Article

Core Strength and Lower Extremity Alignment during Single Leg Squats

June 2006
Medicine and Science in Sports and Exercise 38(5):945-52

DOI:10.1249/01.mss.0000218140.05074.fa

Source
PubMed

Authors:

John D Willson

East Carolina University

Mary Lloyd Ireland

University of Kentucky

Irene S Davis

Harvard Medical School

Muscles of the trunk, hip, and knee influence the orientation of the lower extremity during weight bearing activities. The purpose of this study was threefold: first, to compare the orientation of the lower extremity during a single leg (SL) squat among male and female athletes; second, to compare the strength of muscle groups in the trunk, hips, and knees between these individuals; and third, to evaluate the association between trunk, hip, and knee strength and the orientation of the knee joint during this activity. Twenty-four male and 22 female athletes participated in this study. Peak isometric torque was determined for the following muscle actions: trunk flexion, extension, and lateral flexion, hip abduction and external rotation, and knee flexion and extension. The frontal plane projection angle (FPPA) of the knee during a 45 degrees SL squat was determined using photo editing software. Males and females moved in opposite directions during the SL squat test (F(1,42) = 5.05, P = 0.03). Females typically moved toward more extreme FPPA during SL squats (P = 0.056), while males tended to move toward more neutral alignment (P = 0.066). Females also generated less torque in all muscle groups, with the exception of trunk extension. The projection angle of the knee during the SL squat test was most closely associated with hip external rotation strength. Using instruments suitable for a clinical setting, females were found to have greater FPPA and generally decreased trunk, hip, and knee isometric torque. Hip external rotation strength was most closely associated with the frontal plane projection angle.

Effect of hip abductors training on pelvic drop and knee valgus in runners with medial tibial stress syndrome: a randomized controlled trial

Article

Full-text available

Oct 2024
J Orthop Surg Res

Background Medial tibial stress syndrome (MTSS) is a prevalent running-related injury that could impact athletic performance and quality of life. The purpose of the study was to investigate the effectiveness of functional hip abductor strength training on reducing contralateral pelvic drop angle (hip frontal plane projection angle), and dynamic knee valgus (knee frontal plane projection angle) in runners with medial tibial stress syndrome (MTSS). Methods Forty male and female recreational runners were diagnosed with MTSS for at least one month. The age ranged from 25 to 35 years old, and the body mass index (BMI) ranged between (18.5 and 25 kg/m²) participated in this study. This was a single-blind, randomized controlled trial. Participants were randomized into two groups: a control group (Group A, n = 20) received a selected physical therapy exercise program, and an experimental group (Group B, n = 20) received the same program plus functional hip abductor strength training. Dynamic knee valgus (frontal plane projection angle) and contralateral pelvic drop angle were measured using 2D video and analyzed by Kinovea software at baseline and after 8 weeks. Mixed-effect multifactor analysis of variance (MANOVA) was conducted to compare within and between groups effects on FPPA and pelvic drop angle. Results After 8 weeks, Group B exhibited a significantly decreased frontal plane projection and pelvic drop angles compared to Group A (p < 0.05). Group A also demonstrated a reduced pelvic drop angle, but to a lesser extent, and their frontal plane projection angle increased. Conclusions This study demonstrates that 8 weeks of functional hip abductor strength training, combined with traditional physical therapy, effectively improves lower extremity kinematics in runners with MTSS by reducing dynamic knee valgus and contralateral pelvic drop. This targeted approach likely addresses underlying muscle weakness and movement dysfunction, offering hope for potentially reducing MTSS recurrence. Trial registration: clinicaltrials.gov. NO: NCT05637476. Date: December 1, 2022.

Relationship between Hip Abductor Muscle Strength and Frontal Plane Kinematics: A Cross-Sectional Study in Elite Handball Athletes

Article

Full-text available

Oct 2022

Frontal plane kinematics of the lower limb could be especially relevant in the risk of injuries in handball (HB) athletes. An association between lower limb frontal plane kinematics and hip abductor muscles strength has been investigated in different populations. However, the relationship between pelvis, hip, and knee frontal plane kinematics and the hip abductor strength in HB athletes has not been considered. Therefore, the objective of this study was to evaluate the relationship between hip abductor muscles strength and frontal plane kinematics (contralateral pelvic drop, femoral adduction, and knee valgus) in elite HB athletes using 2D analysis. Design: Cross-sectional and correlational study. Methods: Thirty-four male professional HB athletes were recruited. Athletes had to perform a deep single-leg squat. The frontal plane was recorded using the Camera app on iPhone (5SE). The clinical variables were hip abductor muscles strength assessed using a Lafayette hand-held dynamometer version 01165, and frontal plane kinematics measured with Kinovea 2D software version 0.9.4. Both variables were measured independently by two different examiners. Results: The correlation analysis showed a statistically significant negative correlation between the hip abductor muscles strength and the pelvic drop angle (p < 0.001; PCC: −0.873). A statistically significant positive correlation was found between the hip abductor muscles strength and the femoral adduction angle (p < 0.001; PCC: 0.767) and between the hip abductor muscles strength and the knee valgus angle (p < 0.001; PCC: 0.855). Conclusion: Hip abductor muscles strongly correlate with frontal plane kinematics in HB athletes.

Association between Selected Screening Tests and Knee Alignment in Single-Leg Tasks among Young Football Players

Article

Full-text available

May 2022
Int J Environ Res Publ Health

This study aimed to examine the relationship between knee valgus in the frontal plane projection angle (FPPA) during single-leg squat (SLS), single-leg landing (SLL), and other selected clinical tests in young athletes. Forty-three young healthy elite football players (age: 13.2 (1.7) years) that were regularly training in a local sports club participated in the study. The FPPA was assessed using 2D video analysis. The screening tests included the passive single-leg raise (PSLR), hip external and internal rotation (hip ER and IR), sit and reach test, weight-bearing lunge test (WBLT), modified star excursion balance test (mSEBT), countermovement jump (CMJ), single-leg hop for distance (SLHD), and age peak height velocity (APHV). There was a significant positive relationship between the knee valgus angles in the SLS test and the sit and reach test (r = 0.34) and a negative relationship with the hip ER ROM (r = −0.34) (p < 0.05). The knee valgus angles in the SLL were negatively associated with the hip IR (r = −0.32) and ER ROM (r = −0.34) and positive associated with the WBLT (r = 0.35) and sit and reach test (r = 0.33) (p < 0.05). Linear regression analysis showed that the results of the hip ER ROM and sit and reach tests were independent predictors of the FPPA in the SLS test (r2 = 0.11, p = 0.03 and r2 = 0.12, p = 0.02, respectively). The conducted study showed that individuals with more hip range of motion, more spine flexion extensibility, and less ankle dorsiflexion ROM may be more likely to experience high degrees of knee valgus in FPPA.

Assessment of Lower Limb Muscular Strength among Medical Students

Research

Full-text available

May 2019

INFLUENCE OF THE STABILITY OF THE HIP MUSCULATURE ON THE BIOMECHANICAL PATTERN OF RUNNING IN MIDDLE-DISTANCE AND LONG- DISTANCE ATHLETES

Thesis

Full-text available

Jun 2022

Fernando Matarranz González

El propósito de este trabajo ha sido realizar una serie de test físicos para valorar la estabilidad y fuerza en la cadera junto con un estudio biomecánico a 7 atletas de medio fondo y fondo (5 hombres y 2 mujeres) de nivel competitivo, para detectar posibles desequilibrios musculares y riesgo lesivo. Antes de comenzar el estudio se tomaron datos antropométricos de los participantes y se les pidió que rellenaran una encuesta con sus datos personales. Tras ello se realizaron los test físicos de (i.e., Fuerza Isométrica de core, Trendelenburg, Y-Balance y Abducción-Aducción isométrica máxima de cadera) y acto seguido un análisis biomecánico en 2 dimensiones donde se analizaron 3 variables (i.e., basculación de cadera, flexión de rodilla y ventana de rodilla). Los resultados de los test físicos informaron de algunas deficiencias de fuerza en la musculatura de la cadera. El principal desequilibrio muscular encontrado fue la basculación excesiva de la cadera en 6 de 7 participantes. En conclusión, se ha observado que todos los test utilizados son válidos para valorar la estabilidad de cadera pero algunos muestran resultados más acordes a las descompensaciones encontradas en el estudio biomecánico como es el de Abducción-Aducción isométrica máxima de cadera.

Effect of Core Stability Trainings on Functional Movement Screening Scores and Trunk Muscle Endurance in Female Kyokushin Karate Athletes

Article

Full-text available

Oct 2023

Background: The objective of this study was to examine the impact of six weeks of core instability training on functional movement screening (FMS) scores and core trunk endurance in female Kyokushin karate athletes. Methods: Thirty female Kyokushin Karate athletes aged 14 - 18 years were recruited and randomly assigned to either an experimental group or a control group (n = 15 per group). Functional movement patterns, including the FMS, Sorenson, and McGill tests, were assessed before and after the intervention. The experimental group underwent six weeks of Kyokushin Karate training, while the control group performed core stability exercises. The statistical analysis involved paired t-tests and analysis of covariance (ANCOVA), with a significance level set at P ≤ 0.05. Results: The paired t-test results indicated a significant difference in pre- and post-test scores in both the control and experimental groups (P < 0.05). However, the ANCOVA showed no significant differences between the groups (P > 0.05). Conclusions: Both Kyokushin training and core stability exercises have been found to increase core stability and FMS scores. Therefore, it can be suggested that Kyokushin Karate athletes may not need to perform separate core stability exercises as part of their training routine.

Assessment of Lower Limb Muscular Strength among Medical Students

Article

Full-text available

May 2019

the objective of the study was to assess the lower limb muscular strength among medical students of Karachi. It was a cross sectional study and sample size of 150 medical students were selected for the study. On-probability convenience sampling technique was used. Data was collected through Performa. SPSS version 21 was used for data analysis. The findings of the study revealed that 36.0% participants (n=54) had muscle strength below than average. 29.3% (n=44) had average strength. 21.3% (n=32) had poor strength. 9.3% (n=14) had above average strength. 2.7% (n=4) had good strength. 0.7% (n=1) had excellent strength and 0.7% (n=1) had very poor muscular strength of lower limb. The study concluded that the lower limb muscular weakness was found to be common among medical students of Karachi. The study further concluded that most of medical students have decreased lower limb muscular strength because they were not engaged in physical fitness program nor in a habit of doing muscular strengthen exercises.

There is not relationship of hip, ankle and foot angular measurements with frontal plane medial femur deviation in professional male soccer players

Article

Full-text available

Nov 2022

The aim of the study was to evaluate and correlate the angular measurements of the hip, knee and foot with medial displacement of the femur in the frontal plane in male professional soccer players. It was a cross-sectional observational study ncluding twenty-nine professional soccer players recruited from a soccer team who participated in the preseason evaluation, with mean age 22 years (± 4.36), Body Mass 73.74 (± 9.88) kg and Height 179.00 (± 0.09) cm. Angular measurements were collected on both lower limbs of Active Forefoot Alignment, Active Ankle Dorsiflexion Movement Range, Passive Medial Hip Rotation, Body Mass Index, and frontal alignment of the knee and hip through the Step Down Test. For the right lower limb, there was no significant correlation for the variables analyzed in relation to medial deviation of the femur. The same happens with the lower left limb in relation to the medial deviation of the femur. When the relationship of the variables between the two limbs was evaluated, a significant value was observed for medial displacement of the femur (r = 0.694); as well as for ankle dorsiflexion (r = 0.841) and medial hip rotation (r = 0.477). For forefoot alignment, there were no significant values between the sides (0.389). It is concluded that there is no relation between the angular measurements of active ankle dorsiflexion, active forefoot alignment, passive medial hip rotation and body mass index with femoral medial deviation in professional soccer players. Keywords: Stress test; Athletes; Knee joint; Athlete injuries.

The relationship between core muscle endurance and functional movement screen scores in females with lumbar hyperlordosis: a cross-sectional study

Article

Full-text available

Oct 2022

Background Core muscle endurance is essential for proper movement and lower extremity injury prevention. In addition, the Functional Movement Screen (FMS) score is a tool to assess body movement patterns to predict the risk of injury. Although various researches have investigated the relationship between the core muscle endurance and the FMS score, no study has ever assessed the effect of postural deformity on the FMS score. This study investigates the relationship between core muscle endurance and FMS scores in females with lumbar hyperlordosis. Methods 42 healthy females aged 24.03 ± 4.4 years with hyperlordosis ( > = 45/66 degrees) participated in this study. Core muscle endurance was assessed by the McGill stability test. Correlations were evaluated between the FMS score, McGill test, and lordosis angle using spearman correlation coefficients (p ≤ 0.05). Results Most individual FMS scores were not correlated with the McGill test except stability trunk push up. Also, lordosis angle was not correlated with the FMS composite score (r=-0.077; p = 0.631), while it was negatively correlated with the McGill test (r=-0.650; p = 0.000). Conclusion The lack of correlation between the FMS score and the McGill test implies that one’s level of core endurance may not influence their functional movement patterns. In contrast, the lumbar lordosis angle might impact one’s core muscle endurance but not their functional movement patterns.

Impact of Neuromuscular Fatigue on Dynamic Knee Valgus in Female Basketball Players

Article

Full-text available

May 2025

Dynamic knee valgus is a biomechanical condition often linked to an increased risk of knee injuries, particularly in female athletes, due to greater hip adduction, internal rotation, and knee abduction during dynamic movements. This study aimed to assess the impact of neuromuscular fatigue on dynamic knee valgus in female basketball players during single-leg drop jumps (DJ-SL) and change of direction (COD) tests at 45° and 90°. Thirty-three athletes, divided into national and regional performance groups, performed these movements before and after a fatigue protocol. Fatigue was induced through a series of anaerobic exercises, and frontal plane projection angle (FPPA) was used to measure knee valgus. The results showed that dynamic knee valgus increased with the angle of directional change (from 24.77° ± 8.25 at 45° to 34.55° ± 10.40 at 95° pre-fatigue, and from 26.59° ± 12.30 at 45° to 35.87° ± 10.37 post-fatigue), but was not significantly affected by neuromuscular fatigue. The national group demonstrated lower valgus angles compared to the regional group, indicating potential performance differences based on competitive level. These findings suggest that while neuromuscular fatigue does not notably impact knee valgus, the higher valgus angles during directional changes warrant attention in injury prevention programs for female basketball players. Further research is needed to explore other factors influencing knee mechanics and injury risk.

Implementation of a Decision Support System to Enhance Movement Proficiency Assessment in Sport

Article

Full-text available

Mar 2025

Background/Objectives: This study aimed to determine the relationships between seven descriptors of movement proficiency used by an expert to grade an athlete’s single-leg squat and the overall subjective ‘grade’ and the ability to predict a ‘grade’ based on the descriptors. A secondary aim was to determine the relationships between biomechanical data, the expert-defined descriptors, and the subjective ‘grade’ and its ability to predict the descriptors’ presence and the overall ‘grade’. Methods: Single-leg squats in 55 male athletes were graded using expert evaluation, synchronized video, biomechanical data, and decision tree and logistic regression analysis. Results: The model that most accurately predicted ‘grade’ (94.7%) was a decision tree with the descriptors as inputs. The model with biomechanical data for the descriptor ‘foot’ was the most accurate one (96.3%), followed by ‘lumbar’ and ‘depth’ (85.2%), ‘knee’ (81.2%), ‘pelvis/hip’ (71.7%), and ‘trunk’ (62.3%). These accuracies followed similar order to the intra-rater agreement: ‘foot’ (0.789), ‘lumbar’ (0.776), ‘knee’ (0.725), ‘depth’ (0.682), ‘pelvis/hip’ (0.662), and ‘trunk’ (0.637), indicating that ‘trunk’, ‘pelvis/hip’, and ‘depth’ are potentially the hardest descriptors to assess by the expert. Conclusions: The models developed in this study demonstrate that subjective perceptions can be somewhat accurately explained through a small number of biomechanical indicators. The results of this study support the notion that human movement evaluations should consider both subjective and objective assessments in a complementary manner to accurately evaluate an athlete’s movement proficiency.

Exercise Modalities for Improving Frontal Plane Knee and Foot Posture in Healthy Adults: A Systematic Review

Article

Full-text available

Feb 2025

Lower extremity misalignments increase the risk of chronic overload and acute injuries during sports and daily activities. Medial positioning of the knee and foot in the frontal plane is one of the key biomechanical risk factors associated with lower extremity injuries and pain. Different exercise interventions have been implemented to counteract misalignments. However, most studies have been conducted on clinical populations. Therefore, in this review, we aimed to assess the preventive effects of exercise interventions on frontal plane knee and foot posture in healthy individuals. Electronic databases (PubMed, Web of Science, PEDro) were systematically searched for original articles published between 2008 and 2024. This review included clinical trials on healthy adults (18–45 years) with or without lower extremity biomechanical misalignments, examining the effects of exercise interventions alone on knee and foot frontal plane biomechanics. Eligible studies reported at least one relevant frontal plane foot and knee biomechanical measure, such as knee valgus/abduction, medial knee displacement, foot pronation/eversion, or navicular drop. Studies involving non-exercise interventions, single-session protocols, and participants with neurological or spinal disorders, pain, or injury were excluded. A total of 35 articles with 1095 participants were included in this review. A total of 20 studies included individuals without a biomechanical misalignment, and 15 studies focused on individuals with a biomechanical misalignment. Mean values, standard deviations, and p-values were extracted from the included studies. Effect sizes and confidence intervals were then calculated to provide a quantitative presentation of the data. In conclusion, in healthy individuals without biomechanical misalignment, technique training and core muscles strengthening were most effective for improving knee valgus. Hip, core, and foot muscle strengthening reduced foot pronation in those with pronated feet, while short foot exercises improved foot positioning in individuals with flat feet. Combining lower extremity strengthening with knee position control training may reduce knee valgus in individuals with increased knee valgus.

Identifying the Primary Kinetic Factors Influencing the Anterior–Posterior Center of Mass Displacement in Barbell Squats: A Factor Regression Analysis

Article

Full-text available

Jan 2025
SENSORS-BASEL

Background: Barbell squats are commonly used in strength training, but the anterior–posterior displacement of the Center of Mass (COM) may impair joint stability and increase injury risk. This study investigates the key factors influencing COM displacement during different squat modes.; Methods: This study recruited 15 male strength training enthusiasts, who performed 60% of their one-repetition maximum (1RM) in the Front Barbell Squat (FBS), High Bar Back Squat (HBBS), and Low Bar Back Squat (LBBS). Joint moments at both the hip, knee, and ankle were collected using a motion capture system and force plates, and a factor regression analysis was conducted using SPSS.; Results: In the FBS, primary factors influencing COM displacement included right knee adduction–abduction (38.59%), knee flexion–extension (31.08%), and hip internal–external rotation (29.83%). In the HBBS, they were right ankle internal–external rotation (19.13%), hip flexion–extension (−19.07%), and left knee flexion–extension (19.05%). In the LBBS, the key factors were left knee adduction–abduction (27.82%), right ankle internal–external rotation (27.59%), and left ankle internal–external rotation (26.12%).; Conclusion: The study identifies key factors affecting COM displacement across squat modes, with knee flexion–extension being dominant in the FBS and hip moments more significant in the HBBS and LBBS. These findings have implications for optimizing squat training and injury prevention strategies.

Localized electrocortical activity as a function of single-leg squat phases and its relationship to knee frontal plane stability

Article

Full-text available

Sep 2024
EXP BRAIN RES

This study investigated differences in electroencephalography (EEG) activity within motor-related brain areas during three phases of a single-leg squat (SLS)—i.e., descending, holding, and ascending phases. Specifically, utilizing advanced magnetic resonance imaging guided EEG source localization techniques and markerless motion capture technology, we explored the interplay between concurrently recorded lower-extremity biomechanics and brain activity. Among the phases of a nondominant leg SLS, differences in contralateral brain activity (right hemisphere) were found in the activity of the precentral gyrus, the postcentral gyrus, and the sensory motor area. Alternatively, during the dominant SLS leg, differences among the three SLS phases in contralateral brain activity were fewer. Hemispheric dependent brain activity also significantly correlated with participants’ knee valgus angle range of motion (right hemisphere) and peak knee valgus angles (left hemisphere). In addition to the novel brain and biomechanical findings, this study sheds light on the technical feasibility of recording EEG during complex multi-joint movements and its potential applications in understanding sensorimotor behavior.

Article

Sep 2024

Understanding the changes in running mechanics caused by fatigue is essential to assess its impact on athletic performance. Changes in running biomechanics after constant speed conditions are well documented, but the adaptive responses after a maximal incremental test are unknown. We compared the spatiotemporal, joint kinematics, elastic mechanism, and external work parameters before and after a maximal incremental treadmill test. Eighteen recreational runners performed 2-minute runs at 8 km·h ⁻¹ before and after a maximal incremental test on a treadmill. Kinematics, elastic parameters, and external work were determined using the OpenCap and OpenSim software. We did not find differences in spatiotemporal parameters and elastic parameters (mechanical work, ankle, and knee motion range) between premaximal and postmaximal test conditions. After the maximal test, the runners flexed their hips more at contact time (19.4°–20.6°, P = .013) and presented a larger range of pelvis rotation at the frontal plane (10.3°–11.4°, P = .002). The fatigue applied in the test directly affects pelvic movements; however, it does not change the lower limb motion or the spatiotemporal and mechanical work parameters in recreational runners. A larger frontal plane motion of the pelvis deserves attention due to biomechanical risk factors associated with injuries.

Between-Session Reliability of Athletic Performance and Injury Mitigation Measures in Female Adolescent Athletes in the United States

Article

Full-text available

Jul 2024

Adolescence is a fundamental period for female athletes to develop athletic performance, mitigate injury risk, and gain collegiate sport scholarships, but there is also a high incidence of sport-related injuries. Physical profiling and athlete screening can support the individualisation of training programmes; however, there is a lack of data pertaining to the reliability of athletic performance and injury surrogate measures in adolescent female athletes. The aim of this study was to quantify the between-session reliability of an athletic performance and injury mitigation testing battery in female adolescent athletes. A total of 31 post-peak height velocity (PHV) (3.00 ± 0.82 years) female athletes (age: 16.20 ± 1.20 years; standing height: 166.00 ± 6.00 cm; mass: 65.5 ± 10.70 kg) from various sports (track and field = 1; lacrosse = 2; basketball = 2; soccer = 3; softball = 11; volleyball = 12) completed two sessions of a multicomponent testing battery 48 h to 1 week apart including the assessment of 33 measures addressing lower-limb isometric strength, eccentric strength, reactive strength, linear sprint and change of direction speed, and lower limb control. Of the 33 measures, between sessions, 29 had a high to nearly perfect intraclass correlation coefficient (ICC) (0.508–0.979), and 26 measures were not statistically significantly different between sessions (p ≤ 0.05). All measures demonstrated low to acceptable coefficient variation (CV%) (0.61–14.70%). The testing battery used can be utilised for recruitment and longitudinal monitoring within sports organisations for female adolescent athletes.

Correlation between frontal plane projection angle and pain, dynamic balance and function in patients with patellofemoral pain syndrome

Article

Jun 2024

Localized electrocortical activity as a function of single-leg squat phases and its relationship to knee frontal plane stability

Preprint

Jun 2024

Effects of High-intensity Training and Electrical Stimulation on Pain, Disability, Knee Kinematic and Performance in Patellofemoral Pain: A Randomized Controlled Trial Efectos del entrenamiento de alta intensidad y la estimulación eléctrica sobre el dolor, la discapacidad, la cinemática de la rodilla y el rendimiento en el dolor femororrotuliano: un ensayo controlado aleatorio

Article

Full-text available

May 2024

Patellofemoral pain (PFP) is a widespread problem in athletes who participate in jumping, cutting, and pivoting sports. Forty-four players participated in this study. They were divided into two groups: exercise plus Electro Myo Stimulation (EMS, G1) and exercise without EMS (G2), both with 12 women and 10 men. The exercise consisted of 8 weeks of a high-intensity strength program for 45-60 minutes, plus cooling and a warm-up phase. Visual analogue scale (VAS), disability (Kujala patellofemoral score), knee valgus angle (KVA) and single-leg hop (SLH) were tested before (pre-test) and after training (post-test at 8 weeks) using a within-between group analysis (ANOVA 2×2). At baseline, no differences between groups were found (p > 0.05). After the intervention, both groups improved VAS, KVA, SLH (p < 0.001), and disability (p = 0.042). G1 showed more improvements than G2 for VAS (-63.4 vs-51.5 %, p = 0.021, p2 = 0.13), disability (+ 32.6 vs + 18.4 %, p = 0.001, p2 = 0.52), KVA (+ 4.2 vs + 2.2 %, p = 0.016, p2 = 0.214) and SLH (+ 12.3 vs + 6.0 %, p = 0.003, p2 = 0.20) respectively. No differences were found between the sexes for each group. Despite both interventions being valid, high-intensity strength training combined with EMS improved pain, disability, knee kinematics, and lower extremity performance more than exercise alone in professional handball athletes with PFP. Resumen. El dolor patelofemoral (PFP) es un problema generalizado en los atletas que practican deportes de salto, corte y pivote. En este estudio participaron cuarenta y cuatro jugadores. Se dividieron en dos grupos: ejercicio más EMS (G1) y ejercicio sin EMS (G2), ambos con 12 mujeres y 10 hombres. El ejercicio realizado fue de 8 semanas de un programa de fuerza de alta intensidad durante 45-60 minutos, más una fase de enfriamiento y calentamiento. La escala analógica visual (EVA), la discapacidad (puntuación femororrotuliana de Kujala), el ángulo en valgo de la rodilla (KVA) y el salto con una sola pierna (SLH) se evaluaron antes (prueba previa) y después del entrenamiento (prueba posterior a las 8 semanas) utilizando un intervalo de-análisis entre grupos (ANOVA 2×2). Al inicio no se encontraron diferencias entre los grupos (p > 0,05). Después de la intervención, ambos grupos mejoraron EVA, KVA, SLH (p < 0,001) y discapacidad (p = 0,042). G1 mostró más mejoras que G2 en EVA (-63,4 vs-51,5 %, p = 0,021, p2 = 0,13), discapacidad (+ 32,6 vs + 18,4 %, p = 0,001, p2 = 0,52), KVA (+ 4,2 vs + 2,2 %, p = 0.016, p2 = 0.214) y SLH (+ 12.3 vs + 6.0 %, p = 0.003, p2 = 0.20) respectivamente. No se encontraron diferencias entre sexos para cada grupo. A pesar de que ambas intervenciones fueron válidas, el entrenamiento de fuerza de alta intensidad combinado con EMS mejoró el dolor, la discapacidad, la cinemática de la rodilla y el rendimiento de las extremidades inferiores más que el ejercicio solo en atletas profesionales de balonmano con PFP.

Effects of High-intensity Training and Electrical Stimulation on Pain, Disability, Knee Kinematic and Performance in Patellofemoral Pain: A Randomized Controlled Trial

Article

Full-text available

May 2024

Factors associated with the Single Leg Squat test in female soccer players: a cross-sectional study

Article

Full-text available

Apr 2024

Background The Single Leg Squat (SLS) test is widely used in the clinical setting to examine and evaluate rehabilitation goals. It is simple to perform and is proposed to have biomechanical and neuromuscular similarities to athletic movements. The aim of the present study was to investigate whether demographics, previous injuries, and biomechanical and psychosocial factors are associated with the outcome of the SLS, assessed as a total score for all segments and as a separate knee segment in elite and sub-elite female soccer players. Methods We conducted a cross-sectional study involving 254 female soccer players (22 yrs; SD ± 4, height 1.69 m; SD ± 0.1, weight 64 kg; SD ± 6) from divisions 1–3 of the Swedish Soccer League. During the preseason, we assessed the participants using the SLS and tested their hip strength and ankle mobility. Demographics, previous injury, sleep quality, fear of movement, anxiety, and perceived stress were assessed with questionnaires. Logistic regression models were built to analyse the association between the outcome of the SLS and the independent variables for the dominant and non-dominant leg. Results Significantly more participants failed the SLS on the dominant leg compared with the non-dominant leg (p < 0.001). The outcome of the SLS associated with various biopsychosocial factors depending on if the dominant or non-dominant leg was tested. The total score associated with hip strength for the dominant (OR 0.99, 95% CI 0.98–0.99, p = 0.04) and the non-dominant leg (OR 0.99, 95% CI 0.97–0.99, p = 0.03). The knee segment associated with division level for the dominant (div 2; OR 2.34, 95% CI 1.01–5.12, p = 0.033. div 3; OR 3.07, 95% CI 1.61–5.85, p = 0.001) and non-dominant leg (div 2; OR 3.30, 95% CI 1.33-8.00, p = 0.01. div 3; OR 3.05, 95% CI 1.44–6.43, p = 0.003). Conclusions This study identified that leg dominance, division level, hip strength, and psychosocial factors were associated with the outcome of the SLS when assessed as a total score and as a separate knee segment. This indicates that clinicians need to understand that movement control is associated with factors from several domains. Whether these factors and, the results of the SLS are related to injury need to be studied prospectively. Trial registration Clinical Trials Gov, date of registration 2022-03-01. Clinical trials identifier: NCT05289284A.

Three-dimensional kinematics of the trunk, pelvis, hip, and knee during the single-leg squat and hip torque in subjects with isolated patellofemoral osteoarthritis compared to individually matched controls: Preliminary results

Article

Full-text available

Mar 2024

Objectives: This study aimed to compare three-dimensional kinematic of the trunk, pelvis, hip, and knee during the single-leg squat and hip torque in individuals with and without isolated patellofemoral osteoarthritis (PFOA). Patients and methods: This cross-sectional study evaluated trunk, pelvis, hip, and knee kinematics at 30°, 45°, and 60° knee flexion during the single-leg squat using the Vicon motion capture and analysis system, the Nexus System 2.1.1, and 3D Motion Monitor software. Sixteen individuals (8 males, 8 females; mean age: 49.3±6.2 years; range 40 to 61 years) participated in the study, of which eight were PFOA patients and eight were healthy controls. Isometric hip abductor, extensor, and external rotator torques were evaluated using a handheld dynamometer. Results: The PFOA group exhibited greater hip adduction at 30° (p=0.008), 45° (p=0.005), and 60° (p=0.008) knee flexion in the descending phase of the single-leg squat, as well as at 60° (p=0.009) and 45° (p=0.03) knee flexion in the ascending phase. No significant differences were found between groups for other kinematic variables (p>0.05). The PFOA group exhibited lower isometric hip abductor (p=0.02), extensor (p< 0.001), and external rotator (p=0.007) torques. Conclusion: Individuals with PFOA exhibited excessive hip adduction that could increase stress on the lateral patellofemoral joint at 30°, 45°, and 60° knee flexion during the single-leg squat and exhibited weakness of the hip abductors, extensors, and external rotators in comparison to healthy controls.

Evaluation of Load Transmission to the Knee Joint in a Three- dimensional Femur Model Using a Finite Element Analysis Method

Article

Full-text available

Jun 2021

hip biomechanics

Sex‐specific bone and muscular morphological features in ischiofemoral impingement: A three‐dimensional study

Article

Full-text available

Mar 2023
CLIN ANAT

The study aimed to investigate how hip bone and muscular morphology features differ between ischiofemoral impingement (IFI) patients and healthy subjects among males and females. Three‐dimensional models were reconstructed based on magnetic resonance imaging images from IFI patients and healthy subjects of different sexes. Bone morphological parameters and the cross‐sectional area of the hip abductors were measured. The diameter and angle of the pelvis were compared between patients and healthy subjects. Bone parameters of the hip and cross‐sectional area of the hip abductors were compared between affected and healthy hips. The comparison results of some parameters were significant for females but not males. For females, the comparison results of pelvis parameters showed that the anteroposterior diameter of the pelvic inlet (p = 0.001) and intertuberous distance (p < 0.001) were both larger in IFI patients than in healthy subjects. Additionally, the comparison results of hip parameters showed that the neck shaft angle (p < 0.001) and the cross‐sectional area of the gluteus medius (p < 0.001) and gluteus minimus (p = 0.005) were smaller, while the cross‐sectional area of the tensor fasciae latae (p < 0.001) was significantly larger in affected hips. Morphological changes in IFI patients demonstrated sexual dimorphism, including bone and muscular morphology. Differences in the anteroposterior diameter of the pelvic inlet, intertuberous distance, neck shaft angle, gluteus medius, and gluteus minimus may explain why females are more susceptible to IFI.

The effects of core stabilization exercises on the neuromuscular function of athletes with ACL reconstruction

Article

Full-text available

Feb 2023

Athletes who have undergone anterior cruciate ligament reconstruction (ACLR) often exhibit persistently impaired kinematics and strength. Core stability training appears to be effective for reducing high-risk landing mechanics and preventing primary anterior cruciate ligament (ACL) injuries; however, there have been few attempts to examine their effects in athletes who have undergone ACLR. This study aimed to investigate the effect of eight weeks of simple core stability training on core endurance, hip strength, and knee kinematics in ACLR athletes. Twenty-six male athletes (20-30 years old) with a history of ACL surgery with hamstring tendon autograft were randomly divided into training (n = 13) and control groups (n = 13). The training group performed core stability exercises for eight weeks before starting their team training; the control group did not receive any intervention. Both groups continued their regular team schedule. The core endurance, hip muscle strength, and knee kinematics were assessed by the McGill test, a hand-held dynamometer, and video-taping, respectively. Analysis of covariance test was used for data analysis. The training group showed a significant increase in core endurance, hip abductor and external rotator strength, knee flexion angle, and a significant decrease in the knee valgus angle during single-leg landing in post-training tests compared to their baseline tests (P < 0.05). Our results demonstrated that core stability exercise alters neuromuscular function to a level that is clinically acceptable and statistically significant. Because of the high incidence rate of secondary ACL injury after ACLR, it is recommended that athletes with a history of ACLR benefit from adding core stability exercises to warm-up routines or tertiary prevention programs even after completing post-operative rehabilitation. It is fast and not time-consuming to perform for athletes to reduce the risk factors of re-injury.

The Association of Trunk and Hip Kinematic With Knee Abduction Angle During Single-Leg Landing

Article

Dec 2022

Objectives: Children aged 10 to 12 years often show dangerous maneuvers during landing, which include increased knee valgus, placing them at higher risk of anterior cruciate ligament (ACL) injuries. The study aimed to investigate the relation of the trunk and hip kinematics with the peak knee abduction angle during single-leg landing among preadolescent female soccer players. Methods: Thirty-six preadolescent female soccer players aged 10 to 12 years attended the study. Participants did a static trial and after that performed landing trials. A single-leg landing was applied to assess the landing kinematics. A three-dimensional motion capture system was applied to analyze trunk, hip, and knee kinematics. Results: Pearson correlation coefficient demonstrated a significantly positive relationship between peak hip internal rotation angle (r=0.361) (P=0.03) and peak knee abduction angle. Furthermore, no significant relationship was identified between peak hip adduction (r=-0.102) (P=0.55), peak trunk rotation (r=0.239) (P=0.16), peak trunk lateral flexion (r=0.052) (P=0.76), and peak valgus knee. Discussion: Peak hip rotation angle was correlated with the valgus knee with a weak correlation value among preadolescent female soccer players. Future studies should consider kinematic risk factors related to ACL injuries in combination with neuromuscular control trunk and hip during more demanding tasks.

Ankle dorsiflexion range of motion and trunk muscle endurance are not associated with hip and knee kinematics during the forward step-down test in CrossFit® practitioners

Article

Full-text available

Jan 2023
Sport Sci Health

PurposeCrossFit® (CF) is a high-intensity training method with a large number of practitioners, having an injury prevalence similar to other sports. Although excessive dynamic knee valgus is related to several injuries and associated with the trunk muscles’ endurance and dorsiflexion range of motion (DF-ROM), no study has evaluated these parameters in CF practitioners. The aim of the study was to investigate the association between lower limb alignment during the step-down test, DF-ROM and lateral trunk muscle endurance in CrossFit® (CF) practitioners.Methods Forty-two CF practitioners performed the following tests on both limbs: (i) DF-ROM with the weight-bearing lunge test; (ii) knee frontal plane projection angle (FPPA) and hip adduction (hip ADD) ankle during the forward step-down test; (iii) trunk lateral flexors’ endurance with the side plank test.ResultsNo significant associations were found between knee FPPA and DF-ROM in both limbs (preferred: r = 0.192; p = 0.230; non-preferred: r = 0.089; p = 0.581) or side plank time (preferred: r = 0.086; p = 0.594; non-preferred: r = 0.248; p = 0.117). Moreover, no significant associations were found between hip ADD and DF-ROM in both limbs (preferred: r = 0.005; p = 0.975; non-preferred: r = 0.175; p = 0.275) or side plank time (preferred: r = – 0.134; p = 0.403; non-preferred: r = 0. 171; p = 0.284).Conclusion Lateral trunk flexors’ endurance and ankle dorsiflexion range of motion are not associated with hip and knee kinematics during the forward step-down test in CrossFit®.

Does the 2D Frontal Plane Projection Angle Predict Frontal Plane Knee Moments during Stepping, Landing, and Change of Direction Tasks?

Article

Full-text available

Dec 2022
Int J Sports Phys Ther

Background Although dynamic knee valgus can be visually identified using the 2D frontal plane projection angle (FPPA), the validity of the FPPA in terms of predicting frontal plane knee kinematics has been questioned. The biomechanical utility of the FPPA may lie in its ability to predict frontal plane knee moments. Hypothesis/Purpose The purpose of the current study was to comprehensively evaluate the ability of the FPPA to predict the frontal plane knee kinetics (peak moment, average moment, and moment at peak knee flexion) across a wide range of tasks (stepping, landing, and change of direction). Design Crossover Study Design. Methods Three-dimensional lower-extremity kinetics and 2D video were obtained from 39 healthy athletes (15 males and 24 females) during execution of six tasks (step down, drop jump, lateral shuffle, deceleration, triple hop, side-step-cut). Linear regression analysis was performed to determine if the 2D FPPA at peak knee flexion predicted frontal plane knee moment variables during the deceleration phase of each task (peak moment, average moment, moment at peak knee flexion). Results The FPPA was found to significantly predict the peak frontal plane knee moment for two tasks (deceleration and side-step-cut, R ² = 12% to 25%), average frontal plane knee moment for five tasks (drop jump, shuffle, deceleration, triple hop, side-step-cut, R ² = 15% to 40%), and frontal plane knee moment at peak knee flexion for five tasks (drop jump, shuffle, deceleration, triple hop, side-step-cut, R2 = 16% to 45%). Conclusion An increased FPPA (medial knee collapse) predicted increased knee valgus moments (or decreased knee varus moments) during landing and change of direction tasks (but not stepping). However, the predictive ability of the FPPA was weak to moderate.

Importance of Lower Extremity Muscle Performance and Knee Proprioception During First 60 Degrees of Knee Flexion at Three Months After Anterior Cruciate Ligament Reconstruction

Article

Full-text available

Oct 2022

Background: Knee proprioception and neuromuscular control may be important factors contributing to re-injury occurrences. Objectives: To examine lower extremity muscular performance and knee proprioception preoperatively and 3 months after anterior cruciate ligament (ACL) reconstruction. Methods: Twelve participants underwent ACL reconstruction using the hamstring tendon. All participants were assessed for knee proprioceptive sense using an isokinetic dynamometer at 15° and 60° of knee flexion. Lower extremity muscular performance was examined using the single-leg squat test (SLS) with two-dimensional motion analysis in frontal and sagittal planes. Results: Mean absolute error angle at a 15-degree-target angle was significantly lower at three months after ACL reconstruction compared with the preoperative state (P = 0.04). Maximal knee flexion angle of the injured The SLS test showed a lesser knee flexion angle of the injured knee at three months after ACL reconstruction (P = 0.01), and injured knee proprioception at 60 degree-flexion did not significantly improve at the three month-postoperative stage. Conclusions: At three months after ACL reconstruction by hamstring graft tendon, knee proprioceptive sense at an inner range of knee extension improved. However, proprioception at the middle range did not significantly develop. The range of hip and knee motions using SLS related to strength changes that the knee extensor needs to improve, especially in the middle range.

The Immediate Effect of Medial Arch Support on Dynamic Knee Valgus During Stair Descent and Its Relationship With the Severity of Pronated Feet

Article

Full-text available

Aug 2022

Knee wobbling during the single-leg-squat-and-hold test reflects dynamic knee instability in patients with anterior cruciate ligament injury

Article

Full-text available

Aug 2022

We propose using the single-leg squat-and-hold (SLSH) task with kinematic analysis to objectively measure dynamic knee stability after anterior cruciate ligament (ACL) injury. There are three objectives of this study: to compare the knee kinematics of ACL-deficient patients and healthy controls by capturing knee wobbling during the SLSH task, to detect kinematic changes after ACL reconstruction, and to correlate the kinematic variables with self-reported knee function. Twenty-five ACL-deficient participants and 18 healthy matched participants were recruited. The knee kinematics involving both the magnitudes and frequency of motion fluctuation was captured during SLSH by 3D motion analysis system (Vicon). Compared to the limbs of the control participants, the ACL involved limbs exhibited a greater range of flexion-extension (4.33 ± 1.96 vs. 2.73 ± 1.15; p = 0.005) and varus-valgus (2.52 ± 0.99 vs. 1.36 ± 0.42; p < 0.001). It also inhibited higher frequency of flexion-extension (4.87 ± 2.55 vs. 2.68 ± 1.23; p = 0.003) and varus-valgus (3.83 ± 2.59 vs. 1.42 ± 0.55; p < 0.001). The range of flexion-extension (4.50 ± 2.24 vs. 2.90 ± 1.01; p = 0.018), frequency of flexion-extension (4.58 ± 2.53 vs. 3.05 ± 1.80; p = 0.038) and varus-valgus (3.46 ± 2.11 vs. 1.80 ± 1.23; p = 0.022) was reduced after ACL reconstruction. Increased frequency of knee varus-valgus was correlated with lower IKDC score (r = −0.328; p = 0.034). Knee wobbling was more prominent in ACL-deficient patients, which was associated with poor knee function. SLSH task with kinematic analysis appears to be a potential assessment method for monitoring dynamic knee stability after ACL injury.

The Lumbopelvic-Hip Complex Contribution During Lower Extremity Screening Tests in Elite Figure Skaters

Article

Jun 2022

Context Figure skating requires power and stability for takeoff and landing from multirotational jumps and various on-ice skills. Repetitive forces may cause overuse injuries distally, making lumbopelvic-hip endurance, strength, and neuromuscular control imperative. Objective To compare lumbopelvic-hip endurance and neuromuscular control in elite figure skaters between sexes and landing and nonlanding limbs using common screening tests. Design Cross-sectional study. Setting US Olympic and Paralympic Training Center. Patients or Other Participants Forty elite figure skaters (20 women, 20 men; age = 23.2 ± 4.3 years) performed the Y-balance test, single-legged squat (SLS), single-legged squat jump (SLSJ), and unilateral hip-bridge endurance test (40 right [R] landing limbs, length = 169.1 ± 12.2 cm). Main Outcome Measure(s) Normalized reach difference (% of leg length) and composite scores [(anterior + posteromedial + posterolateral)/(limb length × 3) × 100] were calculated for the Y-balance test. Skaters held the unilateral hip bridge until failure with a maximum allotted time of 120 seconds. They performed 5 SLSs and 5 SLSJs while barefoot with the contralateral limb held behind them to mimic a landing position. Both tests were scored by the number of times the patella moved medially to the first ray (medial knee displacement [MKD]). Multivariate analyses of variance with post hoc independent t tests were conducted between sexes and groups. Paired t tests were used to analyze limb differences. Results Women had a larger composite Y-balance score (R = 10.8% of leg length, P = .002; left = 10.5%, P = .001) and hip-bridge hold time (R = 26.4 seconds, P = .004; left = 28.2 seconds, P = .002) for both limbs compared with men. Men held the hip-bridge longer on their landing limb. Six skaters performed worse on their nonlanding limb during the SLS, and 11 skaters had no MKD with either the SLS or SLSJ. Conclusions Women performed better on the Y-balance and unilateral hip bridge tests. Increased MKD for some skaters during the SLS and SLSJ may have indicated hip-abductor weakness. Understanding the proximal lumbopelvic-hip variables during takeoff and landing may elucidate contributing factors to distal overuse injuries.

Trunk Stabilization and Its Rehabilitative Effects in Children with Cerebral Palsy

Article

Apr 2022

Frontal plane biomechanics during single-leg squat and hip strength in patients with isolated patellofemoral osteoarthritis compared to matched controls: A cross-sectional study

Article

Full-text available

Apr 2022
PLOS ONE

The patellofemoral compartment of the knee is the most frequently affected by osteoarthritis. However, there is a lack of biomechanics studies on patellofemoral osteoarthritis (PFOA). This study’s purpose was to compare the frontal plane biomechanics of the trunk and lower limb during the single-leg squat and isometric hip abductor torque in individuals with isolated PFOA and controls. Frontal plane kinematics during the single-leg squat were evaluated using a three-dimensional (3-D) motion analysis system. Isometric hip abductor torque was determined using a handheld dynamometer. Twenty individuals participated in the study (10 with PFOA and 10 controls). No significant differences between groups were found regarding age (mean ± SD, PFOA group = 51.8 ± 6.9 versus control group = 47.8 ± 5.5; mean difference = 4, 95% confidence interval [CI] = -1.9 to 9.9, p = 0.20) or body mass index (PFOA group = 27.6 ± 2.2 versus control group = 25.5 ± 2.5; mean difference = 2.1, 95% confidence interval [CI] = -0.1 to 4.3, p = 0.06). Compared to control, the PFOA group presented greater hip adduction in the descending and ascending phases of the single-leg squat at 45° (mean difference [95% CI] = 6.44° [0.39–12.48°], p = 0.04; mean difference [95% CI] = 5.33° [0.24–10.42°], p = 0.045, respectively) and 60° (mean difference [95% CI] = 8.44° [2.15–14.73°], p = 0.01; mean difference [95% CI] = 7.58° [2.1–13.06°], p = 0.009, respectively) of knee flexion. No significant differences between groups were found for the frontal plane kinematics of the trunk, pelvis or knee (p > 0.05). The PFOA group exhibited lower isometric hip abductor torque (mean difference [95% CI] = -0.34 Nm/kg [-0.67 to -0.01 Nm/kg], p = 0.04). The individuals with PFOA presented greater hip adduction than the control group, which could increase lateral patellofemoral joint stress at 45° and 60° of knee flexion in the descending and ascending phases of the single-leg squat. These individuals also exhibited hip abductor weakness in comparison to healthy controls.

Preliminary Analysis of Closed Kinetic Chain Upper Extremity Stability Test Differences Between Healthy and Previously Injured/In-Pain Baseball Pitchers

Article

Apr 2022

Background A comprehensive examination of the kinetic chain during an overhead athlete’s upper extremity assessment, such as the closed kinetic chain upper extremity stability test (CKCUEST), may help clinicians identify potential upper extremity dysfunction. Hypothesis Body position observed on dominant and nondominant hand touch during a CKCUEST trial differs between players with previous injury/pain history compared with healthy counterparts. Study Design Descriptive laboratory study. Level of Evidence Level 5. Methods Seventeen baseball pitchers were recruited to participate (18.03 ± 2.01 years; 185.40 ± 6.57 cm; 83.92 ± 13.87 kg). A medical history questionnaire was used to separate participants into groups, either previous injury/pain or healthy. Kinematic and kinetic data were collected on the participants performing the CKCUEST with an electromagnetic tracking system. Kinematics were analyzed using a pair of 1-way multivariate analyses of variance (MANOVAs). Results The MANOVA for nondominant hand touch in the CKCUEST revealed a significant difference in lumbopelvic-hip complex (LPHC) kinematics between previously injured/pain group and healthy group (Λ = 0.37; F 4,12 = 5.12; P = 0.01). Conclusions The previously injured/pain group displayed less pelvic axial rotation and dominant hip abduction during the nondominant touch indicating more LPHC stability during the nondominant touch. In conclusion, differences were observed in LPHC kinematics during the CKCUEST nondominant touch between a healthy and previously injured/pain group perhaps due to the increased awareness provided through rehabilitative programs for the previously injured/pain group. Clinical Relevance Clinicians can use this information to help address kinetic chain movement efficiency within baseball pitchers. This study provides evidence of LPHC kinematic differences during the nondominant touch of baseball pitchers and may enhance the use of the CKCUEST as a return-to-play assessment.

Association between sensorimotor function and visual assessment of postural orientation in patients with ACL injury

Article

Full-text available

Apr 2022
PHYS THER SPORT

Objectives To investigate the association between sensorimotor function and visual assessment of postural orientation during execution of weight-bearing activities in patients with anterior cruciate ligament reconstruction (ACLR). Design Cross-sectional study. Setting Laboratory. Participants Fifty-two individuals (23 women and 29 men, mean (SD) age 26.5 (6.4)) approximately 7 months after ACLR. Main outcome measures Sensorimotor function (proprioception, ankle dorsiflexion range of motion, and isometric muscle strength of the hip, knee, and trunk) were recorded on the injured leg. Postural orientation errors (POEs) were visually scored from video-recordings of the injured leg during execution of 5 functional tasks, and POE subscales activities of daily living (ADL) and Sport, and Total POE score were used in the analysis. Results Lower hip external rotation strength was associated with higher Total POE score (B = −24.4, p = 0.041) and higher POE subscale ADL score (B = −24.9, p = 0.03). No associations between sensorimotor function and POE subscale Sport were found. Conclusions Decreased hip external rotation strength might contribute to higher scores on the POE subscale ADL and the Total POE score, in men and women following ACLR. Future studies will reveal if strengthening of hip external rotation strength improves postural orientation.

OP5.6 Non-operative rehabilitation principles for use in individuals with acetabular dysplasia: a North American based Delphi study

Article

Mar 2025

Background: Acetabular dysplasia (AD) is defined as a structurally deficient acetabulum and is a well-recognized cause of hip pain in young adults. While treatment of severe AD with a periacetabular osteotomy has demonstrated good long-term outcomes, a trial of non-operative management is often recommended in this population. This may be especially true in patients with milder deformities. Currently, there is a paucity of research pertaining to non-operative management of individuals with AD. The purpose of this study is to present an expert-drive non-operative rehabilitation guidelines for use in individuals with AD. Methods: A panel of 15 physiotherapists from North America who were identified as experts in non-operative rehabilitation of individuals with AD by a high-volume hip preservation surgeon participated in this Delphi study. Panelists were presented with 16 questions regarding evaluation and treatment principles of individuals with AD. A three-step Delphi method was utilized to establish consensus on non-operative rehabilitation principles for individuals presenting with AD. Results: Total (100%) participation was achieved for all three survey rounds. Consensus, defined a piori as > 75%, was reached for 16/16 questions regarding evaluation principles, activity modifications, appropriate therapeutic exercise progression, return to activity/sport criteria, and indications for physician referral. Conclusion: This North American based Delphi study presents expert-based consensus on non-operative rehabilitation principles for use in individuals with AD. Establishing guidelines for non-operative management in this population will help reduce practice variation and is the first step in stratifying individuals who would benefit from non-operative management. Future research should focus on patient-reported outcomes and rate of subsequent surgical intervention to determine the success of the guidelines reported in this study.

Does time of the day affect the outcome of clinical tests to screen knee injury risk?

Article

Nov 2024
Sport Orthop Sport Traumatol

Effects of Exercise-Based ACL Injury Prevention Interventions on Knee Motion in Athletes: A Systematic Review and Bayesian Network Meta-Analysis

Article

Dec 2024
J ORTHOP SPORT PHYS

OBJECTIVE: To compare the effectiveness of injury prevention programs (IPPs) for improving high-risk knee motion patterns in the context of reducing the risk of noncontact anterior cruciate ligament (ACL) injury. DESIGN: Systematic review with Bayesian network meta-analysis (NMA). DATA SOURCES: PubMed, Embase, Web of Science, Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature were searched until September 10 th , 2023. ELIGIBILITY CRITERIA: We included randomized controlled trials (RCTs) involving athletes without prior ACL injury. The trials had to provide data on peak knee flexion and valgus angles, obtained from two-leg drop vertical jump, single-leg drop vertical jump, or side-step cutting test. RESULTS: The NMA synthesized data from 22 RCTs involving 878 participants, evaluating 12 different IPPs. Results of meta-analyses indicated that, in jumping tests, the external focus instructions (mean difference (MD)=26, Credible interval (CrI)=7.5 to 44, Surface Under the Cumulative Ranking curve (SUCRA)=0.94) and internal focus of attention (MD=19, CrI=0.19 to 37, SUCRA=0.81) was effective for increasing peak knee flexion, and core stability training ranked first for reducing knee valgus (MD=−4.40, CrI=−7.7 to -1.1, SUCRA=0.96). None of the IPPs revealed statistically significant effects for the cutting test. CONCLUSION: The external focus instructions and internal focus of attention increased knee flexion, while core stability exercise reduced knee valgus in jumping tests. Intervention effects were inconsistent for cutting tests.

The Effect of Acute Focus of Attention Instructions on Biomechanical Indexes Associated With Anterior Cruciate Ligament Injury Prevention

Article

May 2024

Background and Aims Anterior cruciate ligament (ACL) injury is one of the most common and serious injuries of the knee joint, which accounts for 80% of all knee ligament surgeries. Studies have shown that a significant percentage of this injury (70%) occurs in a non-contact form, usually during activities like deceleration, landing, or side cutting. Studies have shown that focus instructions could improve and promote performance. This study aimed to investigate the acute effect of focus instructions on biomechanical indexes associated with ACL injury prevention. Methods In this research, 24 young football players from the two clubs of the Tehran Premier League, Tehran City, Iran, were randomly divided into two groups: external focus attention (n=12) and internal focus attention (n=12). First, the dynamic postural stability index (DPSI), the peak of vertical, anteroposterior, and mediolateral GRF components, and the rate of loading during the jump-landing movement from a box with 30 cm height were calculated using a force plate with a sampling frequency of 1000 Hz. Then, the internal and external focus instructions were taught to the participants, and the two groups performed a posttest to examine the changes. Statistical methods of repeated measures analysis of variance and paired t test were used to evaluate the changes. Results The results showed significant changes in the vertical component and rate of loading variables in both groups of internal and external focus attention (P≤0.05). However, no significant difference was observed between the two groups in the DPSI, anteroposterior and mediolateral GRF. Conclusion The results of this study showed that acute instructions of both internal and external focus attention can improve landing mechanics and landing-related kinetic variables. It seems that the external focus instructions have increased the motor control of the limb, leading to a further reduction of vertical GRF and the load applied to the lower limb compared to the instructions of internal focus, thus reducing the risk of ACL injury.

Current Exercise Approaches for Common Knee Pathologies

Chapter

Aug 2024

In this book titled Current Exercise Approaches in Orthopedic Disorders: A handbook for rehabilitation professionals, it is aimed to compile the exercise approaches currently used in orthopedic pathologies. A physiotherapist or a health professional interested in rehabilitation processes who reads this book will have access to a world of up-to-date exercise approaches that include all anatomical joint areas of the body. The current exercise approaches explained throughout the book have been tried to be presented in a high-quality manner, supported by visuals. In addition, those who read the book will be able to access important clues about the anatomy and kinesiology of many body joints and important issues regarding possible orthopedic pathologies of the relevant joints. We hope that our book will contribute to the _eld of orthopedic rehabilitation.

Comparison of Foot Pressure Distribution During Single-leg Squat in Individuals With and Without Pronated Foot

Article

Apr 2024

Análisis cinemático en corredores de la quinta región con dolor anterior de rodilla

Thesis

Full-text available

Jul 2014

Background: Running is the second most practiced sport in Chile. This exposes runners to several muscle, tendons and joints injuries, among others; being the knee the most frequent location of injuries in the lower extremity. In the anterior knee pain (DAR), the etiological features are controversial because of its multifactorial nature and the interventions from the therapist. Objective: the objective of this seminar is to compare variables like COP, EMG activity, walking parameters, among others. That can be included in DAR in 18-25 year old runners in the fifth region, Chile. Type of investigation: mixed and non-experimental longitudinal design. Scope: Descriptive. Materials and methods: 18 to 25 year- old subjects. Information gathering: through registration form. Information analysis: the variables were analysed according to their own characteristics through Fisher test and T- student test. Moreover, Pearson interrelation test and Wilcoxon test were used for the statistic analysis. Results: a direct correlation was found in the studied variables from 0,6747 between EMG VMO and pain. Also, a good inverse correlation with significance of -0,7609 between EMG RF amplitude and A-P movement of CoP in DAR groups were found. In the group without DAR a good direct correlation of 0,65809 of amplitude EMG VMO and the movement of CoP in the footprint were found, and a good direct correlation of 0,64229 between EMG VMO time and Q angle. Conclusion: the cinematic values obtained correlate with the bibliographic evidence, highlighting in the DAR group, the electromyographic activity of Rectus Femoris (RF) in the front-to-back (A-P) of the pressure centre (CoP). However, there is a need of a mayor analysis to determine a good correlation and significance in different studied variables.

Y-Balance Test Asymmetry and Frontal Plane Knee Projection Angle During Single-leg squat as Predictors of Patellofemoral Pain in Male Military Recruits

Article

May 2020
PHYS THER SPORT

Objectives Investigate prospectively whether dynamic balance and frontal plane knee projection angle (FPKPA) are risk factors for the development of patellofemoral pain (PFP) in male military recruits. Study design Prospective cohort. Setting Military training center. Participants 135 male military recruits were followed prospectively for six weeks and the incidence of PFP was documented. Main outcomes Baseline measures of the Y-Balance test (YBT) and two-dimensional FPKPA during single-leg squatting were recorded. Mann–Whitney U tests and logistic regression analysis were utilized to identify possible variables associated with the development of PFP. Results A total of 14 male recruits developed PFP during the follow up period. The PFP group had significantly greater asymmetry on the YBT posterolateral direction (mean difference = 3.44 ± 0.57 cm; 95% Confidence Interval [CI] = 2.38–4.51 cm) and greater FPKPA during single-leg squat (mean difference = 5.55°±1.78°; [CI] = 1.81–9.28°) at baseline when compared to controls. Binary logistic regression models revealed that YBT posterolateral asymmetry ≥4.08 cm (Nagelkerke R² = 0.304; X² = 21.63; p < 0.001; OR = 5.46; [CI] = 4.47–8.06) and FPKPA ≥ 4.81° (Nagelkerke R² = 0.249; X² = 17.46; p < 0.001; OR = 4.65; [CI] = 3.32–9.06) were significantly associated with PFP. Conclusions Male military recruits with greater asymmetry on the YBT posterolateral direction and FPKPA were at a greater risk of developing PFP.

Non-Operative Rehabilitation Principles for Use in Individuals with Acetabular Dysplasia: A North American Based Delphi Study

Article

Full-text available

Dec 2023
Int J Sports Phys Ther

Background Acetabular dysplasia (AD) is defined as a structurally deficient acetabulum and is a well-recognized cause of hip pain in young adults. While treatment of severe AD with a periacetabular osteotomy has demonstrated good long-term outcomes, a trial of non-operative management is often recommended in this population. This may be especially true in patients with milder deformities. Currently, there is a paucity of research pertaining to non-operative management of individuals with AD. Purpose To present expert-driven non-operative rehabilitation guidelines for use in individuals with AD. Study Design Delphi study Methods A panel of 15 physiotherapists from North America who were identified as experts in non-operative rehabilitation of individuals with AD by a high-volume hip preservation surgeon participated in this Delphi study. Panelists were presented with 16 questions regarding evaluation and treatment principles of individuals with AD. A three-step Delphi method was utilized to establish consensus on non-operative rehabilitation principles for individuals presenting with AD. Results Total (100%) participation was achieved for all three survey rounds. Consensus, defined a piori as > 75%, was reached for 16/16 questions regarding evaluation principles, activity modifications, appropriate therapeutic exercise progression, return to activity/sport criteria, and indications for physician referral. Conclusion This North American based Delphi study presents expert-based consensus on non-operative rehabilitation principles for use in individuals with AD. Establishing guidelines for non-operative management in this population will help reduce practice variation and is the first step in stratifying individuals who would benefit from non-operative management. Future research should focus on patient-reported outcomes and rate of subsequent surgical intervention to determine the success of the guidelines reported in this study. Level of Evidence Level V

숙련자의 스쿼트 중량 증가에 따라 나타나는 무릎 안쪽 움직임에 대한 운동역학적 연구

Article

Jul 2023

Variation of Muscle Activity and Balance of the Lower Extremity by Deformed in Shoe Out-soles during One-leg Stance

Article

Jun 2023

Postoperative Rehabilitation for Arthroscopic Management of Femoroacetabular Impingement Syndrome: a Contemporary Review

Article

Full-text available

Jun 2023

Purpose of Review Femoroacetabular impingement syndrome (FAIS) is a common cause of hip pain that may potentially lead to osteoarthritis. Operative management of FAIS seeks to arthroscopically reshape the abnormal hip morphology and repair the labrum. For rehabilitation following operative management, a structured physical therapy program is unanimously recommended for the patient to return to their previous level of physical activity. Yet, despite this unanimous recommendation, significant heterogeneity exists among the current recommendations for postoperative physical therapy programs. Recent Findings A four-phase postoperative physical therapy protocol is favored among current literature, with each phase being comprised of its own goals, restrictions, precautions, and rehabilitation techniques. Phase 1 aims to protect the integrity of the surgically repaired tissues, reduce pain and inflammation, and regain ~ 80% of full ROM. Phase 2 guides a smooth transition to full weightbearing, so the patient may regain functional independence. Phase 3 helps the patient become recreationally asymptomatic and restores muscular strength and endurance. Finally, phase 4 culminates in the pain-free return to competitive sports or recreational activity. Summary At this time, there exists no single, unanimously agreed upon postoperative physical therapy protocol. Among the current recommendations, variation exists regarding specific timelines, restrictions, precautions, exercises, and techniques throughout the four phases. It is imperative to reduce ambiguity in current recommendations and more specifically define postoperative physical therapy following operative management of FAIS to more expeditiously return patients to functional independence and physical activity.

Sex-Specific Associations between Hip Muscle Strength and Foot Progression Angle

Article

Nov 2022
J ELECTROMYOGR KINES

The foot progression angle (FPA) influences knee loading during gait, but its determinants are unclear. The purpose of this study was to compare FPA between men and women and also examine the association between lower extremity kinematics during gait, hip strength, and the FPA. 25 males and 25 females completed 5 gait trials while FPA and frontal and transverse plane hip and knee angles were calculated from the dominant limb during the foot flat portion of stance. Hip extensor/flexor, abductor/adductor, and internal/external rotator strength were evaluated using maximum voluntary isometric contractions. One-way MANOVAs compared gait and strength outcomes. Stepwise regression assessed the association between FPA, and MVIC and kinematics after accounting for speed in males and females. There was no difference in FPA between sexes (p>.05), but females had greater frontal and transverse plane hip angles compared with males (all p<0.05). Greater hip abduction (p=.02) strength was associated with greater FPA, but only in males. In males, greater hip muscle strength may contribute to a more neutral position of the foot during gait, which could help maintain an equal knee loading distribution. Our results suggest that there are sex specific control strategies to achieve a similar FPA during gait.

Rehabilitation Guidelines for Use Following a Periacetabular Osteotomy (PAO): A North American Based Delphi Consensus

Article

Full-text available

Oct 2022
Int J Sports Phys Ther

Background Treatment of acetabular dysplasia with a periacetabular osteotomy (PAO) has been shown to improve long term outcomes and is considered the gold standard in the setting of symptomatic hip dysplasia in patients younger than 35 years of age. Post-operative rehabilitation following a PAO plays an important role in helping patients return to their prior level of function and reduce the impact of strength deficits that may persist. Currently, there is a paucity of research supporting post-operative rehabilitation guidelines. The purpose of this study is to present expert-driven rehabilitation guidelines to reduce practice variation following a PAO. Methods A panel of 16 physiotherapists from across the United States and Canada who were identified as experts in PAO rehabilitation by high-volume hip preservation surgeons participated in this Delphi study. Panelists were presented with 11 questions pertaining to rehabilitation guidelines following a PAO. Three iterative survey rounds were presented to the panelists based on responses to these questions. This three-step Delphi method was utilized to establish consensus on post-operative rehabilitation guidelines following a PAO. Results Total (100%) participation was achieved for all three survey rounds. Consensus ( > 75%) was reached for 11/11 questions pertaining to the following areas: 1) weight-bearing and range of motion (ROM) precautions, 2) therapeutic exercise prescription including neuromuscular control, cardiovascular exercise, and flexibility, and 3) objective measures for return to straight line running and return to full participation in sports. Conclusion This Delphi study established expert-driven rehabilitation guidelines for use following a PAO. The standardization of rehabilitative care following PAO is essential for achieving optimal outcomes despite other factors such as geographical location and socioeconomic status. Further research on patient-reported outcomes is necessary to confirm successful rehabilitation following the guidelines outlined in this study.

A behaviorally validated self-report inventory to assess 4 types of lateral preferences

Article

Full-text available

Aug 1979
J CLIN EXP NEUROPSYC

A self-report battery for the assessment of hand, eye, foot and ear preference, which has been validated against behavioral tasks designed to measure the same four types of laterality, is presented. Data showing the concordance between the inventory and the behavioral tests for a sample of 171 individuals is given. The mean degree of concordance between the behavioral and the questionnaire items was 90%. Additional analyses revealed that both forms of measurement provide similar descriptions of both individual and population lateral preference patterns. This report offers the questionnaire battery as a convenient and useful tool for the measurement of the four most common indices of laterality.

Strength Profiles and Performance in Masters' Level Swimmers

Article

Full-text available

Sep 1995
AM J SPORT MED

The purpose of this study was to profile shoulder, trunk, and thigh strength and shoulder range of motion in competitive Masters' level swimmers and to see if these variables were related to swimming performance. Twenty-four Masters' level swimmers (13 men and 11 women) were tested for isometric trunk flexion and extension, isokinetic knee extension and flexion, shoulder abduction, internal rotation, external rotation, and supraspinatus muscle strength; shoulder internal and external rotation range of motion; and 50-yard swimming time. Strength scores were adjusted for weight. The men were significantly stronger than the women in trunk extension and flexion. Shoulder range of motion, shoulder abduction strength, and thigh strength were equal for both the men and the women. The men were stronger than the women in internal and external shoulder rotation. Conversely, the women tested were significantly stronger than the men in the supraspinatus muscle test. The men were significantly faster than the women in the 50-yard swim. Inverse relationships existed between swimming time and trunk flexion, trunk extension, and shoulder internal rotation strength. Trunk flexion strength remained the only significant predictive variable of swimming time in a multiple regression analysis.

Preseason Hamstring Muscle Weakness Associated with Hamstring Muscle Injury in Australian Footballers

Article

Full-text available

Jan 1997
AM J SPORT MED

Hamstring muscle strain is the most prevalent injury in Australian Rules Football, accounting for 16% of playing time missed as a result of injury. Thirty-seven professional footballers from an Australian Football League team had preseason measurements of hamstring and quadriceps muscle concentric peak torque at 60, 180, and 300 deg/sec measured on a Cybex 340 dynamometer. Players were studied prospectively throughout the 1995 season. During that time, six players sustained clinically diagnosed hamstring muscle injuries that caused them to miss match-playing time. The injured hamstring muscles were all weaker than in the opposite leg in absolute values and hamstring-to-quadriceps muscle ratios. According to our t-test results, hamstring muscle injury was significantly associated with a low hamstring-to-quadriceps muscle peak torque ratio at 60 deg/sec on the injured side and a low hamstring muscle side-to-side peak torque ratio at 60 deg/sec. Flexibility (as measured by the sit-and-reach test) did not correlate with injury. Discriminant-function analysis using the two significant ratio variables resulted in a canonical correlation with injury of 0.4594 and correctly classified legs into injury groups with 77.4% success. These results indicate that preseason isokinetic testing of professional Australian Rules footballers can identify players at risk of developing hamstring muscle strains.

Prediction of 10 Repetition Maximum for Short-Arc Quadriceps Exercise From Hand-Held Dynamometer and Anthropometric Measurements

Article

Full-text available

Sep 1998

Short-arc quadriceps exercise are commonly prescribed in physical therapy for strengthening knee extensor musculature. Determining the appropriate starting resistance has traditionally been a trial-and-error procedure. Therefore, developing an expedient method of estimating the correct starting resistance may lead to a more accurate exercise prescription. The primary purpose of this study was to establish a technique for predicting an individual's 10 repetition maximum (10 RM) based on hand-held dynamometer (HHD) strength recording and additional anthropometric predictor variables. Fifty healthy subjects (31 males and 19 females), aged 22-53 years, participated in the study. A prediction equation for determining 10 RM using HHD strength recording, weight, gender, and age was developed. By implementing this equation, clinicians can predict a normal, healthy, young to middle-aged adult's 10 RM within +/- 4.17 kg with a 95% confidence level (SEE = 2.13 kg).

The Effect of Neuromuscular Training on the Incidence of Knee Injury in Female Athletes A Prospective Study

Article

Full-text available

Nov 1999
AM J SPORT MED

To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.

Influence of Joint Position on Electromyographic and Torque Generation During Maximal Voluntary Isometric Contractions of the Hamstrings and Gluteus Maximus Muscles

Article

Full-text available

Jan 2002

Repeated measures analysis of joint angle effects on hip and knee muscle electromyographic (EMG) activity. To simultaneously determine angle-dependent changes in maximal voluntary isometric contraction (MVIC) torque and EMG activity during hip extension and knee flexion. Procedures for normalizing EMG data and for determining torque-angle relationships for various joint motions both entail asking subjects to exert an MVIC. The implicit assumption in these paradigms is that magnitude of the EMG response is at a constant, maximum level so that observed angle-dependent variations in torque are due to mechanical factors, such as muscle length and muscle moment arm. Fifty subjects (25 men and 25 women) participated in this study (age, 23.5 +/- 4.6 y; range, 18-38 y). Subjects performed maximal isometric knee flexion at 4 knee angles and maximal isometric hip extension at 4 hip angles. The dependent variables were normalized root-mean-square EMG and torque. The process for normalizing EMG and torque data consisted of determining the largest mean value for each subject across testing positions for the muscle of interest. That value was designated as corresponding to 100% MVIC, and all other data for that muscle were expressed as a percentage of the MVIC value. Repeated measures was used to determine angle-dependent changes in normalized MVIC-torque and MVIC-EMG values for each muscle group. Mean torque-angle relationships were generally consistent with previous reports, though considerable intersubject variability was observed. There were significant angle-dependent differences in maximal EMG for both the hamstring and gluteus maximus muscles. Mean percentages of hamstring MVIC-EMG at knee angles of 30 degrees (81 +/- 19) and 60 degrees (82 +/- 22) were greater than at 0 degrees (68 +/- 20) or 90 degrees (74 +/- 20). The mean percentage of gluteus maximus MVIC-EMG at a hip angle of 0 degrees (94 +/- 10) was greater than at 30 degrees (84 +/- 13), 60 degrees (80 +/- 14), or 90 degrees (64 +/- 20), and gluteus maximus maximal voluntary isometric EMG at 90 degrees was less than at all other angles. These differences could not be explained solely by muscle length-dependent effects on EMG amplitude, suggesting that despite instructions for maximal effort, motor unit activation was not maintained at a constant, maximal level throughout the range of motion. The form of the EMG/angle relationships differed markedly from the torque-angle relationships. These findings have implications for the use of MVIC-EMG for reference values in EMG normalization procedures and for the interpretation of mechanisms underlying the torque-angle relationships observed in vivo.

Differences in Kinematics and Electromyographic Activity between Men and Women during the Single-Legged Squat

Article

Full-text available

May 2003
AM J SPORT MED

Numerous factors have been identified as potentially increasing the risk of anterior cruciate ligament injury in the female athlete. However, differences between the sexes in lower extremity coordination, particularly hip control, are only minimally understood. There is no difference in kinematic or electromyographic data during the single-legged squat between men and women. Descriptive comparison study. We kinematically and electromyographically analyzed the single-legged squat in 18 intercollegiate athletes (9 male, 9 female). Subjects performed five single-legged squats on their dominant leg, lowering themselves as far as possible and then returning to a standing position without losing balance. Women demonstrated significantly more ankle dorsiflexion, ankle pronation, hip adduction, hip flexion, hip external rotation, and less trunk lateral flexion than men. These factors were associated with a decreased ability of the women to maintain a varus knee position during the squat as compared with the men. Analysis of all eight tested muscles demonstrated that women had greater muscle activation compared with men. When each muscle was analyzed separately, the rectus femoris muscle activation was found to be statistically greater in women in both the area under the linear envelope and maximal activation data. Under a physiologic load in a position commonly assumed in sports, women tend to position their entire lower extremity and activate muscles in a manner that could increase strain on the anterior cruciate ligament.

Modeling of ACL impingement against the intercondylar notch

Article

Full-text available

Jan 2004
CLIN BIOMECH

To develop a 3-D mathematical model that accurately evaluates anterior cruciate ligament impingement against the intercondylar notch. The model simulated physical interactions between the anterior cruciate ligament and the intercondylar notch in tibiofemoral movement. Anterior cruciate ligament impingement has been evaluated through planar radiographic images, which may not characterize the complex 3-D notch shape associated with impingement. After examining potential anterior cruciate ligament impingement in five cadaver knee specimens, the model was implemented using data from an individual cadaveric knee with representative impingement. The knee was loaded passively in various patterns to induce impingement, and the impingement force and six degrees-of-freedom tibiofemoral kinematics were measured. The femur, tibia, and anterior cruciate ligament were digitized. Spatial data points representing the notch surfaces were surface-fitted using bicubic splines. The model detected for impingement during the tibiofemoral movement and used a "crawling algorithm" to determine the deformed geometry of the impinging ligament. The model detected the impingement accurately and the ligament strain determined by the model was highly correlated with the recorded impingement force when impingement occurred during the tibiofemoral movement. Distance between the anterior cruciate ligament and the notch wall was determined when impingement was not detected. The model quantitatively characterized impingement of the anterior cruciate ligament against the intercondylar notch in 3-D space. The approach helps us better understand anterior cruciate ligament injury mechanisms in individual knees. Clinically, the model could potentially be used to analyze subject-specific potential/actual anterior cruciate ligament impingement based on the subject's MRI scans.

Core Stability Measures as Risk Factors for Lower Extremity Injury in Athletes

Article

Full-text available

Jul 2004

Decreased lumbo-pelvic (or core) stability has been suggested to contribute to the etiology of lower extremity injuries, particularly in females. This prospective study compares core stability measures between genders and between athletes who reported an injury during their season versus those who did not. Finally, we looked for one or a combination of these strength measures that could be used to identify athletes at risk for lower extremity injury. Before their season, 80 female (mean age = 19.1 +/- 1.37 yr, mean weight 65.1 +/- 10.0 kg) and 60 male (mean age = 19.0 +/- 0.90 yr, mean weight 78.8 +/- 13.3 kg) intercollegiate basketball and track athletes were studied. Hip abduction and external rotation strength, abdominal muscle function, and back extensor and quadratus lumborum endurance was tested for each athlete. Males produced greater hip abduction (males = 32.6 +/- 7.3%BW, females = 29.2 +/- 6.1%BW), hip external rotation (males = 21.6 +/- 4.3%BW, females = 18.4 +/- 4.1%BW), and quadratus lumborum measures (males = 84.3 +/- 32.5 s, females = 58.9 +/- 26.0 s). Athletes who did not sustain an injury were significantly stronger in hip abduction (males = 31.6 +/- 7.1%BW, females = 28.6 +/- 5.5%BW) and external rotation (males = 20.6 +/- 4.2%BW, females = 17.9 +/- 4.4%BW). Logistic regression analysis revealed that hip external rotation strength was the only useful predictor of injury status (OR = 0.86, 95% CI = 0.77, 0.097). Core stability has an important role in injury prevention. Future study may reveal that differences in postural stability partially explain the gender bias among female athletes.

Groin injuries in professional rugby league players: A prospective study

Article

Full-text available

Aug 2004

Donna O'Connor

Altogether, 100 uninjured professional rugby league players were evaluated over a 2-year period. Their height, body mass, sum of skinfolds, girths and bone diameters were recorded. A Cybex 340 isokinetic dynamometer was used to determine peak torque, work, power, endurance ratios and peak torque ratios of the hip abductors and adductors (5 repetitions at 0.52 and 2.08 rad. s(- 1); 20 repetitions at 3.66 rad. s(- 1)) and knee flexors and extensors (4 repetitions at 1.04 and 3.14 rad. s(- 1); 30 repetitions at 5.22 rad. s(- 1)). Hip abduction and adduction were also assessed with the hip in external rotation. Discriminant function analysis was conducted on all predictor variables to develop a multivariate predictive model capable of classifying players with a high degree of accuracy into groups with and without a groin injury. The model consisted of eight variables and correctly classified 91.7% of the non-injured players and 90.5% of the injured players. The correct classification for the model as a whole was 91.4%. The aetiological factors identified as being related to injury of the groin musculotendinous unit included abduction and adduction-with-rotation peak torque, angle of adduction and abduction-with-rotation peak torque, strength ratio of hip muscle groups, bilateral difference in extension peak torque, femur diameter and body mass.

Biomechanical Measures of Neuromuscular Control and Valgus Loading of the Knee Predict Anterior Cruciate Ligament Injury Risk in Female Athletes A Prospective Study

Article

Full-text available

May 2005
AM J SPORT MED

Female athletes participating in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than do male athletes. Prescreened female athletes with subsequent anterior cruciate ligament injury will demonstrate decreased neuromuscular control and increased valgus joint loading, predicting anterior cruciate ligament injury risk. Cohort study; Level of evidence, 2. There were 205 female athletes in the high-risk sports of soccer, basketball, and volleyball prospectively measured for neuromuscular control using 3-dimensional kinematics (joint angles) and joint loads using kinetics (joint moments) during a jump-landing task. Analysis of variance as well as linear and logistic regression were used to isolate predictors of risk in athletes who subsequently ruptured the anterior cruciate ligament. Nine athletes had a confirmed anterior cruciate ligament rupture; these 9 had significantly different knee posture and loading compared to the 196 who did not have anterior cruciate ligament rupture. Knee abduction angle (P<.05) at landing was 8 degrees greater in anterior cruciate ligament-injured than in uninjured athletes. Anterior cruciate ligament-injured athletes had a 2.5 times greater knee abduction moment (P<.001) and 20% higher ground reaction force (P<.05), whereas stance time was 16% shorter; hence, increased motion, force, and moments occurred more quickly. Knee abduction moment predicted anterior cruciate ligament injury status with 73% specificity and 78% sensitivity; dynamic valgus measures showed a predictive r2 of 0.88. Knee motion and knee loading during a landing task are predictors of anterior cruciate ligament injury risk in female athletes. Female athletes with increased dynamic valgus and high abduction loads are at increased risk of anterior cruciate ligament injury. The methods developed may be used to monitor neuromuscular control of the knee joint and may help develop simpler measures of neuromuscular control that can be used to direct female athletes to more effective, targeted interventions.

Evaluation of a two dimensional analysis method as a screening and evaluation tool for anterior cruciate ligament injury

Article

Full-text available

Jul 2005
BRIT J SPORT MED

Increased knee valgus predicts the risk of anterior cruciate ligament (ACL) injury, particularly in women. Reducing injury rates thus relies on detecting and continually evaluating people with relatively large valgus motions. To examine the potential of a two dimensional (2D) video analysis method for screening for excessive valgus. Ten female and 10 male National Collegiate Athletic Association basketball players had three dimensional (3D) knee valgus and two dimensional (2D) frontal plane knee angle quantified during side step, side jump, and shuttle run tasks. 3D valgus was quantified from external marker coordinates using standard techniques, and 2D data were obtained from both the frontal plane projections of these coordinates (2D-Mot) and manual digitization of digital video footage (2D-Cam). A root mean square (RMS) error was calculated between 2D-Mot and 2D-Cam data to evaluate the reliability of the latter. Correlations between 2D-Cam and 3D data (intersubject and intrasubject) were also conducted, and regression slope and r2 values obtained. 2D-Cam and 2D-Mot data were consistent for side step (RMS = 1.7 degrees) and side jump (RMS = 1.5 degrees) movements. Between subjects, 2D-Cam and 3D data correlated well for the side step (r2 = 0.58) and side jump (r2 = 0.64). Within subjects, 2D-Cam and 3D data correlated moderately for the side step (r2 = 0.25 (0.19)) and side jump (r2 = 0.36 (0.27)). The 2D-Cam method can be used to screen for excessive valgus in elite basketball players, particularly for movements occurring primarily in the frontal plane. This method may also be a useful training evaluation tool when large reductions in dynamic valgus motions are required.

Gender differences in lower extremity kinematics, kinetics and energy absorption during landing

Article

Full-text available

Sep 2003
CLIN BIOMECH

To determine whether gender differences exist in lower extremity joint motions and energy absorption landing strategies between age and skill matched recreational athletes. Mixed factor, repeated measures design. Compared to males, females execute high demand activities in a more erect posture potentially predisposing the anterior cruciate ligament to greater loads and injury. The preferred energy absorption strategy may provide insight for this performance difference. Inverse dynamic solutions estimated lower extremity joint kinematics, kinetics and energetic profiles for twelve males and nine females performing a 60 cm drop landing. Females demonstrated a more erect landing posture and utilized greater hip and ankle joint range of motions and maximum joint angular velocities compared to males. Females also exhibited greater energy absorption and peak powers from the knee extensors and ankle plantar-flexors compared to the males. Examinations of the energy absorption contributions revealed that the knee was the primary shock absorber for both genders, whereas the ankle plantar-flexors muscles was the second largest contributor to energy absorption for the females and the hip extensors muscles for the males. Females may choose to land in a more erect posture to maximize the energy absorption from the joints most proximal to ground contact. Females may be at a greater risk to anterior cruciate ligament injury during landing due to their energy absorption strategy.

Posture-dependent isometric trunk extension and flexion strength in normal male and female subjects

Article

Aug 2002
J SPINAL DISORD TECH

The objective of this study was to quantify the relationship between trunk posture and trunk muscle function in a group of young, normal male and female subjects. Ten male and 10 female subjects performed. isometric flexion and extension tasks using a trunk dynamometer. Peak isometric torque was recorded in flexion and extension at 10degrees increments over a sagittal posture range of -20degrees extension to +50degrees of flexion. Significant differences in trunk strength (isometric torque) were found between males and females, at various sagittal plane trunk postures, and between flexion (F) and extension (E) tasks. Flexion torque was greatest at 20degrees to 30degrees flexion, whereas extension torque was greatest at 50degrees flexion. Gender-specific differences in trunk strength were markedly reduced when the torque data were normalized by the subject's height multiplied by body weight. The E/F torque ratio showed a relatively linear, over twofold increase with increasing flexion angle, and was significantly greater for female subjects compared with male subjects at most sagittal postures. The baseline trunk isometric strength data provided by this study should help clinicians to use strength testing more precisely and specifically in prevention and diagnosis of patients at risk for back disorders.

ACL research retreat: The gender bias April 6-7, 2001

Article

Dec 2001
CLIN BIOMECH

A comparison of knee joint motion patterns between men and women in selected athletic tasks

Article

Jul 2001
CLIN BIOMECH

Background: Women have higher non-contact anterior cruciate ligament injury rate than men do in sport activities. Non-contact anterior cruciate ligament injuries frequently occur in sports requiring cutting tasks. Alternated motor control strategies have identified as a potential risk factor for the non-contact anterior cruciate ligament injuries. The purpose of this study was to compare the patterns of knee kinematics and electromyographic activities in running, side-cutting, and cross-cutting between men and women recreational athletes. Methods: Three-dimensional kinematic data of the knee and electromyographic data of selected muscles across the knee joint were collected for 11 men and 9 women recreational athletes in running, side-cutting, and cross-cutting. Regression analyses with dummy variables for comparison of knee motion patterns between men and women. Results: Women tend to have less knee flexion angles, more knee valgus angles, greater quadriceps activation, and lower hamstring activation in comparison to men during the stance phase of each of the three athletic tasks. Literatures suggest these alternated knee motion patterns of women tend to increase the load on the anterior cruciate ligament. Conclusion: Women on average may have certain motor control strategies that may alter their knee motion patterns. Women's altered knee motion patterns may tend to increase the load on the anterior cruciate ligament in the selected athletic tasks, which may contribute to the increased anterior cruciate ligament injury rate among women. Relevance: Non-contact anterior cruciate ligament injuries frequently occur in sports. Altered motor control strategies and lower extremity motion patterns are likely to play an important role in non-contact anterior cruciate ligament injuries. Non-contact anterior cruciate ligament injuries may be prevented by correcting altered motor control strategies and associated lower extremity motion patterns through certain training programs.

Fundamentals of Biostatistics

Article

Jul 1969

Agnes Berger

In vivo knee stability. A quantitative assessment using an instrumented clinical testing apparatus

Article

Aug 1978

Twenty-eight male and twenty-one female subjects with no history of previous injury to their knees were examined using a newly developed clinical testing apparatus designed to record anterior-posterior tibial force versus displacement and varus-valgus moment versus angulation during manual manipulation of the knee. Joint stiffness and laxity were measured from test tracings made with the knee muscles relaxed and tensed. Agreement between these measurements and those made previously on thirty-five fresh cadaver knee specimens was very good. Anterior-posterior laxity averaged 3.7 millimeters in full extension, 5.5 in 20 degrees of flexion, and 4.8 millimeters in 90 degrees of flexion, while the mean varus-valgus laxity was 6.7 degrees in full extension. The common clinical assumption that normal right-left differences are negligible was found to be invalid. Individual right-left differences averaged 26 to 35 per cent for laxity and 19 to 24 per cent for stiffness. There was no discernible tendency for one knee to be more stable than the other; random interchanges of relative stability between the right and left knees were observed for each individual at different knee positions. When requested to tense the knee muscles, these subjects were able to increase their knee stiffness an average of two to four times while knee laxity was reduced to 25 to 50 per cent of the normal value.

Quantitative Measurements of Hip Strength in Different Age Groups

Article

Oct 1989

The purpose of this study was to develop a clinically useful method of assessing the strength of the hip musculature and to develop a normal data base with this technique. The strength of 72 subjects aged 20-81 years (37 women and 35 men) was measured through the use of a modified Cybex II with an upright stabilization frame for testing sagittal and frontal plane motions; transverse plane motions of internal and external rotation were tested in the seated position. The subjects were tested at multiple isokinetic speeds and isometric angles. Regardless of age or gender, hip extensors were the strongest muscle group, following by flexors, adductors, abductors, and rotators. As the velocity of exercise increased, the magnitude of the torques produced decreased. Demographically, younger men produced the greatest torques and older women the lowest. The strength values of older men and younger women were similar. The results have clinical implications for objective assessment of strength in pathologic patient populations.

Combined knee loading states that generate high anterior cruciate ligament forces

Article

Nov 1995

Injuries to the anterior cruciate ligament frequently occur under combined mechanisms of knee loading. This in vitro study was designed to measure levels of ligament force under dual combinations of individual loading states and to determine which combinations generated high force. Resultant force was recorded as the knee was extended passively from 90 degrees of flexion to 5 degrees of hyperextension under constant tibial loadings. The individual loading states were 100 N of anterior tibial force, 10 Nm of varus and valgus moment, and 10 Nm of internal and external tibial torque. Straight anterior tibial force was the most direct loading mechanisms; the mean ligament force was approximately equal to applied anterior tibial force near 30 degrees of flexion and to 150% of applied tibial force at full extension. The addition of internal tibial torque to a knee loaded by anterior tibial force produced dramatic increases of force at full extension and hyperextension. This loading combination produced the highest ligament forces recorded in the study and is the most dangerous in terms of potential injury to the ligament. In direct contrast, the addition of external tibial torque to a knee loaded by anterior tibial force decreased the force dramatically for flexed positions of the knee; at close to 90 degrees of flexion, the anterior cruciate ligament became completely unloaded. The addition of varus moment to a knee loaded by anterior tibial force increased the force in extension and hyperextension, whereas the addition of valgus moment increased the force at flexed positions. These states of combined loading also could present an increased risk for injury. Internal tibial torque is an important loading mechanism of the anterior cruciate ligament for an extended knee. The overall risk of injury to the ligament from varus or valgus moment applied in combination with internal tibial torque is similar to the risk from internal tibial torque alone. External tibial torque was a relatively unimportant mechanism for generating anterior cruciate ligament force.

Reference Values for Extremity Muscle Strength Obtained by Hand-Held dynamometry From Adults Aged 20 to 79 Years

Article

Feb 1997
ARCH PHYS MED REHAB

Richard Wallace Bohannon

Only a few studies have provided reference values for muscle strength obtained by hand-held dynamometry. Such values are essential for establishing the degree to which an individual's strength is impaired. This descriptive study was conducted to provide reference values for the strength of 10 extremity muscle actions. SUBJECTS AND INSTRUMENTATION: A convenience sample of 106 men and 125 women volunteers was tested twice with an Ametek digital hand-held dynamometer. The measurements were found to be reliable. Predictive equations are provided for the measurements. Reference values generated are expressed in Newtons and as a percentage of body weight and are organized by gender, decade of age, and side. The values can be employed in a clinical setting to document whether an individual is impaired relative to healthy subjects of the same gender and age.

Endurance times for low back stabilization exercises: Clinical targets for testing and training from a normal database

Article

Sep 1999
ARCH PHYS MED REHAB

To establish isometric endurance holding times, as well as ratios between torso extensors, flexors, and lateral flexors (stabilizers), for clinical assessment and rehabilitation targets. Simple measurement of endurance times in four tests performed in random order by a healthy cohort. To measure reliability, a subsample also performed the tests again 8 weeks later. University laboratory. Seventy-five young healthy subjects (31 men, 44 women). Women had longer endurance times than men for torso extension, but not for torso flexion or for the "side bridge" exercise, which challenges the lateral flexors (stabilizers). Men could sustain the "side bridge" for 65% of their extensor time and 99% of their flexion time, whereas women could sustain the "side bridge" for only 39% of their extensor time and 79% of their flexion time. The tests proved reliable, with reliability coefficients of >.97 for the repeated tests on 5 consecutive days and again 8 weeks later. Healthy young men and women possess different endurance profiles for the spine stabilizing musculature. Given the growing support for quantification of endurance, these data of endurance times and their ratios between extensor, flexor, and lateral flexor groups in healthy normal subjects are useful for patient evaluation and for providing clinical training targets.

The effect of neuromuscular training on the incidence of knee injury in female athletes: a prospective study

Article

Jan 1999
AM J SPORT MED

W G Clancy

To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P 0.05) and 4.8 times higher than male athletes (P 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.

Female and male trunk geometry: Size and prediction of the spine loading trunk muscles derived from MRI

Article

Feb 2001
CLIN BIOMECH

Develop a gender specific database of trunk muscle cross-sectional areas across multiple levels of the thoracic and lumbar spine and develop prediction equations for the physiological cross-sectional area as a function of gender and anthropometry. This study quantified trunk muscle cross-sectional areas of male and female spine loading muscles. There is a lack of comprehensive data regarding the female spine loading muscle size. Although biomechanical models often assume females are the same as males, little is known regarding gender differences in terms of trunk muscle areas and no data exist regarding the prediction of trunk muscle physiological cross-sectional areas from commonly used external anthropometric measures. Magnetic resonance imaging scans through the vertebral bodies from T(8) through S(1) were performed on 20 females and 10 males. Muscle fiber angle corrected cross-sectional areas were recorded at each vertebral level. Linear regression techniques taking into account anthropometric measures were utilized to develop prediction equations for the physiological cross-sectional area for each muscle of interest, as well as tests for differences in cross-sectional areas due to gender and side of the body. Significant gender differences were observed for the prediction of the erector spinae, internal and external obliques, psoas major and quadratus lumborum physiological cross-sectional areas. Anthropometric measures about the xyphoid process and combinations of height and weight resulted in better predictions of cross-sectional areas than when using traditional anthropometry. This study demonstrates that the trunk muscle geometry of females and males are different, and that these differences should be considered in the development of biomechanical models of the torso. Relevance. The prediction of physiological cross-sectional areas from external anthropometric measures provide gender specific equations to assist in estimation of forces of muscles which load the spine for biomechanical purposes.

ACL research retreat: the gender bias. April 6-7, 2001. Meeting report and abstracts

Article

Jan 2002
CLIN BIOMECH

The effects of tibial rotation on the patellofemoral joint: Assessment of the changes in in situ strain in the peripatellar retinaculum and the patellofemoral contact pressures and areas

Article

Sep 2001

The objective of this study was to determine the effects of tibial rotation on in situ strain in the peripatellar retinaculum and patellofemoral contact pressures and areas. Patellofemoral joint biomechanics demonstrate a strong correlation with the etiology of patellofemoral disorders, such as chondromalacia, and are significantly influenced by tibial rotation. Six human cadaveric knees were used along with a patellofemoral joint testing jig that permits physiological loading of the knee extensor muscles. Patellofemoral contact pressures and areas were measured with a Fuji pressure-sensitive film, and the changes in in situ strain in the peripatellar retinaculum were measured with four differential variable reluctance transducers. Tibial rotation had a significant effect on patellofemoral joint biomechanics. The data showed an inverse relationship between increasing knee flexion angles and the change in patellofemoral contact pressures and in situ strain with tibial rotation. At higher knee flexion angles, the patella is well-seated in the trochlear groove and the function of the peripatellar retinaculum is minimized and less affected by tibial rotations.

Gender Differences in Strength and Lower Extremity Kinematics During Landing

Article

Sep 2002

This study evaluated kinematic, vertical ground reaction forces, and strength variables in healthy collegiate female basketball, volleyball, and soccer players compared with matched male subjects. Thirty athletes did single-leg landing and forward hop tasks. An electromagnetic tracking device synchronized with a force plate provided kinematic data and vertical ground reaction force data, respectively. Maximum angular displacement and time to maximum angular displacement kinematic variables were calculated for hip flexion, abduction, rotation, knee flexion, and lower leg rotation. Vertical ground reaction force data normalized to body mass provided impulse, maximum force, time to maximum force, and stabilization time variables. An isokinetic device measured quadriceps and hamstring peak torque to body mass at 60 degrees /second. With both tasks, females had significantly less knee flexion and lower leg internal rotation maximum angular displacement, and less knee flexion time to maximum angular displacement than males. For the single-leg land, females had significantly more hip internal rotation maximum angular displacement, and less lower leg internal rotation time to maximum angular displacement than males. For the forward hop, females had significantly more hip rotation time to maximum angular displacement than males. Females also had significantly less peak torque to body mass for the quadriceps and hamstrings than males. Weaker thigh musculature may be related to the abrupt stiffening of the knee and lower leg on landing in females.

Posture-Dependent Isometric Trunk Extension and Flexion Strength in Normal Male and Female Subjects

Article

Sep 2002
J SPINAL DISORD TECH

The objective of this study was to quantify the relationship between trunk posture and trunk muscle function in a group of young, normal male and female subjects. Ten male and 10 female subjects performed isometric flexion and extension tasks using a trunk dynamometer. Peak isometric torque was recorded in flexion and extension at 10 degrees increments over a sagittal posture range of -20 degrees extension to +50 degrees of flexion. Significant differences in trunk strength (isometric torque) were found between males and females, at various sagittal plane trunk postures, and between flexion (F) and extension (E) tasks. Flexion torque was greatest at 20 degrees to 30 degrees flexion, whereas extension torque was greatest at 50 degrees flexion. Gender-specific differences in trunk strength were markedly reduced when the torque data were normalized by the subject's height multiplied by body weight. The E/F torque ratio showed a relatively linear, over twofold increase with increasing flexion angle, and was significantly greater for female subjects compared with male subjects at most sagittal postures. The baseline trunk isometric strength data provided by this study should help clinicians to use strength testing more precisely and specifically in prevention and diagnosis of patients at risk for back disorders.

Gender Differences in Muscular Protection of the Knee in Torsion in Size-Matched Athletes

Article

Jun 2003

Female athletes who participate in sports involving jumping and cutting maneuvers are up to eight times more likely to sustain a rupture of the anterior cruciate ligament than are men participating in the same sports. We tested the hypothesis that healthy young women are able to volitionally increase the apparent torsional stiffness of the knee, by maximally activating the knee muscles, significantly less than are size-matched men participating in the same type of sport. Twenty-four NCAA (National Collegiate Athletic Association) Division-I athletes (twelve men and twelve women) competing in sports associated with a high risk of injury to the anterior cruciate ligament (basketball, volleyball, and soccer) were compared with twenty-eight collegiate endurance athletes (fourteen men and fourteen women) participating in sports associated with a low risk of such injuries (bicycling, crew, and running). Male and female pairs were matched for age, height, weight, body mass index, shoe size, and activity level. Testing was performed with a weighted pendulum that applied a medially directed 80-N impulse force to the lateral aspect of the right forefoot. The resulting internal rotation of the leg was measured optically, to the nearest 0.25 degrees, at 30 degrees and 60 degrees of knee flexion, both with and without maximal activation of the knee muscles. Maximal rotations of the leg were greater in women than in men in both the passive and the active muscle state (16% and 27% greater [p = 0.01 and p = 0.02], respectively). Moreover, female athletes exhibited a significantly (18%) smaller volitional increase in apparent torsional stiffness of the knee under internal rotation loading than did the matched male athletes (p = 0.014); this was particularly the case for those who participated in sports involving jumping and pivoting maneuvers (42% difference between genders, p = 0.001). The collegiate female athletes involved in high-risk sports exhibited less muscular protection of the knee ligaments during external loading of the knee than did size and sport-matched male athletes.

Valgus Knee Motion during Landing in High School Female and Male Basketball Players

Article

Nov 2003

The purpose of this study was to utilize three-dimensional kinematic (motion) analysis to determine whether gender differences existed in knee valgus kinematics in high school basketball athletes when performing a landing maneuver. The hypothesis of this study was that female athletes would demonstrate greater valgus knee motion (ligament dominance) and greater side-to-side (leg dominance) differences in valgus knee angle at landing. These differences in valgus knee motion may be indicative of decreased dynamic knee joint control in female athletes. Eighty-one high school basketball players, 47 female and 34 male, volunteered to participate in this study. Valgus knee motion and varus-valgus angles during a drop vertical jump (DVJ) were calculated for each subject. The DVJ maneuver consisted of dropping off of a box, landing and immediately performing a maximum vertical jump. The first landing phase was used for the analysis. Female athletes landed with greater total valgus knee motion and a greater maximum valgus knee angle than male athletes. Female athletes had significant differences between their dominant and nondominant side in maximum valgus knee angle. The absence of dynamic knee joint stability may be responsible for increased rates of knee injury in females but is not normally measured in athletes before participation. No method for accurate and practical screening and identification of athletes at increased risk of ACL injury is currently available to target those individuals that would benefit from neuromuscular training before sports participation. Prevention of female ACL injury from five times to equal the rate of males would allow tens of thousands of young females to avoid the potentially devastating effects of ACL injury on their athletic careers.

The effect of tibiofemoral joint kinematics on patellofemoral contact pressures under simulated muscle loads

Article

Aug 2004

Altered patellofemoral joint contact pressures are thought to contribute to patellofemoral joint symptoms. However, little is known about the relationship between tibiofemoral joint kinematics and patellofemoral joint contact pressures. The objective of this paper was to investigate the effect of tibiofemoral joint kinematics on patellofemoral joint pressures using an established in vitro robotic testing experimental setup. Eight cadaveric knee specimens were tested at 0 degrees, 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion under an isolated quadriceps load of 400 N and a combined quadriceps/hamstrings load of 400 N/200 N. Tibiofemoral joint kinematics were measured by the robot and contact pressures by a TekScan pressure sensor. The isolated quadriceps loading caused anterior translation and internal rotation of the tibia up to 60 degrees of flexion and posterior translation and external rotation of the tibia beyond 60 degrees. The co-contraction of the hamstring muscles caused a posterior translation and external rotation of the tibia relative to the motion of the tibia under the quadriceps load. Correspondingly, the contact pressures were elevated significantly at all flexion angles. For example, at 60 degrees of flexion, the hamstrings co-contraction increased the posterior tibial translation by approximately 2.8 mm and external tibial rotation by approximately 3.6 degrees. The peak contact pressure increased from 1.4+/-0.8 to 1.7+/-1.0 MPa, a 15% increase. The elevated contact pressures after hamstrings co-contraction indicates an intrinsic relation between the tibiofemoral joint kinematics and the patellofemoral joint biomechanics. An increase in posterior tibial translation and external rotation is accompanied by an increase in contact pressure in the patellofemoral joint. These results imply that excessive strength conditioning with the hamstring muscles might not be beneficial to the patellofemoral joint. Knee pathology that causes an increase in tibial posterior translation and external rotation might contribute to degeneration of the patellofemoral joint. These results suggest that conservative treatment of posterior cruciate ligament injury should be reconsidered.

Differences in normal and perturbed walking kinematics between male and female athletes

Article

Jul 2004
CLIN BIOMECH

Objective: To identify differences in lower extremity kinematic movement patterns between genders during walking through the application of an expected perturbation. Design: Randomized limb kinematics were compared between healthy active males and females. Background: Lower extremity kinematics during jump landing and cutting have been implicated as a potential source of the discrepancy in anterior cruciate ligament injury rates between genders. Kinematic differences between genders have been identified during tasks that are not provocative of anterior cruciate ligament injury but do result in increased ligament strain. Repetition of movement patterns that increase anterior cruciate ligament strain may increase the likelihood they will be reproduced during athletic tasks that produce force loads that exceed anterior cruciate ligament tensile strength. Methods: Twenty subjects (10 women, 10 men) classified as a level I or II athlete underwent motion analyses while performing self-paced walking trials. Five trials were undisturbed, and five each with a platform translating either laterally or anteriorly at heel contact. Sagittal, frontal, and transverse hip angles as well as sagittal and frontal knee angles were collected during stance. Results: Excursions in the frontal and transverse planes were greater at the hip and knee for females compared to males in each walking condition. The rate of these excursions also occurred more rapidly for females than males. There was no difference for joint angles at initial contact between genders, and there was no difference in the amount of sagittal plane excursion for the hip and knee when comparing genders. Conclusions: Females demonstrate characteristics during both normal and perturbed gait that may potentially contribute to increased anterior cruciate ligament strain. Repetition of these potentially harmful movement patterns during provocative athletic maneuvers may lead to anterior cruciate ligament injury. Relevance: Females exhibit lower extremity kinematic patterns that differ from males. Female kinematic patterns may contribute to an increased risk for anterior cruciate ligament injury.

Gender differences in lower extremity mechanics during running

Article

Jun 2003
CLIN BIOMECH

To compare differences in hip and knee kinematics and kinetics in male and female recreational runners. Gait analysis of 20 men and 20 women recreational runners. Female runners are reported to be more likely to sustain certain lower extremity injuries compared to their male counterparts. This has been attributed, in part, to differences in their structure and it has been postulated that these structural differences may lead to differences in running mechanics. It was hypothesized that females would exhibit greater peak hip adduction, hip internal rotation, knee abduction and decreased knee internal rotation compared to their male counterparts. It was also hypothesized that females would exhibit greater hip and knee negative work in the frontal and transverse planes compared to males. Comparisons of hip and knee three-dimentional joint angles and negative work during the stance phase of running gait were made between genders. Female recreational runners demonstrated a significantly greater peak hip adduction, hip internal rotation and knee abduction angle compared to men. Female recreational runners also demonstrated significantly greater hip frontal and transverse plane negative work compared to male recreational runners. Female recreational runners exhibit significantly different lower extremity mechanics in the frontal and transverse planes at the hip and knee during running compared to male recreational runners. Understanding the differences in running mechanics between male and female runners may lend insight into the etiology of different injury patterns seen between genders. In addition, these results suggest that care should be taken to account for gender when studying groups of male and female recreational runners.

The mechanical consequences of gender differences in single limb alignment during landing

Jan 2003
24-25

A Chaudhari
B Hearn
L Leveille

CHAUDHARI, A., D. CAMARILLO, B. HEARN, L. LEVEILLE, and T. ANDRIACCI. The mechanical consequences of gender differences in single limb alignment during landing. J. Orthop. Sports Phys. Ther. 33:A24–A25, 2003.

Groin injuries in professional rugby league players: a prospective study Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers

Jan 1997
629-63681

O Connor
J Marsden

O'CONNOR, D. Groin injuries in professional rugby league players: a prospective study. J. Sports Sci. 22:629–636, 2004. 26. ORCHARD, J., J. MARSDEN, S. LORD, and D. GARLICK. Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers. Am. J. Sports Med. 25:81–85, 1997.

The mechanical consequences of gender differences in single limb alignment during landing.

Jan 2003
A24

Chaudhari

Core Strength and Lower Extremity Alignment during Single Leg Squats

Abstract

No full-text available

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