Gender differences in trunk, pelvis and lower limb kinematics during a single leg squat

Sociocultural constructs and sensorimotor control: a scoping review examining implications for anterior cruciate injury

OBJECTIVE

There is a need to explore the many factors that may have a more subtle influence on, or relationship with, sensorimotor control as it pertains to anterior cruciate ligament injury risk. Due to well-established sex/gender-related differences in sensorimotor control, a close examination of key sociocultural constructs is warranted. This scoping review examined the connection between sociocultural constructs and sensorimotor control.

DESIGN

Scoping review.

DATA SOURCES

The following databases were searched: PubMed, Embase, Scopus, CINAHL Complete, Academic Search Complete, Pre-Prints Database and Rehabilitation Reference Center from inception to September 2023. Additionally, relevant grey literature was identified.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Two blinded reviewers independently performed screening, study selection and data extraction. Original references in English, Spanish and German reporting on sociocultural constructs and motor task performance were included.

RESULTS

Data were extracted from 68 included articles. Stereotype threat, gender and race have been examined more than other sociocultural constructs. Sensorimotor control was assessed in upper and lower quarter tasks and physical activity (PA). Task assessment methods varied, often focusing on task completion or completion speed. It is evident that sociocultural constructs influence sensorimotor control, but the exact mechanism remains unclear.

CONCLUSION

Sociocultural constructs can influence sensorimotor control and PA. Future research should further explore this connection as it relates to biomechanical profiles associated with increased injury risk. Additionally, sociocultural construct inventory scores could be added to existing injury screening programmes to create a more gendered approach to risk mitigation.

Single-leg horizontal jump is more suitable for assessing lower limb function compared to single-leg vertical jump in patellofemoral pain patients

BACKGROUND

The single-leg vertical jump (SLVJ) and single-leg horizontal jump (SLHJ) are commonly used assessments for individuals with lower limb injuries. Despite previous studies comparing these tasks across various individuals, their comparative effectiveness in evaluating lower limb function in individuals with patellofemoral pain (PFP) and any potential sex differences in these functional tests remain uncertain.

RESEARCH QUESTION

The purpose of this study was to determine which jump task is more suitable for functional assessment in PFP patients by comparing the differences in jump performance and biomechanical variables between PFP patients and healthy individuals during the SLVJ and SLHJ. Furthermore, the study aimed to determine whether the more suitable functional assessment for male and female PFP patients is consistent.

METHODS

A total of 24 PFP patients (15 males, 9 females) and 17 healthy individuals (9 males, 8 females) were recruited. Three-dimensional kinematic and kinetic data were collected during the propulsion and landing phases of the SLVJ and SLHJ. Two-way ANOVA was used to compare each dependent variable between groups (PFP vs. healthy controls) and sex (male vs. female).

RESULTS

Both male and female PFP groups presented a reduced jump distance than the control group in the SLHJ (p = 0.002), but no significant difference was detected in the SLVJ. Both male and female PFP groups displayed increased hip work (p = 0.005) and contribution (p = 0.009) and reduced knee work contribution (p = 0.034) during the propulsion phase of the SLHJ compared to the control group. Moreover, female participants of PFP and control groups performed shorter jump distances (p ≤ 0.001) and had less knee work (p < 0.001) during the propulsion phase of vertical and horizontal jumps than males.

CONCLUSION

Single-leg horizontal jump is more suitable for assessing lower limb function in PFP patients, characterized by reduced knee work contribution impacting jump performance, and this applies to both male and female PFP patients.

Torso kinematic patterns associated with throwing shoulder joint loading and ball velocity in Little League pitchers

The purpose of this study was to investigate the associations between kinematic patterns of the torso segment and shoulder joint loading as well as pitching performance in youth pitchers. Twenty-four Little League pitchers threw fastballs while motion capture and force plate data were collected and ball speed was measured with a radar gun. Three-dimensional torso segment kinematics (absolute angles and angular velocities) and shoulder net joint moments (NJM) and forces were calculated. The time-series kinematic data were used as inputs to a principal components analysis to extract torso movement patterns. Associations between torso movement patterns and discrete peak shoulder NJM, compressive force, and ball speed were investigated with nonparametric correlations. Torso segment motion patterns related to forward flexion, lateral flexion (away from pitching arm), and axial rotation and rotational velocities were associated with shoulder joint kinetics and ball speed. In addition, excessive axial (transverse plane) torso rotation at ball release correlated positively with shoulder joint loads but not ball speed, which may indicate the prospect for decreasing joint kinetics while maintaining pitching performance through targeted interventions. These results provide a deeper understanding about the interrelationships between torso kinematic patterns, shoulder kinetics, and pitching performance.

Comparison of kinematic parameters, muscle activity and movement timing between "good" and "poor" performers of a single-leg squat

INTRODUCTION

Visual scales offer a cost-effective alternative to complex biomechanical analysis for single-leg squat (SLS) performance. There is a lack of consensus on the relationship between visual rating and kinematic measurements in physical therapy assessments. The study aimed to compare kinematic parameters, muscle activity and timing between good and poor performers of SLS, selected based on visual evaluation of movement.

METHODS

Forty asymptomatic male volunteers were classified based on a visual assessment of their SLS movements. For participants rated as good performers (n = 19) and poor performers (n = 8), electromyographic activity, kinematic parameters and movement timing were compared.

RESULTS

SLS execution was significantly different in groups in terms of the hip frontal plane and spine transversal plane of movement and the timing of the hip and knee motion. There were no statistically significant differences between groups in multifidus muscle activity during SLS, frontal plane movement of the knee and squat depth.

CONCLUSIONS

The findings of this study indicate that coordination and timing of movements should be carefully considered during SLS examinations to obtain a comprehensive evaluation for planning exercise rehabilitation.

Osteon shape variation in the femoral diaphysis: A geometric-morphometric approach on human cortical bone microstructure in an elderly sample

Geometric morphometrics (GMM) have been applied to understand morphological variation in biological structures. However, research studying cortical bone through geometric histomorphometrics (GHMM) is scarce. This research aims to develop a landmark-based GHMM protocol to depict osteonal shape variation in the femoral diaphysis, exploring the role of age and biomechanics in bone microstructure. Proximal, midshaft, and distal anatomical segments from the femoral diaphysis of six individuals were assessed, with 864 secondary intact osteons from eight periosteal sampling areas being manually landmarked. Observer error was tested using Procrustes ANOVA. Average osteonal shape and anatomical segment-specific variation were explored using principal component analysis. Osteon shape differences between segments were examined using canonical variate analysis (CVA). Sex differences were assessed through Procrustes ANOVA and discriminant function analysis (DFA). The impact of osteonal size on osteonal shape was investigated. High repeatability and reproducibility in osteon shape landmarking were reported. The average osteon shape captured was an elliptical structure, with PC1 reflecting more circular osteons. Significant differences in osteon shape were observed between proximal and distal segments according to CVA. Osteon shape differed between males and females, with DFA showing 52% cross-validation accuracies. No effect of size on shape was reported. Osteonal shape variation observed in this study might be explained by the elderly nature of the sample as well as biomechanical and physiological mechanisms playing different roles along the femoral diaphysis. Although a larger sample is needed to corroborate these findings, this study contributes to the best of our knowledge on human microanatomy, proposing a novel GHMM approach.

Descriptive Epidemiology of Musculoskeletal Injuries During Marine Corps Recruit Training in Gender-Integrated and Male-Only Training Units

INTRODUCTION

Musculoskeletal injuries (MSIs) occur frequently in military personnel. U.S. Marine Corps (USMC) recruits participate in an intense 13-week training program designed to transform civilians into basically trained Marines, during which they are susceptible to MSIs. Previous injury epidemiology research with USMC recruits was conducted in a non-gender-integrated training. Data for the current study were derived from a larger study, the USMC Gender-Integrated Recruit Training study, that was initiated to provide data-driven recommendations for gender integration during USMC recruit training. The purpose of the current analysis was to describe the unique profile of MSIs during USMC recruit training and compare MSIs between female and male recruits in gender-integrated training.

MATERIALS AND METHODS

Medical record-reviewed MSI data were obtained for recruits in three models of USMC recruit training: two models of gender-integrated recruit training at Marine Corps Recruit Depot (MCRD) Parris Island-the older Series Track (ST) model and the newer Integrated Company (IC) model, and a Male-Only (MO) cohort at MCRD San Diego. Incidence, anatomic region and subregion, event at the time of MSI, MSI type and onset, and disposition following MSI were described for each model. Group comparisons were conducted using Fisher's exact tests or independent samples t tests, as appropriate.

RESULTS

MSI data were available for 584 recruits (ST: 98 female recruits, 95 male recruits; IC: 85 female recruits, 106 male recruits; MO: 200 male recruits). The cumulative incidence of MSIs was significantly higher among female compared to male recruits in the ST (59.2% vs. 29.5%, P < .001) and in the IC (25.9% vs. 12.3%, P = .023) cohorts. The most frequent anatomic location for MSIs was the lower extremity (female recruits: ST: 76.5% of MSIs, IC: 88.6%; male recruits: ST: 81.1%, IC: 80.0%, MO: 83.8%). The most frequent body part affected was the hip among female recruits (ST: 26.5% of MSIs, IC: 37.1%). The most frequent body part affected by MSIs among the male recruits was the knee in the ST (32.4%) and IC (53.3%) cohorts and the lower leg (27.0%) in the MO cohort. A significantly greater percentage of female compared to male recruits sustained a hip MSI in the ST (23.5% vs. 2.1%, P < .001) and IC (12.9% vs. 0.0%, P < .001) cohorts. There was no significant difference in knee MSI incidence between sexes in the ST (P = .323) or IC (P = .757) cohorts. A large percentage of MSIs resulted in light duty (female recruits: ST: 69.4% of MSIs, IC: 74.3%; male recruits: ST: 64.9%, IC: 73.3%, MO: 94.6%).

CONCLUSIONS

This was the first study to assess the burden of MSIs concurrently among female and male USMC recruits in gender-integrated training. MSIs, especially those affecting the lower extremity, continue to occur frequently in this population. Female recruits are more susceptible to MSIs during USMC recruit training compared to male recruits and are especially prone to hip MSIs. Future research should focus on identifying modifiable risk factors for MSIs in this population, with a focus on reducing lower-extremity MSIs in all recruits and hip MSIs in female recruits.

Males with patellofemoral pain have altered movements during step-down and single-leg squatting tasks compared to asymptomatic males: A cross-sectional study

Background and Aims

Patellofemoral pain (PFP) is common in males, causing reduced physical activity and chronic pain. One proposed cause of PFP is aberrant biomechanics during tasks loading the patellofemoral joint. Consistent evidence exists for females with PFP, but it is uncertain if males with PFP have altered biomechanics. This study investigated the kinematics of males with PFP compared to pain-free males during forward step-down (StDn) and single-leg squat (SLSq).

Methods

A cross-sectional study including 40 males aged 20-39 years (28.28 ± 5.46) was conducted (20 PFP, 20 pain-free). Participants performed StDn and SLSq while motion was captured with a video-based motion capture system (Motion Analysis Corporation). Triplanar peak angles and angular ranges of motion (ROM) of the trunk, pelvis, and weight-bearing hip, knee, and ankle were dependent variables. Mixed-model ANOVA tests were used to determine the presence of significant interactions and main effects of group and task.

Results

Males with PFP had significantly lower peak knee adduction angles compared to pain-free males (p = 0.01). Significant group x task interactions were found for hip and pelvis ROM (p < 0.05). PFP participants had increased hip and pelvis ROM during StDn in the frontal and transverse planes but reduced or nearly equal ROM for these variables during SLSq. Peak hip adduction, hip internal rotation, contralateral pelvic drop and anterior tilt, trunk flexion, and ankle dorsiflexion were greater during StDn compared to SLSq (p < 0.05). ROM of the hip, pelvis, trunk, and ankle were greater during StDn compared to SLSq (p < 0.05).

Conclusion

Males with PFP had reduced peak knee adduction angles in StDn and SLSq. Males with PFP demonstrated increased hip and pelvis ROM during StDn versus SLSq, particularly in the frontal and transverse planes. Clinicians should consider StDn as a clinical test since aberrant movement may be easier to detect than in SLSq.

Impact of Sacroiliac Interosseous Ligament Tension and Laxity on the Biomechanics of the Lumbar Spine: A Finite Element Study

OBJECTIVE

To investigate the influence of sacroiliac interosseous ligament tension and laxity on the biomechanics of the lumbar spine.

METHODS

A static analysis of a three-dimensional finite element model of the Lumbar-Pelvic is conducted to verify the model's effectiveness. Adjusting the sacroiliac ligament's elasticity modulus under a 10Nm lumbar flexion/extension moment, it simulates ligament tension/laxity to calculate vertebrae displacements, intervertebral disc stress and deformation, nucleus pulposus pressure, facet joint force, and ligament stress.

RESULTS

With the elastic modulus of the sacroiliac ligament changing by +50%, -50%, and -90%, the angular displacement of vertebra 3 in forward flexion changes by +1.64%, -4.84%, and -42.3%, and the line displacements change by +5.7%, -16.4%, and -144.9%, respectively; and the angular displacements in backward extension change by +0.2%, -0.6%, -5.9% and the line displacements change by +5.5%, -14.3%, and -125.8%. However, the angular displacement and center distance between adjacent vertebrae do not change, leading to no change in the maximum stress of the intervertebral disc and the maximum pressure in the nucleus pulposus. Flexion and extension directly affect the deformation and stress magnitude and distribution in the lumbar spine.

CONCLUSIONS

While sacroiliac interosseous ligament laxity and tension have little effect on disc deformation and stress, and nucleus pulposus pressure, they reduce the stability of the lumbar-sacral vertebrae. In a forward flexion state, the lumbar ligaments bear a large load and are prone to laxity, thereby increasing the risk of lumbar injury.

Age- and sex-related differences in trunk kinematics during walking in able-bodied adults

INTRODUCTION

Trunk motion during walking acts as a biomarker for decreased mobility and can differ between sexes. Knowing how age and sex affect trunk motion and energy conservation can help clinicians decide when and in whom to intervene with physiotherapy to prolong functional mobility.

METHODS

A large sample of 138 able-bodied males and females in the age-categories 20-39 years, 40-59 years, 60-69 years, 70-79 years, and 80-89 years received a full-body 3D gait analysis. A two-factor ANOVA was performed to examine the effect of age and sex and their interaction on 3D trunk kinematics and positive mechanical work of the lower limbs, head-arms-trunk (HAT) segment and whole body.

RESULTS

A significant decrease in walking speed was only found in those above 80 years (~ .05 nm/s, p < .006), while changes in 3D trunk kinematics were observed earlier. From 60 years on, trunk rotations decreased (~ 2-3°, p < .05), from 70-year frontal pelvic motion (~ 4°, p < .001), and from the age of 80 years sagittal thorax motion (~ 1-6°, p < .05). There were only small aging effects for mechanical energy demands that were more pronounced in females, showing decreased of HAT contributions (p = .020). Furthermore, age-related differences in trunk kinematics are highly dependent on sex whereby age-related changes were observed sooner in females than males in all three planes of motion.

CONCLUSIONS

Age-related differences in 3D trunk kinematics are observed from 60 years onward and increase with age. Age-related stiffening of the trunk did not seem to affect the body's total mechanical work. Importantly, our data did show a stark contrast between males and females, indicating that training to prolong mobility should be tailored to sex. Future research should include sex-matched data when examining normal age and pathologic gait decline.

Sex differences in lower extremity kinematics during overhead and single leg squat tests

The Overhead Squat (OHS) and Single-Leg Squat (SLS) are two clinical tests used by practitioners to identify high-risk biomechanical movement patterns. Several published studies have reported sex differences in SLS performance; however, few have investigated variations during the OHS and none has measured kinematics with a marker-less motion capture system. Therefore, this study aimed to compare biomechanical movement patterns between male and female collegiate athletes during OHS and SLS testing. Seventy-five females and 58 male athletes completed OHS and SLS . A Microsoft Kinect sensor using Athletic Movement Assessment software (PhysiMax®) was used to measure kinematics. For the OHS, males displayed greater peak knee frontal plane projection angles (FPPA) (M:26°±10°, F:20°±8°; P < 0.05), peak hip flexion (M:-94°±14°, F:-87°±15°; P < 0.05), and peak trunk flexion angles (M:11°±11°, F:6°±9°; P < 0.05). For the SLS (dominant-limb), males displayed greater peak trunk flexion (M:32°±6°, F:27°±7°; P < 0.05). For the non-dominant limb, females displayed greater peak knee FPPA (F:-12°±9°, M:-8°±9°; P < 0.05) whereas males displayed greater peak trunk flexion angles (M:32°±5°, F:27°±7°; P < 0.05). These findings suggest the need for practitioners to develop sex-specific corrective exercise programmes in effort to improve lower extremity kinematics in athletes.

Hip Range of Motion During Passive and 1-Leg Exercises Is Greater in Women: A Meta-analysis and Systematic Review

PURPOSE

To summarize sex-related differences in hip range of motion (ROM), including flexion, extension, abduction, adduction, internal rotation, and external rotation.

METHODS

We performed a systematic search of 3 databases (PubMed, CINAHL [Cumulative Index to Nursing and Allied Health Literature], and Embase). The search terms were as follows: hip, pelvis, range of motion, kinematic, men, and women. Included studies reported sex-specific data on hip ROM in healthy, uninjured adults. To generate hip ROM mean differences, a DerSimonian-Laird random-effects model was used. Effect sizes were pooled for each exercise. Subgroup analyses compared hip ROM by physical activity group: passive ROM, 1-leg hop or jump, 2-leg hop or jump, 2-leg drop or landing, 1-leg squat, 2-leg squat, walking, and jogging/running. Positive effect sizes represent greater ROM in women.

RESULTS

Thirty-eight studies with 3,234 total subjects were included; of these subjects, 1,639 were women (50.1%). The mean age was 25.3 years. An effect difference was considered statistically significant if P < .05 and clinically significant if the mean difference was greater than 4.0°. Women showed statistically and clinically significantly greater hip flexion in passive ROM (mean difference, 6.4°) and during the 1-leg hop or jump exercise (mean difference, 6.5°). Women also showed statistically and clinically significantly greater hip adduction during the 1-leg hop or jump (mean difference, 4.5°) and 1-leg squat (mean difference, 4.4°) exercises, as well as statistically and clinically significantly greater hip internal rotation in passive ROM (mean difference, 8.2°). In contrast, men showed statistically and clinically significantly greater flexion during the 2-leg hop or jump exercise (mean difference, -9.1°). No clinically significant differences in extension, abduction, or external rotation were found between women and men.

CONCLUSIONS

On average, women showed statistically and clinically significantly greater flexion, adduction, and internal rotation during passive and 1-leg exercises whereas men showed statistically and clinically significantly greater flexion during the 2-leg hop or jump exercise.

LEVEL OF EVIDENCE

Level IV, meta-analysis and systematic review of Level II-IV studies.

Sex differences in pelvis, thigh, and shank coordination during walking

Differences in lower limb kinematics between males and females during functional activities may be attributed to sex differences in the incidence of patellofemoral pain, which is more common in females. To better comprehend the knee joint motion, it is necessary to understand both inter-segmental coordination patterns and angular amplitude. This exploratory study aimed to assess sex differences in pelvis-thigh and thigh-shank coordination patterns in the frontal and horizontal planes during walking. Data regarding the kinematic characteristics of the pelvis, thigh, and shank segments were collected from 26 males and 26 females performing walking at self-selected speeds using a 3D motion capture system. Furthermore, we compared the kinematics of the pelvis, thigh, and shank during walking as well as the pelvis-thigh and thigh-shank coordination patterns in the frontal and horizontal planes during the stance phase between males and females. Compared to males, females had greater thigh adduction (p < 0.001) and internal rotation (p < 0.001) throughout the stance phase; significantly greater frequency of the pelvis-thigh anti-phase pattern in the frontal plane in the early (p = 0.002) and mid-stance (p = 0.003); and significantly greater thigh-shank anti-phase pattern in the frontal plane in the early (p = 0.001) and mid-stance (p = 0.015). These results suggest the presence of sex differences in the inter-segmental coordination of the pelvis and lower limb during walking. However, as this study could not determine a causal relationship between female sex and knee joint injury, further longitudinal studies are needed to determine the effects of differences in coordination patterns on the pathophysiology of the injury and pain generation.

Forward step down test - clinical rating is correlated with joint angles of the pelvis and hip: an observational study

BACKGROUND

Clinical methods for assessing quality of movement and functional tests are important to clinicians. Typical deviations from normal kinematics during the clinical test of Forward Step Down Test (FSDT) are pelvic tilt and hip adduction which are associated with the risk of knee pain.

OBJECTIVES

(1) to examine the correlation between clinical assessment of the FSDT and joint angle measurements of pelvis, hip, knee and ankle joints in males and females; (2) to examine the differences in joint angles between individuals rated as good, fair or poor in a FSDT performance test.

METHODS

Ninety-two healthy individuals performing FSDT were video-taped with two-dimensional digital video cameras. The clinical assessment of the FSDT was rated by two experienced physical therapists as good, fair, or poor based on a Crossley et al. (2011) validated scale. Measurements of pelvic drop, hip adduction and knee valgus were taken using Image J software.

RESULTS

Out of 177 lower limbs, 74 (37 in each limb) were clinically rated as "good/fair" (41.80%) while 103 (52 in the dominant leg and 51 in the non-dominant leg) were rated as "poor" (58.19%). No significant differences were observed between dominant and non-dominant legs or between males and females in clinical rating of the FSDT. Pelvic drop angle was significantly higher and hip adduction angle was significantly lower for "poor" clinical rating compared to "good/fair" in both dominant and non-dominant legs (p < 0.001) in males and females. Females demonstrated higher pelvic drop, lower hip adduction and higher knee valgus angles compared with males (p < 0.05).

CONCLUSIONS

This study showed that the clinical rating of FSDT is correlated with joint angle measurements suggesting that this assessment can be utilized in clinical practice. Individuals with poor quality performance of FSDT showed higher pelvic drop and hip adduction movement. Further studies examining different populations with diverse disorders or pathologies are essential.

The Use of Elastic Resistance Bands to Reduce Dynamic Knee Valgus in Squat-Based Movements: A Narrative Review

An elastic band wrapped around the distal thighs has recently been proposed as a method for reducing dynamic knee valgus (medial movement of the knee joint in the frontal/coronal plane) while performing squats. The rationale behind this technique is that, by using an external force to pull the knees into further knee valgus, the band both exaggerates the pre-existing movement and provides additional local proprioceptive input, cueing individuals to adjust their knee alignment. If these mechanisms are true, then elastic bands might indeed reduce dynamic knee valgus, which could be promising for use in injury prevention as excessive knee valgus may be associated with a greater risk of sustaining an ACL rupture and/or other knee injuries. Due to this possibility, certain athletic populations have already adopted the use of elastic bands for training and/or rehab, despite a limited number of studies showing beneficial findings. The purpose of this narrative review is to examine current literature that has assessed lower limb muscle activity and/or lower limb kinematics performance on squat-based movements with or without an elastic band(s). Importantly, this paper will also discuss the key limitations that exist in this area, propose suggestions for future research directions, and provide recommendations for training implementations.

Level of Evidence

5.

Estimating vertical ground reaction forces during gait from lower limb kinematics and vertical acceleration using wearable inertial sensors

One of the most important forces generated during gait is the vertical ground reaction force (vGRF). This force can be measured using force plates, but these can limit the scope of gait analysis. This paper presents a method to estimate the vGRF using inertial measurement units (IMU) and machine learning techniques. Four wearable IMUs were used to obtain flexion/extension angles of the hip, knee, and ankle joints, and an IMU placed over the C7 vertebra to measure vertical acceleration. We trained and compared the performance of two machine learning algorithms: feedforward neural networks (FNN) and random forest (RF). We investigated the importance of the inputs introduced into the models and analyzed in detail the contribution of lower limb kinematics and vertical acceleration to model performance. The results suggest that the inclusion of vertical acceleration increases the root mean square error in the FNN, while the RF appears to decrease it. We also analyzed the ability of the models to construct the force signal, with particular emphasis on the magnitude and timing of the vGRF peaks. Using the proposed method, we concluded that FNN and RF models can estimate the vGRF with high accuracy.

First Insights in the Relationship between Lower Limb Anatomy and Back Squat Performance in Resistance-Trained Males and Females

Identifying key criteria of squat performance is essential to avoiding injuries and optimizing strength training outcomes. To work towards this goal, this study aimed to assess the correlation between lower limb anatomy and back squat performance during a set-to-exhaustion in resistance-trained males and females. Optical motion captures of squat performance and data from magnetic resonance imaging (MRI) of the lower limbs were acquired in eight healthy participants (average: 28.4 years, four men, four women). It was hypothesized that there is a correlation between subject-specific musculoskeletal and squat-specific parameters. The results of our study indicate a high correlation between the summed volume of the hamstrings and quadriceps and squat depth normalized to thigh length (r = -0.86), and a high correlation between leg size and one-repetition maximum load (r = 0.81), respectively. Thereby, a marked difference was found in muscle volume and one-repetition maximum load between males and females, with a trend of females squatting deeper. The present study offers new insights for trainers and athletes for targeted musculoskeletal conditioning using the squat exercise. It can be inferred that greater muscle volume is essential to achieving enhanced power potential, and, consequently, a higher 1RM value, especially for female athletes that tend to squat deeper than their male counterparts.

A markerless motion capture system can reliably determine peak trunk flexion while squatting with and without a weighted vest

Markerless motion capture has improved physical screening efficiency in sport and occupational settings; however, reliability of kinematic measurements from commercial systems must be established. Further, the impact of torso-borne equipment on these measurements is unclear. The purpose of this study was to evaluate the reliability of HumanTrak, a markerless motion capture system, for estimating peak trunk flexion in squat movements with and without a weighted vest. Eighteen participants completed body weight squats (BWSQ) and overhead squats (OHSQ) to their maximum depth (unrestricted-range) and to a plyometric box (fixed-range) while wearing no body armour (NBA) or 9 kg body armour (BA9). Peak trunk flexion was measured using HumanTrak. Testing was performed in two sessions on one day (intra-day) and one session on a separate day (inter-day) to assess reliability. HumanTrak had a standard error of measurement < 3.74° across all movements and conditions. Reliability was good to excellent (ICC = 0.82-0.96) with very large to nearly perfect Pearson correlations (r > 0.80) for all comparisons except unrestricted-range BWSQ with BA9 (ICC = 0.60-0.71, r = 0.71). HumanTrak was more reliable for intra- than inter-day, but reliability was still excellent for almost all inter-day comparisons (ICC > 0.82). HumanTrak is reliable for detecting differences in peak trunk flexion > 8.5° when body armour is not worn and > 10.5° when body armour is worn. Practitioners can assess meaningful changes in sagittal plane trunk motion when screening squat movements regardless of whether body armour is worn.

The association between hip strength, physical function and dynamic balance in people with unilateral knee osteoarthritis: A cross-sectional study

BACKGROUND

In people with knee osteoarthritis, the association between multidirectional hip strength and physical function or balance is unknown.

OBJECTIVE

To determine the relationship between hip flexion, extension, abduction, adduction, external and internal rotation strength and (1) physical function and (2) dynamic balance.

DESIGN

Cross-sectional.

METHODS

Forty-seven participants (20 men and 27 women, age 66.2 ± 8.2 years) with unilateral knee osteoarthritis were included. Hip strength was assessed with hand-held dynamometry; physical function was assessed with the 40m fast-paced walk test (40mFPWT), 30-s chair-stand test (30sCST), and stair-climb test (SCT); and dynamic balance was assessed in 3 directions using the Star Excursion Balance Test. Multivariable linear regression analysis was used to determine the strength of relationships between measures.

RESULTS

Hip strength, in all directions except for internal rotation, was positively associated with better physical function (40mFPWT: R2 = 0.48 to 0.65; SCT: R2 = 0.5 to 0.54; 30sCST: R2 = 0.39 to 0.42), and dynamic balance (anterior: R2 = 0.33 to 0.45; posteromedial: R2 = 0.32 to 0.45; posterolateral: R2 = 0.27 to 0.35). Hip strength, after adjusting for knee extension strength, explained an additional 8%-12% (p < 0.05) and 5%-12% (p < 0.05) reach in the anterior and posteromedial directions of the Star Excursion Balance Test, respectively.

CONCLUSIONS

Hip strength in multiple directions is associated with measures of physical function and dynamic balance in people with unilateral knee osteoarthritis. Clinicians are encouraged to consider hip strength in multiple directions in the context of the patients' functional and/or balance goals when developing exercise programs for people with knee osteoarthritis.

Sex Difference in Lower-limb Electromyography and Kinematics when Using Resistance Bands during a Barbell Back Squat

The aim of this study was to compare the muscle activity of the gluteus medius (GMe), gluteus maximus (GMa), biceps femoris (BF), vastus lateralis (VL), vastus medialis (VM) and erector spinae (ES) as well as medial knee displacement (MKD) while using varying stiffness resistance bands (red: 1.68 kg; black: 3.31 kg; gold: 6.44 kg) during a barbell back squat (BBS) among males and females. A total of 23 (females: 11) resistance trained people were recruited for this study. Muscle activity was measured using electromyography, and motion capture cameras tracked lower-limb kinematics and MKD. Three resistance bands were placed at the distal end of the femur while performing a BBS at their 85% repetition maximum (RM). Parametric and non-parametric statistical analyses were conducted with the alpha level of 0.05. The gold resistance band resulted in a smaller knee-width-index value (i.e., greater MKD) compared to other bands (p < 0.01). Males exhibited less MKD compared to females during the BBS for each resistance band (p = 0.04). Males produced greater VL activity when using the black and gold resistance bands during the BBS (p = 0.03). When using a gold resistance band, the GMe muscle activation was higher compared to other resistance bands (p < 0.01). VM muscle activity was reduced when using a gold resistance band compared to no band condition (p < 0.01). BF (p = 0.39) and ES (p = 0.88) muscle activity did not change when using different resistance bands. As a result, females may be at a biomechanical disadvantage when using resistance bands compared to males while performing the BBS hindering them from optimal performance.

Relationship Among 3 Different Core Stability Tests in Healthy Young Adults: Validity and Gender Differences

CONTEXT

Core stability is important for preventing injury and improving performance. Although various tests for evaluating core stability have been reported to date, information on their relationship and the effect of gender differences is limited. This study aimed to (1) identify correlations among the 3 core stability tests and to examine the validity of each test and (2) identify gender differences in the test relationship and determine whether gender influenced test selection.

DESIGN

Cross-sectional study.

METHODS

Fifty-one healthy volunteers (27 men and 24 women) participated in the study. The participants underwent the following 3 tests: Sahrmann Core Stability Test (SCST), the lumbar spine motor control tests battery (MCBT), and Y Balance Test (YBT). Each parameter was analyzed according to all parameters and gender using the Spearman rank correlation coefficient.

RESULTS

Overall, there was a strong positive correlation between SCST and MCBT and moderate positive correlations between SCST and YBT and between MCBT and YBT. Conversely, gender-specific analyses revealed no significant correlations between YBT and SCST and between YBT and MCBT in women, although significantly strong correlations were found among all tests in men.

CONCLUSION

Although these 3 tests evaluated interrelated functions and may be valid as core stability tests, the results should be carefully interpreted when performing YBT in women.

Females with knee osteoarthritis use a detrimental knee loading strategy when squatting

BACKGROUND

The purpose of this study was to identify sex differences in lower limb kinematics, kinetics, and muscle activation patterns between individuals with osteoarthritis and healthy controls during a two-legged squat.

METHOD

Thirty OA (15 females) and 30 healthy (15 females) participants performed three 2-legged squats. Sagittal and frontal plane hip, knee, and ankle kinematics and kinetics were calculated. Two-way ANOVAs (Sex X OA Status) were used to characterize differences in squatting strategies between sexes and between those with and without knee OA.

RESULTS

A greater decrease in sagittal hip, knee, and ankle range of motion and knee joint power was observed in the OA participants compared to the healthy controls. Females with OA had significantly reduced hip and knee adduction angles compared to the healthy females and males with OA. Females also had decreased hip power, hip flexion, and hip adduction moments and knee adduction moments compared to their male counterparts, with the greatest deficits observed in the females with OA. Females with OA also had the highest magnitude of muscle activation for the quadriceps, hamstrings, and gastrocnemius throughout the squat, while males with OA showed increased activation of the vastus lateralis and medial gastrocnemius compared to the healthy males.

CONCLUSIONS

OA significantly altered biomechanics and neuromuscular control during the squat, with males employing a hip-dominant strategy, allowing them to achieve a greater lower limb range of motion.

Motor control strategies differ between monoarticular and biarticular quadriceps muscles during bipedal squats

The interplay between biarticular and monoarticular muscles of the knee and hip joints during bipedal squats (SQ_BP ) requires adequate central-nervous control mechanisms to enable smooth and dynamic movements. Here, we investigated motor control between M. vastus medialis (VM), M. vastus lateralis (VL), and M. rectus femoris (RF) in 12 healthy male recreational athletes during SQ_BP with three load levels (50%, 62.5% & 75% of 3-repetition maximum) following a standardized strength training protocol (3 sets of 10 repetitions). To quantify differences in motor control mechanisms in both time and frequency domains, we analyzed (1) muscle covariation via correlation analyses, as well as (2) common neural input via intermuscular coherence (IMC) between RF, VM, and VL. Our results revealed significantly higher gamma IMC between VM-VL compared to RF-VL and RF-VM for both legs. Correlation analyses demonstrated significantly higher correlation coefficients during ascent periods compared to descent periods across all analyzed muscle pairs. However, no load-dependent modulation of motor control could be observed. Our study provides novel evidence that motor control during SQ_BP is characterized by differences in common input between biarticular and monoarticular muscles. Additionally, muscle activation patterns show higher similarity during ascent compared to descent periods. Future research should aim to validate and extend our observations as insights into the underlying control mechanisms offer the possibility for practical implications to optimize training concepts in elite sports and rehabilitation.

Sexual Dimorphism Impact on the Ground Reaction Force Acting on the Mediolateral Direction During Level Walking: Hip Abductor Muscle Biomechanics and Its Correlation to GRF Moment Arm

The female pelvis morphology represents an evolved compensation between two opposing needs: a broad pelvis enough to deliver a sizeable brained offspring while remaining narrow enough to allow for effective bipedal gait. The precise expectation of hip abductor force generation is critical in anthropological studies and experimental practice of human stride mechanics. Hip implants and surgical procedures for hip anatomy reconstruction are based on the static single-leg stance paradigm. The current work investigated the impact of sexual dimorphism on the ground reaction force (GRF) acting on the mediolateral direction during level walking, emphasizing the difference in hip abductor muscle biomechanics and its correlation to ground reaction force moment arm, R. The ground reaction force in the mediolateral direction, hip abduction and adduction moments during the gait cycle and ground reaction force moment arm, R were measured. The current study concludes that the male individuals exhibit significantly higher mass-specific mediolateral ground reaction force during level walking. In contrast, hip abductor moments/kg body weight, medialization of the trochanter, R, and hip coronal were more significant in female individuals. We conclude that increased abductor moment and medialization of the greater trochanter will increase R, hip coronal and decrease abductor moment arm, r, in female individuals, affecting the effective mechanical advantage (EMA) of hip abductors in single-limb stance during level walking.

Age and Gender Differences in Injuries and Risk Factors in Elite Junior and Professional Tennis Players

BACKGROUND

Elite tennis athletes experience injuries throughout the entire body. Impairments in trunk stability, lower limb flexibility, and hip range of motion (ROM) are modifiable risk factors that can impact injuries and performance. Information on nonmodifiable risk factors such as age and gender is limited. The purpose of this investigation was to provide information on risk factors to direct clinical decision-making and injury prevention and rehab programming in this population.

HYPOTHESIS

Prevalence and location of injuries will differ by age group and gender. Trunk stability, lower limb flexibility, and hip ROM will differ by age group and gender.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A de-identified database (n = 237; females = 126) from the United States Tennis Association High Performance Profile (HPP) 2014-2015 was used for the analysis. Subjects were elite junior and professional tennis players (mean age 14.6 [range, 9-27] years). The HPP is a tennis-specific assessment and questionnaire that includes retrospective information on injury history. Subjects were categorized by injury, gender, and age. Injury locations were classified by region. Trunk stability measures included drop vertical jump (DVJ), single-leg squat, and prone and side planks. Lower limb measures included hamstring, quadriceps and hip flexor flexibility, and hip rotation ROM.

RESULTS

A total of 46% of athletes reported an injury. Significant differences were found for injury prevalence and location by age group. Adolescent athletes (age 13-17 years) had more trunk injuries, while adult athletes (age ≥18 years) had more lower limb injuries. Adolescent athletes performed worse on DVJ, dominant side plank, and hamstring flexibility compared with young (age ≤12 years) and adult athletes. Significant gender differences in hip ROM included internal rotation on both the dominant and nondominant sides.

CONCLUSION

Impairments in trunk stability, lower limb flexibility, and hip rotation ROM may affect both health and performance outcomes in this population. Elite tennis athletes may benefit from additional off court programming to address trunk and lower limb impairments.

CLINICAL RELEVANCE

Adolescent elite tennis athletes may be at higher risk of trunk injuries. Age, gender, injury history, and impairments should be considered with all assessments and programming.

Symmetry and sex differences in knee kinematics and ACL elongation in healthy collegiate athletes during high-impact activities revealed through dynamic biplane radiography

The objectives of this study were to determine symmetry and sex differences in knee kinematics and anterior cruciate ligament (ACL) elongation waveforms in healthy athletes without a history of a knee injury during fast running, drop jump, and 180° internal/external rotation hops. It was hypothesized that knee abduction angle and ACL relative elongation would be greater in women than in men during all activities. Bilateral knee kinematics and ACL relative elongation were determined in 19 collegiate athletes using dynamic biplane radiography. Sex differences in kinematics and ACL relative elongation waveforms were identified using statistical parametric mapping. Average absolute side-to-side differences (SSD_A ) in kinematics and ACL relative elongation waveforms were determined for each activity. Women had up to 2.3° (all p < 0.05) less knee adduction angle and had greater ACL relative elongation (max. 4.8%-9.2%; all p < 0.01) than men during all activities, in support of the hypotheses. SSD_A in kinematics were 1.4 mm and 5.5° or less in all components of translation and rotation, respectively, while SSD_A in ACL relative elongation was 3.6% or less across all activities. Greater ACL relative elongation across a variety of activities may make women more susceptible to ACL injury than men. This study provides valuable reference data for identifying abnormal asymmetry in knee kinematics and ACL elongation in athletes after the ACL injury. These novel results improve our understanding of ACL elongation during demanding athletic activities and may help guide the development of sex-specific risk screening metrics, return to play assessments, and rehabilitation protocols after the ACL injury.

Asymmetries in Dynamic Valgus Index After Anterior Cruciate Ligament Reconstruction: A Proof-of-Concept Study

Individuals with anterior cruciate ligament reconstruction (ACLR) are at a higher risk for subsequent anterior cruciate ligament (ACL) tears. Risk factors for ACL injuries likely involve a combination of anatomical, biomechanical, and neuromuscular factors. Dynamic knee valgus has been indicated as a possible biomechanical factor for future ACL injuries. Given that knee valgus is often accompanied by contralateral pelvic drop during single-leg activities, a dynamic valgus index (DVI) that quantifies combined kinematics of the knee and hip in the frontal plane has recently been developed. As the premise of asymmetrical DVI between limbs in the ACLR population has not been examined, this cross-sectional study was conducted with the aim to compare DVI between individuals with ACLR and healthy controls. Videos were taken for 12 participants with ACLR and 20 healthy controls when they performed single-leg hopping. One-way ANOVA revealed a higher DVI in the injured limb of the ACLR group when compared to their non-injured limb and to the healthy limb of the control group. As our data showed increased DVI in the injured limb of the ACLR group, the DVI approach accounting for hip and knee kinematics may be used to identify frontal plane movement deficits during single-leg hopping in individuals with ACLR.

Local dynamic stability of the lower-limb as a means of post-hoc injury classification

Since most sporting injuries occur at the lower extremity (50% to 66%) and many of those injuries occur at the knee (30% to 45%), it is important to have robust metrics to measure risk of knee injury. Dynamic measures of knee stability are not commonly used in existing metrics but could provide important context to knee health and improve injury screening effectiveness. This study used the Local Dynamic Stability (LDS) of knee kinematics during a repetitive vertical jump to perform a post-hoc previous injury classification of participants. This study analyzed the kinematics from twenty-seven female collegiate division 1 (D1) soccer, D1 basketball, and club soccer athletes from Auburn University (height = 171 ± 8.9cm, weight = 66.3 ± 8.6kg, age = 19.8 ± 1.9yr), with 7 subjects having sustained previous knee injury requiring surgery and 20 subjects with no history of injury. This study showed that LDS correctly identified 84% of previously injured and uninjured subjects using a multivariate logistic regression during a fatigue jump task. Findings showed no statistical difference in kinematic position at maximum knee flexion during all jumps between previously injured and uninjured subjects. Additionally, kinematic positioning at maximum knee flexion was not indicative of LDS values, which would indicate that future studies should look specifically at LDS with respect to injury prevention as it cannot be effectively inferred from kinematics. These points suggest that the LDS preserves information about subtle changes in movement patterns that traditional screening methods do not, and this information could allow for more effective injury screening tests in the future.

Relationship between passive ankle dorsiflexion range, dynamic ankle dorsiflexion range and lower limb and trunk kinematics during the single-leg squat

BACKGROUND

Limited passive ankle dorsiflexion range has been associated with increased knee valgus during functional tasks. Increased knee valgus is considered a contributing factor for musculoskeletal disorders in the lower limb. There is conflicting evidence supporting this association. The extent of passive ankle dorsiflexion range is associated with dynamic ankle dorsiflexion range and the way how these variables are related to lower limb or trunk kinematics is unclear.

RESEARCH QUESTION

What is the association between passive ankle dorsiflexion range or dynamic ankle dorsiflexion range with shank, thigh, pelvis or trunk movements during the single-leg squat?

METHODS

This is a cross-sectional study with a convenience sample. Thirty uninjured participants performed the single-leg squat with their dominant limb. Ankle, shank, thigh, pelvis and trunk 3D kinematics were recorded. Passive ankle dorsiflexion range was assessed through the weight-bearing lunge test and the dynamic ankle dorsiflexion range was defined as the ankle dorsiflexion range of motion in the sagittal plane during the single-leg squat.

RESULTS

Greater passive ankle dorsiflexion range was associated with smaller thigh internal rotation (r= -0.38). Greater dynamic ankle dorsiflexion range was associated with smaller trunk flexion (r = 0.59) and pelvis anteversion (r= -0.47). Passive ankle dorsiflexion range and dynamic ankle dorsiflexion range were not associated.

SIGNIFICANCE

Greater passive ankle dorsiflexion range seems to be associated with a better lower limb alignment during the single-leg squat, while dynamic ankle dorsiflexion range seems to reflect different lower limb and trunk kinematic strategies.

The trunk is exploited for energy transfers of maximal instep soccer kick: A power flow study

The purpose of this study was to investigate the angular kinetic energy transfers and expenditure among the trunk (bisegmented), the pelvis and the kick limb during maximal soccer instep kicking, and to characterize kicking kinetics and kinematics. Eighteen adult male amateur soccer players (24.0 ± 4.1 years old) were assessed. Three-dimensional kinematics and ground reaction force were measured. A 6-degrees-of-freedom model was assumed, comprising the upper trunk, lower trunk, pelvis, thigh, shank and foot, and the thoraco-lumbar, lumbo-pelvic, hip, knee, and ankle joints. Angular kinematics and joint moments were computed. Power flow analysis was done by calculating the joint powers (to describe joint-to-segments energy transfers) and the proximal and distal segment powers (to describe segment-to-segment transfers). Power, kinematic and kinetic time series were presented to describe the energy flows' directions. The total mechanical energy expenditure (TMEE) at each joint was also calculated. The TMEEs pointed to substantial energy expenditure at the trunk (27% of the summed work produced by the analyzed joints). In the initial phases of kicking, the trunk generates downward energy flows from the upper to the lower trunk and from the lower trunk to the pelvis, and then to the lower limb, sequentially, which favors angular motions for ball contact. There is a formation and release of a tension arc only at the hip joint, and deceleration of the segments slightly sooner than ball contact, differently from theoretical accounts. There are energy flows, hitherto unknown, among the trunk, pelvis and kick limb, revealing mechanical strategies of kicking.

The Single Leg Squat Test: A "Top-Down" or "Bottom-Up" Functional Performance Test?

BACKGROUND

Medial knee deviation (MKD) during the single leg squat test (SLST) is a common clinical finding that is often attributed to impairments of proximal muscular structures. Investigations into the relationship between MKD and the foot and ankle complex have provided conflicting results, which may impact clinicians' interpretation of the SLST.

PURPOSE

The purpose of this study was to compare ankle dorsiflexion range of motion (ROM) and foot posture in subjects that perform the SLST with MKD (fail) versus without MKD (pass).

HYPOTHESIS

There will be a difference in ankle dorsiflexion ROM and/or foot posture between healthy individuals that pass and fail the SLST for MKD.

STUDY DESIGN

Cross-sectional study.

METHODS

Sixty-five healthy, active volunteers (sex = 50 female, 15 male; age = 25.2 +/- 5.6 years; height = 1.7 +/- .1 m; weight = 68.5 +/- 13.5 kg) who demonstrated static balance and hip abductor strength sufficient for performance of the SLST participated in the study. Subjects were divided into pass and fail groups based on visual observation of MKD during the SLST. Foot Posture Index (FPI-6) scores and measures of non-weight bearing and weight bearing active ankle dorsiflexion (ROM) were compared.

RESULTS

There were 33 individuals in the pass group and 32 in the fail group. The groups were similar on age (p = .899), sex (p = .341), BMI (p = .818), and Tegner Activity Scale score (p = .456). There were no statistically significant differences between the groups on the FPI-6 (pass group mean = 2.5 +/- 3.9; fail group mean = 2.3 +/- 3.5; p = .599), or any of the measures of dorsiflexion range of motion (non-weight bearing dorsiflexion with knee extended: pass group = 6.9o +/- 3.7o, fail group = 7.8o +/- 3.0o; non-weight bearing dorsiflexion with knee flexed: pass group = 13.5o +/- 5.6o, fail group = 13.9o +/- 5.3o; weight bearing dorsiflexion: pass group = 42.7o +/- 6.0o, 42.7o +/- 8.3o, p = .611).

CONCLUSIONS

Failure on the SLST is not related to differences in clinical measures of active dorsiflexion ROM or foot posture in young, healthy individuals. These findings suggest that clinicians may continue using the SLST to assess neuromuscular performance of the trunk, hip, and knee without ankle dorsiflexion ROM or foot posture contributing to results.

LEVEL OF EVIDENCE

Level 3.

Effect of simulated rehabilitation on hip joint loading during single limb squat in patients with hip dysplasia

Rehabilitation for patients with developmental dysplasia of the hip (DDH) addresses modifiable factors in an effort to reduce symptoms and prevent or delay the development of osteoarthritis, yet its effect on joint mechanics remains unknown. Our objective was to establish how rehabilitation (muscle strengthening and movement training), simulated with a musculoskeletal model and probabilistic analyses, alters hip joint reaction forces (JRF) in patients with DDH during a single limb squat. In four patients with DDH, hip abductor strengthening was simulated by increasing the maximum isometric force value between 0 and 32.6% and movement training was simulated by decreasing the hip adduction angle between 0 and 10° relative to baseline. 2,000 Monte Carlo simulations were performed separately to simulate strengthening and movement training, from which 99% confidence bounds and sensitivity factors were calculated. Our results indicated that simulated movement training aimed at decreasing hip adduction had a substantially larger influence on hip JRF than strengthening, as indicated by 99% confidence bounds of the resultant JRF (0.88 ± 0.55 xBW vs. 0.31 ± 0.12 xBW, respectively). Relative to baseline, movement training that resulted in a 10° decrease in hip adduction decreased the resultant JRF by 0.78 ± 0.65 xBW, while strengthening the abductors by 17.6% increased resultant JRF by 0.18 ± 0.06 xBW. To our knowledge, these results are the first to provide evidence pertaining to the effect of rehabilitation on joint mechanics in patients with DDH and can be used to inform more targeted interventions.

A Comparison between Male and Female Athletes in Relative Strength and Power Performances

The aim of this study was to compare male vs. female athletes in strength and power performance relative to body mass (BM) and lean body mass (LBM) and to investigate the relationships between muscle architecture and strength in both genders. Sixteen men (age = 26.4 ± 5.0 years; body mass = 88.9 ± 16.6 kg; height = 177.6 ± 9.3 cm) and fourteen women (age = 25.1 ± 3.2 years; body mass = 58.1 ± 9.1 kg; height = 161.7 ± 4.8 cm) were tested for body composition and muscle thickness (MT) of vastus lateralis muscle (VT), pectoralis major (PEC), and trapezius (TRAP). In addition, participants were tested for lower body power at countermovement jump (CMJP) and upper-body power at bench press throw (BPT). Participants were also assessed for one repetition maximum (1RM) at bench press (1RMBP), deadlift (1RMDE), and squat (1RMSQ). Significantly greater (p < 0.01) MT of the VL, PEC and TRAP muscles and LBM were detected in men compared to women. Significantly greater (p < 0.05) 1RMBP and BPT adjusted for LBM were detected in men than in women. No significant gender differences after adjusting for LBM were detected for 1RMSQ (p = 0.945); 1RMDE (p = 0.472) and CMJP (p = 0.656). Significantly greater (p < 0.05) results in all performance assessments adjusted for MT of the specific muscles, were detected in males compared to females. Superior performances adjusted for MT and LBM in men compared to women, may be related to gender differences in muscle morphology and LBM distribution, respectively.

Muscle activation in pelvic anteversion and retroversion

Abstract Introduction: The inability to maintain good pelvic stability has been attributed to inefficient muscle coordination and deconditioning of the stabilizing muscles. Despite this, little is known about the role of the pelvic muscles in anteversion and retroversion movements. Objective: To compare the neuromuscular activity of the tensor fascia lata, gluteus medius, upper and lower portions of the gluteus maximus, and multifidus in pelvic anteversion and retroversion. Methods: The neuromuscular activity of 17 healthy young adults (aged 25.3 ± 4.6 years) was assessed during five repetitions of the pelvic anteversion and retroversion movements. The Vicon-Nexus system (10 cameras) was used for the kinematic analysis of the pelvis in the sagittal plane (anteversion and retroversion), and the TeleMyo DTS Desk Receiver electromyograph and the Myomuscle v. 3.8 software to measure neuromuscular activity. The paired samples t-test was used to compare muscle activity between pelvic anteversion and retroversion movements using the Statistica v.8 software with a significance level of p < 0.05. Results: The comparison of the movements showed greater muscle activity in the inferior gluteus maximus in retroversion and greater activity in the multifidus in pelvic anteversion. The upper portion of the gluteus maximus showed relevant activation in both movements. Conclusion: There was more pronounced activity of the lower portion of the gluteus maximus in retroversion, while the upper gluteus maximus showed relevant activation level in both movements. The multifidi were more active in retroversion.

Mechanical Energy Expenditure at Lumbar Spine and Lower Extremity Joints During the Single-Leg Squat Is Affected by the Nonstance Foot Position

Hirsch, SM, Chapman, CJ, Frost, DM, and Beach, TAC. Mechanical energy expenditure at lumbar spine and lower extremity joints during the single-leg squat is affected by the nonstance foot position. J Strength Cond Res XX(X): 000-000, 2020-Previous research has shown that discrete kinematic and kinetic quantities during bodyweight single-leg squat (SLS) movements are affected by elevated foot positioning and sex of the performer, but generalizations are limited by the high-dimensional data structure reported. Using a 3D inverse dynamical linked-segment model, we quantified mechanical energy expenditure (MEE) at each joint in the kinetic chain, the total MEE (sum of MEE across aforesaid joints), and the relative contribution of each joint to total MEE during SLSs performed with elevated foot positioned beside stance leg (SLS-Side), and in-front of (SLS-Front) and behind (SLS-Back) the body. Total MEE differed between SLS variations (p = 0.002), with the least amount observed in the SLS-Back (effect size [ES] = 0.066-0.069). Approximately 50% of total MEE was contributed by the knee joint in each SLS variation, whereas MEE at the ankle, hip, and lumbar spine (in absolute and relative terms) varied complexly as a function of the elevated foot position. Total MEE (p = 0.0192, ES = 0.852) and the absolute MEE at the knee and spine was greater in men across the SLS variations performed (p = 0.025-0.036, ES = 0.715-0.766), but only the lumbar spine contribution to total MEE was larger in men across all SLS variations (p = 0.045, ES = 0.607). Otherwise, there were no other sex-specific responses observed. Biomechanically, SLS movements are generally "knee-dominant," but changing elevated foot position effectively redistributes MEE among other joints in the linkage. Consistent with the previous conclusions reached based on discrete kinematic and kinetic data, not all SLSs are equal.

Knee Valgus Versus Knee Abduction Angle: Comparative Analysis of Medial Knee Collapse Definitions in Female Athletes

The knee valgus angle (KVA) is heavily researched as it has been shown to correlate to anterior cruciate ligament (ACL) injuries when measured during jumping activities. Many different methods of KVA calculation are often treated as equivalent. The purpose of this study is to elucidate differences between these commonly used angles within and across activities to determine if they can indeed properly be treated as equivalent. The kinematics of 23 female athletes, D1 soccer, D1 basketball, and club soccer (height = 171.2 ± 88.9 cm, weight = 66.3 ± 8.6 kg, age = 19.8 ± 1.9 years), was analyzed using a motion capture system during activities related to their sport and daily living. The abduction KVA, measured using body fixed axes, only correlated to the two-dimensional (2D) global reference frame angle (KVA 2G) in three of the six activities (walking, squatting, and walking down stairs), and one out of six in the three-dimensional (3D) measurements (jogging). This suggests that the abduction KVA does not always relate to other versions of KVA. The KVA with reference to the pelvis coordinate system (KVA 2P) correlated to the KVA 2G in six out of six activities (r = 0.734  ±  0.037, P << 0.001) suggesting the pelvis can be utilized as a reference plane during rotating tasks, such as run-to-cut, when a fixed global system is less meaningful. Not all measures of KVA are equivalent and should be considered individually. A thorough understanding of the equivalence or nonequivalence of various measures of KVA is essential in understanding ACL injury risk.

Sex-dependent differences in single-leg squat kinematics and their relationship to squat depth in physically active individuals

The purpose of this study is to compare recreationally physically active females and males with regard to spine, pelvis and lower limb joints peak angles in each plane of motion during a single leg squat (SLS). The second aim is to investigate the relationship between kinematics and SLS depth in females and males. Fifty-eight healthy, young adults performed 5 repetitions of a single right leg squat to maximal depth while keeping their balance. Kinematic data were obtained using an optical motion capture system. At the hip, greater adduction and greater internal rotation were observed in females than in males. Females had more extended spines and less outward bended knees throughout the SLS than did men. In males, squat depth was significantly, positively correlated with the maximal angle of the ankle (r = 0.60, p < 0.001), the knee (r = 0.87, p < 0.001), the hip (r = 0.73, p < 0.001) and the pelvis (r = 0.40, p = 0.02) in the sagittal plane. A positive significant correlation was found between SLS depth and maximal angle of the knee (r = 0.88, p < 0.001) and the ankle (r = 0.53, p = 0.01) in the sagittal plane in females. Males and females used different motor strategies at all levels of the kinematic chain during SLS.

Relationship Between Hip Frontal Dynamic Joint Stiffness and Frontal and Transverse Plane Hip Kinematics During Gait: Sex Differences

CONTEXT

Previous studies have reported that the incidence of patellofemoral pain in women is 2.2 times higher than that in men. Lower hip frontal dynamic joint stiffness in women may be related to the magnitude of hip adduction and internal rotation associated with patellofemoral pain.

OBJECTIVE

To identify sex differences in hip frontal dynamic joint stiffness and examine the relationship between hip frontal dynamic joint stiffness and hip adduction and internal rotation during gait.

DESIGN

Cross-sectional study.

SETTING

University campus.

PARTICIPANTS

A total of 80 healthy volunteers (40 women and 40 men) participated in this study.

INTERVENTION(S)

Kinematic and kinetic data during gait were collected using a motion capture system and force plates.

MAIN OUTCOME MEASURES

Hip frontal dynamic joint stiffness, hip adduction, and hip internal rotation were calculated during gait.

RESULTS

Women demonstrated lower hip frontal dynamic joint stiffness than men during gait (P < .01). They also displayed decreased hip frontal dynamic joint stiffness associated with increased hip adduction (r = -.85, P < .001) and internal rotation (r = -.48, P < .001). Conversely, in men, decreased hip frontal dynamic joint stiffness was associated with increased hip adduction (r = -.74, P < .001) but not internal rotation (r = .17, P = .28).

CONCLUSIONS

Sex differences between hip frontal dynamic joint stiffness and hip internal rotation during gait may contribute to the increased incidence of patellofemoral pain in women.

Intermuscular coherence between homologous muscles during dynamic and static movement periods of bipedal squatting

Coordination of functionally coupled muscles is a key aspect of movement execution. Demands on coordinative control increase with the number of involved muscles and joints, as well as with differing movement periods within a given motor sequence. While previous research has provided evidence concerning inter- and intramuscular synchrony in isolated movements, compound movements remain largely unexplored. With this study, we aimed to uncover neural mechanisms of bilateral coordination through intermuscular coherence (IMC) analyses between principal homologous muscles during bipedal squatting (BpS) at multiple frequency bands (alpha, beta, and gamma). For this purpose, participants performed bipedal squats without additional load, which were divided into three distinct movement periods (eccentric, isometric, and concentric). Surface electromyography (EMG) was recorded from four homologous muscle pairs representing prime movers during bipedal squatting. We provide novel evidence that IMC magnitudes differ between movement periods in beta and gamma bands, as well as between homologous muscle pairs across all frequency bands. IMC was greater in the muscle pairs involved in postural and bipedal stability compared with those involved in muscular force during BpS. Furthermore, beta and gamma IMC magnitudes were highest during eccentric movement periods, whereas we did not find movement-related modulations for alpha IMC magnitudes. This finding thus indicates increased integration of afferent information during eccentric movement periods. Collectively, our results shed light on intermuscular synchronization during bipedal squatting, as we provide evidence that central nervous processing of bilateral intermuscular functioning is achieved through task-dependent modulations of common neural input to homologous muscles.

NEW & NOTEWORTHY It is largely unexplored how the central nervous system achieves coordination of homologous muscles of the upper and lower body within a compound whole body movement, and to what extent this neural drive is modulated between different movement periods and muscles. Using intermuscular coherence analysis, we show that homologous muscle functions are mediated through common oscillatory input that extends over alpha, beta, and gamma frequencies with different synchronization patterns at different movement periods.

How Are Squat Timing and Kinematics in The Sagittal Plane Related to Squat Depth?

The aim of this study was to analyze the relationship of range of motion (ROM) in the sagittal plane and timing parameters during a bodyweight squat to the depth of the squat. Sixty participants (20 females and 40 males) took part in this study. They were instructed to perform a bodyweight squat to the maximal depth position. Kinematic data were obtained using the optical motion capture system. The time for the descent phase of squatting was normalized from 0% (initial position, start of movement) to 100% (squat position-stop of movement). The ROM of ankle, knee, hip, pelvis and spine in the sagittal plane and the normalized time when the maximum joint angles occurred during the descent were analyzed to investigate the relationship between them and the squat depth in males and females. The knee ROM contributed most significantly, from all joints to squatting depth in both females and males (r = 0.92, p < 0.001). The squat depth was related to lumbar, hip and knee motion in females and to all kinematics parameters in males. Maximal ankle dorsiflexion and pelvis anterior tilt were reached earlier than the maximal angles of knee, hip and spine during squatting. Pelvis and ankle timing was negatively correlated with the squat depth (r_s = -0.64, p < 0.001 and r_s = -0.29, p = 0.02, respectively). This suggests that pelvis and ankle timing can be important to keeping balance during squatting and can lead to achieving the desired depth.

Validity of a New 3-D Motion Analysis Tool for the Assessment of Knee, Hip and Spine Joint Angles during the Single Leg Squat

Aim: Study concurrent validity of a new sensor-based 3D motion capture (MoCap) tool to register knee, hip and spine joint angles during the single leg squat. Design: Cross-sectional. Setting: University laboratory. Participants: Forty-four physically active (Tegner ≥ 5) subjects (age 22.8 (±3.3)) Main outcome measures: Sagittal and frontal plane trunk, hip and knee angles at peak knee flexion. The sensor-based system consisted of 4 active (triaxial accelerometric, gyroscopic and geomagnetic) sensors wirelessly connected with an iPad. A conventional passive tracking 3D MoCap (OptiTrack) system served as gold standard. Results: All sagittal plane measurement correlations observed were very strong for the knee and hip (r = 0.929–0.988, p < 0.001). For sagittal plane spine assessment, the correlations were moderate (r = 0.708–0.728, p < 0.001). Frontal plane measurement correlations were moderate in size for the hip (ρ = 0.646–0.818, p < 0.001) and spine (ρ = 0.613–0.827, p < 0.001). Conclusions: The 3-D MoCap tool has good to excellent criterion validity for sagittal and frontal plane angles occurring in the knee, hip and spine during the single leg squat. This allows bringing this type of easily accessible MoCap technology outside laboratory settings.

Three-Dimensional Finite Element Analysis of the Effects of Ligaments on Human Sacroiliac Joint and Pelvis in Two Different Positions

To present the ligament effects on sacroiliac joint (SIJ) stability and human pelvis biomechanical characteristics in two different positions by using three-dimensional (3D) finite element (FE) models of pelvis. Based on the computed tomography (CT) data of human pelvis, three-dimensional FE models of human pelvis in sitting and standing positions were established, which include the bone (sacrum, ilium, and coccyx) and six ligaments (sacroiliac, sacrospinous, sacrotuberous, inguinal, superior pubic, and arcuate pubic ligaments). 600 N vertical load was applied at the upper surface of sacrum to analyze the stress and displacement distribution of pelvis and SIJ. The simulation results demonstrated that the maximum stresses of sacrum and ilium on SIJ contact surface were 5.63 MPa and 7.40 MPa in standing position and 7.44 MPa and 7.95 MPa in sitting position. The stresses of ligament dysfunction group were higher than that of health group, which increased by 22.6% and 35.7% in standing position and 25.2% and 43.6% in sitting position in sacrum and ilium. The maximum displacements located on the upper surface of sacrum, which were 0.13 mm and 1.04 mm in standing and sitting positions. Ligaments dysfunction group increased 30.7% and 9.6% than health group in standing and sitting positions. The integral displacement of pelvis was greater in sitting position. The location of stress concentration and displacement distribution of pelvic bone are closely resembled previous research results in two different positions. The simulation results may provide beneficial information and theoretical models for clinical research of pelvic fracture, joint movement, and ligament functional injuries, and so on.

Peak horizontal ground reaction forces and impulse correlate with segmental energy flow in youth baseball pitchers

The purpose of this study was to determine associations between horizontal ground reaction force (GRF) kinetics and energy flow (EF) variables in youth baseball players. Twenty-four youth baseball players pitched fastballs in an indoor laboratory while motion capture and force plate data were collected. Horizontal GRF variables were extracted (peak GRF and GRF impulse) while EF was calculated by integrating magnitudes of mechanical powers transferred into and out of the pelvis, trunk, and arm segments via joint force power (JFP) and joint moment power (JMP) components. Peak propulsive GRF of the drive (back) leg correlated with EF into proximal segments, whereas peak braking GRF of the stride (lead) leg correlated with EF into distal segments. Furthermore, peak GRF of the drive leg and GRF impulse of both legs correlated with the JFP components of EF into the pelvis and trunk segments. In contrast, peak GRF and GRF impulse of the stride leg both correlated with the JMP components of EF into the arm segment. These results suggest that horizontal GRF impulse from the drive and stride leg contribute to EF between major segments of the lower and upper extremity. In addition, these results also suggest that propulsion kinetics of the drive leg play a role in transferring linear power via the pelvis and trunk segments in the throwing direction of the pitch, whereas braking kinetics of the stride leg play a role in creating rotational power that is transferred between the trunk and arm segment via the shoulder joint.

Exploring sexual dimorphism of the modern human talus through geometric morphometric methods

Sex determination is a pivotal step in forensic and bioarchaeological fields. Generally, scholars focus on metric or qualitative morphological features, but in the last few years several contributions have applied geometric-morphometric (GM) techniques to overcome limitations of traditional approaches. In this study, we explore sexual dimorphism in modern human tali from three early 20th century populations (Sassari and Bologna, Italy; New York, USA) at intra- and interspecific population levels using geometric morphometric (GM) methods. Statistical analyses were performed using shape, form, and size variables. Our results do not show significant differences in shape between males and females, either considering the pooled sample or the individual populations. Differences in talar morphology due to sexual dimorphism are mainly related to allometry, i.e. size-related changes of morphological traits. Discriminant function analysis using form space Principal Components and centroid size correctly classify between 87.7% and 97.2% of the individuals. The result is similar using the pooled sample or the individual population, except for a diminished outcome for the New York group (from 73.9% to 78.2%). Finally, a talus from the Bologna sample (not included in the previous analysis) with known sex was selected to run a virtual resection, followed by two digital reconstructions based on the mean shape of both the pooled sample and the Bologna sample, respectively. The reconstructed talus was correctly classified with a Ppost between 99.9% and 100%, demonstrating that GM is a valuable tool to cope with fragmentary tali, which is a common occurrence in forensic and bioarchaeological contexts.

Risk Factors for Lower-Extremity Injuries Among Contemporary Dance Students

OBJECTIVE

To determine whether student characteristics, lower-extremity kinematics, and strength are risk factors for sustaining lower-extremity injuries in preprofessional contemporary dancers.

DESIGN

Prospective cohort study.

SETTING

Codarts University of the Arts.

PATIENTS

Forty-five first-year students of Bachelor Dance and Bachelor Dance Teacher.

ASSESSMENT OF RISK FACTORS

At the beginning of the academic year, the injury history (only lower-extremity) and student characteristics (age, sex, educational program) were assessed using a questionnaire. Besides, lower-extremity kinematics [single-leg squat (SLS)], strength (countermovement jump) and height and weight (body mass index) were measured during a physical performance test.

MAIN OUTCOME MEASURES

Substantial lower-extremity injuries during the academic year were defined as any problems leading to moderate or severe reductions in training volume or in performance, or complete inability to participate in dance at least once during follow-up as measured with the Oslo Sports Trauma Research Center (OSTRC) Questionnaire on Health Problems. Injuries were recorded on a monthly basis using a questionnaire. Analyses on leg-level were performed using generalized estimating equations to test the associations between substantial lower-extremity injuries and potential risk factors.

RESULTS

The 1-year incidence of lower-extremity injuries was 82.2%. Of these, 51.4% was a substantial lower-extremity injury. Multivariate analyses identified that ankle dorsiflexion during the SLS (OR 1.25; 95% confidence interval, 1.03-1.52) was a risk factor for a substantial lower-extremity injury.

CONCLUSIONS

The findings indicate that contemporary dance students are at high risk for lower-extremity injuries. Therefore, the identified risk factor (ankle dorsiflexion) should be considered for prevention purposes.

A comparison of knee joint moments during high flexion squatting and kneeling postures in healthy individuals

BACKGROUND

Deep knee bending has been reported as an occupational hazard to workers who have to adopt such postures. High knee joint moments have been associated with knee osteoarthritis initiation and progression.

OBJECTIVE

This study aimed to compare four high knee flexion postures (dorsiflexed and plantarflexed kneeling, and flat-foot and heels-up squatting) to determine which one results in lower knee joint flexion and ab/adduction moments.

METHODS

Forty-three participants performed five trials of each posture. Peak (for descent/ascent) and mean (for the static hold) external knee flexion and ab/adduction moments were analyzed for each posture using 2-way ANOVAs and post-hoc pairwise comparisons.

RESULTS

It was observed that the flat-foot squat resulted in significantly lower knee flexion moment compared to the other three postures (4.63±0.99 % BW·H during the static phase, and 5.83±1.24 % BW·H and 5.94±1.24 % BW·H during descent and ascent phases, respectively). During ascent phase, significant differences was indicated in peak adduction moments for the flat-foot squat in comparison to both styles of kneeling.

CONCLUSIONS

When high knee flexion is required but posture is not dictated, flat-foot squat will reduce exposures to high knee moments.

Hip Biomechanics During a Single-Leg Squat: 5 Key Differences Between People With Femoroacetabular Impingement Syndrome and Those Without Hip Pain

BACKGROUND

The hip joint biomechanics of people with femoroacetabular impingement (FAI) syndrome are different from those of healthy people during a double-leg squat. However, information on biomechanics during a single-leg squat is limited.

OBJECTIVES

To compare hip joint biomechanics between people with FAI syndrome and people without hip pain during double-leg and single-leg squats.

METHODS

Fourteen people with FAI syndrome (cam, n = 7; pincer, n = 1; mixed, n = 6) and 14 people without hip pain participated in this cross-sectional, case-control, laboratory-based study. Three-dimensional biomechanics data were collected while all participants performed a double-leg and a single-leg squat. Two-way mixed-model analyses of variance were used to assess group-by-task interactions for hip joint angles, thigh and pelvis segment angles, hip joint internal moments, and squat performance variables. Post hoc analyses for all variables with a significant group-by-task interaction were performed to identify between-group differences for each task.

RESULTS

There were significant group-by-task interactions for peak hip joint (P = .014, η² = 0.211) and thigh segment (P = .009, η² = 0.233) adduction angles, and for peak hip joint abduction (P = .002, η² = 0.308) and extension (P = .016, η² = 0.203) internal moments. There were no significant group-by-task interactions for squat performance variables.

CONCLUSION

Biomechanical differences at the hip between people with FAI syndrome and those without hip pain were exaggerated during a single-leg squat compared to a double-leg squat task.

LEVEL OF EVIDENCE

Diagnosis, level 4. J Orthop Sports Phys Ther 2019;49(12):908-916. Epub 23 Jul 2019. doi:10.2519/jospt.2019.8356.

Dynamic knee valgus kinematics and their relationship to pain in women with patellofemoral pain compared to women with chronic hip joint pain

BACKGROUND

Dynamic knee valgus (DKV) is an abnormal movement pattern visually characterized by excessive medial movement of the lower extremity during weight bearing. Differences in hip and knee kinematic components of DKV may explain the emergence of different pain problems in people who exhibit the same observed movement impairment. Using a secondary analysis of exiting data sets, we sought to determine whether hip and knee frontal and transverse plane angles during a functional task differed between women with patellofemoral pain and women with chronic hip joint pain, and the relationship between joint-specific kinematics and pain in these 2 pain populations.

METHODS

In the original studies, 3-dimensional hip and knee kinematics during a single leg squat were obtained in 20 women with patellofemoral pain and 14 women with chronic hip joint pain who demonstrated visually classified DKV. Pain intensity during the squat was assessed in both groups. For the secondary analysis, kinematic data were compared between pain groups using their respective control groups as a reference. Within each pain group, correlation coefficients were used to determine the relationship between kinematics and pain during the squat.

RESULTS

Hip adduction and contralateral pelvic drop were greater in those with chronic hip joint pain compared to those with patellofemoral pain (effect sizes ≥ 0.40). Greater knee external rotation (r=0.47, p=0.04) was correlated with greater knee pain in those with patellofemoral pain, while greater hip adduction (r =0.53, p =0.05) and greater hip internal rotation (r =0.55, p =0.04) were correlated with greater hip pain in those with chronic hip joint pain.

CONCLUSION

Hip frontal plane motion was greater in those with chronic hip joint pain compared to those with patellofemoral pain. In both groups, greater abnormal movement at the respective joint (e.g. knee external rotation in the patellofemoral pain group and hip adduction and internal rotation in the chronic hip joint pain group) was associated with greater pain at that joint during a single leg squat.

Position of the non-stance leg during the single leg squat affects females and males differently

BACKGROUND

Kinematic differences between females and males for the single leg squat (SLS) have been identified. However, kinetic differences between sexes and how variations of the non-stance leg position during the SLS may affect kinematics and kinetics differently in females and males have not been examined.

OBJECTIVES

Examine sex-specific kinematic and kinetic differences during the SLS task with 3 different non-stance leg positions.

DESIGN

Controlled laboratory study, cross-sectional design.

METHODS

Thirty-two healthy adults (16 females, 16 males) performed the 3 SLS tasks while data were collected using a motion capture system and force plates. At 60 degrees of knee flexion (60KF) and peak knee flexion (PKF), kinematics and joint moments were compared between sexes and SLS tasks using a linear regression analysis.

RESULTS

Females exhibited less ipsilateral trunk flexion (P < 0.001) and greater anterior pelvic tilt (P ≤ 0.021) and hip adduction (P < 0.001) than males across tasks at 60KF and PKF. Across tasks, females had a smaller knee flexion moment than males at PKF (P = 0.001). Females had a greater hip abduction moment during SLS-Front than SLS-Middle (P = 0.044) and SLS-Back (P = 0.003) at PKF, but males had similar hip abduction moments across tasks (P ≥ 0.299). At 60KF, males had a greater knee adduction moment during SLS-Front compared to the other tasks (P ≤ 0.019) while females had similar hip abduction moments across tasks (P ≥ 0.459).

CONCLUSION

Altering the non-stance leg position during the SLS affects the kinematics and kinetics of both females and males. The position of the non-stance leg can be modified for assessment and treatment purposes and should be reported in research.

The effects of foot position on lower extremity kinematics during single leg squat among adolescent male athletes

Objectives

The purpose of this study was to investigate the effect of transverse plane foot position on lower limb kinematics during a single leg squat.

Methods

This was a cross-sectional study conducted among highly-trained male athletes. Only participants who showed normal knee valgus during a drop landing screening test were recruited. Twelve junior athletes performed single leg squats while maintaining a knee flexion angle of 60°. The squats were executed in three foot positions: neutral (0°), adduction (−10°), and abduction (+10°). Three-dimensional motion analysis was used to capture the lower extremity kinematics of the participants’ preferred limb. The hip and knee kinematics in the sagittal, frontal, and transverse planes during squatting were compared across the three foot positions using one-way ANOVA.

Results

The participants showed a normal range of dynamic knee valgus (5.3°±1.6). No statistically significant differences were observed in hip flexion (p = 0.322), adduction (p = 0.834), or internal rotation (p = 0.967) across different foot positions. Similarly, no statistically significant differences were observed in knee flexion (p = 0.489), adduction (p = 0.822), or internal rotation (p = 0.971) across different foot positions.

Conclusion

Small changes in transverse plane foot position do not affect lower extremity kinematics during single leg squat in highly trained adolescent males with normal dynamic knee valgus. Our findings may provide guidance on safer techniques for landing, pivoting, and cutting during training and game situations.