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Context: The hip adductor and abductor muscles play vital roles as stabilizers in the lower-extremity. Their activation during soccer-specific actions is essential, but local muscular fatigue can hinder athletic performance and increase the risk of injury. Design: This study aimed to observe the variations in frontal plane hip strength in female college soccer players before and after a high-workload soccer-specific training session. Furthermore, the study sought to compare the relative changes in hip strength with the internal and external load measures obtained during that session. Methods: Twenty female college soccer players participated in a retrospective observational study. Isometric hip adductor and abductor strength were measured before and after a training session in the college spring season. Measurements were taken with a handheld dynamometer (MicroFET 2) while the players were supine. Global positioning system sensors (Catapult Vector S7), commonly worn by players during training sessions and competitive matches, were used to measure external and internal loads. Statistical analyses were performed using paired samples t test to assess hip adductor and abductor strength changes before and after the training session. Spearman rank was used to identify correlation coefficients between global positioning system data and isometric hip strength. Results: The findings revealed significant decreases in the strength of the right hip adduction (P =.012, −7% relative change), right abduction (P =.009, −7.6% relative change), and left abduction (P =.016, −4.9% relative change) after the training session. Furthermore, relative decreases in hip isometric adduction and abduction strength are related to the distance covered at high speeds. Conclusion: The results of this study highlight that hip isometric adduction and abduction strength tend to decrease after exposure to high workloads during soccer-specific training. [ABSTRACT FROM AUTHOR]

Individuals with knee osteoarthritis (KOA) and flat feet are more likely to experience increased pain and cartilage damage. This study aimed to investigate the knee kinetics, kinematics, pain, and physical function in individuals with moderate symptomatic KOA, in comparison to asymptomatic control participants. Thirty volunteers with moderate KOA (with flat feet n = 15, with normal feet n = 15) and 30 asymptomatic people (with flat feet n = 15, with normal feet n = 15) were evaluated. The knee adduction angular impulse, knee flexion moment, knee flexion angular impulse, and knee flexion angle were measured during level walking. The pain was assessed in patients with KOA. The study found that individuals with KOA had a significant increase in the knee adduction angular impulse compared with the asymptomatic people (P <.05). The KOA with flat feet group had significantly lower knee flexion moment, knee flexion angular impulse, and knee flexion angle values than the KOA with normal feet group (P <.05). Furthermore, the KOA with flat feet group had a higher pain score than the KOA with normal feet group. Individuals with osteoarthritis and flat feet had lower knee flexion moments which may indicate reduced knee force exerted through compensatory mechanisms. Despite this reduction, they reported significantly higher levels of pain compared with those without flat feet, a finding that warrants further investigation in future studies. [ABSTRACT FROM AUTHOR]

Altering baseball pitching mechanics affects both performance and the risk of injury. The purpose of this study is to investigate the relationships of shoulder external over internal rotation ratio (SEIR) and other shoulder rotational properties during physical exam and biomechanics of pitching for 177 collegiate baseball pitchers. The shoulder range of motion was quantitatively measured using a custom-made wireless device. Pitching motion data were collected at 240 Hz, and a custom program was created to calculate the throwing arm motion and loading during baseball pitching. Linear regression and analysis of variance tests were performed to investigate the relationships between the shoulder physical exam outcomes and throwing arm biomechanics. SEIR had significant correlations with shoulder horizontal adduction angle at foot contact, maximum shoulder external rotation angle, maximum shoulder linear velocity, and elbow angle at ball release. SEIR groups had significant differences in shoulder proximal force, adduction torque, internal rotation torque, and horizontal adduction torque, and in elbow medial force and varus torque. Glenohumeral internal rotation deficit and total rotational motion deficit had no relationships with throwing arm motions or joint loadings. Shoulder health should be monitored to improve understanding of pitching mechanics in collegiate baseball pitchers. [ABSTRACT FROM AUTHOR]

Context: Piriformis syndrome is often associated with muscle spasms and shortening of the piriformis muscle (PM). Physical therapy, including static stretching of the PM, is one of the treatments for this syndrome. However, the effective stretching position ofthe PM is unclear in vivo. This study aimed to determine the effective stretching positions of the PM using ultrasonic shear wave elastography. Design: Observational study. Methods: Twenty-one healthy young men (22.7 [2.41 y) participated in this study. The shear elastic modulus of the PM was measured at 12 stretching positions using shear wave elastography. Three of the 12 positions were tested with maximum internal rotation at 0°, 20°, or 40° hip adduction in 90° hip flexion. Nine of the 12 positions were tested with maximum external rotation at positions combined with 3 hip-flexion angles (70°, 90°, and 110°) and 3 hip-adduction angles (0°, 20°, and 40°). Results.' The shear elastic modulus of the PM was significantly higher in the order of 40°, 20°, and 0° of adduction and higher in external rotation than in internal rotation. The shear elastic modulus of the PM was significantly greater in combined 110° hip flexion and 40° adduction with maximum external rotation than in all other positions. Conclusion.- This study revealed that the position in which the PM was most stretched was maximum external rotation with 110° hip ftexion and 40° hip adduction. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the preliminary effects of movement pattern training (MoveTrain) versus strengthening/flexibility (standard) treatment on hip and pelvic biomechanics in patients with chronic hip-related groin pain. This is a secondary analysis of data collected during a pilot randomized clinical trial. Thirty patients with hip pain, between the ages of 15 and 40 years, were randomized to MoveTrain or standard. Both groups completed 10 treatment sessions over 12 weeks along with a daily home exercise program. Three-dimensional motion analysis was used to collect kinematic and kinetic data of the pelvis and hip during a single-leg squat task at pretreatment and immediately posttreatment. Compared with the standard group, the MoveTrain group demonstrated smaller hip adduction angles (P =.006) and smaller hip external adduction moments (P =.008) at posttreatment. The desired changes to hip joint biomechanics, as found in this study, may require specificity in training that could allow health care professionals to better customize the rehabilitation of patients with hip pain. These findings can also be applied to the design and implementation of future clinical trials to strengthen our understanding of the long-term implications of different rehabilitation techniques for patients with hip pain. [ABSTRACT FROM AUTHOR]

Prior studies have explored the relationship between knee valgus and musculoskeletal variables to formulate injury prevention programs, primarily for females. Nonetheless, there is insufficient evidence pertaining to professional male soccer players. Here, the aim was to test the correlation of lateral trunk inclination, hip adduction, hip internal rotation, ankle dorsiflexion range of motion, and hip isometric strength with knee valgus during the single-leg vertical jump test. Twenty-four professional male soccer players performed a single-leg vertical hop test, hip strength assessments, and an ankle dorsiflexion range of motion test. A motion analysis system was employed for kinematic analysis. Maximal isometric hip strength and ankle dorsiflexion range of motion were tested using a handheld dynamometer and a digital inclinometer, respectively. The correlation of peak knee valgus with peak lateral trunk inclination was.43 during the landing phase (P =.04) and with peak hip internal rotation was −.68 (P <.001). For knee valgus angular displacement, only peak lateral trunk inclination presented a moderate positive correlation (r =.40, P =.05). This study showed that trunk and hip kinematics are associated with knee valgus, which could consequently lead to increased knee overload in male professional soccer players following a unilateral vertical landing test. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Injuries that affect the groin region are among the most common in football players. To prevent this condition, studies have focused on strengthening the adductors, hip flexors, or abdominal muscles. Recent investigations have used an eccentric-biased exercise (Copenhagen Adduction Exercise [CAE]) that promotes functional and architectural adaptations in the muscle tissue, though its effect on injury risk reduction is unknown. Clinical Question: Can the Copenhagen Adduction Exercise prevent groin injuries in soccer players? Summary of Key Findings: The literature was searched for studies investigating the potential groin injury risk reduction effect of the CAE. (1) Three studies met the inclusion criteria and were used for this appraisal; (2) one study observed a significantly lower injury rate ratio favoring the group that used the CAE program; and (3) 2 studies found similar or higher injury rates in the intervention groups, not supporting the inclusion of the CAE as a preventative tool. Clinical Bottom Line: There is conflicting evidence that usage of the CAE is superior to not performing adductor strengthening exercises in mitigating the risk of sustaining groin injuries. Given the evidence supporting these findings, it is advisable to exercise caution when contemplating the incorporation of the CAE into training regimens aimed at preventing groin injuries. Strength of Recommendation: There is Grade B evidence to suggest that inclusion of the CAE may not be associated with reduced injury rates. [ABSTRACT FROM AUTHOR]

Context: Posterior shoulder tightness evaluated as limited glenohumeral internal rotation and horizontal adduction is a risk factor for throwing-related shoulder and elbow injuries. Given that the throwing motion uses the entire body kinematics, limited lower-limb flexibility might be associated with posterior shoulder tightness. Therefore, we aimed to investigate the relationships between posterior shoulder tightness and lower-limb flexibility in college baseball players. Design: Cross-sectional study. Setting: University laboratory. Participants: Twenty-two college baseball players (20 right-handed and 2 left-handed). Methods: To investigate the relationships between glenohumeral range of motion and lower-limb flexibility using simple linear regression analysis, we measured passive range of motion of glenohumeral internal rotation and horizontal adduction, hip internal/external rotation in the prone/sitting position, ankle dorsiflexion, and quadriceps and hamstrings flexibility from both shoulders and legs. Results: Our analysis indicated that decreases in the lead leg hip external rotation in the prone position were moderately associated with limitations in glenohumeral internal rotation (R2 =.250, β [95% confidence interval, CI] = 0.500 [0.149 to 1.392], P =.018) and horizontal adduction (R2 =.200, β [95% CI] = 0.447 [0.051 to 1.499], P =.019) on the throwing shoulder. Furthermore, there were significant moderate relationships between decreases in glenohumeral internal rotation and limited lead leg quadriceps flexibility (R2 =.189, β [95% CI] = 0.435 [0.019 to 1.137], P =.022), and between decreases in glenohumeral horizontal adduction and limited stance leg ankle dorsiflexion (R2 =.243, β [95% CI] = 0.493 [0.139 to 1.438], P =.010). Conclusion: College baseball players with limited lower-limb flexibilities including the lead leg hip external rotation in the prone position, the lead leg quadriceps flexibility, and the stance leg ankle dorsiflexion showed excessive posterior shoulder tightness. The current results support the hypothesis that lower-limb flexibility is associated with posterior shoulder tightness in college baseball players. [ABSTRACT FROM AUTHOR]

Purpose: To develop and validate the Brazilian Adductor Performance Test (BAPT) for predicting hip adductor muscle injuries in elite soccer athletes. Methods: A total of 108 soccer athletes were assessed, followed up for 3 months, and evaluated for a history of adductor injury 6 months before BAPT evaluation. The Shapiro–Wilk test was used as the normality test. The Mann–Whitney U test was used to compare BAPT scores between injured and uninjured athletes. Binary logistic regression was performed to identify the athletes' chances of injury based on their BAPT scores. A receiver operating characteristic curve was used to determine the cutoff point for the number of repetitions in the BAPT and Spearman bivariate correlation and identify factors potentially related to the test score. Furthermore, the intraclass correlation coefficient was used to determine interexaminer agreement. The level of significance was set at 95%. Results: The BAPT scores for hip adductor injury history did not differ significantly (P =.08). A significant deficit was identified in the BAPT scores of the injured athletes at the 3-month follow-up (P =.001). The cutoff point identified was 33 repetitions. Low BAPT scores increased the chance of injury by 20% (odds ratio, 1.20%; P =.001). The interexaminer agreement was.96 (P =.001). Conclusion: BAPT can be used to identify athletes most likely to sustain hip adductor muscle injuries, indirectly reducing the rate of this injury in soccer clubs. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament injury prevention should focus primarily on reduction of the knee abduction moment (KAM) in landing tasks. Gluteus medius and hamstring forces are considered to decrease KAM during landing. The effects of different muscle stimulations on KAM reduction were compared using 2 electrode sizes (standard 38 cm2 and half size 19 cm2) during a landing task. Twelve young healthy female adults (22.3 [3.6] y, 1.62 [0.02] m, 50.2 [4.7] kg) were recruited. KAM was calculated under 3 conditions of muscle stimulation (gluteus medius, biceps femoris, and both gluteus medius, and biceps femoris) using 2 electrode sizes, respectively versus no stimulation during a landing task. A repeated-measures analysis of variance determined that KAM differed significantly among stimulation conditions and post hoc analysis revealed that KAM was significantly decreased in conditions of stimulating either the gluteus medius (P <.001) or the biceps femoris (P <.001) with the standard electrode size, and condition of stimulating both gluteus medius and biceps femoris with half-size electrode (P =.012) when compared with the control condition. Therefore, stimulation on the gluteus medius, the biceps femoris, or both muscles could be implemented for the examination of anterior cruciate ligament injury potential. [ABSTRACT FROM AUTHOR]

Context: Elite golfers have a high incidence of low back pain. Recent reviews have emphasized the need for investigation into how to prevent low back pain in golfers, prompting the current study. Design: Prospective longitudinal cohort study. Methods: Forty-one injury-free golfers were included in this study. At baseline, lower quadrant joint angles and club and ball performance were measured while each golfer performed 10 drives. The golfers were then monitored for 6 months and were allocated into 2 groups depending on whether or not they developed low back pain. The initial, baseline kinematic variables of the low back pain group and the uninjured group were then compared. Results: Over the 6-month monitoring period, 17 (41%) of the golfers developed low back pain. At baseline assessment, the low back pain group had 4° less lead ankle dorsiflexion at setup (P = .01; effect size = 0.82), 6° less lead knee flexion at the top of the backswing (P = .05; effect size = 0.64), 6° less lead ankle dorsiflexion at the top of the backswing (P = .01; effect size = 0.82), 6° more trail hip adduction at the top of the backswing (P = .02; effect size = 0.79), 9° more trail knee flexion at impact (P = .05; effect size = -0.64), and 6° more trail hip adduction at the end of follow through (P < .00; effect size = 1.00). Conclusion: Golfers who developed low back pain during the 6-month monitoring period displayed distinct differences in biomechanics at baseline when all golfers were injury free. These biomechanical differences may be considered a precursor to injury. Three-dimensional motion analysis may indicate whether elite golfers are at risk of developing low back pain. Research is needed to assess whether targeted exercise and sports drills aimed at addressing the biomechanical risk factors identified may prevent low back pain in elite golfers. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to compare functional movement screen (FMS) scores and drop vertical jump (DVJ) kinematics between those with and without anterior cruciate ligament reconstruction (ACLR), and to evaluate the association between FMS composite score and DVJ kinematics. Design: Cross-sectional. Participants: Sixty individuals with and without a history of ACLR. Main Outcome Measures: Composite FMS score and the dorsiflexion, knee-flexion, hip-flexion, knee abduction, hip adduction, and trunk-flexion angles during a DVJ. Results: The FMS scores did not differ between groups (P > .05). There were smaller peak and initial contact hip-flexion angles in the ACLR and contralateral limbs compared with controls, and smaller peak dorsiflexion angles in the ACLR compared with contralateral limbs (P < .05). Lower FMS score was associated with a smaller peak dorsiflexion angle, smaller peak knee-flexion angle, and larger peak knee abduction angle in the ACLR limb (ΔR² = .14-.23); a smaller peak dorsiflexion angle and smaller peak knee-flexion angle in the contralateral limb (ΔR² = .17-.19); and a smaller peak dorsiflexion angle, smaller peak knee-flexion angle, and larger peak knee abduction angle in the control limb (ΔR² = .16-.22). Conclusion: The FMS scores did not differ between groups, but were associated with DVJ kinematics and should be a complementary rather than substitute assessment. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the differences in hip adductor and abductor muscle strength in elite male footballers from youth to senior level. Methods: We tested 125 players from the under-13-years (U'13) to senior squads of a Danish male professional football club in this cross-sectional design study. Hip adductor and abductor force (in newtons), torque (in newton meters), normalized torque (in newton meters per body mass), and adduction-to-abduction ratio were measured using handheld dynamometry. Results: Between U'13 and senior level, adductor force increased by 104%, torque by 127%, and normalized torque by 21%. Abductor force increased by 78%, torque by 126%, and normalized torque by 17%. For incremental differences between age groups, significant increases were observed between the ages of U'13 to U'14 (18%–39%) and U'14 to U'15 (19%–33%) for all strength measures (P ≤.021). No incremental difference was observed for adductor-to-abductor ratio. Conclusions: The large increases in hip adductor and abductor strength occurring between the ages of U'13 and U'15 offer insight into the strength capabilities and stress demands in these players, which may relate to injury vulnerability, and facilitate clinicians in selecting best-suited exercise interventions. [ABSTRACT FROM AUTHOR]

The study aim was to quantify the impact of a commercially available variable stiffness shoe (VSS) on 3-dimensional ankle, knee, and hip mechanics and estimated knee contact forces compared with a control shoe. Fourteen participants (10 females) with knee osteoarthritis completed gait analysis after providing informed consent. Shoe conditions tested were control shoe (New Balance MW411v2) and VSS (Abeo SMART3400). An OpenSim musculoskeletal model with static optimization was used to estimate knee contact forces. There were no differences in joint kinematics or in the knee adduction or flexion moments (P =.06; P =.2). There were increases in the knee internal and external rotation (P =.02; P =.03) and hip adduction and internal rotation moments for VSS versus control (P =.03; P =.02). The estimated contact forces were not different between shoes (total P =.3, medial P =.1, and lateral P =.8), but contact force changes were correlated with changes in the knee adduction moment (medial r2 =.61; P <.007). High variability in knee flexion moment changes and increases in the internal rotation moment combined with small decreases in the knee adduction moment did not lead to decreases in estimated contact forces. These results suggest that evaluation of VSS using only the knee adduction moment may not adequately capture its impact on osteoarthritis. [ABSTRACT FROM AUTHOR]

Context: It is unclear if lower-extremity joint cooling alters biomechanics during a functional movement. Objective: To investigate the effects of unilateral lower-extremity cryotherapy on movement alterations during a single-leg drop jump. Design: A crossover design. Setting: Laboratory. Patients: Twenty healthy subjects (10 males and 10 females; 23 y, 169 cm, 66 kg). Intervention(s): Subjects completed a single-leg drop jump before and after a 20-minute ankle or knee joint cooling on the right leg, or control (seated without cooling) on 3 separate days. Main outcome measures: Time to peak knee flexion, vertical ground reaction force, lower-extremity joint angular velocity (sagittal plane only), and angle and moment (sagittal and frontal planes) in the involved leg over the entire ground contact (GC; from initial contact to jump-off) during the first landing. Time to peak knee flexion was compared using an analysis of variance; the rest of the outcome measures were analyzed using functional analyses of variance (P < .05). Results: Neither joint cooling condition changed the time to peak knee flexion (F2,95 = 0.73, P = .49). Ankle joint cooling reduced vertical ground reaction force (55 N at 4% of GC), knee joint angular velocity (44°/s during 5%-9% of GC), and knee varus moment (181 N·m during 18%-20% of GC). Knee joint cooling resulted in a reduction in knee joint angular velocity (24°/s during 37%-40% of GC) and hip adduction moment (151 N·m during 46%-48% of GC), and an increase in hip joint angular velocity (16°/s during 49%-53% of GC) and plantarflexion angle (1.5° during 11%-29% of GC). Conclusion: Resuming activity immediately after lower-extremity joint cooling does not seem to predispose an individual to injury during landing because altered mechanics are neither overlapping with the injury time period nor of sufficient magnitude to lead to an injury. [ABSTRACT FROM AUTHOR]

Knee abduction/adduction moment and knee internal rotation moment are known surrogate measures of anterior cruciate ligament (ACL) load during tasks like sidestepping and single-leg landing. Previous experimental literature has shown that a variety of kinematic strategies are associated or correlated with ACL injury risk; however, the optimal kinematic strategies needed to reduce peak knee moments and ACL injury are not well understood. To understand the complex, multifaceted kinematic factors underpinning ACL injury risk and to optimize kinematics to prevent the ACL injury, a musculoskeletal modeling and simulation experimental design was used. A 14-segment, 37-degree-of-freedom, dynamically consistent skeletal model driven by force/torque actuators was used to simulate whole-body single-leg jump landing kinematics. Using the residual reduction algorithm in OpenSim, whole-body kinematics were optimized to reduce the peak knee abduction/adduction and internal/external rotation moments simultaneously. This optimization was repeated across 30 single-leg jump landing trials from 10 participants. The general optimal kinematic strategy was to bring the knee to a more neutral alignment in the transverse plane and frontal plane (featured by reduced hip adduction angle and increased knee adduction angle). This optimized whole-body kinematic strategy significantly reduced the peak knee abduction/adduction and internal rotation moments, transferring most of the knee load to the hip. [ABSTRACT FROM AUTHOR]

In this study, the effects of an exercise therapy comprising yoga exercises and medial-thrust gait (YogaMT) on lower-extremity kinetics, pain, and function in patients with medial knee osteoarthritis were investigated. Fifty-nine patients were randomly allocated to three treatment groups: (a) the YogaMT group practiced yoga exercises and medial thrust gait, (b) the knee-strengthening group performed quadriceps- and hamstring-strengthening exercises, and (c) the treadmill walking group practiced normal treadmill walking in 12 supervised sessions. The adduction and flexion moments of the hip, knee, and ankle; pain intensity; and 2-min walking test were assessed before and after treatment and at 1-month follow-up. The YogaMT group experienced a significant reduction in knee adduction moment. All groups showed significant improvement in pain and function. The YogaMT may reduce medial knee load in patients with knee osteoarthritis in the short term. A larger clinical trial is required to investigate the long-term outcomes of this intervention. [ABSTRACT FROM AUTHOR]

Novice runners experience a higher incidence of knee injury than experienced runners, which may be related to aberrant frontal and transverse plane kinematics. However, differences in kinematics between novice and experienced runners have not been fully explored. For this study, 10 novice and 10 experienced female runners ran on a treadmill at 2.68 m/s. Ankle, knee, and hip joint angles during the stance phase were measured using a 3-dimensional motion capture system and modeled using cubic splines. Spline models were compared between groups using a generalized linear model (α =.05). Ninety-five percent confidence intervals of the difference between joint angles throughout stance were constructed to identify specific periods of stance where groups differed in joint position. Angle–angle diagrams of ankle and hip position in the frontal and transverse planes were constructed to depict joint coordination. Novice runners displayed less hip adduction, but greater knee abduction and knee internal rotation compared to experienced runners. Differences in knee joint position may be explained by coordination of hip and ankle motion. Greater knee abduction and knee internal rotation displayed by novice runners compared with experienced runners may help to explain their higher risk for injury. [ABSTRACT FROM AUTHOR]

Context: Examining the coordinated coupling of muscle recruitment patterns may provide insight into movement variability in sport-related tasks. Objective: The purpose of this study was to examine the relationship between coupled gluteus maximus and medius recruitment patterns and hip-adduction variability during single-limb step-downs. Design: Cross-sectional. Setting: Biomechanics laboratory. Participants: Forty healthy adults, including 26 women and 14 men, mean age 23.8 (1.6) years, mean body mass index 24.2 (3.1) kg/m2, participated. Interventions: Lower-extremity kinematics were acquired during 20 single-limb step-downs from a 19-cm step height. Electromyography (EMG) signals were captured with surface electrodes. Isometric hip-extension strength was obtained. Main Outcome Measures: Hip-adduction variability, measured as the SD of peak hip adduction across 20 repetitions of the step-down task, was measured. The mean amplitudes of gluteus maximus and gluteus medius EMG recruitment were examined. Determinism and entropy of the coupled EMG signals were computed with cross-recurrence quantification analyses. Results: Hip-adduction variability correlated inversely with determinism (r = −.453, P =.018) and positively with entropy (r =.409, P =.034) in coupled gluteus maximus/medius recruitment patterns but not with hip-extensor strength nor with magnitudes of mean gluteus maximus or medius recruitment (r = −.003,.081, and.035; P =.990,.688, and.864, respectively). Conclusion: Hip-adduction variability during single-limb step-downs correlated more strongly with measures of coupled gluteus maximus and medius recruitment patterns than with hip-extensor strength or magnitudes of muscle recruitment. Examining coupled recruitment patterns may provide an alternative understanding of the extent to which hip neuromuscular control modulates lower-extremity kinematics beyond examining muscle strength or EMG recruitment magnitudes. [ABSTRACT FROM AUTHOR]

Context: Joint mobilizations have been studied extensively in the literature for the glenohumeral joint and talocrural joint (ankle). Consequently, joint mobilizations have been established as an effective means of improving range of motion (ROM) within these joints. However, there is a lack of extant research to suggest these effects may apply within another critical joint in the body, the hip. Objective: To examine the immediate effects of hip joint mobilizations on hip ROM and functional outcomes. Secondarily, this study sought to examine the efficacy of a novel hip mobilization protocol. Design: A prospective exploratory study. Setting: Two research labs. Patients or Other Participants: The study included 19 active male (n = 8) and female (n = 11) college students (20.56 [1.5] y, 171.70 [8.6] cm, 72.23 [12.9] kg). Interventions: Bilateral hip mobilizations were administered with the use of a mobilization belt. Each participant received hip joint mobilization treatments once during 3 weekly sessions followed immediately by preintervention and postintervention testing/measurements. Testing for each participant occurred once per week, at the same time of day, for 3 consecutive weeks. Hip ROM was the first week, followed by modified Star Excursion Balance Test the second week and agility T test during the third week. Main Outcomes Measures: Pretest and posttest measurements included hip ROM for hip flexion, extension, abduction, adduction, internal and external rotation, as well as scores on the modified Star Excursion Balance Test (anterior, posterolateral, and posteromedial directions) and agility T test. Results: A significant effect for time was found for hip adduction, internal and external rotation ROM, as well as the posterolateral and posteromedial directions of the modified Star Excursion Balance Test. A separate main effect for both limbs was found for adduction and internal rotation ROM. Conclusion: Isolated immediate changes in ROM and functional outcomes were evident. Further evaluation is needed. [ABSTRACT FROM AUTHOR]

Context. Previous studies have reported that the incidence of patellofemoral pain in women is 2.2 times higher than that in men. Lower hip frontal dynamic joint stiffness in women may be related to the magnitude of hip adduction and internal rotation associated with patellofemoral pain. Objective: To identify sex differences in hip frontal dynamic joint stiffness and examine the relationship between hip frontal dynamic joint stiffness and hip adduction and internal rotation during gait. Design: Cross-sectional study. Setting: University campus. Participants: A total of 80 healthy volunteers (40 women and 40 men) participated in this study. Intervention(s): Kinematic and kinetic data during gait were collected using a motion capture system and force plates. Main Outcome Measures: Hip frontal dynamic joint stiffness, hip adduction, and hip internal rotation were calculated during gait. Results: Women demonstrated lower hip frontal dynamic joint stiffness than men during gait (P<.01). They also displayed decreased hip frontal dynamic joint stiffness associated with increased hip adduction (r=-.85, P<.001) and internal rotation (r = -.48, P < .001). Conversely, in men, decreased hip frontal dynamic joint stiffness was associated with increased hip adduction (r=-.74, P<,001) but not internal rotation (r= .17, P= .28). Conclusions: Sex differences between hip frontal dynamic joint stiffness and hip internal rotation during gait may contribute to the increased incidence of patellofemoral pain in women. [ABSTRACT FROM AUTHOR]

Context: Patellofemoral pain (PFP) is a challenging condition, with altered kinematics and muscle activity as 2 common impairments. Single applications of patterned electrical neuromuscular stimulation (PENS) have improved both kinematics and muscle activity in females with PFP; however, the use of PENS in conjunction with a rehabilitation program has not been evaluated. Objective: To determine the effects of a 4-week rehabilitation program with PENS on lower-extremity biomechanics and electromyography (EMG) during a single-leg squat (SLS) and a step-down task (SDT) in individuals with PFP. Study Design: Double-blinded randomized controlled trial. Setting: Laboratory. Patients of Other Participants: Sixteen females with PFP (age 23.3 [4.9] y, mass 66.3 [13.5] kg, height 166.1 [5.9] cm). Intervention: Patients completed a 4-week supervised rehabilitation program with or without PENS. Main Outcome Measures: Curve analyses for lower-extremity kinematics and EMG activity (gluteus maximus, gluteus medius, vastus medialis oblique, vastus lateralis, biceps femoris, and adductor longus) were constructed by plotting group means and 90% confidence intervals throughout 100% of each task, before and after the rehabilitation program. Mean differences (MDs) and SDs were calculated where statistical differences were identified. Results: No differences at baseline in lower-extremity kinematics or EMG were found between groups. Following rehabilitation, the PENS group had significant reduction in hip adduction between 29% and 47% of the SLS (MD = 4.62° [3.85°]) and between 43% and 69% of the SDT (MD = 6.55° [0.77°]). Throughout the entire SDT, there was a decrease in trunk flexion in the PENS group (MD = 10.91° [1.73°]). A significant decrease in gluteus medius activity was seen during both the SLS (MD = 2.77 [3.58]) and SDT (MD = 4.36 [5.38]), and gluteus maximus during the SLS (MD = 1.49 [1.46]). No differences were seen in the Sham group lower-extremity kinematics for either task. Conclusion: Rehabilitation with PENS improved kinematics in both tasks and decreased EMG activity. This suggests that rehabilitation with PENS may improve muscle function during functional tasks. [ABSTRACT FROM AUTHOR]

The superficial hip adductor muscles are situated in close proximity to each other. Therefore, relative movement between the overlying skin and the muscle belly could lead to a shift in the position of surface electromyography (EMG) electrodes and contamination of EMG signals with activity from neighboring muscles. The aim of this study was to explore whether hip movements or isometric contraction could lead to relative movement between the overlying skin and 3 adductor muscles: adductor magnus, adductor longus, and adductor gracilis. The authors also sought to investigate isometric torque--EMG relationships for the 3 adductor muscles. Ultrasound measurement showed that EMG electrodes maintained a position which was at least 5 mm within the muscle boundary across a range of hip flexion--extension angles and across different contraction levels. The authors also observed a linear relationship between torque and EMG amplitude. This is the first study to use ultrasound to track the relative motion between skin and muscle and provides new insight into electrode positioning. The findings provide confidence that ultrasound-based positioning of EMG electrodes can be used to derivemeaningful information on output from the adductor muscles and constitute a step toward recognized guidelines for surface EMG measurement of the adductors. [ABSTRACT FROM AUTHOR]

Context: Excessive knee valgus on landing can cause anterior cruciate ligament injury. Therefore, knee valgus alignment may show characteristic energy absorption patterns during landings with lateral movement that impose greater impact forces on the knee joint compared with landings in other alignments. Objective: To investigate the energy absorption strategy in lower-extremities during side steps in females with knee valgus alignment. Design: Controlled laboratory study. Setting: University research laboratory. Participants: A total of 34 female college students participated in this experiment. Interventions: Participants performed single-leg drop vertical jump and side steps. All participants were divided into valgus (n = 13), neutral (n = 9), and varus (n = 12) groups according to knee position during landing in single-leg drop vertical jumps. Main Outcome Measures: Lower-extremity joint angles, moments, and negative works were calculated during landing in side steps, and 1-way analysis of variance and post hoc tests were used to determine between-group differences. Results: Negative works of hip extensors, knee abductors, and ankle plantar flexors during landing in side steps were significantly smaller in the valgus than in the varus group; however, negative work of the knee extensors was significantly greater in the valgus group than in varus group. Conclusions: The findings of this study indicated that landing with knee valgus induced the characteristic energy absorption strategy in the lower-extremity. Knee extensors contributed more to energy absorption when landing in knee valgus than in knee varus alignment. Learning to land in knee varus alignment might reduce the impact on the knee joint by increasing the energy absorption capacities of hip extensors, knee abductors, and ankle plantar flexors. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Ice hockey and soccer are both dynamic sports that involve continuous, unpredictable play. These athletes consistently demonstrate higher rates of groin strains compared with other contact sports. Measuring the hip adductor/ abductor ratio has the potential to expose at-risk players, reduce injury rales, and preserve groin health in players with chronic strains. Focused Clinical Question: What is the clinical utility of measuring the hip adductor/abductor ratio for preseason and in-season ice hockey and soccer players? Summary o f Key Findings: Three studies, all of which were prospective cohort designs, were included. One study involved assessing preseason strength and flexibility as a risk factor for adductor strains in professional ice hockey players. Another study performed with the same professional hockey team used preseason hip adductor/abductor strength ratios to screen for those players who would benefit from a strengthening intervention aimed at reducing the incidence of adductor strains. The final study, which was performed in elite Ul7 soccer players, assessed the effectiveness of monthly in-season strength monitoring as a guide to trigger in-season interventions to decrease injury incidence. Clinical Bottom Line: Measuring the hip adductor/abductor strength ratio in hockey and soccer players can be a beneficial preseason and in-season tool to predict future groin strain risk and screen for athletes who might benefit from a strengthening intervention. Strength o f Recommendation: Level 3 evidence exists to support monitoring the hip adductor/abductor strength ratio to assess and reduce the risk of adductor strains in ice hockey and soccer players. [ABSTRACT FROM AUTHOR]

Context: Compared to shoulder and elbow functions, the hip functional characteristics of baseball pitchers have not been fully investigated. Therefore, little is known about the relationship between hip function and pitching performance. Objective: The purpose of this study was to evaluate the characteristics of hip flexibility and strength, focusing on their influences on the ball velocity in baseball pitchers. Design: Descriptive laboratory study. Setting: Laboratory and university baseball facility. Participants: Twenty-three college baseball pitchers. Interventions: Passive hip range of motion (ROM) and isometric hip muscle strength were bilaterally measured. The pitchers threw 20 fastballs at an official pitching distance. Main Outcome Measures: Bilateral hip ROM and strength in flexion, extension, abduction, adduction, and external and internal rotation; the maximal ball velocity. Results: The pivot side showed smaller hip external rotation ROM (P< .01), larger hip internal rotation ROM (P = .03), and greater hip adduction strength (P = .03) than the stride side. The hip extension ROM on the stride side had a negative correlation with the maximal ball velocity (r = -.58, P < .01). The maximal ball velocity (135.3 [4.1] km/h) positively correlated with the hip extension (r=.59, P< .01), flexion (r= .57, P<.01), abduction (r=.55, P< .01), and adduction (r=.55, Pc.Ol) strength on the pivot leg, and the hip flexion (r=.53, P=.01), abduction (r=.67, P<.01), and adduction (r=.46, P= .03) strength on the stride leg. Conclusions: These findings suggest that baseball pitchers do not have marked side-to-side differences in hip flexibility and strength, and that an important fitness factor for increasing ball velocity is not the hip flexibility but the hip muscle strength of both legs. [ABSTRACT FROM AUTHOR]

To date there is a paucity of information about how different types of conventional running shoes influence lower limb kinematics. The aim of the study was to determine the influence of motion control, neutral, and cushioned running shoes upon lower limb kinematics. Twenty-eight active males completed one test session running in standardized motion control, neutral, and cushioned running shoes on a treadmill at a self-selected pace (2.9 [0.6] m·s−1). Kinematic data were collected using a VICON motion analysis system with hip, knee, and ankle joint angles calculated. Discrete parameters associated with stance phase kinematics were compared between footwear conditions. Significant (P <.05) differences in knee flexion and internal rotation at toe off, and knee adduction range of motion were reported between footwear conditions. Significant (P <.05) differences in ankle joint dorsiflexion and adduction upon initial contact, peak dorsiflexion, eversion and abduction, and inversion at toe off were reported between footwear conditions. The influence of motion control, neutral, and cushioned running shoes on joint function dissipates moving proximally, with larger changes reported at the ankle compared with knee and hip joints. Although significant differences were reported between footwear conditions, these changes were of a small magnitude and effect size. [ABSTRACT FROM AUTHOR]

To examine the relationship between anterior cruciate ligament injury risk factors in unanticipated cutting and decelerating. Three-dimensional kinematics and ground reaction forces were collected on 11 females (22 [2] y, 1.67 [0.08] m, and 68.5 [9.8] kg) during 2 unanticipated tasks. Paired samples t tests were performed to compare dependent variables between tasks. Spearman rank correlation coefficients were calculated to analyze the relationship between peak internal knee adduction moment and peak anterior tibial shear force (ASF) during 2 unanticipated tasks. Significantly greater knee abduction angles, peak knee adduction moments, and peak ASFs were observed during cutting (P ≤.05). A strong positive correlation existed between decelerating ASF and cutting ASF (ρ =.67), while correlations between decelerating knee adduction moment and cutting knee adduction moment and decelerating ASF and cutting knee adduction moment were not significant. In situations where time management is a necessity and only one task can be evaluated, it may be more appropriate to utilize an unanticipated cutting task rather than an unanticipated deceleration task because of the increased knee adduction moment and ASF. These data can help future clinicians in better designing more effective anterior cruciate ligament injury risk screening methods. [ABSTRACT FROM AUTHOR]

Context: A limiting factor for reducing anterior cruciate ligament injury risk is ensuring that the movement adaptions made during the prevention program transfer to sport-specific activity. Virtual reality provides a mechanism to assess transferability, and neuroimaging provides a means to assay the neural processes allowing for such skill transfer. Objective: To determine the neural mechanisms for injury risk–reducing biomechanics transfer to sport after anterior cruciate ligament injury prevention training. Design: Cohort study. Setting: Research laboratory. Participants: Four healthy high school soccer athletes. Interventions: Participants completed augmented neuromuscular training utilizing real-time visual feedback. An unloaded knee extension task and a loaded leg press task were completed with neuroimaging before and after training. A virtual reality soccer-specific landing task was also competed following training to assess transfer of movement mechanics. Main Outcome Measures: Landing mechanics during the virtual reality soccer task and blood oxygen level–dependent signal change during neuroimaging. Results: Increased motor planning, sensory and visual region activity during unloaded knee extension and decreased motor cortex activity during loaded leg press were highly correlated with improvements in landing mechanics (decreased hip adduction and knee rotation). Conclusion: Changes in brain activity may underlie adaptation and transfer of injury risk–reducing movement mechanics to sport activity. Clinicians may be able to target these specific brain processes with adjunctive therapy to facilitate intervention improvements transferring to sport. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Shoulder range of motion (ROM) in throwing athletes relies on a balance of mobility and stability to maintain proper function and health that, if disrupted, can lead to shoulder injury. There have been several studies that address the relationship between ROM deficits and overhead injuries; however, it may be unclear to clinicians which interventions are most effective for increasing ROM in the glenohumeral joints of overhead athletes. Clinical Question: In overhead athletes who have deficient shoulder ROM, is instrument-assisted soft tissue mobilization (IASTM) more effective at acutely increasing ROM over the course of a patient’s treatment when compared with self-stretching? Summary of Key Findings: A thorough literature review yielded 3 studies relevant to the clinical question, and all 3 studies were included. Two articles found a significant increase in acute ROM when compared with a self-stretch measure. All 3 articles showed increases in internal rotation and horizontal adduction, and 1 study reported an increase in total arc of shoulder ROM. Clinical Bottom Line: There is moderate evidence to support the use of IASTM to acutely increase ROM in the glenohumeral joint of overhead athletes. Clinicians should be aware of the variability with recommended treatment times; however, positive results have been seen with treatments lasting 5 to 6 minutes per treatment region. There is no consensus for treatment intensity, and certain IASTM tools require certification. Strength of Recommendation: Grade B evidence exists that IASTM is more effective at increasing shoulder ROM (ie, internal rotation, horizontal adduction, external rotation, total arc of motion) in overhead athletes than self-stretching measures. [ABSTRACT FROM AUTHOR]

Given its apparent representation of cumulative (vs peak) loads, this feasibility study investigates vertical ground reaction impulse (vGRI) as a real-time biofeedback variable for gait training aimed at reducing lower limb loading. Fifteen uninjured participants (mean age = 27 y) completed 12 2-min trials, 1 at each combination of 4 walking speeds (1.0, 1.2, 1.4, and 1.6 m/s) and 3 targeted reductions in vGRI (5, 10, and 15%) of the assigned ("target") limb, with the latter specified relative to an initial baseline (no feedback) condition at each speed. The ability to achieve targeted reductions was assessed using step-by-step errors between measured and targeted vGRI. Mean (SD) errors were 5.2% (3.7%); these were larger with faster walking speeds but consistent across reduction targets. Secondarily, we evaluated the strategy used to modulate reductions (ie, stance time or peak vertical ground reaction force [vGRF]) and the resultant influences on knee joint loading (external knee adduction moment [EKAM]). On the targeted limb, stance times decreased (P < .001) with increasing reduction target; first and second peaks in vGRF were similar (P > .104) across all target conditions. While these alterations did not significantly reduce EKAM on the target limb, future work in patients with knee pathologies is warranted. [ABSTRACT FROM AUTHOR]

Vertical stiffness may contribute to lower-extremity injury risk; however, it is unknown whether athletes with different stiffness levels display differences in biomechanics. This study compared differences in biomechanics between female athletes (n = 99) with varying stiffness levels during a repetitive, single-leg, vertical hopping task. Vertical stiffness was calculated as the ratio of peak vertical ground-reaction force to maximum center-of-mass displacement. Tertiles were established using stiffness values, and separate 1-way ANOVAs were used to evaluate between-group differences. Stance times decreased, and flight times, ground-reaction force, and stiffness increased, from the low- to high-stiffness group (P < .050). The high-stiffness group displayed: (1) greater lateral trunk flexion (P = .009) and lesser hip adduction (P = .022) at initial ground contact compared to the low- and moderate-stiffness groups, respectively; (2) lesser peak hip adduction compared to the low-stiffness group (P = .040); (3) lesser lateral trunk-flexion (P = .046) and knee-flexion (P = .010) excursion compared to the moderate- and low-stiffness groups, respectively; and (4) greater peak hip-flexion (P = .001), ankle-dorsiflexion (P = .002), and ankle-eversion (P = .038) moments compared to the low-stiffness group. A wide range of variability in stiffness exists within a relatively homogenous population. Athletes with varying stiffness levels display biomechanical differences that may help identify the potential mechanism(s) by which stiffness contributes to injury risk. [ABSTRACT FROM AUTHOR]

The Microsoft Kinect is becoming a widely used tool for inexpensive, portable measurement of human motion, with the potential to support clinical assessments of performance and function. In this study, the relative osteokinematic Cardan joint angles of the hip and knee were calculated using the Kinect 2.0 skeletal tracker. The pelvis segments of the default skeletal model were reoriented and 3-dimensional joint angles were compared with a marker-based system during a drop vertical jump and a hip abduction motion. Good agreement between the Kinect and marker-based system were found for knee (correlation coefficient = 0.96, cycle RMS error = 11°, peak flexion difference = 3°) and hip (correlation coefficient = 0.97, cycle RMS = 12°, peak flexion difference = 12°) flexion during the landing phase of the drop vertical jump and for hip abduction/adduction (correlation coefficient = 0.99, cycle RMS error = 7°, peak flexion difference = 8°) during isolated hip motion. Nonsagittal hip and knee angles did not correlate well for the drop vertical jump. When limited to activities in the optimal capture volume and with simple modifications to the skeletal model, the Kinect 2.0 skeletal tracker can provide limited 3-dimensional kinematic information of the lower limbs that may be useful for functional movement assessment. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of foot progression angle on the reduction in knee adduction moment caused by a lateral wedged insole during walking. Twenty healthy, young volunteers walked 10 m at their comfortable velocity wearing a lateral wedged insole or control flat insole in 3 foot progression angle conditions: natural, toe-out, and toe-in. A 3-dimensional rigid link model was used to calculate the external knee adduction moment, the moment arm of ground reaction force to knee joint center, and the reduction ratio of knee adduction moment and moment arm. The result indicated that the toe-out condition and lateral wedged insole decreased the knee adduction moment in the whole stance phase. The reduction ratio of the knee adduction moment and the moment arm exhibited a close relationship. Lateral wedged insoles decreased the knee adduction moment in various foot progression angle conditions due to decrease of the moment arm of the ground reaction force. Moreover, the knee adduction moment during the toe-out gait with lateral wedged insole was the smallest due to the synergistic effect of the lateral wedged insole and foot progression angle. Lateral wedged insoles may be a valid intervention for patients with knee osteoarthritis regardless of the foot progression angle. [ABSTRACT FROM AUTHOR]

The goal of this pilot study was to characterize the effects of gait training on the capacity of muscles to produce body accelerations and relate these changes to mobility improvements seen in children with cerebral palsy (CP). Five children (14 years ± 3 y; GMFCS I-II) with spastic diplegic CP participated in a 6-week gait training program. Changes in 10-m fast-as-possible walking speed and 6-minute walking endurance were used to assess changes in mobility. In addition, musculoskeletal modeling was used to determine the potential of lower-limb muscles to accelerate the body's center of mass vertically and forward during stance. The mobility changes after the training were mixed, with some children demonstrating vast improvements, while others appeared to be minimal. However, the musculoskeletal results revealed unique responses for each child. The most common changes occurred in the capacity for the hip and knee extensors to produce body support and the hip flexors to produce body propulsion. These results cannot yet be generalized to the broad population of children with CP, but demonstrate that therapy protocols may be enhanced by modeling analyses. The pilot study results provide motivation for gait training emphasizing upright leg posture, mediolateral balance, and ankle push-off. [ABSTRACT FROM AUTHOR]

Context: Gluteal-muscle strength has been identified as an important component of injury prevention and rehabilitation in several common knee injuries. However, many conventionally prescribed gluteal-strengthening exercises are not performed during dynamic weight-bearing activities, which is when most injuries occur. Objectives: To compare lower-limb muscle-activation patterns between conventional gluteal-strengthening exercises and off-axis elliptical exercises with motorized foot-plate perturbations designed to activate gluteal muscles during dynamic exercise. Evidence Acquisition: Twelve healthy volunteers (26.1 ± 4.7 y) participated in the study. They performed 3 conventional exercises (single-leg squat, forward lunge, and clamshell) and 3 elliptical exercises (regular, while resisting an adduction force, and while resisting an internal-rotation torque). Gluteus medius (GMed) and maximus (GMax), quadriceps, hamstrings, and gastrocnemius muscle activations during each exercise were recorded using surface electromyography (EMG) and normalized to maximal voluntary isometric contraction (MVIC). Evidence Synthesis: Normalized GMed EMG was the highest during the adduction-resistance elliptical exercise (22.4% ± 14.8% MVIC), significantly greater than forward lunge (8.2% ± 3.8% MVIC) and regular elliptical (6.4% ± 2.5% MVIC) and similar to clamshell (19.1% ± 8.8% MVIC) and single-leg squat (18.4% ± 7.9% MVIC). Normalized GMax EMG during adduction-resistance (11.1% ± 7.6% MVIC) and internal-rotation-resistance elliptical (7.4% ± 3.8% MVIC) was significantly greater than regular elliptical (4.4% ± 2.4% MVIC) and was similar to conventional exercises. The single-leg squat required more muscle activation from the quadriceps and gastrocnemius than the elliptical exercises. Conclusions: Off-axis elliptical exercise while resisting an adduction force or internal-rotation torque activates gluteal muscles dynamically while avoiding excessive quadriceps activation during a functional weight-bearing activity compared with conventional gluteal-strengthening exercises. [ABSTRACT FROM AUTHOR]

Context: Athletic pelvic and groin injuries are a common yet challenging problem. Pelvic belts have been successfully used to reduce pain and improve function but are not a practical solution for athletes. Therefore, there is scope to explore the use of a more dynamic intervention developed to aid in the management of this type of injury. Objectives: To undertake a preliminary investigation into the effectiveness of a dynamic elastomeric fabric orthosis (DEFO) in supporting the management of athletic pelvic and groin injury. Design: A case series with an AB design. Daily assessments were undertaken over 15 days; the onset of intervention was randomized with a minimum baseline period of 6 d. Follow-up assessment was undertaken after 1 mo. Settings: Community and university. Participants: 8 athletes presenting with pelvic or groin injury confirmed through clinical screening. Intervention: A bespoke DEFO. Main Outcome Measures: Force produced on bilateral resisted hip adduction and self-scored pain (using a numerical rating scale of 0-10) at rest and during an active straight-leg raise and a broad jump. Results: In 7 cases a significant improvement was observed on at least 1 measure (2-SD method, celeration line, and/or the point of nonoverlapping data). The remaining case showed minimal symptoms during testing. [ABSTRACT FROM AUTHOR]

Purpose: Training in martial arts is commonly performed by repeating a technical action continuously for a given number of times. This study aimed to investigate if the repetition of the task alters the proper technical execution, limiting the training efficacy for the technical evaluation during competition. This aim was pursued analyzing lower-limb kinematics and muscle activation during repeated roundhouse kicks. Methods: Six junior karate practitioners performed continuously 20 repetitions of the kick. Hip and knee kinematics and sEMG of vastus lateralis, biceps (BF), and rectus femoris were recorded. For each repetition, hip abduction-adduction and flexion-extension and knee flexion-extension peak angular displacements and velocities, agonist and antagonist muscle activation were computed. Moreover, to monitor for the presence of myoelectric fatigue, if any, the median frequency of the sEMG was computed. All variables were normalized with respect to their individual maximum observed during the sequence of kicks. Linear regressions were fitted to each normalized parameter to test its relationship with the repetition number. Results: Linear-regression analysis showed that, during the sequence, the athletes modified their technique: Knee flexion, BF median frequency, hip abduction, knee-extension angular velocity, and BF antagonist activation significantly decreased. Conversely, hip flexion increased significantly. Conclusions: Since karate combat competitions require proper technical execution, training protocols combining severe fatigue and technical actions should be carefully proposed because of technique adaptations. Moreover, trainers and karate masters should consider including specific strength exercises for the BF and more generally for knee flexors. [ABSTRACT FROM AUTHOR]

Context: Hip- and knee-joint kinematics during drop landings are relevant to lower-extremity injury mechanisms. In clinical research the "gold standard" for joint kinematic assessment is 3-dimensional (3D) motion analysis. However, 2-dimensional (2D) kinematic analysis is an objective and feasible alternative. Objective: To quantify the relationship between 2D and 3D hip and knee kinematics in single-leg drop landings and test for a set of 3D hip and knee kinematics that best predicts 2D kinematic measures during single-leg drop landings Design: Descriptive, comparative laboratory study. Participants: 31 healthy college-age women (65.5 kg [SD 12.3], 168.1 cm [SD 6.7]). Methods: Participants performed five 40-cm single-leg landings during motion capture at 240 Hz. Multiple regressions were used to predict relationships for knee and hip between 2D frontal-plane projection angles (FPPA) and 3D measurements. Results: 2D knee FPPA had a strong relationship with 3D frontal-plane knee kinematics at initial contact (IC) (r² = .72), which was only minimally improved with the addition of knee sagittal-plane and hip transverse-plane positions at IC (r² = .77). In contrast, 2D knee FPPA had a low relationship with 3D knee-abduction excursion (r² = .06). The addition of knee sagittal-plane and hip transverse-plane motions did not improve this relationship (r² = .14). 2D hip FPPA had a moderate relationship with 3D frontal-plane hip position at IC (r² = .52), which was strengthened with the addition of hip sagittal-plane position (r² = .60). In addition, hip 2D FPPA into adduction excursion had a strong association with 3D hip-adduction excursion (r² = .70). Conclusion: 2D kinematics can predict 3D frontal-plane hip and knee position at IC during a single-leg landing but predict 3D frontal-plane knee excursion with far less accuracy. [ABSTRACT FROM AUTHOR]

Context: Ice hockey athletes frequently injure the hip complex via a noncontact mechanism. The authors investigated patterns of strength and range of motion (ROM) to establish major differences compared with soccer athletes. Soccer athletes were compared with ice hockey athletes due to similarities between the 2 sports with regard to the intermittent nature and high number of lower-limb injuries. Objective: To compare the differences in ROM and strength of the hip for both the dominant (Dom) and nondominant (Ndom) limbs in ice hockey and soccer athletes. Design: Case-control study. Setting: Bilateral ROM in hip flexion in sitting (FS) and lying (FL), extension, abduction, adduction, and internal rotation (IR) and external rotation (ER) were measured using a goniometer and assessed for strength using a handheld dynamometer on both the Dom and Ndom limbs. Participants: 24 male, active, uninjured NCAA Division III ice hockey (16) and soccer (8) athletes. Main Outcome Measures: ROM and strength for hip FS, FL, extension, abduction, adduction, IR, and ER. A mixed-model ANOVA was used to investigate interactions and main effects. Results: Ice hockey athletes exhibited greater hip-adduction ROM than soccer athletes in the Dom leg (both P = .002) and when both limbs were combined (P= .010). Ice hockey athletes had less ROM inER (P - .042) than soccer athletes. Ice hockey athletes displayed less strength in adduction in their Ndom leg than in their Dom leg (P - .02), along with less adduction than soccer players in their Ndom leg (P = .40). Ice hockey athletes displayed less strength in hip adduction (P = .030), FS (P - .023) and FL (P = .030) than soccer athletes. Conclusions: The findings suggest that ice hockey athletes may present an at-risk profile for noncontact hip injuries in comparison with soccer athletes with regard to strength and ROM of the hip. [ABSTRACT FROM AUTHOR]

Context: Ankle immobilization is often used after ankle injury. Objective: To determine the influence of 1 week's unilateral ankle immobilization on plantar-flexor strength, balance, and walking gait in asymptomatic volunteers. Design: Repeated-measures laboratory study. Setting: University laboratory. Participants: 6 physically active male participants with no recent history of lower-limb injury. Interventions: Participants completed a 1-wk period of ankle immobilization achieved through wearing a below-knee ankle cast. Before the cast was applied, as well as immediately, 24 h, and 48 h after cast removal, their plantar-flexor strength was assessed isokinetically, and they completed a single-leg balance task as a measure of proprioceptive function. An analysis of their walking gait was also completed Main Outcome Measures: Peak plantar-flexor torque and balance were used to determine any effect on muscle strength and proprioception after cast removal. Ranges of motion (3D) of the ankle, knee, and hip, as well as walking speed, were used to assess any influence on walking gait. Results: After cast removal, plantar-flexor strength was reduced for the majority of participants (P = .063, CI = -33.98 to 1.31) and balance performance was reduced in the immobilized limb (P < .05, CI = 0.84-5.16). Both strength and balance were not significantly different from baseline levels by 48 h. Walking speed was not significantly different immediately after cast removal but increased progressively above baseline walking speed over the following 48 h. Joint ranges of motion were not significantly different at any time point. Conclusions: The reduction in strength and balance after such a short period of immobilization suggested compromised central and peripheral neural mechanisms. This suggestion appeared consistent with the delayed increase in walking speed that could occur as a result of the excitability of the neural pathways increasing toward baseline levels. [ABSTRACT FROM AUTHOR]

Context: Hip-adductor strains are among the most common lower-extremity injuries sustained in athletics. Treatment of these injuries involves a variety of exercises used to target the hip adductors. Objective: To identify the varying activation levels of the adductor longus during common hip-adductor exercises. Design: Descriptive study. Setting: Laboratory. Participants: 24 physically active, college-age students. Intervention: None. Main Measurement Outcomes: Peak and average electromyographic (EMG) activity of the adductor longus muscle during the following 6 hip-adductor rehabilitation exercises: side-lying hip adduction, ball squeezes, rotational squats, sumo squats, standing hip adduction on a Swiss ball, and side lunges. Results: The side-lying hip-adduction exercise produced more peak and average activation than any other exercise (P < .001). Ball squeezes produced more peak and average activation than rotational squats, sumo squats, and standing adduction on a Swiss ball (P < .001). Ball squeezes had more average activation than side lunges (P = .001). All other variables for peak activation during the exercises were not statistically significant (P > .08). These results allowed the authors to provide an overall ranking system (highest to lowest muscle activation): side-lying hip adduction, ball squeezes, side lunges, standing adduction on a Swiss ball, rotational squats, and sumo squats. Conclusion: The study provides a ranking system on the activation levels of the adductor longus muscle for 6 common hip-adductor rehabilitation exercises, with the side-lying hip-adduction and ball-squeeze exercises displaying the highest overall activation. [ABSTRACT FROM AUTHOR]

Context: Decreased flexibility in muscles and joints of lower extremities is commonly observed in runners. Understanding the effect of decreased flexibility on knee walking kinematics in runners is important because, over time, altered gait patterns can make runners vulnerable to overuse injuries or degenerative pathologies. Objectives: To compare hamstring and iliotibial-band (ITB) flexibility and knee kinematics in runners and nonrunners. Design: A descriptive, comparative laboratory study. Setting: Hamstring and ITB flexibility were measured with the active knee-extension test and the modified Ober test, respectively, in both groups of participants. Three-dimensional (3D) walking kinematic data were then recorded at the knee using a motion-tracking system. Participants: 18 runners and 16 nonrunners. Main Outcome Measures: Knee-extension angle (hamstring flexibility) and hip-adduction angle (ITB flexibility). Knee kinematic parameters of interest included knee angle at initial contact, peak knee angles, and knee-angle range in all planes of movement. Results: The runners had a significantly less flexible ITB than the nonrunners (hip adduction [-] and adduction [+] angles, 3.1° ± 5.6° vs -6.4° ± 4.5°; P < .001). The runners demonstrated a greater mean tibial external-rotation angle at initial contact (7.3° ± 5.8° vs 2.0° ± 4.0°; P = .01) and a smaller mean peak tibial internal-rotation angle (-1.6° ± 3.0° vs -4.2° ± 3.2°; P = .04) than the nonrunners. Conclusion: This study provides new insight into the relationship between muscle flexibility and 3D knee kinematics in runners. This supports the premise that there is an association between muscle flexibility and transverse-plane knee kinematics in this population. [ABSTRACT FROM AUTHOR]

Limited data exists on knee biomechanics in alpine ski turns despite the high rate of injuries associated with this maneuver. The purpose of the current study was to compare knee joint loading between a carved and a skidded ski turn and between the inner and outer leg. Kinetic data were collected using Kistler mobile force plates. Kinematic data were collected with five synchronized, panning, tilting, and zooming cameras. Inertial properties of the segments were calculated using an extended version of the Yeadon model. Knee joint forces and moments were calculated using inverse dynamics analysis. The obtained results indicate that knee joint loading in carving is not consistently greater than knee joint loading in skidding. In addition, knee joint loading at the outer leg is not always greater than at the inner leg. Differentiation is required between forces and moments, the direction of the forces and moments, and the phase of the turn that is considered. Even though the authors believe that the analyzed turns are representative, results have to be interpreted with caution due to the small sample size. [ABSTRACT FROM AUTHOR]

Baseball players have demonstrated greater thoracolumbar rotation (TLR) range of motion (ROM) toward their nonthrowing arm sides. This imbalance is thought to be compensatory to ROM deficiencies at the throwing arm's shoulder. The purpose of this study was to examine the relationship between TLR and glenohumeral (GH) ROM measures (internal rotation, external rotation, horizontal adduction) among collegiate baseball players. Findings demonstrated limited and no relationships between TLR and GH ROM. Future research should advance these findings by examining symptomatic participants and hip ROM as additional variables. Doing so may enhance clinicians' abilities to comprehensively predict, prevent, detect, and treat movement deficiencies, and subsequent injuries, suffered by competitive baseball players. [ABSTRACT FROM AUTHOR]

Context: Previous studies investigated the relationship between ultrasound-derived anatomical muscle thickness (MTH) and individual muscle cross-sectional area (CSA) and muscle volume in several limb and trunk muscles; however, the adductor muscle that contributes to hip adduction and pelvic stabilization, as well as balance ability, has not been studied. Objective: To examine the relationship between MTH of the lower, middle, and upper thigh measured by B-mode ultrasound and the muscle CSA and volume of adductor muscle obtained by magnetic resonance imaging (MRI) to confirm the possibility of predicting adductor muscle CSA/volume using ultrasound-derived MTH. Setting: University research laboratory. Subjects: 10 men and 10 women (20-41 y old) volunteered to participate in this study. Main Outcome Measures: A series of continuous muscle CSAs along the thigh were measured by MRI scans (1.5-T scanner, GE Signa). In each slice, the anatomical CSA of the adductors was analyzed, and the muscle volume was calculated by multiplying muscle CSA by slice thickness. Thigh MTH was measured by B-mode ultrasound (Aloka SSD-500) at 5 sites (anterior 30%, 50%, and 70% and posterior 50% and 70% of thigh length). Results: A strong correlation was observed between anterior 30% MTH and 30% adductor CSA in men (r = .845, P < .002) and women (r = .952, P < .001) and in both groups combined (r = .922, P < .001). Anterior 30% MTH was also strongly correlated to adductor muscle volume when combined with thigh length (n = 20, r = .949, P < .001). However, there were moderate or nonsignificant correlations between anterior and posterior 50% and 70% MTH and adductor muscle CSA/volume. Conclusions: The results suggest that MTH in the upper portion of anterior thigh best reflects adductor muscle CSA or muscle volume, while the lower portions of the anterior and posterior sites are least likely to predict adductor muscle size. [ABSTRACT FROM AUTHOR]

Context: Posterior shoulder tightness has been associated with altered shoulder range of motion (ROM) and several pathologic entities in baseball players. This tightness is hypothesized to be the result of the cumulative stress placed on the posterior shoulder during the deceleration phase of the throwing motion. The role of the posterior shoulder static restraints is to absorb this load while the glenohumeral (GH) external rotators eccentrically decelerate the arm after ball release and therefore also help dissipate this force. As such, the authors hypothesized that if the GH external rotators are weak, an excessive amount of this deceleration force is placed on the static restraints, which may lead to subsequent tightness. Objective: To compare the relationship between GH external-rotation strength and posterior shoulder tightness as measured by GH horizontal-adduction and internal-rotation ROM. Design: Descriptive study. Setting: Laboratory. Participants: 45 professional baseball players. Main Outcome Measures: GH external-rotation strength and GH horizontal-adduction and internal-rotation ROM. Results: GH external-rotation strength showed no relationship with either GH horizontal-adduction ROM (r2 = .02, P = .40) or GH internal-rotation ROM (r2 = .002, P = .77). Conclusion: There is little to no relationship between GH external-rotation strength and posterior shoulder tightness in professional baseball players. The posterior static restraints of the shoulder may absorb a large majority of the deceleration forces during the throwing motion. Although strengthening of the posterior shoulder dynamic restraints should not be overlooked, routine stretching of the static restraints may be more beneficial for decreasing posterior shoulder tightness and the subsequent risks associated with this tightness, although future research is warranted. [ABSTRACT FROM AUTHOR]

Context: Recently, attention in sports has been given to eccentric hip-muscle function, both in preventing musculoskeletal injuries and improving performance. Objective: To determine the key isokinetic variables of eccentric hip torque that predict the functional performance of women in the single-leg triple long jump (TLJ) and the timed 6-m single-leg hop (TH). Design: Within-subject correlational study. Setting: Musculoskeletal laboratory. Participants: 32 healthy women age 18-25 y. Intervention: The participants performed 2 sets of 5 eccentric hip-abductor/adductor and lateral/medial-rotator isokinetic contractions (30°/s) and 3 attempts in the TLJ and TH. Main Outcome Measurements: The independent variables were the eccentric hip-abductor and -adductor and medial- and lateral-rotator isokinetic peak torque, normalized according to body mass (Nm/kg). The dependent variables were the longest distance achieved in the TLJ normalized according to body height and the shortest time spent during the execution of the TH. Results: The forward-stepwise-regression analysis showed that the combination of the eccentric hip lateral-rotator and -abductor isokinetic peak torque provided the most efficient estimate of both functional tests, explaining 65% of the TLJ variance (P < .001) and 55% of the TH variance (P < .001). Conclusions: Higher values for eccentric hip lateral-rotator and hip-abductor torques reflected better performance. Thus, the eccentric action of these muscles should be considered in the development of physical training programs that aim to increase functional performance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effect of cross-slope on gait dynamics. Ten young adult males walked barefoot along an inclinable walkway. Ground reaction forces (GRFs), lower-limb joint kinematics, global pelvis orientation, functional leg-length, and joint reaction moments (JRMs) were measured. Statistical analyses revealed differences across limbs (up-slope [US] and down-slope [DS]) and inclinations (level; 0°; and cross-sloped, 6°). Adaptations included increases of nearly 300% in mediolateral GRFs (p < .001), functional shortening the US-limb and elongation of the DS-limb (p < .001), reduced step width (p = .024), asymmetrical changes in sagittal kinematics and JRM, and numerous pronounced coronal plane differences including increased US-hip adduction (and adductor moment) and decreased DS-hip adduction (and adductor moment). Data suggests that modest cross-slopes can induce substantial asymmetrical changes in gait dynamics and may represent a physical obstacle to populations with restricted mobility. [ABSTRACT FROM AUTHOR]

This experiment examined the magnitude and structure of force variability in isometric index finger force production tasks at 5, 15, 25, 35, 45, 55, 65, 75, 85, and 95% of maximal force in two different finger orientations. In the finger flexion task, the participants generated a downward isometric force through index finger flexion. In the finger abduction task, isometric force was generated by adducting the index finger (mediolateral motion of the middle finger and forearm were restricted). The task-related, normal force (Fz) and tangential forces (Fx and Fy) were collected with a three-dimensional force transducer. The standard deviation (SD) of the task-related force output (Fz) increased exponentially with force level. With increasing force level, approximate entropy (ApEn, a measure of irregularity) of Fz followed an inverted-U function for finger flexion, but decreased linearly in finger abduction. However, changes in the ApEn of the tangential forces were generally opposite to that of Fz, revealing compensations in the irregularity of force output between force dimensions. The findings provide evidence that force variability is related to muscle force-length characteristics (Feldman, 1966; Gottlieb & Agarwal, 1988). [ABSTRACT FROM AUTHOR]