Effects of an Intervention Program on Lower Extremity Biomechanics in Stop-Jump and Side-Cutting Tasks

Return to play and athletic performance in division I female volleyball players following anterior cruciate ligament injury

OBJECTIVES

The purpose of this study is to examine NCAA Division I volleyball players' return to play rates and performance statistics compared to pre-injury levels following ACL injury.

METHODS

Female volleyball players that sustained ACL injuries from 2008 to 2020 and competed in one of seven collegiate conferences (n = 99) were identified via an internet search algorithm. Players were categorized by position, academic year, and playing time pre- and post-injury. Post-injury performance statistics were gathered for a subset of outside hitters and middle blockers that played in ≥35 sets in a single season for up to 3 years following injury (mean 1.7 seasons). A control group (n = 512) was generated for demographic and statistical comparison. Mean pre-injury and post-injury statistics were compared for players that did not change positions and played ≥35 sets before and after injury.

RESULTS

Volleyball attackers were 54.7% of the control population but sustained 78.8% of identified injuries. Following ACL injury, 6.1% of players registered no in-game statistics, 16.2% played in <35 sets, 65.7% played in ≥35 sets, and 12.1% graduated. Mean performance statistics increased linearly the more years players were from ACL injury.

CONCLUSIONS

Female collegiate volleyball players return to play following ACL injury at high rates (93.1%) and maintain pre-injury performance levels. Volleyball attackers sustain ACL injuries more commonly than setters and libero/defensive specialists.

Injury Prevention Programmes Fail to Change Most Lower Limb Kinematics and Kinetics in Female Team Field and Court Sports: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

BACKGROUND

One mechanism by which exercise interventions may be effective in reducing anterior cruciate ligament (ACL) injury risk is through changes in lower limb biomechanics. Understanding how training programmes affect lower-limb kinematics and kinetics may help refine injury prevention programmes.

OBJECTIVE

The aim of this systematic review and meta-analysis was to assess the effect of injury prevention programmes on kinematics and kinetics during tasks related to ACL injury in female team field and court sports.

DATA SOURCES

Five databases were searched in October 2022.

ELIGIBILITY CRITERIA

Randomised controlled trials assessing the effect of injury prevention programmes compared with usual training/no training on lower limb kinematics and kinetics in female team field and court sports were eligible for review.

RESULTS

Sixteen studies were included. A total of 976 female athletes were included. Most of the studies included interventions with multiple components (12/16). Commonly used components were plyometrics (12/16), strength (8/16), and balance/stability (7/16). Thirteen studies had routine training or sham interventions as the control group and three studies had no training. Very low certainty evidence suggests that injury prevention programmes increase knee flexion angles (mean difference = 3.1° [95% confidence interval 0.8-5.5]); however, very low to low certainty evidence suggests no effect on hip flexion angles/moments, knee flexion moments, hip adduction angles/moments, knee adduction angles/moments, hip internal rotation angles/moments, ankle dorsiflexion angles, and ground reaction forces, compared with usual training/no training.

CONCLUSION

Injury prevention programmes may be effective in increasing knee flexion angles during dynamic landing and cutting tasks but may have no effect on other lower limb biomechanical variables. As such, the benefits of injury prevention programmes may be mediated by factors other than altered biomechanics and/or may happen through other biomechanical measures not included in this review.

The impact of whole-body vibration training and proprioceptive neuromuscular facilitation on biomechanical characteristics of lower extremity during cutting movement in individuals with functional ankle instability: A parallel-group study

BACKGROUND

We compared the effects of whole-body vibration training and proprioceptive neuromuscular facilitation on the biomechanical characteristics of the lower limbs in functional ankle instability patients during cutting movement to ascertain the superior rehabilitation method.

METHODS

Twenty-two male College students with unilateral functional ankle instability volunteered for this study and were randomly divided into whole-body vibration training group and proprioceptive neuromuscular facilitation group. Kinematics data and ground reaction forces were collected using infrared motion capture system and 3-D force plates synchronously during cutting. Repeated measures two-way ANOVA was performed to analyze the data.

FINDINGS

Both training methods reduced the maximum hip abduction angle (p = 0.010, effect size: proprioceptive neuromuscular facilitation = 0.69; whole-body vibration training = 0.20), maximum knee flexion angle (p = 0.008, effect size: proprioceptive neuromuscular facilitation = 0.39, whole-body vibration training = 1.26) and angular velocity (p = 0.014, effect size: proprioceptive neuromuscular facilitation = 0.62, whole-body vibration training = 0.55), maximum ankle inversion angular velocity (p = 0.020, effect size: proprioceptive neuromuscular facilitation = 0.52, whole-body vibration training = 0.81), and knee flexion angle at the time of maximum vertical ground reaction forces (p = 0.018, effect size: proprioceptive neuromuscular facilitation = 0.27, whole-body vibration training = 0.76), and increased the maximum ankle dorsiflexion moment (p = 0.049, effect size: proprioceptive neuromuscular facilitation = -0.52, whole-body vibration training = -0.22). Whole-body vibration training reduced the maximum ground reaction forces value in the mediolateral directions (p = 0.010, effect size = 0.82) during cutting movement.

INTERPRETATION

These findings suggested that the two types of training might increase neuromuscular conduction function around the ankle. After these two types of training, functional ankle instability patients showed a similar risk of injury to the lateral ankle ligaments during cutting.

Ankle biomechanics of the three-step layup in a basketball player with chronic ankle instability

At present, the effects of chronic ankle instability (CAI) on the biomechanics of the ankle joint in the three-step layup of basketball players are not clear. This work aims to thoroughly investigate the impact of CAI on the biomechanical characteristics of the ankle during the execution of a three-step layup in basketball players. Thirty male basketball players were stratified into distinct groups-namely, a CAI group and a non-CAI group-comprising 15 individuals each, based on the presence or absence of CAI. Demographic attributes, including age, weight, height, and the Cumberland Ankle Instability Tool (CAIT) score, were subjected to rigorous statistical examination within both athlete cohorts. The research employed four Whistler 9281CA 3D force measuring platforms (Switzerland), recording at 1000 Hz, in conjunction with eight camera motion analysis systems (USA), functioning at a frequency of 200 Hz. The study recorded maximal plantarflexion angle, inversion angle, dorsiflexion angle, and peak ankle dorsiflexion moment across the subjects during the distinct phases of push-off, landing, and the ensuing landing period. The findings notably exhibited that within the context of the one-foot push-off phase, the maximum ankle inversion angle was notably diminished in the CAI group as contrasted with the non-CAI group, demonstrating statistical significance (t = - 3.006, P < 0.01). The CAI group exhibited a lesser alteration in ankle inversion angle compared to the non-CAI group. Notably, during the one-foot landing period, the CAI group demonstrated a significantly greater maximum ankle inversion angle in contrast to the non-CAI group (t = 8.802, P < 0.001). Furthermore, the CAI group displayed a substantially larger maximum dorsiflexion angle at the ankle joint compared to the non-CAI group (t = 2.265, P < 0.05). Additionally, the CAI group exhibited a prolonged peak time for ankle dorsiflexion moment as compared to the non-CAI group (t = - 2.428, P < 0.05). Collectively, the findings elucidated a reduction in the maximum ankle joint inversion angle during the one-foot push-off phase in individuals with CAI. Furthermore, increased maximum inversion angle and maximum dorsiflexion angle of the ankle joint were observed during the one-foot landing period, alongside a lengthening of the peak time of ankle dorsiflexion moment. These results contribute valuable insights into the selection of training methodologies for basketball players afflicted by CAI.

Training interventions to reduce the risk of injury to the lower extremity joints during landing movements in adult athletes: a systematic review and meta-analysis

Objective

Aim of this systematic review was to summarise training interventions designed to reduce biomechanical risk factors associated with increased risk of lower extremity landing injuries and to evaluate their practical implications in amateur sports.

Design

Systematic review and meta-analysis.

Data sources

MEDLINE, Scopus and SPORTDiscus.

Eligibility criteria

Training intervention(s) aimed at reducing biomechanical risk factors and/or injury rates included the following: (1) prospective or (non-)randomised controlled study design; (2) risk factors that were measured with valid two-dimensional or three-dimensional motion analysis systems or Landing Error Scoring System during jump landings. In addition, meta-analyses were performed, and the risk of bias was assessed.

Results

Thirty-one studies met all inclusion criteria, capturing 11 different training interventions (eg, feedback and plyometrics) and 974 participants. A significantly medium effect of technique training (both instruction and feedback) and dynamic strengthening (ie, plyometrics with/without strengthening) on knee flexion angle (g=0.77; 95% CI 0.33 to 1.21) was shown. Only one-third of the studies had training interventions that required minimal training setup and additional coaching educations.

Conclusion

This systematic review highlights that amateur coaches can decrease relevant biomechanical risk factors by means of minimal training setup, for example, instructing to focus on a soft landing, even within only one training session of simple technique training. The meta-analysis emphasises implementing technique training as stand-alone or combined with dynamic strengthening into amateur sport training routine.

The Soft Prefabricated Orthopedic Insole Decreases Plantar Pressure during Uphill Walking with Heavy Load Carriage

This study aimed to investigate the effect of varying the hardness of prefabricated orthopedic insoles on plantar pressure and muscle fatigue during uphill walking with a heavy backpack. Fifteen healthy male recreational athletes (age: 20.4 ± 1.0 years, height: 176.9 ± 5.7 cm, weight: 76.5 ± 9.0 kg) wore prefabricated orthopedic insoles with foot arch support; a heel cup with medium (MI), hard (HI), and soft (SI) relative hardnesses; and flat insoles (FI). They performed treadmill walking on uphill gradients with 25 kg backpacks. The plantar pressure and surface electromyographic activity were recorded separately, in 30 s and 6 min uphill treadmill walking trials, respectively. The HI, MI, and SI significantly decreased peak plantar pressure in the lateral heel compared to FI. The MI and SI significantly decreased the peak plantar pressure in the fifth metatarsal compared to FI. The MI significantly reduced the pressure–time integral in the lateral heel compared to FI. The HI significantly increased the peak plantar pressure and pressure–time integral in the toes compared to other insoles, and decreased the contact area in the metatarsal compared to SI. In conclusion, a prefabricated orthopedic insole made of soft material at the fore- and rearfoot, with midfoot arch support and a heel cup, may augment the advantages of plantar pressure distribution during uphill weighted walking.

Reducing Knee Joint Load during a Golf Swing: The Effects of Ball Position Modification at Address

As the modern golf swing has changed, the incidence of knee pain in professional golfers is increasing. For those with previous knee injuries, developing a golf-swing modification that reduces knee loading may be necessary to recover performance after injury. The purpose of this study was to test whether ball position modification reduces knee joint load in a golf swing. Thirteen male professional golfers participated in the study. Golf swings were captured using a three-dimensional motion capture system and two force platforms, with conditions for self-selected ball position and eight additional ball positions. Knee internal rotation and adduction moments were calculated. The length of one golf ball (4.27 cm) backward ball position (closer to the golfer) significantly reduced the peak internal rotation moment of the lead knee (- 13.8%) (p &lt; 0.001) and the length of one golf ball (4.27 cm) away from the target ball position significantly reduced the peak adduction moment of the lead knee (- 11.5%) (p &lt; 0.001) compared with that of the self-selected ball position. Based on these observations, we conclude that the backward ball position modification might be suggested for golfers with anterior cruciate ligament injuries, and the away from the target modification might be suggested for golfers with medial compartment knee osteoarthritis.

The effect of arch-support insole on knee kinematics and kinetics during a stop-jump maneuver

BACKGROUND

Anterior cruciate ligament injuries commonly occur during sports that involve sudden stops or direction changes. Although athletes often use arch-support insoles in competition and training, little is known about the effect of foot insoles on knee biomechanics and jump take-off performances.

OBJECTIVE

This study aimed to investigate the effects of arch-support insoles on knee kinematics and kinetics during the stop-braking phase and the subsequent jump take-off performances.

STUDY DESIGN

That is a quasi-experimental study, repeated-measures design.

METHODS

Twenty male healthy recreational university basketball athletes performed stop-jump with maximum effort in both arch-support and flat insole conditions. Paired t -tests were performed on knee kinetics and kinematics and jump performance variables to determine whether there were significant differences between insole conditions.

RESULTS

Wearing arch-support insoles experienced larger ground reaction forces (GRFs), loading rates of peak vertical and posterior GRFs, peak knee adduction and rotation moments, and knee flexion angular velocity than the flat insoles ( P < 0.05).

CONCLUSIONS

The increased GRFs and knee loading in arch-support insoles are indicative of a higher risk of anterior cruciate ligament injuries. The findings could be insightful to the knee mechanics that are related to performance and injury potential during stop-jump maneuvers.

Knee biomechanical factors associated with patellofemoral pain in recreational runners

BACKGROUND

Patellofemoral pain (PFP) is a common injury among runners. Knee biomechanical factors associated with PFP, however, remain unclear. The purpose of this study was to determine possible associations between knee biomechanics and symptoms of PFP in recreational runners.

METHODS

Fifteen male and 15 female recreational runners with PFP were enrolled as the PFP group, 30 matched runners without PFP were recruited as the control group. The PFP group was tested running with and without knee pain, while the control group had only one running test. Reflective marker coordinates and ground reaction force data were collected in each test. Knee kinematics and kinetics during running were reduced and compared between groups (PFP group without knee pain and control group) and between pain conditions (PFP group with knee pain and without knee pain), as well as between sexes.

RESULTS

Female and male participants with PFP had an increased peak knee valgus angle when running without pain compared to matched controls (P = 0.001), and to themselves when running with pain (P = 0.001). Male participants with PFP also had an increased peak knee flexion angle when running without pain compared to matched controls (P = 0.008), however did not decrease their peak knee flexion angle when running with pain (P = 0.245). No significant main effect of group or pain condition on any peak knee joint moment during running was detected (P ≥ 0.175).

CONCLUSIONS

Increased peak knee valgus angle during running appears to be a critical biomechanical factor associated with PFP in recreational runners, while decreasing knee valgus angle during running may be an adaptation to reduce symptoms of PFP. Increased peak knee flexion angle during running appears to be another biomechanical factor associated with PFP that is sex specific for male recreational runners.

Effects of Video Task With a High-Level Exercise Illustration on Knee Movements in Male Volleyball Spike Jump

Hazardous knee biomechanics, such as excessive knee affordance link with injuries in volleyball spike jumps (SPJs) and can be reconfigured by the enhancement of internal focus. The study aimed to explore the effects of video tasks illustrating a high-level SPJ on knee movement in the volleyball SPJ with 15 elite male volleyball athletes. This study investigated the knee movements in sagittal, coronal, and transverse planes before and after the video task in SPJ using one-dimensional statistical parametric mapping (SPM 1D) and discrete statistics. The SPM 1D indicated a larger knee flexion angle (31.17–73.19%, t = 2.611, and p = 0.012), increased knee flexion moment (19.72–21.38%, t = 0.029, and p = 0.029), and increased knee adduction angular velocity (49.07–62.64%, t = 3.148, and p = 0.004) after video task; alternatively, smaller knee external rotation angular velocity (45.85–49.96%, t = 5.199, and p = 0.017) and vertical ground reaction (vGRF) (3.13–5.94%, t = 4.096, and p = 0.014; 19.83–21.97%, t = 4.096, and p = 0.024) were found after the task. With discrete value statistics, the video task increased the peak of knee flexion angle while decreased the peak of extension moment, flexion moment, abduction moment, external moment, the first peak vGRF, and related loading rate.

Conclusions: The results indicate that knee biomechanics in volleyball SPJ positively influenced by the video task. The task has the athletes control the knee movements more actively and improves the original hazardous movement strategies. Therefore, the video task presumably can abate the occurrence of knee injuries in volleyball SPJ. Further validation especially in the exercise effect is needed in the future.

Increased Ankle Range of Motion Reduces Knee Loads During Landing in Healthy Adults

Decreased dorsiflexion range of motion (DROM) can be modified using static stretching and joint mobilizations and may attenuate known knee anterior cruciate ligament injury risk factors. It is not known how these interventions compare to each other and how they improve knee landing mechanics. This study's purpose was to determine the immediate effects of static stretching and joint mobilization interventions on DROM measurement changes and right-leg drop jump knee landing mechanics. Eighteen females and 7 males, all recreationally active, completed 2 study sessions. Active and passive DROM, the weight-bearing lunge test, the anterior reach portion of the Star Excursion Balance Test, and a right-leg drop jump landing task were completed before and after the intervention. Change in DROM (ΔDROM) was calculated for DROM assessments between preintervention and postintervention. Pairwise dependent t tests determined no differences in ΔDROM between interventions, and statistical parametric mapping determined increased knee flexion (P = .004) and decreased anterior shear force (P = .015) during landing after both interventions. Increased DROM improves sagittal plane displacement and loading at the knee. Stretching may be a more feasible option in a healthy population for those wanting to maintain range of motion and decrease knee injury risk without physical therapist involvement.

The Effects of Internal Attention on Knee Biomechanics in Volleyball Spike Jump through Augmented Video Feedback

Poor knee biomechanics in a volleyball spike jump generally result in a higher knee injury risk, which can be altered by an internal focus of attention (FOA). The constrained action hypothesis (CAH) purports that the FOA inhibits sports performance whereas no ecologically valid evidence has been found in previous studies. The purpose of this research is to explore the effect of video feedback on knee biomechanics in a volleyball spike jump including landing and take-off phases. The video feedback was performed in a natural way. Fourteen volleyball male players were recruited in this study. A paired t-test was used to detect the effect of the feedback; meanwhile, statistical parameter mapping (SPM) statistics were used for the continuum differences during movement. After biofeedback, the initial contact flexion angle of the knee (t = 2.179, p = 0.049), the maximal flexion angle of the knee (t = 3.242, p = 0.006) and the maximal internal rotation angular velocity of the knee (t = 5.209, p = 0.003) increased significantly; the maximal extension moment of the knee (t = 3.962, p < 0.001) and the maximal flexion moment of the knee (t = −3.711, p = 0.002) significantly decreased; the maximal abduction moment significantly decreased (t = 3.069, p = 0.037) but the maximal internal rotation moment significantly increased (t = 2.813, p = 0.018); the first peak of the vertical ground reaction force (vGRF) (t = 7.618, p < 0.001) and the average loading rate to the first peak (t = 4.205, p = 0.004) significantly decreased; the other peaks of the vGRF were not found to have differences; a larger knee flexion was found during the phase from 31.17 to 73.19% (t = 2.611, p = 0.012); a larger adduction angular velocity was found during the phase from 49.07 to 62.46% (t = 3.148, p = 0.004); a smaller external rotational angular velocity was found during the phase from 45.85 to 49.96% (t = 5.011 p = 0.017); there was an increased flexion moment of the knee during the phase from 19.72 to 21.38% (t = 0.029, p = 0.029) and an external moment of the knee during the phase from 85.55 to 95.06% (t = 4.214, p < 0.001); the vGRF significantly decreased during the phase from 3.13 to 5.94% (t = 4.096, p = 0.014) and 19.83–21.97% (t = 4.096, p = 0.024) but significantly increased in the phase of 91.43–100% (t = 4.096, p < 0.001). The impulse of the vGRF and knee power were not found to be different compared with before biofeedback. Therefore, our study suggests video feedback in a natural practice has the potential to improve knee movement whilst not altering the performance in a volleyball spike jump. This indicates that the CAH theory is possibly not suitable in a real competition. Due to the complexity of human movements and the limitations of this study, muscle activities must be considered in the future.

Whole-Body Change-of-Direction Task Execution Asymmetries After Anterior Cruciate Ligament Reconstruction

Cutting maneuvers can be executed at a range of angles and speeds, and these whole-body task descriptors are closely associated with lower-limb mechanical loading. Asymmetries in angle and speed when changing direction off the operated and nonoperated limbs after anterior cruciate ligament reconstruction may therefore influence the interpretation of interlimb differences in joint-level biomechanical parameters. The authors hypothesized that athletes would reduce center-of-mass heading angle deflection and body rotation during the change-of-direction stance phase when cutting from the operated limb, and would compensate for this by orienting their center-of-mass trajectory more toward the new intended direction of travel prior to touchdown. A total of 144 male athletes 8 to 10 months after anterior cruciate ligament reconstruction performed a maximum-effort sidestep cutting maneuver while kinematic, kinetic, and ground reaction force data were recorded. Peak ground reaction force and knee joint moments were lower when cutting from the operated limb. Center-of-mass heading angle deflection during stance phase was reduced for cuts performed from the operated limb and was negatively correlated with heading angle at touchdown. Between-limb differences in body orientation and horizontal velocity at touchdown were also observed. These systematic asymmetries in cut execution may require consideration when interpreting joint-level interlimb asymmetries after anterior cruciate ligament reconstruction and are suggestive of the use of anticipatory control to co-optimize task achievement and mechanical loading.

The Effect of Training Interventions on Change of Direction Biomechanics Associated with Increased Anterior Cruciate Ligament Loading: A Scoping Review

Change of direction (COD) manoeuvres are associated with anterior cruciate ligament (ACL) injury risk due to the propensity to generate large multiplanar knee joint loads. Given the short- and long-term consequences of ACL injury, practitioners are interested in methods that reduce knee joint loads and subsequent ACL loading. An effective strategy to reduce ACL loading is modifying an athlete’s movement mechanics to reduce knee joint loading. The purpose of this scoping review was to critically appraise and comprehensively synthesise the existing literature related to the effects of training interventions on COD biomechanics associated with increased knee joint loads and subsequent ACL loading, and identify gaps and recommend areas for future research. A review of the literature was conducted using Medline and Sport DISCUS databases. Inclusion criteria consisted of pre-post analysis of a COD task, a minimum 4-week training intervention, and assessments of biomechanical characteristics associated with increased ACL loading. Of the 1,027 articles identified, 22 were included in the scoping review. Based on current literature, balance training and COD technique modification are the most effective training modalities for reducing knee joint loading (small to moderate effect sizes). One study reported dynamic core stability training was effective in reducing knee joint loads, but further research is needed to definitively confirm the efficacy of this method. Perturbation-enhanced plyometric training, the F-MARC 11 + soccer specific warm-up, Oslo Neuromuscular warm-up, and resistance training are ineffective training modalities to reduce COD knee joint loads. Conflicting findings have been observed for the Core-Pac and mixed training programme. Consequently, practitioners should consider incorporating balance and COD technique modification drills into their athletes’ training programmes to reduce potentially hazardous knee joint loads when changing direction. However, training intervention studies can be improved by investigating larger sample sizes (> 20), including a control group, acknowledging measurement error when interpreting their findings, and considering performance implications, to confirm the effectiveness of training interventions and improve adherence.

Prediction of Knee Kinematics at the Time of Noncontact Anterior Cruciate Ligament Injuries Based on the Bone Bruises

Biomechanical risk factors associated with the alignment and position of the knee for anterior cruciate ligament (ACL) injury are still not conclusive. As bone bruises identified on magnetic resonance imaging (MRI) following acute ACL injury could represent the impact footprint at the time of injury. To improve understanding of the ACL injury mechanism, we aimed to determine the knee kinematics during ACL injury based on the bone bruises. Knee MRI scans of patients who underwent acute noncontact ACL injuries were acquired. Numerical optimization was used to match the bone bruises of the femur and tibia and predict the knee positions during injury. Knee angles were compared between MRI measured position and predicted position. The knee flexion, abduction, and external tibial rotation angles were significantly greater in the predicted position than that in MRI measured position. Relative to MRI measured position, patients had a mean of 34.3 mm of anterior tibial translation, 4.0 mm of lateral tibial translation, and 16.0 mm superior tibial translation in the predicted position. The results suggest that knee valgus and external tibial rotation accompanied by knee flexion are high-risk movement pattern for ACL injury in patients with lateral compartment bone bruising in conjunction with ACL injury.

The Influence of Hip Structure on Functional Valgus Collapse During a Single-Leg Forward Landing in Females

Clinical femoral anteversion (Craig test) and hip range of motion (ROM) have been associated with valgus collapse, but their clinical usefulness in predicting biomechanics is unknown. Our purpose was to determine the individual and combined predictive power of femoral anteversion and passive hip ROM on 3-dimensional valgus collapse (hip internal rotation and adduction, knee rotation, and abduction) during a single-leg forward landing in females. Femoral anteversion and passive hip ROM were measured on 20 females (24.9 [4.1] y, 168.7 [8.0] cm, 63.8 [11.6] kg). Three-dimensional kinematics and kinetics were collected over 5 trials of the task. Each variable was averaged across trials. Backward, stepwise regressions determined the extent to which our independent variables were associated with valgus collapse. The combination of greater hip internal and external rotation ROM (partial r = .52 and .56) predicted greater peak knee internal rotation moment (R2 = .38, P = .02). Less hip internal rotation ROM (partial r = −.44) predicted greater peak knee abduction moments (R2 = .20, P = .05). Greater total hip ROM (internal and external rotation ROM) was not consistently associated with combined motions of valgus collapse but was indicative of isolated knee moments. Passive hip ROM is more associated with knee moments than is femoral anteversion as measured with Craig test.

Muscle Strength Training Alters Muscle Activation of the Lower Extremity during Side-Step Cutting in Females

The objective of this study was to examine the effects of muscle strength training on knee kinematics/kinetics and muscle activation patterns during anticipated side-step cutting. Three-dimensional knee kinematics/kinetics data and muscle activation of selected lower extremity muscles were measured while performing cutting before and after completing 10-week circuit strength training mixed typical resistance training and power training (intervention) or no training (control) from 25 female subjects. The muscle strength of quadriceps and hamstrings were measured before and after training using isokinetic dynamometer. No statistically significant differences were observed in quadriceps and hamstrings muscle strength, all kinematic/kinetic variables, and muscle activation for the control group. Both quadriceps (p = 0.005) and hamstrings (p = 0.030) muscle strength were increased after training. An increased biceps femoris (p = 0.003) and H:Q ratio of activation (p = 0.016), as well as decreased gastrocnemius muscle activation (p = 0.012) during pre-activation phase in intervention group were found. No significant differences were found in knee kinematics and kinetics both at the time frame of the initial contact and the peak tibial anterior shear force after training. In conclusion, muscle strength training altered some muscle activations of lower extremity muscles, which might affect the risk of ACL injury, but it did not change the kinematic/kinetic parameters.