STRENGTHENING AND STABILIZATION EXERCISES IN PREVENTION OF SHOULDER INJURIES

sportlogia ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 149-160
Author(s):  
Bernarda Letnar ◽  
Keyword(s):  
Training Program ◽  
Internal Rotation ◽  
Shoulder Joint ◽  
External Rotation ◽  
Shoulder Injuries ◽  
Serratus Anterior ◽  
Warm Up ◽  
Overhead Athletes ◽  
Daily Training ◽  
Stretching Exercises

The shoulder joint is the most flexible joint in the human body which experiences high loads during certain sport activities involving overhead motion. Overhead athletes experience rapid shoulder elevation, abduction and external rotation during the movement and rapid deceleration after the movement, making them susceptible to shoulder injuries. Due to the extreme ranges of motion, overhead athletes tend to develop increased external rotation, combined with decreased range of internal rotation, emphasizing the need for balanced shoulder care program in the training process to prevent such occurrences. The aim of the research paper was to develop training regimen for injury prevention and shoulder maintenance that can be incorporated in daily training activities of the athletes in order to decrease the occurrence of injuries. Three part training program was designed consisting of specific warm up, strengthening and stabilization exercises and stretching exercises. The aim of the specific warm up was to prepare the shoulder for the training loads, mimicking the overhead movements and stimulating the stabilization in the joint. Strengthening and stabilization exercises aimed to strengthen external rotators in the shoulder and improve the stabilization of the shoulder joint by targeting specific muscles such as serratus anterior. The focus of stretching exercises was to stretch internal rotation muscles, which experience high loads in the overhead athlete's training. An effective training program that can be performed with minimal equipment and in a short time frame was designed to enable its simple incorporation into the daily training of overhead athletes.

scholarly journals Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

2011 ◽  
Vol 46 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Mithun Joshi ◽  
Charles A. Thigpen ◽  
Kevin Bunn ◽  
Spero G. Karas ◽  
Darin A. Padua
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
External Rotation ◽  
Shoulder Injuries ◽  
Serratus Anterior ◽  
Overhead Athletes ◽  
Scapular Kinematics ◽  
Fatigue Protocol ◽  
Upper Trapezius ◽  
Lower Trapezius

Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Intervention(s): We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending-phase lower trapezius activity (F1,25 = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P = .04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular and glenohumeral force couples. Fatigue-induced alterations in the lower trapezius might predispose the infraspinatus to injury through chronically increased activation.

scholarly journals Effect of a 6-Week Strengthening Program on Shoulder and Scapular-Stabilizer Strength and Scapular Kinematics in Division I Collegiate Swimmers

2012 ◽  
Vol 21 (3) ◽  
pp. 253-265 ◽  
Author(s):  
Elizabeth E. Hibberd ◽  
Sakiko Oyama ◽  
Jeffrey T. Spang ◽  
William Prentice ◽  
Joseph B. Myers
Keyword(s):  
Muscle Strength ◽  
Internal Rotation ◽  
Intervention Program ◽  
External Rotation ◽  
Division I ◽  
Shoulder Injuries ◽  
Scapular Kinematics ◽  
Outcome Measurements ◽  
Weight Room ◽  
Stretching Exercises

Context:Shoulder injuries are common in swimmers because of the demands of the sport. Muscle imbalances frequently exist due to the biomechanics of the sport, which predispose swimmers to injury. To date, an effective shoulder-injury-prevention program for competitive swimmers has not been established.Objective:To assess the effectiveness of a 6-wk strengthening and stretching intervention program on improving glenohumeral and scapular muscle strength and scapular kinematics in collegiate swimmers.Design:Randomized control trial.Setting:University biomechanics research laboratory.Participants:Forty-four Division I collegiate swimmers.Interventions:The intervention program was completed 3 times per week for 6 wk. The program included strengthening exercises completed using resistance tubing—scapular retraction (Ts), scapular retraction with upward rotation (Ys), scapular retraction with downward rotation (Ws), shoulder flexion, low rows, throwing acceleration and deceleration, scapular punches, shoulder internal rotation at 90° abduction, and external rotation at 90° abduction—and 2 stretching exercises: corner stretch and sleeper stretch.Main Outcome Measurements:Scapular kinematics and glenohumeral and scapular muscle strength assessed preintervention and postintervention.Results:There were no significant between-groups differences in strength variables at pre/post tests, although shoulder-extension and internal-rotation strength significantly increased in all subjects regardless of group assignment. Scapular kinematic data revealed increased scapular internal rotation, protraction, and elevation in all subjects at posttesting but no significant effect of group on the individual kinematic variables.Conclusions:The current strengthening and stretching program was not effective in altering strength and scapular kinematic variables but may serve as a framework for future programs. Adding more stretching exercises, eliminating exercises that overlap with weight-room training and swim training, and timing of implementation may yield a more beneficial program for collegiate swimmers.

scholarly journals Programa de prevención de lesiones para la mejora de la salud articular del hombro en jóvenes triatletas (Injury prevention program for the improvement of shoulder health in young triathletes)

Retos ◽  
2018 ◽  
pp. 80-86
Author(s):  
Manuel Jesús Cabeza-Carmona ◽  
Yaira Barranco-Ruiz ◽  
Emilio Villa-González
Keyword(s):  
Internal Rotation ◽  
Shoulder Joint ◽  
Intervention Program ◽  
External Rotation ◽  
Intervention Group ◽  
Control Group ◽  
Shoulder Injuries ◽  
Before And After ◽  
Injury Prevention Program ◽  
External Test

La aparición de lesiones por sobreuso del complejo articular del hombro en la disciplina de natación en triatletas jóvenes anima a una profundización en el estudio de métodos efectivos para la prevención de dichas lesiones. Objetivo: Analizar la efectividad de un programa de intervención diseñado para la prevención de lesiones del complejo articular del hombro en la disciplina de natación en jóvenes triatletas. Métodos: 26 jóvenes (edad entre 8-17 años) fueron aleatorizados en Grupo-Intervención (GI, n=17), y Grupo-Control (GC, n=9). La salud del complejo articular del hombro se evaluó antes y después de un programa de intervención (cuatro semanas de duración: dos-sesiones/30-minutos/semana), mediante los siguientes test: 1) Test del ángulo de cabeza adelantada–Ángulo hombro adelantado, 2) Test de Rotación Glenohumeral, 3) Test de opresión durante la abducción horizontal de hombro, 4) Test Longitud del Pectoral menor. Se utilizó un análisis intra-sujeto y otro análisis inter-sujeto para analizar las diferencias significativas (p<.05) en las variables de estudio, antes y después del programa de intervención. Resultados: Tras el programa de intervención se observaron mejoras significativas en el GI comparado con el GC en las variables: ángulo de adelantamiento de la cabeza (p<.001), rotación interna del hombro dominante (p=.001), rotación externa del hombro dominante, (p=.046), rotación interna del hombro no dominante (p=0.002), abducción horizontal del hombro (p=.003), longitud del pectoral derecho (p<0.001) y longitud del pectoral izquierdo (p=.001). Conclusión: Un programa de intervención diseñado para la prevención de lesiones en el complejo articular del hombro de cuatro semanas de duración (dos-sesiones/30-minutos/semana), fue efectivo mejorando la salud articular y movilidad del hombro en jóvenes triatletas.Abstract. The onset of overuse injuries of the shoulder joint complex in the discipline of swimming in young triathletes prompts the need to deepen the study of effective methods for the prevention of such lesions. Objective: To analyze the effectiveness of an intervention program designed for the prevention of injuries of the shoulder joint complex in the discipline of swimming in young triathletes. Methods: 26 youngsters (aged 8-17 years) were randomly assigned to an Intervention Group (GI, n = 17), and a Control Group (GC, n = 9). The health of the shoulder joint complex was evaluated before and after an intervention program (four weeks duration: two-sessions / 30-minutes / week), using the following tests: (1) Forward head angle test, Forward shoulder translation test, (2) Rotation Glenohumeral internal and external test, (3) Oppression during horizontal abduction of shoulder test, (4) Pectoral minor length test. An intra-subject and an inter-subject analyses were used to analyze significant differences (p <.05) in the study variables, before and after the intervention program. Results: After the intervention program, significant improvements in GI were observed compared to the CG in the variables: head advancement angle (p<.001), internal rotation of the dominant shoulder (p=.002), external rotation of the dominant shoulder (p=.046), internal rotation of the shoulder (p=.002), horizontal abduction of the shoulder (p=.003), right pectoral length (p<.001) and left pectoral length (p=.001). Conclusion: A 4-week (2-session / 30-minutes / week) intervention program designed for the prevention of shoulder injuries was effective in improving shoulder health in young triathletes.

GIRD syndrome in male handball and volleyball players: Is the decrease of total range of motion the turning point to pathology?

2021 ◽  
pp. 1-8
Author(s):  
Jonas Schmalzl ◽  
Helen Walter ◽  
Wolfram Rothfischer ◽  
Sören Blaich ◽  
Christian Gerhardt ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Turning Point ◽  
External Rotation ◽  
Constant Score ◽  
High Rate ◽  
Overhead Athletes ◽  
Glenohumeral Internal Rotation Deficit ◽  
Total Range ◽  
Volleyball Players

BACKGROUND: Adaptations in glenohumeral range of motion may affect overhead athletes and lead to shoulder pathologies. OBJECTIVE: The purpose of this study was to evaluate glenohumeral internal rotation deficit (GIRD) and postero-superior impingement among male handball and volleyball players and the relationship between these pathologies and training level (amateur vs. professional), position (attack vs. no attack), experience (> 5 years vs. < 5 years) and sports. METHODS: Sixty-seven handball players and 67 volleyball players with a mean age of 25 [± 5] years were included. The range of motion including external and internal rotation in 90∘ abduction of the dominant and non-dominant shoulder was measured of each examined athlete. Visual analogue scale, disabilities of the shoulder and hand score, constant score and subjective shoulder value were recorded. The athletes were examined for postero-superior impingement and abduction force was measured with an isokinetic dynamometer. RESULTS: Internal rotation was significantly lower and external rotation was significantly greater in the dominant arm for both sports. 72% presented with GIRD. GIRD was more prevalent in athletes active for > 5 years (odds ratio (OR) 3), in those training > 3 times per week (OR 1.4) and in handball players (OR 2.7). 24% presented with postero-superior impingement. Players active for > 5 years (OR 1.22), professionals (OR 1.14), volleyball players (OR 1.19), offensive players (OR 2.2) and athletes with GIRD > 10∘ (OR 1.5) showed a higher prevalence of postero-superior impingement. CONCLUSION: GIRD is a common phenomenon in handball and volleyball players. Offensive players are frequently suffering from postero-superior impingement. GIRD > 10∘ leads in nearly 75% of the athletes to a decrease of total range of motion and a high rate of postero-superior impingement. Thus, a decreased range of motion seems to be the turning point from adaptation to pathology. Therefore, regular controls of range of motion and countermeasures by means of stretching the posterior shoulder joint should be integrated in the training content.

scholarly journals The Relationship Between Shoulder Range of Motion and Arm Stress in College Pitchers: A MOTUS Baseball Study

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0040
Author(s):  
Caleb Gulledge ◽  
Toufic Jildeh ◽  
Joseph Tramer ◽  
Fabien Meta ◽  
Kevin Taylor ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Upper Extremity ◽  
Internal Rotation ◽  
External Rotation ◽  
Outcome Measurement ◽  
Overhead Athletes ◽  
Shoulder Range Of Motion ◽  
Patient Reported ◽  
The Relationship ◽  
Shoulder Range

Objectives: Overuse injuries in overhead athletes are becoming more prevalent, with an unclear relationship between shoulder biomechanics and medial elbow symptoms and injury. The purpose of this study was to investigate the relationship of shoulder range of motion to torque across the medial elbow in college pitchers using a validated MOTUS sensor baseball sleeve. Methods: Pitchers were recruited from three local university baseball teams. Exclusion criteria included injury or restricted activity due to pain. They were evaluated in the preseason, within two weeks before their first game of the season. Pitchers completed workload questionnaires and patient reported outcome measurement information system (PROMIS) pain interference (PI), physical function (PF), and upper extremity (UE) surveys. Shoulder range of motion and upper extremity lengths were measured bilaterally. After adequate warm-up, pitchers were fitted with a MOTUS sensor baseball sleeve (Motus Global, Massapequa, NY) and instructed to throw 5 fastballs in a standardized manner off the mound at game-speed effort. The sensor placed at the medial elbow reported elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. The primary outcome was to evaluate the relationship between shoulder range of motion and increased stress across the medial elbow. Additional outcomes evaluated pitcher characteristics, demographics, and outcome scores. Outcomes were assessed via a multivariable model, which controlled for possible covariates. Results: Twenty-eight pitchers were included in the preseason analysis with an average (SD) age of 20.1 (1.3) years and playing experience of 15.3 (1.8) years, 2.5 (1.2) of those years at collegiate level. The dominant shoulder demonstrated decreased internal rotation (54.5+/-10.6 vs 65.8+/-9.1) and increased external rotation (ER, 94.1+/-10.4 vs 88.4+/-9.2) relative to the non-dominant side (p < 0.001), while total rotational range of motion (TRROM) was significantly decreased in the dominant arm (148.6+/-12.4 vs 154.1+/-10.6, p < 0.001). The average glenohumeral internal rotation deficiency (GIRD) was 11.3 (9.87) and average external rotation gain (ERG) was 5.71 (8.8). External rotation was found to be a predictor of arm stress, with an increase in 0.35 Nm of elbow torque for every degree increase in ER (beta = 0.35+/-0.06, p = 0.003); there was moderate correlation between ER and arm stress (r = .45, P<.001). Pitchers demonstrated significantly greater arm stress with the following shoulder ROM measurements: GIRD < 20 as compared to greater than 20 degrees (46.6 +/- 0.5 versus 43.5 +/- 1.1, P=.011), ERG greater than 5 as compared to < 5 degrees (47.4 +/- 0.7 versus 45.1 +/- 0.6, P=.014), and loss of total rotational ROM less than 5 as compared to > 5 degrees (46.6 +/- 0.5 versus 43.6 +/- 1.1, P=.013). Multivariate analysis demonstrated significant predictors of PROMIS PF and UE scores were arm stress, ERG, and GIRD (p<0.05), while increased PROMIS PI scores were predicted by increased ERG and GIRD (p<0.05). Conclusion: We found medial elbow stress, arm speed, arm slot, and shoulder rotation as measured by the MOTUS baseball sensor sleeve were influenced by rotational adaptations of the pitching shoulder in collegiate throwing athletes prior to their season. Likewise, arm stress and shoulder rotational adaptations were reflected as predictors of PROMIS PF, UE, and PI scores.

Rotator Cuff Training for Pitchers

1998 ◽  
Vol 7 (4) ◽  
pp. 285-299 ◽  
Author(s):  
Michael E. Powers
Keyword(s):  
Rotator Cuff ◽  
Internal Rotation ◽  
High Speed ◽  
External Rotation ◽  
Shoulder Abduction ◽  
Muscular Endurance ◽  
Shoulder Injuries ◽  
Three Stages ◽  
Two Stages

This paper reviews the role of the rotator cuff during two key phases of the pitching sequence and presents a training program for these muscles. The program uses a periodization design consisting of three stages, beginning with a high-resistance/low-repetition eccentric strengthening stage. This is followed by a low-resistance/high-repetition stage for training muscular endurance. The core exercises for these two stages are prone external rotation in the 90/90 position, prone horizontal abduction, side-lying D2 flexion pattern, supine internal rotation in the 90/90 position, prone elevation with 100° of shoulder abduction and external rotation, and standing scapular plane elevation. The final stage of the program uses high-speed functional exercises: 90/90 external rotation, 90/90 internal rotation, D2 PNF flexion pattern, D2 PNF extension pattern, supine plyometric 90/90 internal rotation with a medicine ball, and the “arm whip” through the D2 PNF flexion pattern. The goal of this program is to prepare the muscles for the stresses of pitching and prevent shoulder injuries.

scholarly journals Comparison of Shoulder Functions Between Workers With and Without Shoulder Impingement Syndrome

2020 ◽  
Author(s):  
Jun-hee Kim ◽  
Oh-yun Kwon ◽  
Chung-hwi Yi ◽  
Hye-seon Jeon ◽  
Woo-chol Joseph Choi ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Internal Rotation ◽  
External Rotation ◽  
Impingement Syndrome ◽  
Shoulder Abduction ◽  
Shoulder Impingement Syndrome ◽  
Asymmetry Ratio ◽  
Shoulder Injuries ◽  
Shoulder Impingement ◽  
The Asymmetry

The occurrence of shoulder impingement syndrome (SIS) is associated with the frequent handling and lifting of heavy loads and excessive repetitive work above the shoulder level. Thus, assembly workers have a high prevalence of shoulder injuries, including SIS. The purpose of this study was to investigate differences in shoulder ROM, muscle strength, asymmetry ratio, function, productivity, and depression between workers with and without SIS.Sixty-seven assembly line male workers (35 workers with SIS and 32 workers without SIS) participated in this study. The four shoulder ROMs and the five muscle strengths were measured using a Smart KEMA system. The asymmetry ratios were calculated using the asymmetry ratio formula; shoulder functions were measured using the shoulder pain and disability index (SPADI), disabilities of the arm, shoulder, and hand (DASH), and visual analogue scale (VAS); and Endicott work productivity scale (EWPS). Severity of depression was measured using the Beck depression inventory (BDI). Independent t-tests were performed for statistical analysis.The SPADI, DASH, and VAS values of workers with SIS were significantly higher than those of workers without SIS. Also, workers with SIS had significantly smaller shoulder internal rotation and shoulder abduction compared to workers without SIS. In addition, workers with SIS exhibited significantly lower SIR muscle strength than workers without SIS. Workers with SIS had significantly higher asymmetry ratios in shoulder internal rotation, shoulder external rotation, and elbow flexion muscle strength than workers without SIS.The SPADI and DASH scores, which indicate shoulder function, were higher, and the intensity of self-aware pain was higher in workers with SIS. Also, workers with SIS exhibited reduced SIR and SAB ROMs; decreased SIR muscle strength. Particularly, the asymmetry ratios of SIR, SER, EF muscle strength are good comparable factors for workers with and without SIS. In addition, the asymmetry ratios of shoulder muscle strengths could provide an important baseline comparison for the workers with SIS.

scholarly journals Kinematic instrumental analysis of the shoulder and elbow joint in normal conditions and with hypermobility of the joint in the gait cycle

2019 ◽  
Vol 7 (1) ◽  
pp. 35-42
Author(s):  
Olga I. Vorontcova ◽  
Larisa A. Udochkina ◽  
Marina S. Baranec ◽  
Marina V. Grechitaeva ◽  
Ludmila A. Goncharova
Keyword(s):  
Internal Rotation ◽  
Shoulder Joint ◽  
Elbow Joint ◽  
External Rotation ◽  
Joint Hypermobility ◽  
Instrumental Method ◽  
Joint Hypermobility Syndrome ◽  
Arm Swing ◽  
Common Sign ◽  
Analysis System

Background. There is evidence for violation or a complete change in the arm swing cycle during walking in a number of pathologic conditions. Aim. We assess the functional state of the shoulder and elbow joints in normal conditions and with joint hypermobility syndrome (JHS) using the kinematic instrumental method of analyzing gait. Material and methods. We studied 27 adolescent girls 1215 years old with JHS and healthy subjects. A Vicon motion capture analysis system (Vicon, Oxford, Great Britain) was used to record biomechanical parameters. Results. A decrease in limb movement amplitudes was noted in the shoulder joint around the frontal and sagittal axes in patients with JHS compared to the norm. During the arm swing cycle in the normal state, the shoulder is in a state of internal rotation, whereas in the girls with JHS, the shoulder is in a state of external rotation for most of the arm swing cycle. The elbow joint in the JHS subjects showed a significant increase in flexion angle of the forearm in the swing phase of 41.5 0.90 and a decrease in this angle in the stance phase. The JHS group also showed a decrease in power of the muscles acting on the shoulder joint. Conclusions. A common sign of changes in the range of motion of the links of the upper limb in the shoulder and elbow joints in subjects with JHS was decreased amplitude of their flexion and decreased power of the joints. In the adolescents with JHS in the shoulder joint, a significant decrease in the internal rotation angles and reduction of the limb was found.

scholarly journals Changes in Fatigue, Multiplanar Knee Laxity, and Landing Biomechanics During Intermittent Exercise

2015 ◽  
Vol 50 (5) ◽  
pp. 486-497 ◽  
Author(s):  
Sandra J. Shultz ◽  
Randy J. Schmitz ◽  
John R. Cone ◽  
Robert A. Henson ◽  
Melissa M. Montgomery ◽  
...  
Keyword(s):  
Internal Rotation ◽  
Hierarchical Linear Modeling ◽  
Intermittent Exercise ◽  
External Rotation ◽  
Knee Laxity ◽  
Knee Valgus ◽  
Linear Modeling ◽  
Warm Up ◽  
Landing Biomechanics ◽  
Before And After

Context Knee laxity increases during exercise. However, no one, to our knowledge, has examined whether these increases contribute to higher-risk landing biomechanics during prolonged, fatiguing exercise. Objectives To examine associations between changes in fatigue (measured as sprint time [SPTIME]), multiplanar knee laxity (anterior-posterior [APLAX], varus-valgus [VVLAX] knee laxity, and internal-external rotation [IERLAX]) knee laxity and landing biomechanics during prolonged, intermittent exercise. Design Descriptive laboratory study. Setting Laboratory and gymnasium. Patients or Other Participants A total of 30 male (age = 20.3 ± 2.0 years, height = 1.79 ± 0.05 m, mass = 75.2 ± 7.2 kg) and 29 female (age = 20.5 ± 2.3 years, height = 1.67 ± 0.08 m, mass = 61.8 ± 9.0 kg) competitive athletes. Intervention(s) A 90-minute intermittent exercise protocol (IEP) designed to simulate the physiologic and biomechanical demands of a soccer match. Main Outcome Measure(s) We measured SPTIME, APLAX, and landing biomechanics before and after warm-up, every 15 minutes during the IEP, and every 15 minutes for 1 hour after the IEP. We measured VVLAX and IERLAX before and after the warm-up, at 45 and 90 minutes during the IEP, and at 30 minutes after the IEP. We used hierarchical linear modeling to examine associations between exercise-related changes in SPTIME and knee laxity with exercise-related changes in landing biomechanics while controlling for initial (before warm-up) knee laxity. Results We found that SPTIME had a more global effect on landing biomechanics in women than in men, resulting in a more upright landing and a reduction in landing forces and out-of-plane motions about the knee. As APLAX increased with exercise, women increased their knee internal-rotation motion (P = .02), and men increased their hip-flexion motion and energy-absorption (P = .006) and knee-extensor loads (P = .04). As VVLAX and IERLAX increased, women went through greater knee-valgus motion and dorsiflexion and absorbed more energy at the knee (P ≤ .05), whereas men were positioned in greater hip external and knee internal rotation and knee valgus throughout the landing (P = .03). The observed fatigue- and laxity-related changes in landing biomechanics during exercise often depended on initial knee laxity. Conclusions Both exercise-related changes in fatigue and knee laxity were associated with higher-risk landing biomechanics during prolonged exercise. These relationships were more pronounced in participants with greater initial knee laxity.

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