Hip Medial Rotation Research Articles

"Knees Out" or "Knees In"? Volitional Lateral vs. Medial Hip Rotation During Barbell Squats.

Chiu, LZF. "Knees out" or "Knees in"? Volitional lateral versus medial hip rotation during barbell squats. J Strength Cond Res 38(3): 435-443, 2024-Medial or lateral hip rotation may be present during barbell squats, which could affect the hip frontal and transverse plane moments. Male (n = 14) and female (n = 18) subjects performed squats using their normal technique and with volitional medial and lateral hip rotation. Hip net joint moments (NJM) were calculated from 3-dimensional motion capture and force platform measurements. Statistical significance was set for omnibus tests (α = 0.05) and Bonferroni's corrected for pairwise comparisons (αt-test = 0.0056). Normal squats required hip extensor, adductor, and lateral rotator NJM. Lateral rotation squats had smaller hip extensor (p = 0.002) and lateral rotator (p < 0.001) NJM and larger hip adductor (p < 0.001) NJM than normal squats. Medial rotation squats had smaller hip extensor (p = 0.002) and adductor (p < 0.001) NJM and larger hip lateral rotator (p < 0.001) NJM than normal squats. These differences exceeded the minimum effects worth detecting. As gluteus maximus exerts hip extensor and lateral rotator moments, and the adductor magnus exerts hip extensor and adductor moments, these muscles combined would be required to meet these hip demands, supporting previous research that has established these muscles as the primary contributors to the hip extensor NJM. Lateral rotation squats reduce hip lateral rotator and increase hip adductor NJM, which may be hypothesized as preferentially loading adductor magnus. Medial rotation squats increase hip lateral rotator and decrease hip adductor NJM; therefore, this variant may shift loading to the gluteus maximus.

Effect of side-sling plank exercise on trunk and hip muscle activation in subjects with gluteus medius weakness.

The effectiveness of side-sling plank (SSP) exercises on trunk and hip muscle activation in subjects with gluteus medius (Gmed) weakness is unclear. To quantify muscle activation of the rectus abdominis (RA), external oblique (EO), erector spinae (ES), lumbar multifidus (LM), Gmed, gluteus maximus (Gmax), and tensor fasciae latae (TFL) during SSP with three different hip rotations compared to side-lying hip abduction (SHA) exercise in subjects with Gmed weakness. Twenty-two subjects with Gmed weakness were recruited. SHA and three types of SSP exercises were performed: SSP with neutral hip (SSP-N), hip lateral rotation (SSP-L), and hip medial rotation (SSP-M). Surface electromyography was used to measure the activation of the trunk and hip muscles. The trunk and hip muscles activations were generally significantly higher level during three SSP than SHA. SSP-M showed significantly lower EO activation while significantly higher ES and LM activation than SSP-L. Gmed activation was significantly higher during SSP-M than during SSP-L. TFL activation was significantly lower during SSP-M than during SSP-N and SSP-L. SSP could be prescribed for patients who have reduced Gmed strength after injuries. Especially, SSP-M could be applied for patients who have Gmed weakness with dominant TFL.

Hip medial rotator action of gluteus medius in Japanese macaque (Macaca fuscata) and implications to adaptive significance for quadrupedal walking in primates.

The gluteus medius (GM) muscle in quadrupedal primates has long been thought to mainly act as a hip extensor. However, previous reports argue that it may be a prime hip medial rotator and functions to rotate the pelvis in the horizontal plane, suggesting the functional differentiation between the GM and other hip extensors as hamstrings. In this study, we aim to quantify the muscle actions of the GM and hamstrings using muscle moment arm lengths and discuss the functional differentiation among hip extensors. Muscle attachment sites of eight specimens of Japanese macaque (Macaca fuscata) were digitized, and musculoskeletal models were constructed. Flexor-extensor, abductor-adductor, and medial-lateral rotator moment arms were calculated as the models were moved following the experimentally acquired kinematic data during walking on a pole substrate. Using electromyography, we also recorded the pattern of muscle activation. The GM showed a larger medial rotator moment arm length than the extensor moment arm length when it was activated, suggesting this muscle acts mainly as a hip medial rotator rather than as a hip extensor. The medial rotator action of the GM in the early support phase may rotate the pelvis in the horizontal plane and function to help contralateral forelimb reaching as a previous study suggested and facilitate contralateral hindlimb swinging to place the foot near the ipsilateral forelimb's hand.

Hip torques and the effect of posture in side-stepping with elastic resistance

BackgroundThe way movement-based exercises affect targeted muscles is not always obvious. Side stepping with an elastic band around the forefeet is aimed at strengthening hip abductors and lateral rotator muscles, with the premise that it creates an external torque of adduction and medial rotation of the femur around the pelvis that needs to be counteracted by hip muscles. However, hip torques during this exercise have not been previously quantified. Research questionIs the premise that the side-stepping exercise creates an external torque of adduction and medial rotation of the femur around the pelvis correct? MethodsThirty-six adults performed the exercise in an upright and a squat posture while 3D kinetic and kinematic data were collected. Hip muscle torques were calculated using inverse dynamics. The effect of posture and potential interactions with sex, side-stepping phases, and trailing/leading directions were analyzed using Pearson correlation and mixed-model ANOVAs. ResultA hip net muscle torque of extension, abduction and medial rotation was required to perform the exercise, regardless of phase and direction. The net muscle torque towards medial rotation required during the exercise was smaller (P < 0.001) in the upright (0.05–0.12 N m kg-1 m-1 across phases) compared to the squat posture (0.10–0.24 N m kg-1 m-1). In contrast, hip abductor torque was not affected by posture. When averaged across phases and directions, the normalized hip medial rotator muscle torque was highly correlated with knee flexion (r = 0.93, P < 0.001). SignificanceThe assumption that the side-stepping with the elastic band on the forefeet creates an external hip torque of medial rotation is erroneous. The resistance imposed to the hip during this exercise is consistent with the goal of strengthening the muscles that contribute to hip abduction and hip medial (not lateral) rotation. Changing the knee flexion angle is an effective way to manipulate hip rotator torque when prescribing this exercise in strength training and rehabilitation programs.

Tensor fascia latae and gluteal muscles myoelectric responses to increasing levels of hip medial rotation torque

Medial hip rotation is typically attributed to the tensor fascia latae (TFL) and lateral rotation, to the gluteus maximus. However, experimental studies in cadavers suggest that the TFL lacks a moment arm for medial rotation and that the gluteus maximus may act as hip medial rotator depending on the hip flexion angle. In order to address this contradictory thinking, we measured the myoelectric activity of TFL, gluteus medius and gluteus maximus (superior portion, GMaxS, and inferior portion, GMaxI) for increasing levels of medial rotation torque applied to the hip. To keep frontal and sagittal plane hip joint net torques constant during the experiments, the medial hip rotation torque was changed by displacing standard weights along an aluminum bar device, thereby producing pure medial hip rotation torques. The effect of increasing medial hip rotation torque was investigated for a fully extended hip (0°), and at 45° and 90° of flexion. We found an increase in the myoelectric activity of the TFL (∼90%↑, p = 0.002) at 90° of flexion and of the GMaxS (∼7%↑, p = 0.048) at the extended position with an increase in medial hip torque application (from 0 to 7.4 N.m.). For the GMed (regardless of hip position) and for the 45° position (regardless of muscle), no systematic changes across torque conditions were observed. In contrast to the common clinical assumption and current practice thinking, our results indicate that an increase in TFL activity is required to control for an increase in external torque towards hip medial rotation.

27646 Spinal Control Impairments During Two Clinical Tests of Lower Limb Movement in People with and without Low Back Pain

ABSTRACT IMPACT: Our work may be able to impact the examination and clinical decision making of a clinician to identify and target movement impairments to treat people with low back pain. OBJECTIVES/GOALS: Test if the magnitude of spinal control impairments is different in two clinical tests of lower limb movement in people with and without low back pain (LBP). The impairment is defined as the time difference between the start of limb to lumbopelvic motion. Also, test if the magnitude of impairments across tests is associated with LBP intensity and function. METHODS/STUDY POPULATION: 18 controls and 21 people with LBP (51.6% F, 34.5 ±11.5 yrs) participated in a cross-sectional, laboratory-based study. Subjects completed the modified Oswestry Disability Questionnaire (LBP-related functional limitation measure; 0-100%) and the Numeric Pain Rating Scale (LBP intensity; average pain prior 7 days; 0-10) self-report surveys and clinical tests of hip medial and lateral rotation performed in prone. A three-dimensional motion capture system was used to capture angular lumbopelvic and hip motion across time. A 2x2 mixed model ANOVA will be used to examine the effects of group, hip rotation test, and group x hip rotation test. Separate bivariate correlations will be used to quantify the association of magnitude of the impairment to (1) average LBP intensity and (2) LBP-related functional limitation. RESULTS/ANTICIPATED RESULTS: We hypothesize that, compared to healthy controls, people with LBP will display a greater magnitude of impairment across the hip medial and lateral rotation tests. In addition, we hypothesize that the magnitude of the difference in impairment between people with LBP vs controls will be larger during the hip lateral rotation test compared to the hip medial rotation test. Finally, we hypothesize that in people with LBP the magnitude of the impairments across tests will be associated with LBP intensity and LBP-related functional limitation. DISCUSSION/SIGNIFICANCE OF FINDINGS: If our hypotheses are supported, the hip rotation tests would further be recognized as a key part of a clinician’s examination and an important target for treatment of LBP.

Reliability of a musculoskeletal profiling test battery in elite academy soccer players.

The study aimed to quantify the measurement error / reliability of a musculoskeletal profiling test battery administered in young, elite academy soccer players, and to examine if the order in which the test battery was administered, and who it was administered by, influenced reliability. Players (n = 75; age 12–20 years; stature 1.47–1.95 m; body mass 36–89 kg) from U-12 to U-23 age groups were assigned to either: 1) intra-rater-fixed order; 2) intra-rater-non-fixed order; 3) inter-rater-fixed order; or, 4) inter-rater-non-fixed order groups. On two separate occasions separated by 3 to 7 days, 12 raters conducted a musculoskeletal profiling test battery comprising 10 tests (Supine Medial Hip Rotation, Supine Lateral Hip Rotation, Hamstring 90/90, Prone Medial Hip Rotation [degrees]; Combined Elevation, Thoracic Rotation, Weight-Bearing Dorsiflexion, Y-Balance [centimetres]; Beighton, Lumbar Quadrant [categorical]). The measurement error / reliability for tests measured in degrees and centimetres was evaluated using the intraclass correlation (relative reliability), coefficient of variation and ratio limits of agreement (absolute reliability). Intraclass correlations varied from 0.04 (“poor”) to 0.95 (“excellent”), coefficient of variation from 2.9 to 43.4%, and the ratio limits of agreement from 1.058 (*/÷ 1.020) to 2.026 (*/÷ 1.319) for the tests measured in degrees and centimetres. The intraclass correlation, coefficient of variation and ratio limits of agreement were smallest for five out of eight tests measured in degrees and centimetres when the tests were administered in an intra-rater-fixed test order. These findings emphasise that different testing methods, and the administration of a musculoskeletal profiling test battery using a less than optimal design, will influence measurement error and hence test reliability. These observations need to be considered when investigating musculoskeletal function and age, injury, training or asymmetry in young, elite academy soccer players.

The effects of small and large varus alignment of the foot-ankle complex on lower limb kinematics and kinetics during walking: A cross-sectional study

BackgroundThe alignment of the foot-ankle complex may influence the kinematics and kinetics of the entire lower limb during walking. ObjectivesThis study investigated the effect of different magnitudes of varus alignment of the foot-ankle complex (small versus large) on the kinematics and kinetics of foot, ankle, knee, and hip in the frontal and transverse planes during walking. DesignCross-sectional study. MethodFoot-ankle complex alignment in the frontal plane was measured as the angle between the metatarsal heads and the inferior edge of the examination table, measured with the volunteer in prone maintaining the ankle at 0° in the sagittal plane. The participants (n = 28) were divided into two groups according to their alignment angles. The first group had values equal to or inferior to the 45 percentile, and the second group had values equal to or above the 55 percentile. The lower limb kinematics and kinetics were evaluated with the participant walking at self-select speed in an instrumented treadmill. ResultsThe group of large varus alignment showed significantly higher (p < 0.03) forefoot inversion angle at initial contact, amplitude of rearfoot-shank eversion, and peak of inversion ankle moment. There were no differences (p > 0.05) between the groups for knee and hip amplitudes and moments in the frontal and transverse planes. The durations of rearfoot-shank eversion, knee abduction, knee medial rotation, hip adduction, and hip medial rotation were not different between groups (p > 0.05). ConclusionLarge varus alignment of the foot-ankle complex may increase the magnitude of foot pronation and ankle inversion moment during walking.

Clinical and Radiographic Aspects of Patients with Femoroacetabular Impingement Syndrome: Is There Difference between Symptomatic and Asymptomatic Hip?

Objective This paper aims to compare clinical and radiographic features of symptomatic and asymptomatic hips in patients with unilateral femoroacetabular impingement syndrome (FAIS) and to establish a correlation between these findings. Methods This is a retrospective study, based on medical records of patients diagnosed with FAIS between January 2014 and April 2017. The patients were assessed clinically as per the International Hip Outcome Tool 33 (iHOT33) questionnaire, visual analogue pain scale, hip rotation, and hip and knee muscular strength. The radiographic evaluation consisted of measurements of the alpha angle, crossover signal, acetabular retroversion index, ischial spine signal, and posterior wall sign. Results A total of 45 patients were included in the study, with mean time from symptom onset to diagnosis of 28.6 months and mean iHOT33 score was 39.9. The mean medial rotation was 20.5° in symptomatic hip and 27.2° in asymptomatic hip ( p < 0.001). The crossover signal was positive on 68.9% of the symptomatic hips and 55.6% of the asymptomatic hips ( p = 0.03). The mean retroversion index was 0.15 in symptomatic hips and 0.11 in asymptomatic hips ( p = 0.02). There was a positive correlation between the total time of symptoms and medial hip rotation reduction ( p = 0.04) and between body mass index (BMI) and medial hip rotation reduction ( p = 0.02). Conclusion When comparing clinical and radiographic features, we observed reduction of medial rotation and increase of acetabular retroversion index in the symptomatic hip, as well as association between the long symptom time and the high BMI with loss of medial rotation of the hips.

Comparison of Lumbopelvic Motions During Hip Medial Rotation Depending on Sex Differences and Chronic Lower Back Pain

Purpose: Hip rotation testing is important in the evaluation of chronic back pain. The purpose of this study was to investigate hip and lumbopelvic movement during hip medial rotation (HMR) in individuals with chronic lower back pain (CLBP). Methods: This study targeted 112 subjects in total: 28 healthy males and 28 healthy females, and 27 males with CLBP and 29 females with CLBP. Motion-capture device was used to measure the hip medial rotation angle (HMRA), lumbopelvic rotation angle (LPRA), and the rotation angle of the hip when lumbopelvic rotation starts during hip medial rotation. Results: When evaluating the healthy males and females using the hip medial rotation test (HMRT), healthy males showed a smaller HMRA than did healthy females (p<0.05). When evaluating the healthy males and the males with CLBP using the HMRT, males with CLBP showed a smaller HMRA and more lumbopelvic movements than did healthy males (p<0.05) in addition, their lumbopelvic move ments occurred earlier during HMR (p<0.05). Finally, when evaluating the males and the females with CLBP using the HMRT, males with CLBP showed a smaller HMRA and more lumbopelvic movements (p<0.05), and their lumbopelvic movements occurred earlier during HMR (p<0.05). Conclusion: The HMRT is an important test for the evaluation of males, and especially males with CLBP, as they often experience an in creased LPRA and decreased HMRA, with lumbopelvic movement occurring earlier during HMR when compared to other groups.

Effects of Positions of Pressure Biofeedback Unit on Lumbopelvic Rotation during Prone Hip Medial Rotation

Effects of Positions of Pressure Biofeedback Unit on Lumbopelvic Rotation during Prone Hip Medial Rotation

Hip and Knee Exercise for Patellofemoral Pain: Using the Evidence to Guide Physical Therapist Practice.

The etiology of patellofemoral pain (PFP) is thought to include both local factors (those near the patellofemoral joint and surrounding tissues) and nonlocal factors (those related to the mechanics of the distal and proximal joints). Traditionally, PFP rehabilitation protocols have focused on local factors. Strengthening of the hip may reduce excessive hip adduction and medial rotation during weightbearing activities and so decrease patellofemoral joint stresses. However, while previous studies indicate that including hip strengthening may lessen the intensity of PFP, the effects on strength and activity remain uncertain. J Orthop Sports Phys Ther 2018;48(1):33. doi:10.2519/jospt.2018.0502.

Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during step-down task

BackgroundStrengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight-bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step-down task in women. MethodsThirty-four young women who demonstrated dynamic knee valgus during step-down were divided into two groups. The experimental group underwent three weekly sessions of strengthening exercises for eight weeks, and the control group continued their usual activities. The following evaluations were carried out: (a) isokinetic maximum concentric and eccentric work of hip lateral rotators, (b) isokinetic hip passive torque of lateral rotation and resting transverse plane position, and (c) three-dimensional kinematics of the lower limb during step-down. FindingsThe strengthening program increased concentric (P<0.001) and eccentric (P<0.001) work of hip lateral rotators, and changed hip resting position toward lateral rotation (P<0.001). The intervention did not significantly change hip passive torque (P=0.089, main effect). The program reduced hip (P=0.002), thigh (P=0.024) and shank (P=0.005) adduction during step-down task. Hip, thigh and knee kinematics in transverse plane and foot kinematics in frontal plane did not significantly modify after intervention (P≥0.069, main effect). InterpretationHip and trunk strengthening reduced lower limb adduction during step-down. The changes in hip maximum work and resting position may have contributed to the observed kinematic effects.

COMPARISOM BETWEEN THE DIFFERENT HIP ROTATION POSITIONS ON HIP ABDUCTION EXERCISE

Background: The Gluteus Medius (GM) muscle is strongly involved in the control of hip joint stability and is active when postural stability is challenged in the medio-lateral direction. Alterations in activation patterns of these muscles have been documented for patients suffering from low back pain, knee, and ankle injuries. Aim: The purpose of this study was to investigate the effect of different hip rotation angles on myoelectrical activity of the three parts of the GM muscle during hip abduction exercise from side lying position in normal subjects with different angles of hip flexion. Design: A (3 tests×1 group) post experimental design was used.. Setting: The study was conducted in laboratory of biomechanics , Faculty of Physical Therapy, Cairo University. Population: Thirty pain free volunteers From out clinic of Faculty of Physical Therapy, Cairo University, their age ranged from 19 to 28 years old. Methods: A single session, repeated-measures design. The activity of each GM part (anterior, middle, and posterior) was measured in 30 pain free volunteers, their age ranged from 19 to 28 years old, using surface electromyography during three rotation movements ( neutral, 30o internal, and 45o external rotation) of the hip joint with different hip flexion angles(0o,45o, and 90o) from side lying hip abduction exercise. Muscle activation was expressed relative to Maximum Voluntary Isometric Contraction (MVIC). Differences in muscle activation were investigated using one-way repeated measures ANOVA with post-hoc Bonferroni analysis. Results: At neutral and 90o hip flexion, The activations of GM and its parts during the exercises were significantly different (p 0.01). Conclusion: The highest EMG amplitude of the muscle and its parts was when the hip flexed 90o and internally rotated during abduction. The posterior part is more active than the middle and the anterior parts in a relation to MVIC. There were significant differences between the different rotation movements of the gluteus medius muscle and its parts during abduction when the hip was in 90o and neutral hip flexion. Clinical rehabilitation impact: According to the results, the most proper position for strengthening the GM muscle and its parts was from 90o hip flexion with medial hip rotation and it should be used in progression of the rehabilitation program. The movements with less amplitudes are used at the beginning of the rehabilitation program of the GM muscle and the movements of the high amplitudes are used to progress the rehabilitation

Effect of Plyometric Training on Prevention of ACL Injuries in Females Volleyball Players

Objectives:To verify the effects of plyometric training on prevention of ACL injuries with lower limp kinematics,eccentric hip and knee torques,and functional performance.Methods:36 females volleyball players were divided into a training group (TG no:18) that carried out the plyometric training for 12 weeks,and a control group (CG no:18)that carried out no physical training.24 plyometric trainin sessions during approximately 12 weeks with 3 sessions ,30 minutes per week on alternate days. Lower limb kinematics (maximum excursion of hip adduction,hip medial rotation,and knee abduction during the single leg squat),eccentric hip (abductor,adductor,medial and lateral rotator) isokinetic peak torques and knee (flexor and extansor) isokinetic peak torques,and fuctional performance(trşpl hpo test and the 6-m timed hop test).Results:After 12 weeks, only the TG significantly reduced the values for the maximum excursion of knee abduction (P=0.01) and hip adduction (P 0.001).Similarly ,only the TG significantly increased the eccentic hip abductor (P 0.001) and adductor (P=0.01) torques.Finally,only the TG significantly increased the values in the tripl hop test (P 0.001) and significantly decreased the values in the 6-m timed hop test (P 0.001) after intervention.Conclusion:Plyometric training alters lower limb kinematics and increases eccentric hip torque and functional performance, suggesting the incorporation of these exercises in preventive programs for ACL injuries.

Relationship between Hip Medial Rotation Range of Motion and Weight Distribution in Patients with Low Back Pain

A decrease in the left hip joint medial rotation range of motion (ROM) was observed more often than a reduction in the right hip joint medial rotation ROM. However, similar number between right and left side was observed in ground reaction force more weighted. The coefficient between the passive hip joint medial rotation symmetry rate and the weight loading symmetry ratio was -0.19 (p < 0.05). †Corresponding Author : ryu3091@cu.ac.krThis is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Different hip rotations influence hip abductor muscles activity during isometric side-lying hip abduction in subjects with gluteus medius weakness

The purpose of this study was to establish the effects of different hip rotations during isometric side-lying hip abduction (SHA) in subjects with gluteus medius (Gmed) weakness by investigating the electromyographic (EMG) amplitude of the Gmed, tensor fasciae latae (TFL) activity, and gluteus maximus (Gmax), and the activity ratio of the Gmed/TFL, Gmax/TFL, and Gmed/Gmax. Nineteen subjects with Gmed weakness were recruited for this study. Subjects performed three isometric hip abductions: frontal SHA with neutral hips (SHA-N), frontal SHA with hip medial rotation (SHA-MR), and frontal SHA with hip lateral rotation (SHA-LR). Surface EMG amplitude was measured to collect the EMG data from the Gmed, TFL, and Gmax. A one-way repeated-measures analysis of variance was used to determine the statistical significance of the Gmed, TFL, and Gmax EMG activity and the Gmed/TFL, Gmax/TFL, and Gmed/Gmax EMG activity ratios. Gmed EMG activity was significantly greater in SHA-MR than in SHA-N. TFL EMG activity was significantly greater in SHA-LR than in SHA-N. The Gmed/TFL and Gmed/Gmax EMG activity ratios were also significantly greater in SHA-MR than in SHA-N or SHA-LR. The results of this study suggest that SHA-MR can be used as an effective method to increase Gmed activation and to decrease TFL activity during SHA exercises.

Frontal and transverse plane hip kinematics and gluteus maximus recruitment correlate with frontal plane knee kinematics during single-leg squat tests in women

BackgroundHip muscle dysfunction may be associated with knee valgus that contributes to problems like patellofemoral pain syndrome. The purpose of this study was to (1) compare knee and hip kinematics and hip muscle strength and recruitment between “good” and “poor” performers on a single-leg squat test developed to assess hip muscle dysfunction and (2) examine relationships between hip muscle strength, recruitment and frontal plane knee kinematics to see which variables correlated with knee valgus during the test. MethodsForty-one active women classified via visual rating as “good” or “poor” performers on the test participated. Participants completed 5-repetition single-leg squat tests. Isometric hip extension and abduction strength, gluteus maximus and gluteus medius recruitment, and 3-dimensional hip and knee kinematics during the test were compared between groups and examined for their association with frontal plane knee motion. Findings“Poor” performers completed the test with more hip adduction (mean difference=7.6°) and flexion (mean difference=6.3°) than “good” performers. No differences in knee kinematics, hip strength or hip muscle recruitment occurred. However, the secondary findings indicated that increased medial hip rotation (partial r=0.94) and adduction (partial r=0.42) and decreased gluteus maximus recruitment (partial r=0.35) correlated with increased knee valgus. InterpretationWhereas hip muscle function and knee kinematics did not differ between groups as we'd hypothesized, frontal plane knee motion correlated with transverse and frontal plane hip motions and with gluteus maximus recruitment. Gluteus maximus recruitment may modulate frontal plane knee kinematics during single-leg squats.

Effect of Plyometric Training on Lower Limb Biomechanics in Females

To verify the effects of plyometric training on lower limb kinematics, eccentric hip and knee torques, and functional performance. Cohort study. Research laboratory. Thirty-six females were divided into a training group (TG; n = 18) that carried out the plyometric training for 8 weeks, and a control group (CG; n = 18) that carried out no physical training. Twenty-four plyometric training sessions during approximately 8 weeks with 3 sessions per week on alternate days. Lower limb kinematics (maximum excursion of hip adduction, hip medial rotation, and knee abduction during the single leg squat), eccentric hip (abductor, adductor, medial, and lateral rotator) isokinetic peak torques and knee (flexor and extensor) isokinetic peak torques, and functional performance (triple hop test and the 6-m timed hop test). After 8 weeks, only the TG significantly reduced the values for the maximum excursion of knee abduction (P = 0.01) and hip adduction (P < 0.001). Similarly, only the TG significantly increased the eccentric hip abductor (P < 0.001) and adductor (P = 0.01) torques. Finally, only the TG significantly increased the values in the triple hop test (P < 0.001) and significantly decreased the values in the 6-m timed hop test (P < 0.001) after intervention. Plyometric training alters lower limb kinematics and increases eccentric hip torque and functional performance, suggesting the incorporation of these exercises in preventive programs for ACL injuries.

Influence of the Hip Flexion Angle on Isokinetic Hip Rotator Torque and Acceleration Time of the Hip Rotator Muscles

The purpose of this study was to verify the influence of the hip flexion angle on isokinetic rotator torque and acceleration times of the hip medial and lateral rotator muscles. Twenty-one healthy women were included in this study. The hip rotator function was evaluated at 3 different hip flexion angles (10°, 40°, and 90°). The results showed that both eccentric and concentric hip lateral rotator torques were greater at 40° of hip flexion when compared with 90°. Moreover, both the eccentric and concentric hip medial rotator torques were greater at 90° of hip flexion than at 40° and 10°, and greater at 40° than at 10°. In addition, both the eccentric and concentric hip medial to lateral rotator torque ratios were greater at 90° of hip flexion than at 40° and 10°, and greater at 40° than at 10°. Finally, the acceleration times of the hip medial rotator muscles were smaller at 90° of hip flexion than at 10° and smaller at 40° than at 10°. The current results highlight the importance of evaluating the hip rotator muscles at different hip flexion angles to comprehensively assess their functions.