Biomechanics of the Shoulder in Youth Baseball Pitchers

2005 ◽  
Vol 33 (11) ◽  
pp. 1716-1722 ◽  
Author(s):  
Michelle B. Sabick ◽  
Young-Kyu Kim ◽  
Michael R. Torry ◽  
Michael A. Keirns ◽  
Richard J. Hawkins
Keyword(s):  
Body Weight ◽  
External Rotation ◽  
Pitching Motion ◽  
Little League ◽  
Youth Baseball ◽  
Shoulder External Rotation ◽  
Baseball Pitchers ◽  
Force Components ◽  
Simulated Game ◽  
Distraction Force

Background The effects of repetitive throwing on the shoulders of developing athletes are not well understood because of the paucity of data describing the biomechanics of youth pitchers and the plasticity of the developing skeleton. Hypothesis The direction and magnitude of the stresses that exist at the proximal humeral physis during the fastball pitching motion are consistent with the development of proximal humeral epiphysiolysis (Little League shoulder) and/or humeral retrotorsion. Study Design Descriptive laboratory study. Methods A total of 14 elite youth baseball pitchers (mean age, 12.1 ± 0.4 years) were filmed from the front and dominant side while throwing fastballs in a simulated game. The net force and torque acting on the humerus throughout the throwing motion were calculated using standard biomechanical techniques. Results The external rotation torque about the long axis of the humerus reached a peak value of 17.7 ± 3.5 N.m (2.7% ± 0.3% body weight × height) just before maximum shoulder external rotation. A shoulder distraction force of 214.7 ± 47.2 N (49.8% ± 8.3% body weight) occurred at, or just after, ball release. Conclusion Shear stress arising from the high torque late in the arm-cocking phase is large enough to lead to deformation of the weak proximal humeral epiphyseal cartilage, causing either humeral retrotorsion or proximal humeral epiphysiolysis over time. The stresses generated by the external rotation torque are much greater than those caused by distraction forces generated during the pitching motion of youth baseball pitchers. Clinical Relevance The motion of throwing fastballs by youth baseball pitchers results in force components consistent with proposed mechanisms for 2 clinical entities.

The influence of shoulder abduction and external rotation on throwing arm kinetics in professional baseball pitchers

2021 ◽  
pp. 175857322110103
Author(s):  
Joseph E Manzi ◽  
Brittany Dowling ◽  
Nicolas Trauger ◽  
Michael C Fu ◽  
Benjamin R Hansen ◽  
...  
Keyword(s):  
Body Weight ◽  
External Rotation ◽  
Professional Baseball ◽  
Shoulder Abduction ◽  
3D Motion Analysis ◽  
Ball Release ◽  
Ball Velocity ◽  
Shoulder External Rotation ◽  
Baseball Pitchers ◽  
Distraction Force

Background The relationships between shoulder abduction and external rotation with peak kinetic values at the shoulder and elbow in professional baseball pitchers are not well established. Methods Professional pitchers ( n = 322) threw 8–12 fastballs under 3D motion analysis (480 Hz). Pitchers were stratified into quartiles by shoulder abduction and external rotation at distinct timepoints. Regression analyses were performed to quantify associations between shoulder position and kinetics. Results Shoulder abduction remained relatively consistent throughout the pitch (foot contact–ball release: 85.5 ± 11.1–90.7 ± 8.4°); shoulder external rotation increased dramatically (foot contact–ball release: 30.8 ± 24.6–165.2 ± 9.7°). For every 10° increase in maximum shoulder rotation, shoulder superior force increased by 2.3% body weight ( p < 0.01), shoulder distraction force increased by 5.9% body weight ( p < 0.01), and ball velocity increased by 0.60 m/s ( p < 0.01). Shoulder abduction was significantly associated with shoulder superior force at all timepoints but not with ball velocity ( p > 0.05). For every 10° increase in shoulder abduction at ball release, shoulder superior force increased by 3.7% body weight ( p < 0.01) and shoulder distraction force increased by 11.7% body weight ( p < 0.01). Conclusion Increased shoulder abduction at ball release and increased maximum shoulder external rotation were associated with greater superior and distraction forces in the shoulder. Pitchers can consider decreasing shoulder abduction at later stages of the pitch to around 80° in order to minimize shoulder superior force, with no impact on ball velocity.

scholarly journals Correlation of Shoulder and Elbow Kinetics With Ball Velocity in Collegiate Baseball Pitchers

2015 ◽  
Vol 50 (6) ◽  
pp. 629-633 ◽  
Author(s):  
Eric G. Post ◽  
Kevin G. Laudner ◽  
Todd A. McLoda ◽  
Regan Wong ◽  
Keith Meister
Keyword(s):  
External Rotation ◽  
Pearson Correlation ◽  
Anatomical Landmarks ◽  
Positive Correlation ◽  
Weak Positive Correlation ◽  
Ball Velocity ◽  
Collegiate Baseball ◽  
Shoulder External Rotation ◽  
Baseball Pitchers ◽  
Distraction Force

Context Throwing a baseball is a dynamic and violent act that places large magnitudes of stress on the shoulder and elbow. Specific injuries at the elbow and glenohumeral joints have been linked to several kinetic variables throughout the throwing motion. However, very little research has directly examined the relationship between these kinetic variables and ball velocity. Objective To examine the correlation of peak ball velocity with elbow-valgus torque, shoulder external-rotation torque, and shoulder-distraction force in a group of collegiate baseball pitchers. Design Cross-sectional study. Setting Motion-analysis laboratory. Patients or Other Participants Sixty-seven asymptomatic National Collegiate Athletic Association Division I baseball pitchers (age = 19.5 ± 1.2 years, height = 186.2 ± 5.7 cm, mass = 86.7 ± 7.0 kg; 48 right handed, 19 left handed). Main Outcome Measure(s) We measured peak ball velocity using a radar gun and shoulder and elbow kinetics of the throwing arm using 8 electronically synchronized, high-speed digital cameras. We placed 26 reflective markers on anatomical landmarks of each participant to track 3-dimensional coordinate data. The average data from the 3 highest-velocity fastballs thrown for strikes were used for data analysis. We calculated a Pearson correlation coefficient to determine the associations between ball velocity and peak elbow-valgus torque, shoulder-distraction force, and shoulder external-rotation torque (P &lt; .05). Results A weak positive correlation was found between ball velocity and shoulder-distraction force (r = 0.257; 95% confidence interval [CI] = 0.02, 0.47; r2 = 0.066; P = .018). However, no significant correlations were noted between ball velocity and elbow-valgus torque (r = 0.199; 95% CI = −0.043, 0.419; r2 = 0.040; P = .053) or shoulder external-rotation torque (r = 0.097; 95% CI = −0.147, 0.329; r2 = 0.009; P = .217). Conclusions Although a weak positive correlation was present between ball velocity and shoulder-distraction force, no significant association was seen between ball velocity and elbow-valgus torque or shoulder external-rotation torque. Therefore, other factors, such as improper pitching mechanics, may contribute more to increases in joint kinetics than peak ball velocity.

scholarly journals Youth Baseball Pitching Mechanics: A Systematic Review

2017 ◽  
Vol 10 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Samuel F. Thompson ◽  
Trent M. Guess ◽  
Andreas C. Plackis ◽  
Seth L. Sherman ◽  
Aaron D. Gray
Keyword(s):  
Systematic Review ◽  
External Rotation ◽  
Data Extraction ◽  
Level Of Evidence ◽  
Pitching Motion ◽  
Study Selection ◽  
Youth Baseball ◽  
Level 3 ◽  
Shoulder External Rotation ◽  
Manual Extraction

Context: Pitching injuries in youth baseball are increasing in incidence. Poor pitching mechanics in young throwers have not been sufficiently evaluated due to the lack of a basic biomechanical understanding of the “normal” youth pitching motion. Objective: To provide a greater understanding of the kinetics and kinematics of the youth baseball pitching motion. Data Sources: PubMed, MEDLINE, and SPORTDiscus databases were searched from database inception through February 2017. Study Selection: A total of 10 biomechanical studies describing youth pitching mechanics were included. Study Design: Systematic review. Level of Evidence: Level 3. Data Extraction: Manual extraction and compilation of demographic, methodology, kinetic, and kinematic variables from the included studies were completed. Results: In studies of healthy youth baseball pitchers, progressive external rotation of the shoulder occurs throughout the start of the pitching motion, reaching a maximum of 166° to 178.2°, before internally rotating throughout the remainder of the cycle, reaching a minimum of 13.2° to 17°. Elbow valgus torque reaches the highest level (18 ± 4 N·m) just prior to maximum shoulder external rotation and decreases throughout the remainder of the pitch cycle. Stride length is 66% to 85% of pitcher height. In comparison with a fastball, a curveball demonstrates less elbow varus torque (31.6 ± 15.3 vs 34.8 ± 15.4 N·m). Conclusion: Multiple studies show that maximum elbow valgus torque occurs just prior to maximum shoulder external rotation. Forces on the elbow and shoulder are greater for the fastball than the curveball.

Increased Shoulder Distraction Force and Shoulder Horizontal Abduction in Professional Baseball Pitchers With Discordant Torso Rotation Order

2021 ◽  
pp. 036354652110413
Author(s):  
Joseph E. Manzi ◽  
Brittany Dowling ◽  
Joshua S. Dines ◽  
Alexander Richardson ◽  
Kathryn L. McElheny ◽  
...  
Keyword(s):  
Upper Extremity ◽  
Internal Rotation ◽  
External Rotation ◽  
Rotation Velocity ◽  
Mean Difference ◽  
Professional Baseball ◽  
Pelvic Rotation ◽  
Shoulder External Rotation ◽  
Baseball Pitchers ◽  
Distraction Force

Background: Inefficient energy transfer from the pelvis and trunk has been shown to increase compensation at the level of the shoulder. Kinetic chain sequencing of the core segments is underexamined in professional baseball pitchers, especially as it relates to changes in upper extremity kinetics. Purpose: To evaluate elbow and shoulder kinetics in a cohort of professional pitchers differentiated by instances of discordant pelvic to upper torso sequencing during the pitch. Study Design: Descriptive laboratory study. Methods: 285 professional baseball pitchers were evaluated using 3D motion capture (480 Hz). Pitchers were divided into “chronological” and “discordant” groups based on whether maximum pelvic rotation velocity occurred before (chronological) or after (discordant) maximum upper torso rotation velocity during the pitch motion. Pelvic, upper torso, and shoulder kinematic parameters, shoulder distraction force, shoulder internal rotation torque, and pitch efficiency (PE) were compared between groups. Results: Pitchers with discordant torso sequencing (n = 30; 110 pitches) had greater shoulder horizontal adduction at maximum external rotation (mean difference, 3.6°; 95% CI, −5.2° to −2.0°; t = −4.5; P < .001) and greater maximum shoulder external rotation (mean difference, 3.7°; 95% CI, 5.7° to 1.5°; t = −3.5; P < .001) than chronological pitchers (n = 255; 2974 pitches). PE did not differ between groups ( P = .856), whereas ball velocity was significantly faster in the discordant group (mean difference, 0.6 m/s; 95% CI, −1.1 to −0.3 m/s; t = −3.3; P = .0012). Chronological pitchers had significantly reduced shoulder distraction force (mean difference, −4.7% body weight (BW); 95% CI, −7.9% to −1.5% BW; t = −2.9; P = .004) with no difference in shoulder internal rotation torque ( P = .160). These kinematic and kinetic differences were not observed when accounting for interpitcher variability. Conclusion: Between pitchers, those who had a discordant pelvic to upper torso sequence experienced significantly greater shoulder distraction forces, potentially compensating by increasing maximum shoulder external rotation and horizontal abduction. Achieving maximal pelvic rotation velocity before maximal rotation velocity may be advantageous in preventing compensation at the upper extremity and excessive throwing arm loading. Clinical Relevance: Identifying risk factors for increased upper extremity forces has potential implications in injury prevention. Specifically, mitigating shoulder distraction forces may be beneficial in reducing risk of injury.

scholarly journals Effects of Game Pitch Count and Body Mass Index on Pitching Biomechanics in 9- to 10-Year-Old Baseball Athletes

2018 ◽  
Vol 6 (4) ◽  
pp. 232596711876565 ◽  
Author(s):  
Jim D. Darke ◽  
Eshan M. Dandekar ◽  
Arnel L. Aguinaldo ◽  
Scott J. Hazelwood ◽  
Stephen M. Klisch
Keyword(s):  
Body Mass Index ◽  
Body Composition ◽  
Internal Rotation ◽  
Body Mass ◽  
External Rotation ◽  
Joint Torque ◽  
Joint Kinetics ◽  
Youth Baseball ◽  
Baseball Pitchers ◽  
Simulated Game

Background: Pitching while fatigued and body composition may increase the injury risk in youth and adult pitchers. However, the relationships between game pitch count, biomechanics, and body composition have not been reported for a study group restricted to 9- to 10-year-old athletes. Hypothesis: During a simulated game with 9- to 10-year-old athletes, (1) participants will experience biomechanical signs of fatigue, and (2) shoulder and elbow kinetics will correlate with body mass index (BMI). Study Design: Descriptive laboratory study. Methods: Thirteen 9- to 10-year-old youth baseball players pitched a simulated game (75 pitches). Range of motion and muscular output tests were conducted before and after the simulated game to quantify fatigue. Kinematic parameters at foot contact, maximum external rotation, and maximum internal rotation velocity (MIRV), as well as maximum shoulder and elbow kinetics between foot contact and MIRV were compared at pitches 1-5, 34-38, and 71-75. Multivariate analyses of variance were used to test the first hypothesis, and linear regressions were used to test the second hypothesis. Results: MIRV increased from pitches 1-5 to 71-75 ( P = .007), and head flexion at MIRV decreased from pitches 1-5 to 34-38 ( P = .022). Maximum shoulder horizontal adduction, external rotation, and internal rotation torques increased from pitches 34-38 to 71-75 ( P = .031, .023, and .021, respectively). Shoulder compression force increased from pitches 1-5 to 71-75 ( P = .011). Correlations of joint torque/force with BMI were found at every pitch period: for example, shoulder internal rotation ( R2 = 0.93, P < .001) and elbow varus ( R2 = 0.57, P = .003) torques at pitches 1-5. Conclusion: Several results differed from those of previous studies with adult pitchers: (1) pitch speed remained steady, (2) shoulder MIRV increased, and (3) shoulder kinetics increased during a simulated game. The strong correlations between joint kinetics and BMI reinforce previous findings that select body composition measures may be correlated with pitching arm joint kinetics for youth baseball pitchers. Clinical Relevance: The results improve our understanding of pitching biomechanics for 9- to 10-year-old baseball pitchers and may be used in future studies to improve evidence-based injury prevention guidelines.

Internal- and External-Rotation Peak Torque in Little League Baseball Players With Subacromial Impingement Syndrome: Improved by Closed Kinetic Chain Shoulder Training

2016 ◽  
Vol 25 (3) ◽  
pp. 263-265 ◽  
Author(s):  
Dong-Rour Lee ◽  
Laurentius Jongsoon Kim
Keyword(s):  
Angular Velocity ◽  
External Rotation ◽  
Peak Torque ◽  
Subacromial Impingement Syndrome ◽  
Subacromial Impingement ◽  
Kinetic Chain ◽  
Baseball Players ◽  
Little League ◽  
Youth Baseball ◽  
Closed Kinetic Chain

Context:Many studies have explored closed kinetic chain (CKC) shoulder exercises (SEs) with a sling because they are safer and more effective than open-chain exercises, especially in early stages of treatment. However, the application of CKC SE in youth baseball players has rarely been attempted, although teenage baseball players also experience shoulder pain.Objective:To investigate the effects of CKC SE on the peak torque of shoulder internal rotation (IR) and external rotation (ER) in youth baseball players.Design:Single-group pretest, posttest.Setting:Biomechanics laboratory.Participants:23 Little League Baseball players with subacromial impingement syndrome.Interventions:The CKC SE with a sling was CKC shoulder-flexion exercise, extension exercise, IR exercise, and ER exercise. This exercise regimen was conducted 2 or 3 times/wk for 8 wk.Main Outcome Measures:The peak torque of shoulder IR and ER was measured using an isokinetic dynamometer. Concentric shoulder rotation was performed, with 5 repetitions at an angular velocity of 60°/s and 15 at 180°/s.Results:The IR and ER peak torque significantly increased at each angular velocity after the exercise program. In particular, the increase in IR and ER peak torque values was statistically significant at an angular velocity of 180°/s.Conclusions:CKC SE was effective in increasing shoulder IR and ER strength, demonstrating its potential benefits in the prevention and treatment of shoulder injury. In addition, increased IR peak torque appears to improve throwing velocity in baseball players.

scholarly journals Baseball Pitchers’ Kinematic Sequences and Their Relationship to Elbow and Shoulder Torque Production

2019 ◽  
Vol 7 (7_suppl5) ◽  
pp. 2325967119S0042
Author(s):  
Donna Moxley Scarborough ◽  
Shannon E. Linderman ◽  
Javier E. Sanchez ◽  
Eric M. Berkson
Keyword(s):  
Upper Extremity ◽  
External Rotation ◽  
Kinetic Chain ◽  
Joint Torques ◽  
Ball Velocity ◽  
Collegiate Baseball ◽  
Angular Velocities ◽  
Shoulder External Rotation ◽  
Baseball Pitchers ◽  
The Ideal

Objectives: Ball velocity is generated during the overhead baseball pitch via efficient force transmission up the kinetic chain, from the lower body up and outward to the throwing hand. The kinematic sequence, or the sequential timing pattern of peak angular velocities of body segments during a pitch, provides insight to segment position and motion control that drives the kinetic chain (Putnam CA, 1993). Previous publications report an ideal kinematic sequence (KS) where the timing of each body segment’s peak angular velocity occurs in a proximal-to-distal (PDS) pattern resulting in greater ball velocity and reduction in throwing arm injury risk (Fortenbaugh D, et.al, 2009). A recent study revealed that baseball pitchers perform a variety of KSs (Scarborough DM et.al, 2018). There is no known investigation of the relationship of kinematic sequences and throwing arm joint torques. The purpose of this study was to 1) identify the number of different KSs performed by each pitcher and 2) compare elbow valgus and shoulder external rotation (ER) and extension (Ext) torques between the 3 primary KSs performed during the fastball pitch. Methods: Fourteen collegiate baseball pitchers (20.57 ± 1.91 yr) underwent 3D biomechanical pitch analysis using 20 motion-capture Vicon MX™ cameras (360 Hz). A total of 119 fastball pitches with an average of 8.5 ± 2.71 pitches per player were analyzed. Elbow valgus and shoulder external rotation and extension torques were calculated. The timing of peak angular velocities for the pelvis, trunk, arm, forearm and hand body segments were recorded to generate each pitch’s KS. KSs were then divided into groups based on similarities to the ideal PDS pattern. ANCOVA statistical analyses were performed to compare joint torques across these KS groups with ball velocity as a covariate. Results: A total of 13 different KSs were observed across the 14 pitchers resulting in an average of 3 ± 1.41 different KSs per pitcher. Three different primary KS groups were identified: (1) PDS group: with a KS closest to the ideal PDS pattern (2) the Altered Distal Upper Extremity segment: with the forearm peaking after the hand (the most common group) and (3) Altered Proximal Upper Extremity segment order with the arm segment peaking after the hand (2nd most common). Across these three primary KS patterns, statistically significant differences were noted for elbow valgus torque [F(62,2) = 8.785, ɳ2 = .221, p < 0.00], shoulder external rotation (ER) torque [F(62,2) = 14.127, ɳ2 = .313, p < 0.00] and shoulder extension (Ext) torque [F(62,2) = 13.237, ɳ2 = .299, p < 0.00] (Figure 1). Conclusion: Our findings demonstrate that collegiate baseball pitchers performed an average of 3 different kinematic sequence patterns during fastball pitching. This is the first study to demonstrate a relationship between KSs and elbow and shoulder torque production. As anticipated, the PDS KSs produced the least torque across the elbow and shoulder joints. Alterations in Distal Upper Extremity KS was most common and generated the greatest shoulder Ext torques. Alterations in the Proximal Upper Extremity KS demonstrated the greatest elbow valgus and shoulder ER. Further study of the influence of kinematic sequence on joint torques in the baseball pitch may provide insight into pitching injuries and injury avoidance programs.

Relationship between Shoulder Pain and Selected Variables in Patients with Hemiplegia

1988 ◽  
Vol 2 (2) ◽  
pp. 111-117 ◽  
Author(s):  
Richard W Bohannon
Keyword(s):  
Body Weight ◽  
Shoulder Pain ◽  
External Rotation ◽  
Adhesive Capsulitis ◽  
Independent Variables ◽  
Extensor Muscles ◽  
Shoulder External Rotation ◽  
Muscle Groups ◽  
The Relationship ◽  
External Rotator

This investigation was performed to clarify the relationship between six independent variable categories and shoulder pain (SP) in hemiplegia. In this study, 30 hemiplegic patients served as subjects. The Ritchie articular index was used to measure SP. The independent variables were age, body weight, time since onset of stroke, shoulder subluxation, range of shoulder external rotation, and plegic shoulder muscle group strength. Subluxation was judged by palpation. Range of shoulder external rotation was measured goniometrically. Strength of the shoulder internal and external rotator, abductor and extensor muscles was measured with a hand-held dynamometer and normalized against body weight. A strength balance ratio of the shoulder was also determined (external rotators + abductors/internal rotators + extensors). Variables were measured on admission and prior to discharge. Spearman correlations or chi-squares were determined between the initial and final measurements of the independent variables and SP. More than 80% of the patients had SP. Correlated significantly with SP at both assessments and across time were range of shoulder external rotation (−.574 to −.797), and strength of the shoulder external rotator (−.523 to −.583) and abductor (−.375 to −.519) muscles. Correlated significantly at one or more of the assessments were body weight, time since onset and the strength of the other muscle groups (including the strength ratio). Shoulder subluxation was not correlated with SP. Patients with greater weakness may be more prone to the development of pain because their muscles lack adequate strength to move the joint enough to prevent the development of adhesive capsulitis.

scholarly journals Association of Pitch Timing and Throwing Arm Kinetics in High School and Professional Pitchers

2021 ◽  
Vol 49 (12) ◽  
pp. 3386-3394
Author(s):  
Joseph E. Manzi ◽  
Brittany Dowling ◽  
Zhaorui Wang ◽  
Kyle N. Kunze ◽  
Jennifer Estrada ◽  
...  
Keyword(s):  
High School ◽  
Injury Prevention ◽  
Significant Loss ◽  
Mixed Effect ◽  
Pitching Motion ◽  
3 Dimensional ◽  
Ball Velocity ◽  
Angular Velocities ◽  
Baseball Pitchers ◽  
Distraction Force

Background: Understanding the relationship between the temporal phases of the baseball pitch and subsequent joint loading may improve our understanding of optimal pitching mechanics and contribute to injury prevention in baseball pitchers. Purpose: To investigate the temporal phases of the pitching motion and their associations with ball velocity and throwing arm kinetics in high school (HS) and professional (PRO) baseball pitchers. Study Design: Descriptive laboratory study. Methods: PRO (n = 317) and HS (n = 54) baseball pitchers were evaluated throwing 8 to 12 fastball pitches using 3-dimensional motion capture (480 Hz). Four distinct phases of the pitching motion were evaluated based on timing of angular velocities: (1) Foot-Pelvis, (2) Pelvis-Torso, (3) Torso-Elbow, and (4) Elbow-Ball. Peak elbow varus torque, shoulder internal rotation torque, and shoulder distraction force were also calculated and compared between playing levels using 2-sample t tests. Linear mixed-effect models with compound symmetry covariance structures were used to correlate pitch velocity and throwing arm kinetics with the distinct temporal phases of the pitching motion. Results: PRO pitchers had greater weight and height, and faster ball velocities than HS pitchers ( P < .001). There was no difference in total pitch time between groups ( P = .670). PRO pitchers spent less time in the Foot-Pelvis ( P = .010) and more time in the Pelvis-Torso ( P < .001) phase comparatively. Shorter time spent in the earlier phases of the pitching motion was significantly associated with greater ball velocity for both PRO and HS pitchers (Foot-Pelvis: B = −6.4 and B = −11.06, respectively; Pelvis-Torso: B = −6.4 and B = −11.4, respectively), while also associated with increased shoulder proximal force (Pelvis-Torso: B = −76.4 and B = −77.5, respectively). Decreased time in the Elbow-Ball phase correlated with greater shoulder proximal force for both cohorts (B = −1150 and B = −645, respectively) with no significant correlation found for ball velocity. Conclusion: Significant differences in temporal phases exist between PRO and HS pitchers. For all pitchers, increased time spent in the final phase of the pitching motion has the potential to decrease shoulder distraction force with no significant loss in ball velocity. Clinical Relevance: Identifying risk factors for increased shoulder and elbow kinetics, acting as a surrogate for loading at the respective joints, has potential implications in injury prevention.

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