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e60（19）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.398\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.587\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.314\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNote: (1) According to the Shapiro\u0026ndash;Wilk test, height followed a normal distribution and is presented as mean (SD), whereas age and weight did not follow a normal distribution and are presented as median (IQR) using the rank-sum test. (2) p1:unilateral group comparison; p2:bilateral group comparison; P3:overall group comparison.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.2 Biomechanical Loading Curves of LPM\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 4 illustrates the biomechanical trajectories:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.3 Quantitative Comparison of Biomechanical Parameters under Different LPM Manipulation Modes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBiomechanical parameters were extracted for both the preloading and thrust phases of the lumbar posterior manipulation (LPM) under two manipulation modes. As shown in Table 4, no significant differences in biomechanical parameters between the left and right sides were found in the unilateral manipulation group of healthy volunteers (p \u0026gt; 0.05). As shown in Table 5, in the unilateral manipulation mode, the mean values of HPF, HMPF, HIPF, EPF, EMPF, and EIPF were 62.55 N, 106.91 N, 43.54 N, 151.74 N, 249.99 N, and 94.06 N, respectively, with no significant between-group differences between healthy volunteers and LDH patients (p \u0026gt; 0.05). In the bilateral manipulation mode, the mean values of HPF, HMPF, HIPF, EPF, EMPF, and EIPF were 91.15 N, 151.12 N, 59.36 N, 199.74 N, 309.02 N, and 110.80 N, respectively. A significant between-group difference was observed in EPF-A between healthy volunteers and LDH patients (p = 0.032 \u0026lt; 0.05), while no significant differences were found for the other parameters (p \u0026gt; 0.05).\u003c/p\u003e\n\u003cp\u003eTable 4. Comparison of biomechanical parameters between left and right sides in the LPM unilateral manipulation mode among healthy volunteers(n = 25)\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 175px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 214px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean\u003c/strong\u003e\u003cstrong\u003e（\u003c/strong\u003e\u003cstrong\u003eSD\u003c/strong\u003e\u003cstrong\u003e）\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 88px;\"\u003e\n \u003cp\u003e\u003cstrong\u003et/Z\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 91px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLeft\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRight\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 175px;\"\u003e\n \u003cp\u003eHPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e62.33（5.79）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e61.79（6.98）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e-1.388\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e0.178\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 175px;\"\u003e\n \u003cp\u003eHMPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e105.48（10.55）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e105.48（12.49）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e-0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 175px;\"\u003e\n \u003cp\u003eHIPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e43.15（9.41）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e43.68（10.48）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e1.427\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e0.167\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 175px;\"\u003e\n \u003cp\u003eEPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e150.07（14.33）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e151.55（18.54）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e1.684\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e0.105\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 175px;\"\u003e\n \u003cp\u003eEMPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e248.53（16.82）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e249.74（20.46）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e1.599\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e0.123\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 175px;\"\u003e\n \u003cp\u003eEIPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e98.47（17.84）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e98.19（21.93）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e-0.304\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e0.763\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNote:In the LPM unilateral manipulation mode among healthy volunteers, the biomechanical parameters of both the left and right sides conformed to a normal distribution.\u003c/p\u003e\n\u003cp\u003eTable 5.Comparison of LPM biomechanical parameters between healthy volunteers and LDH patients\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"569\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 101px;\"\u003e\n \u003cp\u003eManipulation Mode\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eHealthy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eLDH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003et/Z\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" style=\"width: 101px;\"\u003e\n \u003cp\u003eUnilateral mode（Healthy=25，LDH=32）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eHPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e62.06\u0026nbsp;（6.34）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e63.04（8.28）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.908\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.368\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eHMPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e105.48（11.51）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e108.33（10.62）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.852\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.394\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eHIPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e43.42\u0026nbsp;（9.92）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e43.66（9.90）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.274\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.785\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eEPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e150.81（16.42）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e152.66（21.10）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.012\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.990\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eEMPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e249.14（18.63）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e250.83（16.73）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.370\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.711\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eEIPF-U（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e98.33（19.86）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e89.79（31.97）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e1.153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.254\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" style=\"width: 101px;\"\u003e\n \u003cp\u003eBilateral mode（Healthy=25，LDH=25）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eHPF-A（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e91.03\u0026nbsp;（7.81）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e91.27（5.54）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.572\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.567\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eHMPF-A（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e150.37（14.37）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e151.87（14.03）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.710\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eHIPF-A（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e59.33\u003c/p\u003e\n \u003cp\u003e（14.50）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e59.39（13.10）\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.989\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eEPF-A（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e196.48（19.56）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e203.00（19.51）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-2.145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.032\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eEMPF-A（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e306.36（25.43）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e311.68（28.45）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.697\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.489\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 171px;\"\u003e\n \u003cp\u003eEIPF-A（N）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e112.91（28.25）\u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e108.68（26.70）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.544\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.589\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNote: (1) According to the Shapiro\u0026ndash;Wilk test, HMPF-U, EMPF-U, HPF-A, and EPF-A did not follow a normal distribution; results are therefore presented as median (IQR) and analyzed using the Mann\u0026ndash;Whitney U test to obtain Z and p values. The remaining parameters followed a normal distribution, presented as mean (SD), and analyzed using the independent-samples t-test to obtain t and p values.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.4 Correlation Analysis Among LPM Biomechanical Parameters\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrelation analysis was performed for all LPM biomechanical parameters. As shown in Table 6、Table 7, in the unilateral manipulation mode, EMPF-U and EIPF-U demonstrated a highly significant positive correlation (rs = 0.738, p \u0026lt; 0.01). HMPF-U was significantly positively correlated with HIPF-U and HPF-U (rs = 0.718 and rs = 0.411, respectively; p \u0026lt; 0.01). EPF-U showed a positive correlation with EMPF-U (rs = 0.311, p \u0026lt; 0.05). In the bilateral manipulation mode, HMPF-A and HIPF-A exhibited a highly significant positive correlation (rs = 0.837, p \u0026lt; 0.01). EPF-A was positively correlated with EMPF-A (rs = 0.329, p \u0026lt; 0.05) and negatively correlated with EIPF-A (rs = \u0026ndash;0.302, p \u0026lt; 0.05). EMPF-A and EIPF-A were significantly positively correlated (rs = 0.767, p \u0026lt; 0.01)(Figure 5).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6 Correlation between biomechanical parameters in the LPM unilateral manipulation mode.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHPF-U\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHMPF-U\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHIPF-U\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEPF-U\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEMPF-U\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEIPF-U\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eHPF-U\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eHMPF-U\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e0.411**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eHIPF-U\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e-0.196\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e0.718**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eEPF-U\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e-0.085\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eEMPF-U\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e0.059\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e-0.012\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e0.311*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eEIPF-U\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e-0.084\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e-0.075\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e0.080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e-0.246\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.738**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNote: (1) For certain biomechanical data in the LPM unilateral manipulation mode that did not follow a normal distribution, Spearman\u0026rsquo;s rank correlation was used for correlation analysis. (2) *Correlation is significant at the 0.01 level (two-tailed); correlation is significant at the 0.05 level (two-tailed).\u003c/p\u003e\n\u003cp\u003eTable 7 Correlation between biomechanical parameters in the LPM bilateral manipulation mode.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHPF-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 88px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHMPF-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHIPF-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEPF-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEMPF-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEIPF-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eHPF-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 88px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eHMPF-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.260\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 88px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eHIPF-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e-0.211\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e0.837**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eEPF-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.090\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e-0.093\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e-0.138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eEMPF-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.190\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e0.034\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e-0.069\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e0.329*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003eEIPF-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e0.078\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e0.002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e-0.302*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.767**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNote: (1) For certain biomechanical data in the LPM bilateral manipulation mode that did not conform to a normal distribution, Spearman\u0026rsquo;s rank correlation was used for the correlation analysis. (2) *Correlation is significant at the 0.01 level (two-tailed); correlation is significant at the 0.05 level (two-tailed).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.5 Correlation Analysis Between In Vivo LPM Biomechanical Parameters and Individual Factors\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA correlation analysis was conducted between LPM biomechanical parameters and individual characteristics, with the results presented as a heatmap (Figure 6). In the LPM unilateral manipulation mode, elbow preloading force (EPF-U) showed a negative correlation with lumbar curvature (LC) (p \u0026lt; 0.05). In the LPM bilateral manipulation mode, maximum hand pulling force (HMPF-A) was positively correlated with waist circumference (WC) (p \u0026lt; 0.05), while elbow preloading force (EPF-A) was negatively correlated with femur length (FL) (p \u0026lt; 0.05). No significant correlations were found among the remaining parameters.\u003c/p\u003e"},{"header":"5 Discussions","content":"\u003cp\u003eThe biomechanical characteristics of manual manipulation are key indicators for evaluating the quality of clinical procedures and serve as an important basis for optimizing therapeutic protocols\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. In this study, we analyzed the biomechanical profiles of Lever-Positioning Manipulation (LPM) under different thrust modes, aiming to establish a precision-oriented treatment approach tailored to individual patient needs. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the LPM procedure is a complex three-dimensional composite motion involving multidirectional forces and displacements. We employed a novel wearable biomechanical measurement system equipped with a high-precision pressure sensor array, enabling real-time, dynamic acquisition of three-dimensional biomechanical parameters during manipulation. This system synchronously recorded both the practitioner\u0026rsquo;s operational forces and the subject\u0026rsquo;s mechanical responses, including key parameters such as force magnitude and application time. The primary objective of this study was to systematically compare the biomechanical differences between two distinct thrust modes of LPM, analyze the correlations among parameters and their clinical implications, and investigate the influence of individual subject characteristics on these parameters. The findings provide objective, quantitative metrics for clinical manual therapy, which may facilitate the development of evidence-based, individualized treatment plans, thereby improving therapeutic efficacy and reducing procedural risks.\u003c/p\u003e\u003cp\u003eThis study further performed a detailed biomechanical characterization of different thrust modes in LPM. The results revealed that the two operational modes not only demonstrated significant biomechanical differences but also exhibited specific interrelationships. Force\u0026ndash;time trajectory analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) identified three characteristic biomechanical phases: the preload phase, the instantaneous thrust phase, and the dissipation phase, consistent with the spinal manipulation force\u0026ndash;time curves described by Gyer et al.\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. During the preload phase, the practitioner applied targeted force via the elbow to a point 1 cm lateral to the paraspinal spinous process, producing a smooth and progressive rise in the force curve. Biomechanically, this gradual loading guided the subject\u0026rsquo;s lower limbs into extension, rotating the lumbar spine to its maximal physiological angle; the slow preload increase facilitated adaptive contraction of the paraspinal musculature, induced deformation of the intervertebral disc, and achieved graded stress transmission\u0026mdash;preparing the tissues for the subsequent rapid thrust\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e.In the instantaneous thrust phase, the force curve exhibited a typical \u0026ldquo;high-explosive\u0026rdquo; profile. This rapid thrust generated a pulse-like mechanical stimulus capable of overcoming the facet joint\u0026rsquo;s elastic barrier, producing multiple therapeutic effects: correction of subtle facet joint misalignments, promotion of herniated nucleus pulposus retraction through transient negative pressure, and activation of the disc\u0026rsquo;s hydrodynamic regulation mechanisms\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. Statistical analysis using the Shapiro\u0026ndash;Wilk test indicated that certain biomechanical parameters did not conform to normal distribution, potentially due to altered tactile feedback from wearing the measurement apparatus and the limited statistical power of the 107-case sample. Comparative analysis of left- and right-side manipulations in healthy volunteers showed no statistically significant differences (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), confirming that LPM possesses strong operational symmetry and clinical reproducibility.Regarding safety, all procedures strictly adhered to established clinical safety protocols, and no adverse events were observed during the study period. These findings confirm that, under standardized conditions, the biomechanical parameters generated by LPM remain within a safe and effective range. The safety mechanism appears to be attributable to three main factors: (1) the stress-buffering effect of the preload phase, which protects against excessive force during thrust; (2) precise control of the instantaneous thrust, ensuring accuracy of the mechanical stimulus; and (3) directional force application consistent with lumbar spine biomechanics, minimizing the risk of tissue injury. Collectively, these results provide robust evidence supporting the standardization and clinical application of LPM.\u003c/p\u003e\u003cp\u003eThis study focused on the unilateral and bilateral thrust modes of the Lever Positioning Manipulation (LPM), utilizing a novel wearable biomechanical measurement system to capture and analyze six key biomechanical parameters\u0026mdash;HPF, HMPF, HIPF, EPF, EMPF, and EIPF\u0026mdash;in real time. The mechanical differences between the two modes were systematically compared, the correlations among the parameters were explored, and the influence of individual anthropometric and structural characteristics on the practitioner\u0026rsquo;s force application strategy was analyzed.\u003c/p\u003e\u003cp\u003eThe results showed that, in the unilateral mode of LPM, EMPF-U was highly positively correlated with EIPF-U, suggesting a synergistic enhancement effect between the peak thrust force and the instantaneous impulse generated by the ipsilateral elbow. This may reflect the synchronous contraction and force transmission of the deep lumbar and dorsal muscle groups at the moment of thrust\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. Similar synergistic effects have been reported in high-velocity low-amplitude (HVLA) manipulations\u0026mdash;Nougarou et al.\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e observed a consistent dynamic linkage between preload force and peak force, indicating that the mechanical characteristics of different force application phases can jointly influence treatment outcomes. The significant positive correlations of HMPF-U with HIPF-U and HPF-U suggest the formation of a stable kinetic chain linking hand peak thrust force, instantaneous impulse, and preload force, which facilitates smooth and efficient force output. This finding aligns with the peak\u0026ndash;impulse coupling phenomenon observed by Choi et al.\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003eunder different manipulation strategies.In the bilateral mode, HMPF-A was highly positively correlated with HIPF-A (rs\u0026thinsp;=\u0026thinsp;0.837, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), indicating strong synchronization between the two hands during both peak thrust and instantaneous loading phases. Nyir\u0026ocirc; et al. \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e similarly reported a strong correlation between peak force and loading rate under simultaneous bilateral loading, reflecting the balanced activation of bilateral lumbar extensors and abdominal muscles. The significant positive correlation between EIPF-A and EMPF-A indicates coordinated force generation by both elbows, whereas the negative correlation between EIPF-A and EPF-A suggests the presence of a dynamic modulation mechanism between preload and instantaneous force, possibly to maintain lumbar segmental stability and safety during high-speed thrusting. Reed et al.\u003csup\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e noted that changes in peak force at a constant loading rate can markedly influence spinal kinematics and muscle activation patterns, implying that practitioners may dynamically adjust the balance between preload and explosive force according to the soft tissue and joint structural status of the patient.\u003c/p\u003e\u003cp\u003eWith respect to individual factors, the study found that in the unilateral mode, elbow preload force (EPF-U) was negatively correlated with lumbar curvature (LC), indicating that individuals with greater LC required less vertical elbow support force during the preload phase. This may be explained by the shortening of the posterior facet joint lever arm relative to the practitioner\u0026rsquo;s force direction, along with reduced initial tension of the posterior ligaments and joint capsule, thereby lowering the vertical pressure required to achieve the same degree of joint distraction\u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e. In the bilateral mode, hand peak thrust force (HMPF-A) was positively correlated with waist circumference (WC), supporting the notion that central obesity increases both external and internal lumbar loading\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. Existing computational modeling and epidemiological studies have shown that increased body weight and WC significantly raise L5\u0026ndash;S1 compressive and shear forces, while greater soft tissue thickness and viscoelastic resistance increase the peak traction force needed to overcome passive tissue resistance\u0026mdash;consistent with our observation that HMPF-A increased with WC\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e. Additionally, EPF-A was negatively correlated with femur length (FL) in the bilateral mode, suggesting that FL may influence force transmission efficiency through the pelvic\u0026ndash;lumbar biomechanical linkage. Prior research on lumbopelvic\u0026ndash;hip coordination has indicated that FL, along with its positional relationship to the pelvis, affects load transfer between the hip and lumbar spine\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e; when the lower limb lever arm is longer, practitioners can utilize a more advantageous force transmission pathway, thereby reducing dependence on sustained elbow pressure\u0026mdash;providing a plausible biomechanical explanation for the observed relationship of \u0026ldquo;longer FL, lower EPF\u0026rdquo;\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e"},{"header":"6 Limitations","content":"\u003cp\u003eThis study has certain limitations. First, all participants exhibited varying degrees of lumbar muscle tension. Although thorough lumbar relaxation was performed prior to manipulation to minimize variability from local muscle tone differences, this factor could not be entirely eliminated. Second, the range of quantified parameters was relatively limited, particularly regarding associations between biomechanical variables and individual characteristics, as only a small set of anthropometric variables was considered. Future studies should include clinical variables such as disease duration, pain scores, and lumbar muscle tension, as well as operator-related factors such as manual therapy experience, to establish a more comprehensive and clinically relevant multivariate regression model. Additionally, kinematic parameters such as lumbar angular displacement during manipulation should be incorporated into the evaluation framework to further refine the in vivo biomechanical profile of LPM. Future research could integrate motion capture technology, AnyBody modeling, and three-dimensional finite element analysis to investigate the deeper biomechanical mechanisms of LPM from multiple dimensions, thereby providing a stronger theoretical basis for its optimization and clinical application.\u003c/p\u003e"},{"header":"7 Conclusion","content":"\u003cp\u003eThis study employed a wearable biomechanical measurement system to perform an in vivo quantitative analysis of the unilateral and bilateral thrust modes of LPM. The results indicated that differences between LPM modes were associated with LDH subtypes, supporting the biomechanical rationale for subtype-based manipulation selection. Both modes demonstrated characteristic preload, instantaneous thrust, and dissipation phases. The preload phase exhibited a gradual force increase, facilitating progressive lumbar rotation and soft tissue stress adaptation, whereas the instantaneous thrust phase showed a \u0026ldquo;high-explosiveness\u0026rdquo; profile characteristic of HVLA manipulations. Healthy participants exhibited no significant left\u0026ndash;right differences in unilateral mode parameters, suggesting good operational symmetry and reproducibility. Individual factor analysis revealed that in the unilateral mode, EPF-U was negatively correlated with LC, indicating reduced elbow vertical support requirements in individuals with greater lumbar lordosis; in the bilateral mode, WC was positively correlated with HMPF-A, suggesting that individuals with larger WC require greater peak hand thrust to overcome soft tissue resistance; and FL was negatively correlated with EPF-A, likely due to the influence of lower limb length on force transmission efficiency via the lumbopelvic kinetic chain. These findings highlight the importance of incorporating patient-specific anatomical and anthropometric characteristics into LPM strategies to optimize efficacy and safety.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eLPM: Lever positioning manipulation; LDH: Lumbar disc herniation; HPF: Hand preload force; HMPF: Hand maximum pulling force; HIPF: Hand instantaneous pulling force; EPF: Elbow preload force; EMPF: Elbow maximum pressing force; EIPF: Elbow instantaneous pressing force; WC: Waist circumference; FL: Femur length; LA: Lumbosacral angle; LC: Lumbar curvature; LLA: Lumbar lordosis angle; TCM: Traditional Chinese medicine; BMI: Body mass index\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe studies involving humans were approved by the Institutional Review Board of The Third Affiliated Hospital of Zhejiang Chinese Medical University.The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eQX, LC, ZL, and LL contributed to the conception and design of the work and drafted the manuscript.KW and BW were responsible for data acquisition.ZZ and YT performed statistical analysis.All authors contributed to the analysis and interpretation of data, and critically reviewed the manuscript for important intellectual content.All authors read and approved the final manuscript.All authors had full access to all the data and take responsibility for the integrity of the data and the accuracy of the data analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author(s) declare that financial support was received for the research and/or publication of this article. This study received support from the General Program of the National Natural Science Foundation of China (No. 82474668), the National TCM Advantageous Specialty Construction Unit (State Administration of TCM Medical Policy Document No. 2024-90), the Lv Lijiang Famous Traditional Chinese Medicine Expert Inheritance Studio (No. GZS2021026), and the Key Discipline Project of High-level TCM of the National Administration of Traditional Chinese Medicine (No. GJXK2023-85). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe cooperation of all study participants is appreciated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePublisher’s note\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eZhao L, Ji C, Ma H, Guo J, Li Q. (2024).Research status and future prospects of acupuncture and moxibustion in the treatment of lumbar disc herniation. J Contemp Med Pract. 2024;6(7):188\u0026ndash;91. doi: 10.53469/jcmp.2024.06(07).38.\u003c/li\u003e\n\u003cli\u003eBerg AJ, Ahmadje U, Jayanna HH, Tr\u0026eacute;gou\u0026euml;t P, Sanville P, Kapoor V. (2020). The prevalence of lumbar disc degeneration in symptomatic younger patients: a study of MRI scans. J Clin Orthop Trauma. 2020;11(5):932\u0026ndash;6. doi: 10.1016/j.jcot.2020.07.021.\u003c/li\u003e\n\u003cli\u003eZhang AS, Xu A, Ansari K, Hardacker K, Anderson G, Alsoof D, et al. (2023).Lumbar disc herniation: diagnosis and management. 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J Manipulative Physiol Ther. 2016;39(1):1\u0026ndash;22. doi: 10.1016/j.jmpt.2015.10.006.\u003c/li\u003e\n\u003cli\u003eCao B, Zhou X, Zhang S-P, Zhu Q-G, Kong L-J, Fang M. (2022). Effect of traditional Chinese manual therapy on alleviating pain and dysfunction of lumbar disc herniation: a randomized controlled pilot study. Am J Transl Res. 2022;14(10):6941\u0026ndash;52. PMID: 36398213.\u003c/li\u003e\n\u003cli\u003eGhasabmahaleh SH, Rezasoltani Z, Dadarkhah A, et al. (2021),Spinal manipulation for subacute and chronic lumbar radiculopathy: a randomized controlled trial. Am J Med. 2021;134(1):135\u0026ndash;41. doi: 10.1016/j.amjmed.2020.08.005.\u003c/li\u003e\n\u003cli\u003eZhou X C, Chen L H, Wu S, Wang K Z, Wei Z C, Li T, et al. (2024).Brain effect mechanism of lever positioning manipulation on LDH analgesia based on multimodal MRI: a study protocol. BMC Complement Med Ther. 2024;24(1):246. doi:10.1186/s12906-024-04549-4.\u003c/li\u003e\n\u003cli\u003eLv L, Mao L, Li J, et al. 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Patient and provider characteristics associated with therapeutic intervention selection in a chiropractic clinical encounter: a cross-sectional analysis of the COAST and O-COAST study data. Chiropr Man Ther. 2023;31(1):39.\u003c/li\u003e\n\u003cli\u003eZhou Y .(2021). \u003cem\u003eTuina Manipulation Science\u003c/em\u003e. Beijing: China Press of Traditional Chinese Medicine; 2021.\u003c/li\u003e\n\u003cli\u003eTang J, Chen N, Huang B, et al. Efficacy of acupuncture combined with osteopathic manipulation in treating simple lumbar disc herniation and its effects on pain and lower limb sensory disorders. Zhonghua Zhongyiyao Zazhi. 2020;38(10):244\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eMou C, Shen X, Li G, et al. (2020).Clinical observation on TCM bone-setting manipulation combined with external application of Chinese herbs for improving lumbar curvature in lumbar disc herniation. Lishizhen Med Mater Medica Res. 2020;31(5):1179\u0026ndash;83.\u003c/li\u003e\n\u003cli\u003eGorrell LM, Nyir\u0026ouml; L, Pasquier M, Pag\u0026eacute; I, Heneghan NR, Schweinhardt P, et al. (2023).Spinal manipulation characteristics: a scoping literature review of force-time characteristics. Chiropr Man Ther. 2023;31(1):36. doi: 10.1186/s12998-023-00512-1.\u003c/li\u003e\n\u003cli\u003eGyer G, Michael J, Inklebarger J, Ibne Alam I. (2022). Effects of biomechanical parameters of spinal manipulation: a critical literature review. J Integr Med. 2022;20(1):4\u0026ndash;12. doi: 10.1016/j.joim.2021.10.002.\u003c/li\u003e\n\u003cli\u003eLangenfeld A, Baechler M, Swanenburg J, M\u0026uuml;hlemann M, Nyir\u0026ouml; L, Streuli D, et al. (2025).Systematic review on biomechanical effects of high-velocity, low amplitude spinal manipulation. PLoS One. 2025;20(7):e0328048. doi: 10.1371/journal.pone.0328048.\u003c/li\u003e\n\u003cli\u003eNougarou F, Dugas C, Loranger M, Pag\u0026eacute; I, Descarreaux M. (2016).The role of preload forces in spinal manipulation: experimental investigation of kinematic and electromyographic responses in healthy adults. J Manipulative Physiol Ther. 2014;37(5):287\u0026ndash;93. doi: 10.1016/j.jmpt.2014.04.002.\u003c/li\u003e\n\u003cli\u003eDu HG, Liao SH, Jiang Z, Huang HM, Ning XT, Jiang NY, et al. (2016). Biomechanical analysis of press-extension technique on degenerative lumbar with disc herniation and staggered facet joint. Saudi Pharm J. 2016;24(3):305\u0026ndash;11. doi: 10.1016/j.jsps.2016.04.002.\u003c/li\u003e\n\u003cli\u003eReed WR, Liebschner MAK, Lima CR, Singh H, Hurt CP, Martins DF, et al. (2022). In vivo measurement of intradiscal pressure changes related to thrust and non-thrust spinal manipulation in an animal model: a pilot study. Chiropr Man Ther. 2022;30:36. doi: 10.1186/s12998-022-00445-1.\u003c/li\u003e\n\u003cli\u003eVleeming A, Schuenke MD, Danneels L, Willard FH. (2014).The functional coupling of the deep abdominal and paraspinal muscles: the effects of simulated paraspinal muscle contraction on force transfer to the middle and posterior layer of the thoracolumbar fascia. J Anat. 2014;225(4):447\u0026ndash;62. doi: 10.1111/joa.12227.\u003c/li\u003e\n\u003cli\u003eNougarou F, Pag\u0026eacute; I, Loranger M, Dugas C, Descarreaux M. (2016). Neuromechanical response to spinal manipulation therapy: effects of a constant rate of force application. BMC Complement Altern Med. 2016;16:161. doi: 10.1186/s12906-016-1153-6.\u003c/li\u003e\n\u003cli\u003eChoi G, McGuinty A, Smith NM, Frangakis EM, Starmer D, Howarth SJ, et al. (2025).Efficacy of different biomechanical strategies for modulating force\u0026ndash;time parameters of high-velocity low-amplitude manipulation of the thoracic spine: a randomized crossover experimental study. Chiropr Man Ther. 2025;33(1):25.\u003c/li\u003e\n\u003cli\u003eNyir\u0026ouml; L, Gorrell LM, Cecchini V, Menon C, Elgendi M, Schweinhardt P. (2024).Variability and repeatability of spinal manipulation force\u0026ndash;time characteristics in thoracic spinal manipulation on a manikin. Chiropr Man Ther. 2024;32(1):33. doi: 10.1186/s12998-024-00551-2.\u003c/li\u003e\n\u003cli\u003eReed WR, Long CR, Kawchuk GN, Pickar JG. (2014).Neural responses to the mechanical parameters of a high velocity, low amplitude spinal manipulation: effect of preload parameters. J Manipulative Physiol Ther. 2014;37(2):68\u0026ndash;78. doi: 10.1016/j.jmpt.2013.12.004.\u003c/li\u003e\n\u003cli\u003eM\u0026uuml;ller A, Rockenfeller R, Damm N, Kosterhon M, Kantelhardt SR, Aiyangar AK, et al. (2021).Load distribution in the lumbar spine during modeled compression depends on lordosis. Front Bioeng Biotechnol. 2021;9:661258. doi: 10.3389/fbioe.2021.661258.\u003c/li\u003e\n\u003cli\u003eDu CF, Yang N, Guo JC, Huang YP, Zhang C. (2016).Biomechanical response of lumbar facet joints under follower preload: a finite element study. BMC Musculoskelet Disord. 2016;17:126. doi: 10.1186/s12891-016-0980-4.\u003c/li\u003e\n\u003cli\u003eHajihosseinali M, Arjmand N, Shirazi-Adl A. (2015).Effect of body weight on spinal loads in various activities: a personalized biomechanical modeling approach. J Biomech. 2015;48(2):276\u0026ndash;82. doi: 10.1016/j.jbiomech.2014.11.033.\u003c/li\u003e\n\u003cli\u003eBayoglu R, Galibarov PE, Verdonschot N, Koopman B, Homminga J. (2019).Twente Spine Model: a thorough investigation of the spinal loads in a complete and coherent musculoskeletal model of the human spine. Med Eng Phys. 2019;68:35\u0026ndash;45. doi: 10.1016/j.medengphy.2019.03.015.\u003c/li\u003e\n\u003cli\u003eBahramian M, Arjmand N, El-Rich M, Parnianpour M. (2023).Effect of obesity on spinal loads during load-reaching activities: a subject- and kinematics-specific musculoskeletal modeling approach. J Biomech. 2023;161:111770. doi: 10.1016/j.jbiomech.2023.111770.\u003c/li\u003e\n\u003cli\u003eBallard MT ,Drury C, Bazrgari B. (2020),Changes in lumbo-pelvic coordination of individuals with and without low back pain when wearing a hip orthosis. Front Sports Act Living. 2020;2:90. doi: 10.3389/fspor.2020.00090.\u003c/li\u003e\n\u003cli\u003eBibrowicz K, Szurmik T, Kurzeja P, Bibrowicz B, Ogrodzka-Ciechanowicz K. (2024).Pelvic tilt and stiffness of the muscles stabilising the lumbo-pelvic-hip (LPH) complex in tensiomyography examination. PLoS One. 2024;19(10):e0312480. doi: 10.1371/journal.pone.0312480.\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":"Lever positioning manipulation (LPM), Lumbar disc herniation (LDH), Lumbar disc degeneration, Biomechanics, Individual characteristics","lastPublishedDoi":"10.21203/rs.3.rs-7723433/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7723433/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLever Positioning Manipulation (LPM), an innovative manual therapy derived from traditional lumbar extension manipulation in Traditional Chinese Medicine, has been clinically proven to be effective in treating Lumbar Disc Herniation (LDH). However, clinical observations indicate significant individual variations in patients' responses to LPM treatment, with therapeutic outcomes closely related to the applied manipulation force and individual patient characteristics. Therefore, conducting quantitative research on the mechanical parameters of different LPM manipulation modes and analyzing individual factors hold significant clinical importance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 107 volunteers were recruited from the Department of Tuina, The Third Affiliated Hospital of Zhejiang Chinese Medical University. Biomechanical data of unilateral and bilateral LPM were collected using wearable gloves and elbow sleeves, including hand preload force (HPF), hand maximum pulling force (HMPF), hand instantaneous pulling force (HIPF), elbow preload force (EPF), elbow maximum pressing force (EMPF), and elbow instantaneous pressing force (EIPF). Individual characteristic parameters recorded included waist circumference (WC), femur length (FL), lumbosacral angle (LA), lumbar curvature (LC), and lumbar lordosis angle (LLA). Quantitative and correlation analyses were conducted.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo significant differences were found between left- and right-sided unilateral manipulations (p \u0026gt; 0.05). Compared with LDH patients, healthy participants showed significant differences in EPF-A (p \u0026lt; 0.05), but not in other parameters. In unilateral LPM, EMPF-U correlated strongly with EIPF-U (p \u0026lt; 0.01), HMPF-U with both HIPF-U and HPF-U (p \u0026lt; 0.01), and EPF-U with EMPF-U (p \u0026lt; 0.05). In bilateral LPM, HMPF-A correlated with HIPF-A (p \u0026lt; 0.01); EPF-A correlated positively with EMPF-A (p \u0026lt; 0.05) but negatively with EIPF-A (p \u0026lt; 0.05). EMPF-A and EIPF-A were positively correlated (p \u0026lt; 0.01). Regarding individual characteristics, EPF-U negatively correlated with LC (p \u0026lt; 0.05); in bilateral LPM, HMPF-A correlated positively with WC (p \u0026lt; 0.05), and EPF-A negatively with FL (p \u0026lt; 0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study quantitatively defined biomechanical profiles of unilateral and bilateral LPM and clarified inter-parameter correlations and their associations with individual characteristic parameters. Findings support tailoring manipulation strategies based on lumbar curvature, waist circumference, and femur length to optimize individualized, precision treatment for LDH.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study protocol was registered at ClinicalTrials.gov (ClinicalTrials.gov Registration Number and Date: NCT06872918, Initial Release: 10/03/2025).\u003c/p\u003e","manuscriptTitle":"In vivo biomechanical quantification and individual factor analysis of lever positioning manipulation under different thrust modes：a cross-sectional study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-08 15:16:16","doi":"10.21203/rs.3.rs-7723433/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":"0c5b484e-84aa-498e-8a3f-15d16c38453a","owner":[],"postedDate":"November 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-14T05:08:15+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-08 15:16:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7723433","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7723433","identity":"rs-7723433","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}