The effect of a hip-strengthening program on mechanics during running and during a single-leg squat

Criteria and Guidelines for Returning to Running Following a Tibial Bone Stress Injury: A Scoping Review

Tibial bone stress injuries (BSIs) are common among long-distance runners. They have a high recurrence rate, and complexity emerges in the wider management and successful return to running. Following a tibial BSI, a critical component of complete rehabilitation is the successful return to running, and there is a lack of consistency or strong evidence to guide this process. The objectives of this review were to outline the criteria used in clinical decision-making prior to resuming running, and to establish evidence-based guidelines for the return to running process following a tibial BSI. Electronic databases including MEDLINE, CINAHL, Scopus, SPORTDiscus and AMED were searched for studies that stated criteria or provided guidelines on the objectives above. Fifty studies met the inclusion criteria and were included. Thirty-nine were reviews or clinical commentaries, three were retrospective cohort studies, two were randomised controlled trials, two were pilot studies, one was a prospective observational study, and three were case studies. Therefore, the recommendations that have been surmised are based on level IV evidence. Decisions on when an athlete should return to running should be shared between clinicians, coaches and the athlete. There are five important components to address prior to introducing running, which are: the resolution of bony tenderness, pain-free walking, evidence of radiological healing in high-risk BSIs, strength, functional and loading tests, and the identification of contributing factors. Effective return to running planning should address the athlete's risk profile and manage the risk by balancing the athlete's interests and reinjury prevention. An individualised graduated return to running programme should be initiated, often starting with walk-run intervals, progressing running distance ahead of speed and intensity, with symptom provocation a key consideration. Contributing factors to the initial injury should be addressed throughout the return to run process.

Unveiling the influence of hip isokinetic strength on lower extremity running kinematics in male national middle-distance runners: a correlational analysis

BACKGROUND

The relationship between hip strength deficiency in various planes and musculoskeletal injuries within the movement system has been well-established in numerous studies. The present study sought to explore the relationships between hip strength and specific aspects of lower extremity running kinematics.

METHODOLOGY

To achieve this objective, the three-dimensional running kinematics of 21 male elite middle-distance runners (mean age: 19.7 ± 1.2 years; mean experience 6.5 ± 1.0 years) were assessed using nine high-speed cameras on a treadmill at a speed of 16 km·h⁻¹. Concurrently, isokinetic hip strength was measured at a speed of 60 deg·s⁻¹ in both the dominant and non-dominant legs. The Pearson correlation coefficient and Paired Samples t-test were utilized.

RESULTS

While no significant differences were found in several isokinetic strength measurements, notable differences in running kinematics were observed. Specifically, pelvic drop at midstance (MS) was significantly lower in the DL (5.79 ± 3.00°) compared to the NDL (8.71 ± 1.39°) with a large effect size (t=-4.04, p < 0.001, Cohen's d = 1.25). Additionally, knee adduction at maximum showed a moderate effect size difference, with the DL at 2.99 ± 1.13° and the NDL at 3.81 ± 1.76° (t=-2.74, p = 0.03, Cohen's d = 0.55). Results indicated a moderate to highly positive association between running knee adduction in the dominant leg and hip external rotation (r = 0.67, p < 0.05), concentric extension (r = 0.77, p < 0.05), and concentric abduction (r = 0.78, p < 0.05). Additionally, the running tibial external rotation angle in the dominant leg exhibited an inverse relationship with all strength measurements, with statistical significance observed only for concentric extension force (r=-0.68, p < 0.05). Furthermore, hip internal rotation force demonstrated a highly inverse correlation with foot pronation in the dominant leg (r=-0.70, p < 0.05) and anterior pelvic tilt in the non-dominant leg (r=-0.76, p < 0.05).

CONCLUSIONS

These findings underscore the interrelation between hip strength and running kinematics, particularly on the dominant side. In light of these observations, it is imperative to consider hip strength exercises as integral components for correcting running kinematics. Coaches should also be mindful that kinematic deviations contributing to running injuries may manifest unilaterally or specifically in the dominant leg.

The Effect of Strength Training Methods on Middle-Distance and Long-Distance Runners' Athletic Performance: A Systematic Review with Meta-analysis

BACKGROUND

The running performance of middle-distance and long-distance runners is determined by factors such as maximal oxygen uptake (VO2max), velocity at VO2max (vVO2max), maximum metabolic steady state (MMSS), running economy, and sprint capacity. Strength training is a proven strategy for improving running performance in endurance runners. However, the effects of different strength training methods on the determinants of running performance are unclear.

OBJECTIVE

The aim of this systematic review with meta-analysis was to compare the effect of different strength training methods (e.g., high load, submaximal load, plyometric, combined) on performance (i.e., time trial and time until exhaustion) and its determinants (i.e., VO2max, vVO2max, MMSS, sprint capacity) in middle-distance and long-distance runners.

METHODS

A systematic search was conducted across electronic databases (Web of Science, PubMed, SPORTDiscus, SCOPUS). The search included articles indexed up to November 2022, using various keywords combined with Boolean operators. The eligibility criteria were: (1) middle- and long-distance runners, without restriction on sex or training/competitive level; (2) application of a strength training method for ≥ 3 weeks, including high load training (≥ 80% of one repetition maximum), submaximal load training (40-79% of one repetition maximum), plyometric training, and combined training (i.e., two or more methods); (3) endurance running training control group under no strength training or under strength training with low loads (< 40% of one repetition maximum); (4) running performance, VO2max, vVO2max, MMSS and/or sprint capacity measured before and after a strength training intervention program; (5) randomized and non-randomized controlled studies. The certainty of evidence was assessed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. A random-effects meta-analysis and moderator analysis were performed using Comprehensive meta-analysis (version 3.3.0.70).

RESULTS

The certainty of the evidence was very low to moderate. The studies included 324 moderately trained, 272 well trained, and 298 highly trained athletes. The strength training programs were between 6 and 40 weeks duration, with one to four intervention sessions per week. High load and combined training methods induced moderate (effect size =  - 0.469, p = 0.029) and large effect (effect size =  - 1.035, p = 0.036) on running performance, respectively. While plyometric training was not found to have a significant effect (effect size =  - 0.210, p = 0.064). None of the training methods improved VO2max, vVO2max, MMSS, or sprint capacity (all p > 0.072). Moderators related to subject (i.e., sex, age, body mass, height, VO2max, performance level, and strength training experience) and intervention (i.e., weeks, sessions per week and total sessions) characteristics had no effect on running performance variables or its determinants (all p > 0.166).

CONCLUSIONS

Strength training with high loads can improve performance (i.e., time trial, time to exhaustion) in middle-distance and long-distance runners. A greater improvement may be obtained when two or more strength training methods (i.e., high load training, submaximal load training and/or plyometric training) are combined, although with trivial effects on VO2max, vVO2max, MMSS, or sprint capacity.

Effect of Strength Training Programs in Middle- and Long-Distance Runners' Economy at Different Running Speeds: A Systematic Review with Meta-analysis

BACKGROUND

Running economy is defined as the energy demand at submaximal running speed, a key determinant of overall running performance. Strength training can improve running economy, although the magnitude of its effect may depend on factors such as the strength training method and the speed at which running economy is assessed.

AIM

To compare the effect of different strength training methods (e.g., high loads, plyometric, combined methods) on the running economy in middle- and long-distance runners, over different running speeds, through a systematic review with meta-analysis.

METHODS

A systematic search was conducted across several electronic databases including Web of Science, PubMed, SPORTDiscus, and SCOPUS. Using different keywords and Boolean operators for the search, all articles indexed up to November 2022 were considered for inclusion. In addition, the PICOS criteria were applied: Population: middle- and long-distance runners, without restriction on sex or training/competitive level; Intervention: application of a strength training method for ≥ 3 weeks (i.e., high loads (≥ 80% of one repetition maximum); submaximal loads [40-79% of one repetition maximum); plyometric; isometric; combined methods (i.e., two or more methods); Comparator: control group that performed endurance running training but did not receive strength training or received it with low loads (< 40% of one repetition maximum); Outcome: running economy, measured before and after a strength training intervention programme; Study design: randomized and non-randomized controlled studies. Certainty of evidence was assessed with the GRADE approach. A three-level random-effects meta-analysis and moderator analysis were performed using R software (version 4.2.1).

RESULTS

The certainty of the evidence was found to be moderate for high load training, submaximal load training, plyometric training and isometric training methods and low for combined methods. The studies included 195 moderately trained, 272 well trained, and 185 highly trained athletes. The strength training programmes were between 6 and 24 weeks' duration, with one to four sessions executed per week. The high load and combined methods induced small (ES = - 0.266, p = 0.039) and moderate (ES = - 0.426, p = 0.018) improvements in running economy at speeds from 8.64 to 17.85 km/h and 10.00 to 14.45 km/h, respectively. Plyometric training improved running economy at speeds ≤ 12.00 km/h (small effect, ES = - 0.307, p = 0.028, β1 = 0.470, p = 0.017). Compared to control groups, no improvement in running economy (assessed speed: 10.00 to 15.28 and 9.75 to 16.00 km/h, respectively) was noted after either submaximal or isometric strength training (all, p > 0.131). The moderator analyses showed that running speed (β1 = - 0.117, p = 0.027) and VO2max (β1 = - 0.040, p = 0.020) modulated the effect of high load strength training on running economy (i.e., greater improvements at higher speeds and higher VO2max).

CONCLUSIONS

Compared to a control condition, strength training with high loads, plyometric training, and a combination of strength training methods may improve running economy in middle- and long-distance runners. Other methods such as submaximal load training and isometric strength training seem less effective to improve running economy in this population. Of note, the data derived from this systematic review suggest that although both high load training and plyometric training may improve running economy, plyometric training might be effective at lower speeds (i.e., ≤ 12.00 km/h) and high load strength training might be particularly effective in improving running economy (i) in athletes with a high VO2max, and (ii) at high running speeds.

PROTOCOL REGISTRATION

The original protocol was registered ( https://osf.io/gyeku ) at the Open Science Framework.

Running intralimb coordination patterns after a foot core exercise program in recreational runners

This study investigated the effects of a foot core intervention on the coordination of foot joints in recreational runners. This was a secondary analysis from a randomized controlled trial conducted with 87 recreational runners allocated to the control group (CG), which followed a placebo lower limb stretching protocol, or the intervention group (IG), which underwent an 8-week (3 times/week) foot core training. The participants ran on a force-instrumented treadmill at a self-selected speed (9.5-10.5 km/h) while the foot segment motion was captured. The vector coding technique was used to assess inter-joint coordination for four selected coupled segment and joint angles. The coordination patterns of the calcaneus and midfoot (CalMid) and midfoot and metatarsus (MidMet) joint pairs were affected. In the frontal plane, IG showed an in-phase with proximal dominancy coordination at heel strike, with a decrease in its frequency after the training (P=0.018), suggesting a longer foot supination. Additionally, IG showed an anti-phase with distal dominancy pattern at early stance compared to CG due to a smaller but earlier inversion of the CalMid-MidMet pair (P=0.020). The intervention also had an effect on the transverse plane of the CalMid-MidMet pair, with IG showing a significantly greater frequency of anti-phase coordination with proximal dominancy during propulsion than CG (P=0.013), probably due to a reduction in the CalMid abduction. Overall, the results suggested that the foot core intervention reduces the occurrence of running-related injuries by increasing the resistance to calcaneus pronation and building a more rigid and efficient lever during push-off.

Remote assessment of pelvic kinematics during single leg squat using smartphone sensors: Between-day reliability and identification of acute changes in motor performance

The biomechanical assessment of pelvic kinematics during a single leg squat (SLS) commonly relies on expensive equipment, which precludes its wider implementation in ecological settings. Smartphone sensors could represent an effective solution to objectively quantify pelvic kinematics remotely, but their measure properties need to be evaluated before advocating their use in practice. This study aimed to assess whether measures of pelvic kinematics collected remotely using smartphones during SLS are repeatable between days, and if changes in pelvic kinematics can be identified during an endurance task. Thirty-three healthy young adults were tested remotely on two different days using their own smartphones placed on the lumbosacral region. Pelvic orientation and acceleration were collected during three sets of seven SLS and an endurance task of twenty consecutive SLS. The intersession reliability was assessed using Intraclass Correlation Coefficient (ICC2,k), Standard Error of Measurement, and Minimal Detectable Change. T-tests were used to identify pelvic kinematics changes during the endurance task and to assess between-day bias. Measures of pelvic orientation and frequency features of the acceleration signals showed good to excellent reliability (multiple ICC2,k ≥ 0.79), and a shift of the power spectrum to lower frequencies on the second day (multiple p<0.05). The endurance task resulted in larger contralateral pelvic drop and rotation (multiple p<0.05) and increased spectral entropy (multiple p<0.05). Our findings demonstrate that reliable measures of pelvic kinematics can be obtained remotely using participants' smartphones during SLS. Smartphone sensors can also identify changes in motor control, such as contralateral pelvic drop during an endurance task.

The effectiveness of telehealth gait retraining in addition to standard physical therapy treatment for overuse knee injuries in soldiers: a protocol for a randomized clinical trial

INTRODUCTION

Running is the most common cardiovascular exercise in the military. However, there is a high incidence of running-related overuse injuries that reduces military readiness. Gait retraining is a common intervention to treat running-related injuries, but the high cost of equipment and lack of clinician expertise and availability reduces utilization. Gait retraining intervention in a telehealth format might improve feasibility. The purpose of this randomized clinical trial is to determine the effectiveness of a telehealth gait retraining intervention on pain, self-reported function, and biomechanical risk factors for injury in service members who present to a Military Health System physical therapy clinic with an overuse knee injury.

METHODS

This is a parallel, two-arm, single-blind randomized clinical trial. The two independent variables are intervention (2 levels: telehealth gait retraining intervention with standard of care or only standard of care) and time (3 levels: baseline, 10 weeks or post-intervention, 14 weeks). Participants between the ages of 18 to 60 years will be included if they report knee pain during and/or after running to be anywhere from a 3 to a 7 on the numerical pain rating scale and demonstrate a rearfoot strike pattern. The primary dependent variables are as follows: (1) pain (worst pain during and/or after running) and (2) foot strike pattern (conversion rate from rearfoot to non-rearfoot foot strike pattern during running). Secondary outcomes include patient self-reported function and running biomechanics.

DISCUSSION

The effectiveness of a telehealth gait retraining intervention to reduce pain and modify foot strike pattern is not known. The results of this study may help determine the effectiveness and feasibility of a telehealth gait retraining intervention to reduce pain, change foot strike, improve function, and improve running gait biomechanics.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04269473 . Registered 05 February 2020.

The Association of Joint Power Kinetic Variables with Running Injuries: A Case-Control Study

Background

There is conflicting data on which kinetic variables are important to consider with running injuries. Furthermore, less is understood regarding differences in these variables when considering demographics such as age, sex, weight, and running speed. The primary question was what joint power kinetic variables were different between non-injured and injured runners.

Purpose

The purpose of this study was to identify if there were differences in joint power kinetic variables between non-injured runners and injured runners.

Study Design

Case-Control Study.

Methods

Kinetic data were collected on 122 runners (26 non-injured and 96 injured) over three years with a Bertec force plated treadmill and Qualisys 3D motion capture. The subjects were considered eligible if they self-identified themselves as runners or had running as a key component of their activity. The subjects ran at a comfortable, self-selected pace while two 10-second trials of recordings were used to calculate the means of peak power generated at the hips, knees, and ankles of each gait cycle. Foot strike was categorized by kinematic data. Two sample T-tests were used to compare peak power variables at the hips, knees, and ankles between non-injured and injured runners. Logistic regression analyses examined how a combination of demographics and peak power variables were associated with injuries.

Results

No peak power variable at the hip, knee, or ankle was significantly different between injured and non-injured runners (p=0.07-0.87). However, higher hip power absorbed was found to be protective against injuries (odds ratio, .16; 95% CI .025-.88) when considering demographics using a logistic regression model including sex, foot strike, BMI, speed, age, and power variables from the hip, knee, and ankle. The area under the ROC curve was .74, which is acceptable discrimination.

Conclusion

When controlling for age, sex, BMI, foot strike, and speed; higher hip power absorbed was found to be protective against injury. This could be due to the hip muscles' unique role in absorbing force during early stance phase.

Level of Evidence

3b©The Author(s).

The Effects of FIFA 11+ Kids Prevention Program on Kinematic Risk Factors for ACL Injury in Preadolescent Female Soccer Players: A Randomized Controlled Trial

This study aimed to investigate the effects of the 8-week FIFA 11+ Kids program on kinematic risk factors for ACL injury in preadolescent female soccer players during single-leg drop landing. For this, 36 preadolescent female soccer players (10-12 years old) were randomly allocated to the FIFA 11+ Kids program and control groups (18 players per group). The intervention group performed the FIFA 11+ Kids warm-up program twice per week for 8 weeks, while the control group continued with regular warm-up. Trunk, hip, and knee peak angles (from initial ground contact to peak knee flexion) were collected during the single-leg drop landing using a 3D motion capture system. A repeated measure ANOVA was used to analyze groups over time. Significant group × time interactions were found for the peak knee flexion, with a medium effect size (p = 0.05; effect size = 0.11), and peak hip internal rotation angles, with a large effect size (p < 0.01; effect size = 0.28). We found that the FIFA 11+ Kids program was effective in improving knee flexion and hip internal rotation, likely resulting in reducing ACL stress during single-leg drop landing in young soccer players.

Single-Leg Squat Test in the Clinical Setting Does Not Discriminate Patients With Femoroacetabular Impingement Syndrome From Asymptomatic Individuals

CONTEXT

Laboratorial 3-dimensional kinematic analyses have shown changes in the single-leg squat's (SLS) pattern of patients with femoroacetabular impingement syndrome (FAIS). However, it is unknown whether clinicians are able to detect these changes using 2-dimensional kinematics.

OBJECTIVE

To compare the frontal plane 2-dimensional kinematics of patients with FAIS and asymptomatic individuals in the SLS test performed in a clinical setting.

DESIGN

Case-control study.

SETTING

Physical therapy clinic.

PARTICIPANTS

Twenty men with bilateral FAIS and 20 asymptomatic men.

MAIN OUTCOME MEASURES

Two-dimensional kinematic analysis was collected in the frontal plane during the execution of the SLS test. The outcomes were squat depth, pelvic drop (pelvis angle relative to the horizontal plane), hip adduction (femur angle relative to the pelvis), and knee valgus (femur angle relative to the tibia).

RESULTS

Most and least painful limbs of patients with FAIS had squat depth (9.8% [2.9%] and 9.5% [3.1%] of height), pelvic drop (4.2° [3.9°] and 3.7° [4.2°]), hip adduction (74.9° [5.8°] and 75.9° [5.7°]), and knee valgus (4.0° [11.0°] and 5.0° [9.9°]) similar to asymptomatic individuals (9.0% [2.3%], 4.8° [2.6°], 73.7° [4.9°], and -1.7° [8.5°]; P > .05 for all).

CONCLUSION

The frontal plane 2-dimensional kinematic analysis of the SLS test in the clinical setting is not able to distinguish patients with FAIS from asymptomatic individuals.

Impact of biomechanics on therapeutic interventions and rehabilitation for major chronic musculoskeletal conditions: A 50-year perspective

The pivotal role of biomechanics in the past 50 years in consolidating the basic knowledge that underpins prevention and rehabilitation measures has made this area a great spotlight for health practitioners. In clinical practice, biomechanics analysis of spatiotemporal, kinematic, kinetic, and electromyographic data in various chronic conditions serves to directly enhance deeper understanding of locomotion and the consequences of musculoskeletal dysfunctions in terms of motion and motor control. It also serves to propose straightforward and tailored interventions. The importance of this approach is supported by myriad biomechanical outcomes in clinical trials and by the development of new interventions clearly grounded on biomechanical principles. Over the past five decades, therapeutic interventions have been transformed from fundamentally passive in essence, such as orthoses and footwear, to emphasizing active prevention, including exercise approaches, such as bottom-up and top-down strengthening programs for runners and people with osteoarthritis. These approaches may be far more effective inreducing pain, dysfunction, and, ideally, incidence if they are based on the biomechanical status of the affected person. In this review, we demonstrate evidence of the impact of biomechanics and motion analysis as a foundation for physical therapy/rehabilitation and preventive strategies for three chronic conditions of high worldwide prevalence: diabetes and peripheral neuropathy, knee osteoarthritis, and running-related injuries. We conclude with a summary of recommendations for future studies needed to address current research gaps.

Lower extremity kinematics during running and hip abductor strength in iliotibial band syndrome: A systematic review and meta-analysis

BACKGROUND

Iliotibial band syndrome is a common overuse injury that is twice as likely to affect female runners compared to male runners. It is unclear if there is a consistent running pattern and strength profile exhibited by female and male runners with iliotibial band syndrome.

RESEARCH QUESTION

The purpose of this systematic review and meta-analysis was to determine if any differences existed in lower-extremity kinematics and hip strength between runners who retrospectively, currently, or prospectively had iliotibial band syndrome.

METHODS

Papers included must have reported three-dimensional kinematic running data and/or hip strength data that were statistically analyzed between runners that never developed iliotibial band syndrome and runners with iliotibial band syndrome. Meta-analysis was performed for each kinematic or strength variable reported in at least three studies. Female and male runners were analyzed separately and grouped into three cohorts (retrospective, current, prospective).

RESULTS

Seventeen articles were included in this systematic review. Data from 10 cross-sectional studies were included for meta-analysis. Female runners with current iliotibial band syndrome exhibited smaller peak hip internal rotation angles and lower isometric hip abductor strength compared to controls.

SIGNIFICANCE

Although limited biomechanical evidence exists, risk factors for ITBS are different between female and male runners and may vary according to injury status. Specifically, transverse plane hip motion and hip abductor strength weakness may be biomechanical risk factors in female runners with current iliotibial band syndrome only.

Impact of Pilates mat-based exercises on knee kinematics during running

INTRODUCTION

Core strengthening, balance, and flexibility programs such as Pilates have been advocated to positively impact running mechanics and prevent lower extremity injuries. The purpose of this study was to assess the effects of a 12-week mat-based Pilates exercise program on dynamic knee valgus alignment in runners.

METHODS

Thirty-four novice runners, including young male and female adults performed a running protocol at baseline. The protocol consisted of the participants running on a treadmill at a constant five miles per hour (mph) for 4 min. Post-examination, participants were randomly assigned to a Pilates or control group (n = 16 and n = 18, respectively). A certified Pilates instructor gave the Pilates group a 12-week home-based program. To ensure participants in the Pilates group performed exercises correctly, the Pilates instructor conducted the first session, and provided feedback to each participant. Participants in both groups performed the same running testing protocol every four weeks. Knee valgus was measured as the medial displacement of the knee joint center during the running stance phase. Repeated measures Analysis of Variance (RepANOVA) was calculated at baseline and 4-, 8-, and 12-weeks post examinations to compare knee valgus during running.

RESULTS

Although a reduction in dynamic knee valgus was observed within the Pilates group, the RepANOVA analysis revealed this change was not statistically significant.

CONCLUSIONS

Pilates mat-based exercises may improve knee valgus after 12 weeks but a larger sample size, longer intervention duration, or a supervised program should be considered for future research to evaluate its effectiveness.

The Effect of Real-Time Tibial Acceleration Feedback on Running Biomechanics During Gait Retraining: A Systematic Review and Meta-Analysis

OBJECTIVES

To explore the immediate and retention effect of real-time tibial acceleration feedback on running biomechanics during gait retraining.

METHODS

Five electronic databases were searched to identify relevant studies published before May 2022. The included studies were evaluated for methodological quality and bias risk, and data were extracted. A meta-analysis was conducted on the primary outcomes, including peak tibial acceleration (PTA) and vertical ground reaction force. Subgroup analysis was performed by gender, feedback criterion, mode, dosage, fading, retention period, and running environment to evaluate the source of heterogeneity. Qualitative analysis was performed to describe other variables.

RESULTS

Fourteen studies (174 participants) were eligible. Meta-analysis showed that real-time tibial acceleration feedback reduced PTA (P < .01, P < .01), vertical impact peak (P = .004, P < .01), vertical average loading rate (P < .01, P < .01), and vertical instantaneous loading rate (P < .01, P < .01) after feedback and during retention period (5 min-12 mo). Subgroup analysis showed that the immediate effect of vertical impact peak was more noticeable with mixed gender (P = .005) and fading feedback (P = .005) conditions, and the retention effect of PTA was more noticeable with high feedback dosage (P < .01) and fading feedback (P < .01) conditions.

CONCLUSIONS

Real-time tibial acceleration feedback can reduce PTA and vertical ground reaction force during gait retraining, and for periods of 5 minutes to 12 months when the feedback is removed.

The effectiveness of the comprehensive corrective exercise program on kinematics and strength of lower extremities in males with dynamic knee valgus: a parallel-group randomized wait-list controlled trial

Background

Dynamic knee valgus (DKV) is a prevalent movement impairment widely regarded as a risk factor for lower extremity disorders such as patellofemoral pain syndrome. The present study aimed to investigate the effectiveness of the comprehensive corrective exercise program (CCEP) on kinematics and strength of lower extremities in males with DKV.

Methods

Thirty asymptomatic young men with DKV between the ages of 18 and 28 years participated in this study. They were randomly assigned to the intervention (n = 15) and control groups (n = 15). The intervention group performed the CCEP for three sessions per week for eight weeks, while the control group only did activities of daily living. Hip external rotator and abductor muscle strength and three-dimensional lower extremity kinematics consisting of knee varus/valgus, femur adduction/abduction, femur medial/lateral rotation, and tibial medial/lateral rotation were measured at the baseline and post-test. The data were analyzed using the analysis of covariance (ANCOVA).

Results

There were significant improvements in all kinematics variables in the intervention group after the 8-week CCEP. Moreover, the strength of abductor and external rotator muscle improved in the intervention group (P < 0.05).

Conclusions

The CCEP led to substantial improvements in the selected variables of lower extremity kinematics and muscle strength in participants with DKV during a single-leg squat. These results imply that practitioners should adopt a comprehensive approach to pay simultaneous attention to both proximal and distal segments for improving DKV.

Trial registration

The protocol has been approved in the Registry of Clinical Trials (Registration N: IRCT20180821040843N1) on 2018-12-30.

Clinical Application of Gait Retraining in the Injured Runner

Despite its positive influence on physical and mental wellbeing, running is associated with a high incidence of musculoskeletal injury. Potential modifiable risk factors for running-related injury have been identified, including running biomechanics. Gait retraining is used to address these biomechanical risk factors in injured runners. While recent systematic reviews of biomechanical risk factors for running-related injury and gait retraining have been conducted, there is a lack of information surrounding the translation of gait retraining for injured runners into clinical settings. Gait retraining studies in patients with patellofemoral pain syndrome have shown a decrease in pain and increase in functionality through increasing cadence, decreasing hip adduction, transitioning to a non-rearfoot strike pattern, increasing forward trunk lean, or a combination of some of these techniques. This literature suggests that gait retraining could be applied to the treatment of other injuries in runners, although there is limited evidence to support this specific to other running-related injuries. Components of successful gait retraining to treat injured runners with running-related injuries are presented.

The effect of hip abductor fatigue on knee kinematics and kinetics during normal gait

Objective

To investigate the effect of hip abductor fatigue on the kinematics and kinetics of the knee joint during walking in healthy people to provide a new approach for the prevention and treatment of knee-related injuries and diseases.

Methods

Twenty healthy participants, ten females, and ten males, with a mean age of 25.10 ± 1.2 years, were recruited. Isometric muscle strength testing equipment was used to measure the changes in muscle strength before and after fatigue, and the surface electromyography (SEMG) data during fatigue were recorded synchronously. The Vicon system and an AMTI© force platform were used to record the kinematic parameters and ground reaction force (GRF) of twenty participants walking at a self-selected speed before and after fatigue. Visual 3D software was used to calculate the angles and torques of the hip and knee joints.

Results

After fatigue, the muscle strength, median frequency (MF) and mean frequency (MNF) of participants decreased significantly (P < 0.001). The sagittal plane range of motion (ROM) of the knee (P < 0.0001) and hip joint (P < 0.01) on the fatigue side was significantly smaller than before fatigue. After fatigue, the first and second peaks of the external knee adduction moment (EKAM) in participants were greater than before fatigue (P < 0.0001), and the peak values of the knee abduction moment were also higher than those before fatigue (P < 0.05). On the horizontal plane, there is also a larger peak of internal moment during walking after fatigue (P < 0.01).

Conclusion

Hip abductor fatigue affects knee kinematics and kinetics during normal gait. Therefore, evaluating hip abductor strength and providing intensive training for patients with muscle weakness may be an important part of preventing knee-related injuries.

Sex-specific differences in biomechanics among runners: A systematic review with meta-analysis

Patellofemoral disorders are more common in female runners compared to their male counterparts. Differences in biomechanical characteristics between groups of runners could provide insight into the causes of higher rates of injury in female versus male runners, which would be useful to physical therapists and athletic trainers in development of individualized injury prevention programs. This review compares the differences in biomechanical characteristics between female and male runners. Electronic databases, including PubMed, Scopus, Web of Science, and Embase were searched in December 2021 for studies evaluating sex-specific differences in lower limb mechanics of healthy participants during running. Two independent reviewers determined the inclusion and quality of each research paper. Meta-analyses were used where possible. A total of 13 studies were selected. Means and standard deviations of reported data were retrieved from each selected paper for comparison of results. Three biomechanical variables, including dynamics, muscle activation, and kinematics, were compared between female and male runners. However, no differences were found in kinetic variables or muscle activation between groups due to insufficient data available from the selected studies. Meta-analyses of kinematic variables revealed that female runners exhibited significantly greater hip flexion angle, hip adduction angle, and hip internal rotation angle, but smaller knee flexion angle compared to male runners during running. We found significant differences in kinematic variables between female and male runners, which could influence the training advice of physical therapists and athletic trainers who work with runners, and inform the development of injury prevention programs.

Is there a correlation between isometric muscle strength and the kinematics of the pelvis, hip and knee during functional tasks in women with patellofemoral pain?

OBJECTIVES

To evaluate the correlation between isometric muscle strength of the hip abductors (HABD) and lateral rotators (HLR) with the range of motion (ROM) of the pelvis/hip in the frontal/transverse planes, respectively, and between the strength of the knee extensors (KExt) with the ROM of the knee in the sagittal plane during seven tasks.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Thirty-five women with patellofemoral pain.

MAIN OUTCOME MEASURES

Maximum isometric muscle strength of the HABD, HLR, and KExt was measured using a manual dynamometer, and pelvis and lower limbs kinematics were evaluated using 3D optical system during gait, ascending and descending stairs, the forward and lateral step down tests, and the propulsion and landing phases of the single leg hop test (SLHT).

RESULTS

A weak correlation was found between KExt strength and knee ROM in the sagittal plane (p = 0.05; r = -0.33) during SLHT landing, and a moderate correlation between HABD strength and ROM of pelvic obliquity (p < 0.01; r = 0.50) during ascending stairs.

CONCLUSIONS

The lower strength of KExt has a weak correlation with higher knee flexion during the landing phase of the SLHT, and the lower strength of HABD has a moderate correlation with lower pelvis ROM in the frontal plane when ascending stairs.

Resistance Exercise for Improving Running Economy and Running Biomechanics and Decreasing Running-Related Injury Risk: A Narrative Review

It is well-accepted that at least a certain amount of resistance exercise (RE) is recommended for most endurance athletes. In this review, we aim to summarize the evidence regarding the effects of RE on running economy, running biomechanics, and running-related injury risk in endurance runners. The evidence robustly shows that lower limb RE is effective for improving running economy and performance, with a combination of strength and plyometric training being recommended to improve RE. Isometric training is also emerging as a possible alternative to implement during periods of high overall training load. Lower limb RE may change some aspects of joint kinematics during running; however, the evidence regarding the effects on kinetics is limited. Lower limb RE may help reduce running-related injury risk, but further evidence is needed.

Effects of Foot-Core Training on Foot-Ankle Kinematics and Running Kinetics in Runners: Secondary Outcomes From a Randomized Controlled Trial

This study investigated the effectiveness of an 8-week foot-core exercise training program on foot-ankle kinematics during running and also on running kinetics (impact loads), with particular interest in biomechanical outcomes considered risk factors for running-related injuries in recreational runners. A single-blind, randomized, controlled trial was conducted with 87 recreational runners randomly allocated to either the control (CG) or intervention (IG) group and assessed at baseline and after 8 weeks. The IG underwent foot-core training 3 times/week, while the CG followed a placebo lower-limb stretching protocol. The participants ran on a force-instrumented treadmill at a self-selected speed while foot-segment motion was captured simultaneously with kinetic measurements. After the intervention, there were statistically significant changed in foot biomechanics, such as: IG participants strike the ground with a more inverted calcaneus and a less dorsiflexed midfoot than those in the CG; at midstance, ran with a less plantarflexed and more adducted forefoot and a more abducted hallux; and at push-off, ran with a less dorsiflexed midfoot and a less adducted and more dorsiflexed hallux. The IG runners also had significantly decreased medial longitudinal arch excursion (p = 0.024) and increased rearfoot inversion (p = 0.037). The 8-week foot-core exercise program had no effect on impact (p = 0.129) and breaking forces (p = 0.934) or on vertical loading rate (p = 0.537), but it was positively effective in changing foot-ankle kinematic patterns.”

Relationship between hip muscle strength and hip biomechanics during running in people with femoroacetabular impingement syndrome

BACKGROUND

Hip muscle weakness and altered hip biomechanics during walking are often observed in people with femoroacetabular impingement syndrome, although little is known about biomechanics during higher impact tasks. The aim of our study was to explore relationships between hip muscle strength and hip biomechanics during running in people with femoroacetabular impingement syndrome, including exploring sex as an effect-modifier of this relationship.

METHODS

Forty-two adults with unilateral femoroacetabular impingement syndrome (20 females; age 18-50 years; alpha angle ≥60°) completed assessments of hip muscle strength and hip biomechanics during running. Strength was assessed using a hand-held dynamometer for the hip flexors, extensors, abductors, adductors, internal rotators, and external rotators. Hip biomechanics were assessed during overground running (3-3.5 m/s) using three-dimensional motion capture and a force plate. Linear models assessed the relationships between hip strength and hip biomechanics of the symptomatic limb, controlling for body mass and running velocity along with an interaction term (strength*sex).

FINDINGS

A significant negative relationship was observed between hip external rotator strength and hip frontal plane range of motion (i.e., excursion), independent of sex (estimate = -0.039, 95%CI -0.071 to -0.008, P = 0.02). Four sex-specific interactions were observed, with a significant positive relationship between hip external rotator strength and peak hip extension moment in women (estimate = -0.413, 95%CI -0.713 to -0.114, P = 0.01) but not in men.

INTERPRETATION

We found significant relationships between hip external rotator strength and stance phase running biomechanics, providing further understanding on two impaired physical measures that may inform exercise-based management strategies in femoroacetabular impingement syndrome.

Muscle Activation During Single-Legged Squat Is Affected by Position of the Nonstance Limb

CONTEXT

The single-legged squat (SLS) is appropriate for targeting activation, strengthening, and neuromuscular retraining of the gluteus maximus, gluteus medius, and quadriceps. However, the effects of different nonstance-limb positions on muscle activity have not been fully evaluated.

OBJECTIVE

To compare the muscle activity of selected stance-limb hip muscles during the SLS using 3 nonstance-limb positions: in front (SLS-Front), in the middle (SLS-Middle), and in back (SLS-Back).

DESIGN

Controlled laboratory study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 17 healthy adults (8 men, 9 women; age = 22.6 ± 3.6 years, height = 173.3 ± 10.7 cm, mass = 71.2 ± 11.0 kg) participated.

MAIN OUTCOME MEASURE(S)

Surface electromyographic data of the gluteus maximus, gluteus medius, lateral hamstrings, medial hamstrings, rectus femoris, and tensor fascia lata (TFL) as well as kinetic data of the hip and knee were collected while participants performed the 3 SLS tasks. Mean muscle-activation levels during the descent and ascent phases for the selected hip muscles and hip and knee kinetics in all 3 planes were compared for the 3 tasks. Each variable of interest was analyzed using a separate linear regression model with a generalized estimating equations correction.

RESULTS

Muscle-activation levels of the gluteus maximus, gluteus medius, medial hamstrings, rectus femoris, and TFL for the stance limb during descent (P ≤ .04) and the medial hamstrings and TFL during ascent (P ≤ .002) were different among the SLS tasks. The greatest number of differences occurred between SLS-Front and SLS-Back. During descent, gluteal muscle activity was greater in SLS-Front (P ≤ .03) and SLS-Middle (P = .03) than in SLS-Back. For both phases, TFL activity was greater during SLS-Front than during both SLS-Middle and SLS-Back (P ≤ .006). Kinetic differences at the hip and knee between SLS tasks were also observed (P values ≤ .02).

CONCLUSIONS

The 3 SLS tasks had different muscle-activation and kinetic profiles. Clinicians and researchers can vary nonstance-limb position during the SLS to manipulate muscle-activation levels and tailor the exercise to assist with goals at different stages of rehabilitation.

Hip external rotation isometric torque for soccer, basketball, and volleyball athletes: normative data and asymmetry index

BACKGROUND

Deficits in strength of the hip external rotators (ER) affect trunk, hip, and knee movement patterns, potentially contributing to injury in athletes.

OBJECTIVES

To provide normative data on isometric torque for hip ER in athletes of three distinct sports and to determine if isometric torque for the hip ER and torque asymmetry between legs differ among sports and between sexes.

METHODS

Basketball, soccer, and volleyball athletes (n=451) were evaluated. Hip ER torque was quantified bilaterally with athletes in prone and 90° of knee flexion using a hand-held dynamometer.

RESULTS

Data are expressed as mean and 95% confidence interval. Hip ER torque values in Nm/kg for the dominant and non-dominant limbs were, respectively, 0.46 (0.44, 0.48) and 0.42 (0.40, 0.44) for male soccer athletes; 0.35 (0.32, 0.37) and 0.27 (0.25, 0.29) for male basketball athletes; and 0.37 (0.34, 0.39) and 0.35 (0.32, 0.37) for male volleyball athletes. Hip ER torque in Nm/kg for the female volleyball athletes was 0.29 (0.26, 0.33) for the dominant and 0.29 (0.25, 0.32) for the non-dominant limb. The Limb Symmetry Index for male soccer, basketball, and volleyball players was, respectively, 94% (91, 97), 81% (75, 87), and 95% (91, 99). For female volleyball players the Limb Asymmetry Index was 102% (95, 108). Male volleyball athletes showed higher torque values than female volleyball athletes.

CONCLUSIONS

This study reported normative values for hip ER isometric torque of youth athletes. Clinicians can use the reported data as reference to identify torque deficits in athletes of the three reported sports.

The Iliotibial Band: A Complex Structure with Versatile Functions

The development of a pronounced iliotibial band (ITB) is an anatomically distinct evolution of humans. The mechanical behaviour of this “new” structure is still poorly understood and hotly debated in current literature. Iliotibial band syndrome (ITBS) is one of the leading causes of lateral knee pain injuries in runners. We currently lack a comprehensive understanding of the healthy behaviour of the ITB, and this is necessary prior to further investigating the aetiology of pathologies like ITBS. Therefore, the purpose of this narrative review was to collate the anatomical, biomechanical and clinical literature to understand how the mechanical function of the ITB is influenced by anatomical variation, posture and muscle activation. The complexity of understanding the mechanical function of the ITB is due, in part, to the presence of its two in-series muscles: gluteus maximus (GMAX) and tensor fascia latae (TFL). At present, we lack a fundamental understanding of how GMAX and TFL transmit force through the ITB and what mechanical role the ITB plays for movements like walking or running. While there is a range of proposed ITBS treatment strategies, robust evidence for effective treatments is still lacking. Interventions that directly target the running biomechanics suspected to increase either ITB strain or compression of lateral knee structures may have promise, but clinical randomised controlled trials are still required.

Conservative treatment of iliotibial band syndrome in runners: Are we targeting the right goals?

OBJECTIVE

Iliotibial band syndrome (ITBS) is presumably caused by excessive tension in the iliotibial band (ITB) leading to compression and inflammation of tissues lying beneath it. Usually managed conservatively, there is a lack of scientific evidence supporting the treatment recommendations, and high symptom recurrence rates cast doubt on their causal effectiveness. This review discusses the influence of common physiotherapeutic measures on risk factors contributing to tissue compression beneath the ITB.

METHODS

The potential pathogenic factors are presented on the basis of a simple biomechanical model showing the forces acting on the lateral aspect of the knee. Existent literature on the most commonly prescribed physiotherapeutic interventions is critically discussed against the background of this model. Practical recommendations for the optimization of physiotherapy are derived.

RESULTS

According to biomechanical considerations, ITBS may be promoted by anatomical predisposition, joint malalignments, aberrant activation of inserting muscles as well as excessive ITB stiffness. Hip abductor strengthening may correct excessive hip adduction but also increase ITB strain. Intermittent stretching interventions are unlikely to change the ITB's length or mechanical properties. Running retraining is a promising yet understudied intervention.

CONCLUSIONS

High-quality research directly testing different physiotherapeutic treatment approaches in randomized controlled trials is needed.

Hip passive stiffness is associated with hip kinematics during single-leg squat

INTRODUCTION

Single-leg squat (SLS) is a test commonly used to assess lower limb function in rehabilitation. Increased hip adduction and internal rotation (IR) is associated with dynamic knee valgus, which is related to hip and knee overload. Proximal and distal factors, such as hip passive stiffness, poor hip muscle strength and excessive foot misalignment may influence hip movement. However, previous studies focus on how proximal and distal factors affected knee joint movement and did not reported the influence on hip joint.

OBJECTIVE

This study investigated the association of hip external rotators (ER) strength, hip passive stiffness and shank-forefoot alignment (SFA) with hip adduction and IR during SLS.

DESIGN

Cross-sectional study.

METHOD

Forty-six health participants of both sexes (23.47 ± 4.29 years, 60.40 ± 11.28 kg, 1.67 ± 8.9 m) had SFA, hip ER torque, hip passive stiffness and hip kinematics assessed. Multiple linear regressions were performed to identify the factors which associated with mean and peak hip adduction and IR movement during SLS.

RESULTS

Only hip passive stiffness was associated with mean (R² = 0.164; Confidence Interval (CI) 95% = [-0.250, -0.048]; p = 0.005) and peak (R² = 0.116; CI 95% = [-0.223, -0.210]; p = 0.019) hip IR movement.

CONCLUSION

Hip passive stiffness was associated with mean and peak hip IR movement during the SLS. These results suggest that individuals with reduced hip passive stiffness may demonstrate increased hip IR movement during SLS.

Effect of concurrent strength and endurance training on run performance and biomechanics: A randomized controlled trial

This parallel-group randomized controlled trial investigated the effect of concurrent strength and endurance (CSE) training on running performance, biomechanics, and muscle activity during overground running. Thirty moderately trained distance runners were randomly assigned to 10-week CSE training (n = 15; 33.1 ± 7.5 years) or a control group (n = 15; 34.2 ± 8.2 years). Participants ran ≥30 km per week and had no experience with strength training. The primary outcome measure was 2-km run time. Secondary outcome measures included lower limb sagittal plane biomechanics and muscle activity during running (3.89 m s^-1 and maximal sprinting); maximal aerobic capacity (V̇O₂ max); running economy; and body composition. CSE training improved 2-km run time (mean difference (MD): -11.3 s [95% CI -3.7, -19.0]; p = 0.006) and time to exhaustion during the V̇O₂ max running test (MD 59.1 s [95% CI 8.58, 109.62]; p = 0.024). The CSE training group also reduced total body fat (MD: -1.05 kg [95% CI -0.21, -1.88]; p = 0.016) while total body mass and lean body mass were unchanged. Hip joint angular velocity during the early swing phase of running at 3.89 m s^-1 was the only biomechanical or muscle activity variable that significantly changed following CSE training. CSE training is beneficial for running performance, but changes in running biomechanics and muscle activity may not be contributing factors to the performance improvement. Future research should consider other possible mechanisms and the effect of CSE training on biomechanics and muscle activity during prolonged running under fatigued conditions.

Comparisons of trunk and knee mechanics during various speeds of treadmill running between runners with and without patellofemoral pain: a preliminary study

[Purpose] To determine if runners with patellofemoral pain (PFP) exhibit higher patellofemoral joint (PFJ) stress and trunk extension compared to pain-free runners during treadmill running. [Participants and Methods] Twelve runners (7 with PFP and 5 pain-free) participated in this study. Participants ran at 3 different running conditions: self-selected, fast (120% of self-selected), and slow (80% of self-selected) speeds. Kinematics and kinetics of trunk and lower extremities were obtained. PFJ stress, PFJ reaction force, and PFJ contact area were determined using a biomechanical model. Two-factor ANOVAs with repeated measures were used to compare outcome variables between 3 speeds and between 2 groups. [Results] There was no significant difference in peak PFJ stress between groups across the 3 speeds. Peak PFJ stress was lowest during slow running compared to fast and self-selected running speed conditions across both groups. No significant difference was found in trunk flexion angle, PFJ reaction force, or PFJ contact area between groups across the 3 speeds. [Conclusion] Runners with and without PFP exhibited similar peak PFJ stress and trunk flexion angle during treadmill running. This preliminary work does not support the theory that reduced trunk flexion during running contributes to increased PFJ stress in runners with PFP.

Roller Massage Prior to Running Does Not Affect Gait Mechanics in Well-Trained Runners

CONTEXT

Understanding if roller massage prior to a run can mitigate fatigue-related decrements in muscle force production during prolonged running is important because of the association between fatigue and running-related injury.

OBJECTIVE

The authors investigated whether a bout of roller massage prior to running would (1) mitigate fatigue-related increases in vertical average load rate and free moment of the ground reaction force of running and (2) mitigate decreases in maximal countermovement jump height.

DESIGN

Repeated-measures study.

SETTING

Laboratory.

PARTICIPANTS

A total of 14 recreational endurance athletes (11 men and 3 women) volunteered for the study.

INTERVENTIONS

A 12.5-minute foam roller protocol for the lower extremities and a fatiguing 30-minute treadmill run.

MAIN OUTCOME MEASURES

Vertical average load rate, free moment, and maximal jump height before (PRE) and after (POST) the fatiguing treadmill run on separate experimental days: once where participants sat quietly prior to the fatiguing run (REST) and another where the foam roller protocol was performed prior to the run (ROLL).

RESULTS

A 2-way multiple analysis of variance found no significant differences in vertical average load rate, free moment, and jump height between PRE/POST times in both REST/ROLL conditions.

CONCLUSIONS

The authors concluded that recreational endurance athletes maintain running mechanics and jump performance after a fatiguing run regardless of prerun roller massage and may not rely on prerun roller massage as a form of injury prevention.

Adolescent Running Biomechanics - Implications for Injury Prevention and Rehabilitation

Global participation in running continues to increase, especially amongst adolescents. Consequently, the number of running-related injuries (RRI) in adolescents is rising. Emerging evidence now suggests that overuse type injuries involving growing bone (e.g., bone stress injuries) and soft tissues (e.g., tendinopathies) predominate in adolescents that participate in running-related sports. Associations between running biomechanics and overuse injuries have been widely studied in adults, however, relatively little research has comparatively targeted running biomechanics in adolescents. Moreover, available literature on injury prevention and rehabilitation for adolescent runners is limited, and there is a tendency to generalize adult literature to adolescent populations despite pertinent considerations regarding growth-related changes unique to these athletes. This perspective article provides commentary and expert opinion surrounding the state of knowledge and future directions for research in adolescent running biomechanics, injury prevention and supplemental training.

A preliminary analysis of physical therapist agreement regarding the perceived impairments in cases of runners with knee pain

Background: There is a scarcity of evidence describing how physical therapists use data from clinical examinations to inform the treatment of runners with knee pain.Objective: Our purpose was to examine the between physical therapist agreement on the selection of perceived impairments in runners with knee pain.Methods: Twelve physical therapists reviewed two cases of runners with knee pain. The cases included clinical subjective information, objective data, and review of videos of each participant running. Each rater selected up to three perceived impairments (from a list of eight) that each physical therapist would address at the next physical therapy session. Percent agreement was calculated to determine the between rater agreement on each individual perceived impairment selection and Fleiss Kappa was calculated for each unique combination of three perceived impairments per case.Results: Twelve raters with 51 (18-156) months of clinical experience participated. Percent agreement ranged from 8%-100% for both cases for individual impairments. When assessing the unique combination of three impairments selected, inter-rater agreement was less than what is expected due to chance alone (κ = -0.09, p = .92; κ = -0.09, p = .98) for both cases.Conclusion: The 12 physical therapists demonstrated poor to excellent levels of agreement when selecting an individual perceived impairment. Agreement was worse than chance when selecting a combination of three unique impairments.

How effective is an evidence-based exercise intervention in individuals with patellofemoral pain?

OBJECTIVES

Guidelines for a comprehensive rehabilitation programme for patellofemoral pain (PFP) have been developed by international experts. The aim of this study was to analyse the effect of such a rehabilitative exercise programme on pain, function, kinesiophobia, running biomechanics, quadriceps strength and quadriceps muscle inhibition in individuals with PFP.

DESIGN

Observational study.

SETTING

Clinical environment.

PARTICIPANTS

Twenty-seven participants with PFP.

MAIN OUTCOME MEASURES

Symptoms [numeric pain rating scale (NPRS)and the pain subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS)], function measured by using the KUJALA scale and KOOS, kinesiophobia measured by using the Tampa scale, three-dimensional biomechanical running data, quadriceps isometric, concentric and eccentric strength and arthrogenic muscle inhibition (AMI) were acquired before and after the six-week exercise programme.

RESULTS

Although pain did not significantly improve all patients were pain-free after the six-week exercise programme (NPRS: p = 0.074). Function, kinesiophobia and quadriceps AMI improved significantly after the six-week exercise programme (KUJALA: p = 0.001, KOOS: p = 0.0001, Tampa: p = 0.017, AMI: p = 0.018). Running biomechanics during stance phase did not change after the exercise intervention. Quadriceps strength was not different after the six-week exercise programme (isometric: p = 0.992, concentric: p = 0.075, eccentric: p = 0.351).

CONCLUSION

The results of this study demonstrate that the current exercise recommendations can improve function and kinesiophobia and reduce pain and AMI in individuals with PFP. There is a need for reconsideration of the current exercise guidelines in stronger individuals with PFP.

Sex-Specific Hip Movement Is Correlated With Pelvis and Upper Body Rotation During Running

There is a sex bias for common overuse running injuries that are associated with sex-specific hip kinematics. Gait retraining programs aimed at altering hip kinematics may be more efficient if they incorporated an understanding of how hip kinematics are correlated with the movement of the remaining body segments. We applied a principal component analysis to structure the whole-body running kinematics of 23 runners (12 ♀) into k = 12 principal movements (PM_k), describing correlated patterns of upper and lower body movements. We compared the time-dependent movement amplitudes with respect to each PM_k between males and females using a waveform analysis and interpreted our findings according to stick figure animations. The movement amplitudes of two PMs (PM₆ and PM₈) showed statistically significant effects of "sex," which were independent of running speed. According to PM₈, females showed more hip adduction, which correlated with increased transverse rotation of the pelvis and upper body compared to men. We propose that increased hip adduction and upper body rotation in female runners may be a strategy to compensate for a less efficient arm and upper body swing compared to men. Gait interventions aimed at reducing hip adduction and running-related injuries in female runners should consider instructions for both upper and lower body to maximize training efficacy.

Recommendations for Plyometric Training after ACL Reconstruction - A Clinical Commentary

This paper presents a four-stage plyometric program to be undertaken as part of criterion-based rehabilitation for athletes with anterior cruciate ligament reconstruction (ACLR). After ACLR, the patient experiences alterations of joint mobility, gait and movement patterns, neuromuscular function and general physical fitness. Plyometric training is an important component for neuromuscular and movement re-conditioning after ACLR. Effective use of plyometrics can support enhancements in explosive sporting performance, movement quality and lower risk of injury. Plyometric training, as a component of the ACL functional recovery process, can aid in restoring function and supporting timely return to sport. However, few patients undertake or complete a plyometric program prior to return-to-sport. To truly impact individual patients, a stronger focus on research implementation is needed from researchers to translate efficacious interventions into practice. In designing a plyometric program, it is important to match the specific plyometric tasks to the functional recovery status of the ACLR patient. To do this, it is important to understand the relative intensity of plyometrics tasks, align these tasks to the ACL functional recovery process and monitor the athlete as part of criterion based rehabilitation. Plyometric intensity is based on the intensity of efforts, the vertical and/or horizontal momentum prior to ground contact, the ground contact time and the surface or environment on which they are performed on/in. Furthermore, how the person technically performs the task will influence joint loading. There should be a gradual increase in task intensity and specificity throughout the program, with all tasks used for both neuromuscular and motor control re-conditioning. The aim of this paper is to provide recommendations to clinicians on how to design and implement plyometric training programs for the ACLR patient, as part of the functional recovery process.

LEVEL OF EVIDENCE

5.

Hip and Trunk Muscle Activity and Mechanics During Walking With and Without Unilateral Weight

Pelvic drop is caused by decreased hip abductor muscle activity and is associated with lower-extremity injury. Hip abductor strengthening exercises are well established; however, no standard method exists to increase hip abductor activity during functional activities. The purpose of this research was to study the effects of walking with a unilateral weight. A total of 26 healthy adults walked on an instrumented treadmill with and without handheld weight (15%-20% body weight). Muscle activity, kinematic, and kinetic data were collected using surface electromyography, motion capture, and force plates, respectively. Average hip and trunk muscle activity, hip, pelvic, and trunk angles, and peak internal hip moments during stance were compared for each side (contralateral/ipsilateral to the weight) between conditions (unweighted/weighted) using a generalized linear model with generalized estimating equation correction. Interactions between condition and side were observed for muscle activity, frontal plane pelvic and trunk angles, and frontal plane hip moments (P ≤ .003). Compared with the unweighted condition, the weighted condition had higher hip abductor activity contralateral to the weight (P < .001), while no change was found ipsilateral to the weight (P ≥ .790). Similar changes were found for kinematic and kinetic variables. Walking with a unilateral weight may be a therapeutic option to increase functional hip abductor activity.

Trunk, Hip and Knee Exercise Programs for Pain Relief, Functional Performance and Muscle Strength in Patellofemoral Pain: Systematic Review and Meta-Analysis

Objective

Previous research suggests that muscle strength exercise is the most effective rehabilitation methods in patients with patellofemoral pain (PFP). This systematic review with meta-analysis compared the effects of Hip&Knee, Hip-only and Knee-only exercise programs on pain relief, muscle strength, and functional performance in patients with PFP.

Methods

Literature searches of PubMed, PEDro and CINAHL databases revealed twenty-one studies included in the final descriptive review, thirteen of which were included in the meta-analysis. Data extraction included baseline and post-intervention means and standard deviations of all eligible outcome measures both for the intervention and control groups, participants baseline demographics and intervention characteristics.

Results

The results showed that Hip&Knee and Hip-only exercise programs were comparatively effective, while the Knee-only exercise programs proved to be inferior to the above-mentioned approaches. The Hip&Knee exercise programs showed the greatest pain relief (mean difference = -1.71 (-3.11, -0.30); p = 0.02; I² = 96%) and functional improvement (standardized mean difference = 1.28 (0.45, 2.12); p = 0.003; I² = 84%), although the subgroup analysis did not show any significant difference compared to Hip-only exercise programs (p > 0.05).

Conclusion

Overall, Hip&Knee exercise programs appear to reduce pain and improve function more than other exercise programs and could be used as a primary rehabilitation approach in patients with PFP. However, the difference between the subgroups in most outcome measures suggests that Hip&Knee exercise programs are no more effective than Hip-only exercise programs.

Task-specific movement training improves kinematics and pain during the Y-balance test and hip muscle strength in females with patellofemoral pain

OBJECTIVES

Task-specific movement training is a proposed intervention for patellofemoral pain aimed to optimise movement during daily tasks. Focused, progressive task practice emphasising optimal limb alignment may yield improvements in performance-based function and hip muscle strength, and transfer learnt movement patterns to untrained tasks. The purpose of this study was to determine if task-specific movement training improves performance-based function (composite score, movement, pain during movement) in an untrained task. Our secondary purpose was to test whether hip muscle strength improved following the movement training intervention.

METHODS

This study was a secondary analysis of a prospective, non-randomised, within-group, double-baseline study. Twenty-three females with patellofemoral pain underwent task-specific movement training two times/week for 6 weeks. Outcomes were collected at three time points: enrolment (baseline), 6 weeks (preintervention) and 12 weeks (postintervention). A repeated measures analysis of variance tested whether the change during the intervention phase was greater than the change during the control phase. Y-balance composite score, hip and knee kinematics and pain during the Y-balance test were primary outcome measures; strength of the hip lateral rotator, abductor and extensor muscles was a secondary outcome measure.

RESULTS

The change in composite score for the Y-balance test was not statistically significantly different between the intervention and control phases (p=0.16). The change during the intervention phase exceeded the change during the control phase for hip and knee kinematics and pain during the Y-balance test, with all variables improving (p<0.0001). The change during the intervention phase was greater than the control phase for hip muscle strength, with all variables improving (p<0.04).

CONCLUSION

Although the Y-balance test composite score did not improve, performance-based function during an untrained task, measured by movement and pain during the test, improved following task-specific movement training. Hip muscle strength improved, despite no focused muscle strengthening.

LEVEL OF EVIDENCE

Level II.

Dynamic Knee Alignment and Pelvic Balance: Comparison Regarding Gender in Young Soccer Athletes

Objective  To evaluate knee alignment in the frontal plane and pelvic balance during the step-down test in female and male soccer players.

Methods  Cross-sectional study carried out with male and female soccer players from under-15 and under-17 teams of a professional club in Southern Brazil. The step-down test was performed, filmed with a video camera, and evaluated according to the angular measurements obtained during movement using the Kinovea software (open source), version 0.8.24.

Results  The sample consisted of 38 individuals, 19 males and 19 females. Female athletes had a greater varus angle (9.42° ± 1.65°) compared to male athletes (3.91° ± 2.0°; p  = 0.04). There was no difference regarding the unilateral pelvic drop between the groups. In addition, the association between the hip-related pelvic drop and the projection angle on the frontal plane of the knee was weak in both genders.

Conclusion  Even though the pelvic drop was observed in both genders, young female athletes had greater varus knee angles on the step-down test, which require greater attention to minimize the risk of injury.

Recommendations for Movement Re-training After ACL Reconstruction

It is important to optimise the functional recovery process to enhance patient outcomes after major injury such as anterior cruciate ligament reconstruction (ACLR). Restoring movement quality during sporting-type movements is important prior to return-to-sport (RTS) after ACLR. Alterations in movement quality during an array of functional tasks are common amongst ACLR patients at or near the time of RTS and are associated with worse outcomes after ACLR. The inability to correct movement issues prior to RTS is likely due to the use of incomplete programmes or a lack of volume and intensity of movement re-training programmes. Although most clinicians and researchers understand that re-training movement after ACLR is important (e.g., the 'why'), there is often a disconnect with understanding the 'how' and 'what' of movement re-training post ACLR. The aim of this paper was to discuss factors relevant to movement dysfunction and re-training after ACLR and provide recommendations for clinicians to restore movement quality of patients after ACLR, prior to RTS. The paper recommends: (i) considering the factors which influence the expression of movement quality, which revolve around individual (e.g., neuromuscular, biomechanical, sensorimotor and neurocognitive factors), task-specific and environmental constraints; (ii) incorporating a three-staged movement re-training approach aligned to the ACLR functional recovery process: (1) addressing the neuromuscular and biomechanical and sensorimotor control factors which affect movement quality and motor learning, (2) including a progressive movement re-training approach to re-learn an array of functional tasks optimising coordination and motor learning (3) performing the final aspect of rehabilitation and movement training on the field, in realistic environments progressively simulating the sporting movement demands and environmental constraints; and (iii) effectively designing the movement programme for optimal load management, employing effective coach and feedback techniques and utilising qualitative movement analysis for transition between exercises, stages and for RTS.

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

BACKGROUND

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

PURPOSE

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

HYPOTHESIS

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

STUDY DESIGN

Cross-sectional study.

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level 3.

Wearable Technology May Assist in Retraining Foot Strike Patterns in Previously Injured Military Service Members: A Prospective Case Series

A rearfoot strike (RFS) pattern with increased average vertical loading rates (AVLR) while running has been associated with injury. This study evaluated the ability of an instrumented sock, which provides real-time foot strike and cadence audio biofeedback, to transition previously injured military service members from a RFS to a non-rearfoot strike (NRFS) running pattern. Nineteen RFS runners (10 males, 9 females) were instructed to wear the instrumented socks to facilitate a change in foot strike while completing an independent walk-to-run progression and lower extremity exercise program. Kinetic data were collected during treadmill running while foot strike was determined using video analysis at initial (T1), post-intervention (T2), and follow-up (T3) data collections. Nearly all runners (18/19) transitioned to a NRFS pattern following intervention (8 ± 2.4 weeks after the initial visit). Most participants (16/18) maintained the transition at follow-up (5 ± 0.8 weeks after the post-intervention visit). AVLR of the involved and uninvolved limb decreased 29% from initial [54.7 ± 13.2 bodyweights per sec (BW/s) and 55.1 ± 12.7 BW/s] to post-intervention (38.7 ± 10.1 BW/s and 38.9 ± 10.0 BW/s), respectively. This effect persisted 5-weeks later at follow-up, representing an overall 30% reduction on the involved limb and 24% reduction on the uninvolved limb. Cadence increased from the initial to the post-intervention time-point (p = 0.045); however, this effect did not persist at follow-up (p = 0.08). With technology provided feedback from instrumented socks, approximately 90% of participants transitioned to a NRFS pattern, decreased AVLR, reduced stance time and maintained these running adaptations 5-weeks later.

Biomechanical and clinical outcomes in response to inpatient multidisciplinary hip and groin rehabilitation in UK military personnel

INTRODUCTION

Hip and groin related pain is a common complaint among the military population across UK Defence Rehabilitation and addressing associated biomechanical dysfunction is a key treatment goal. Personnel are exposed to complex occupational loads, therefore assessing movement during demanding tasks may expose biomechanical deficits. Observing biomechanical and clinical outcomes in response to treatment is therefore an important consideration. The aims were to examine clinical and biomechanical outcomes prior to (T₁) and 12 weeks post (T₂) inpatient rehabilitation and explore the influence of pathological subgroup.

METHODS

Prospective cohort study as part of a clinical service evaluation of 25 patients undergoing treatment for hip and groin related pain. Three-dimensional motion capture (3DM) during a single-leg squat, hip strength and patient-reported outcome measures were collected at T₁ and T₂.

RESULTS

Increased abductor and external rotator strength with reductions in contralateral pelvic drop (1.9°; p=0.041) at T₂ on the injured side. Pain reduced by 9.6 mm (p=0.017) but no differences were found for Non-Arthritic Hip Score (NAHS). No statistically significant differences were found between pathological subgroups. Kinematic profiles display variation between diagnostic subgroups and response to treatment.

CONCLUSION

Strength and pain improved with treatment in this service evaluation although biomechanical adaptation and NAHS remain inconclusive. Small and uneven sample size prevents a firm conclusion regarding the effect of pathological subgroupings, however, the data can be considered hypothesis generating for future, larger studies to integrate 3DM for monitoring response to rehabilitation in pathological subgroups to support clinical decision making.

Internal and external focus show similar effect on the gait kinematics in patients with patellofemoral pain: A randomised controlled trial

PURPOSE

The purpose of this study was to examine how attentional focus during training influences the effects of a 6-week hip-knee strength training program on pain, function, strength, and kinematics in males and females with Patellofemoral pain (PFP).

METHODS

Seventy-five males and females with PFP were randomly allocated to a group that trained with an internal focus (n = 25), a group that trained with an external focus (n = 25), or a control group (n = 25). All patients completed testing before (baseline) and after (posttest) the 6-week period. The primary outcome was pain, assessed by Visual Analog Scale (VAS). The secondary outcomes were function, hip muscles strength and lower extremity kinematics, assessed by Kujala Questionnaire, handheld dynamometer and a 2-D motion capture, respectively. All outcomes were measured at the baseline and after the 6-week intervention. Analysis of covariance was used to compare posttest outcomes among the groups while accounting for group differences in baseline performance.

RESULTS

The hip-knee strengthening exercises resulted in improved knee valgus (ES(95 % CI) = 0.43(0.26 to 0.75), p = 0.03), and external rotator strength (ES(95 % CI) = 0.51(0.12 to 0.78), p = 0.03) for males and females who trained with an external compared to internal focus.

CONCLUSIONS

Our findings indicate that males and females with PFP may benefit from completing a hip-knee strengthening training program with an external focus vs. an internal focus. Physical therapists and clinicians should consider using instructions that promote an external focus when implementing hip-knee strengthening training programs with PFP patients. This result could be strengthened or re-enforced by larger studies with longer follow up.

Core Strength Training Can Alter Neuromuscular and Biomechanical Risk Factors for Anterior Cruciate Ligament Injury

BACKGROUND

Core stability is influential in the incidence of lower extremity injuries, including anterior cruciate ligament (ACL) injuries, but the effects of core strength training on the risk for ACL injury remain unclear.

HYPOTHESIS

Core muscle strength training increases the knee flexion angle, hamstring to quadriceps (H:Q) coactivation ratio, and vastus medialis to vastus lateralis (VM:VL) muscle activation ratio, as well as decreases the hip adduction, knee valgus, and tibial internal rotation angles.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 48 male participants were recruited and randomly assigned to either the intervention group (n = 32) or the control group (n = 16). Three-dimensional trunk, hip, knee, and ankle kinematic data and muscle activations of selected trunk and lower extremity muscles were obtained while the participants performed side-step cutting. The core endurance scores were measured before and after training. Two-way analyses of variance were conducted for each dependent variable to determine the effects of 10 weeks of core strength training.

RESULTS

The trunk endurance scores in the intervention group significantly increased after training (P < .05 for all comparisons). The intervention group showed decreased knee valgus (P = .038) and hip adduction angles (P = .032) but increased trunk flexion angle (P = .018), rectus abdominis to erector spinae coactivation ratio (P = .047), H:Q coactivation ratio (P = .021), and VM:VL activation ratio (P = .016). In addition, the knee valgus angle at initial contact was negatively correlated with the VM:VL activation ratio in the precontact phase (R² = 0.188; P < .001) but was positively correlated with the hip adduction angle (R² = 0.120; P < .005). No statistically significant differences were observed in the trunk endurance scores, kinematics, and muscle activations for the control group.

CONCLUSION

Core strength training altered the motor control strategies and joint kinematics for the trunk and the lower extremity by increasing the trunk flexion angle, VM:VL activation ratio, and H:Q activation ratio and reducing the knee valgus and hip adduction angles.

CLINICAL RELEVANCE

Training core muscles can modify the biomechanics associated with ACL injuries in a side-step cutting task; thus, core strength training might be considered in ACL injury prevention programs to alter the lower extremity alignment in the frontal plane and muscle activations during sports-related tasks.

Fatigue-Induced Hip-Abductor Weakness and Changes in Biomechanical Risk Factors for Running-Related Injuries

CONTEXT

Despite overlap between hip-abductor (HABD) weakness and fatigue-induced changes in running, the interaction of these theorized contributors to running injuries has been underevaluated.

OBJECTIVE

To assess the effects of a fatiguing run on HABD torque and evaluate the correlation between HABD torque and previously identified running-related injury pathomechanics while participants were rested or fatigued.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 38 healthy, physically active males (age = 21.61 ± 4.02 years, height = 1.78 ± 0.08 m, body mass = 76.00 ± 12.39 kg).

INTERVENTION(S)

Data collection consisted of rested-state collection, a fatiguing treadmill-run protocol, and fatigued-state collection. For the HABD measures, side-lying handheld-dynamometer isometric tests were performed and converted to torque using femur length. For the gait analysis, kinematic (240 Hz) and kinetic (960 Hz) running (4.0 m/s) data were collected for 3 trials. The fatigue protocol involved a graded exercise test and 80% o2max run to exhaustion. Immediately after the run, fatigued-state measures were obtained.

MAIN OUTCOME MEASURE(S)

Variables of interest were HABD torque and peak angles, velocities, and moments for hip and knee adduction and internal rotation. Differences between conditions were compared using paired t tests. Pearson correlation coefficients were calculated to evaluate relationships between HABD torque and biomechanical variables.

RESULTS

Fatigue decreased HABD torque and increased hip-adduction angle, knee-adduction velocity, and hip and knee internal-rotation velocities and moments (all P values < .05). In the rested state, HABD torque was correlated with hip-adduction velocity (r = -0.322, P = .049). In the fatigued state, HABD torque was correlated with hip-adduction velocity (r = -0.393, P = .015), hip internal-rotation velocity (r = -0.410, P = .01), and knee-adduction angle (r = 0.385, P = .017) and velocity (r = -0.378, P = .019).

CONCLUSIONS

Changes in joint velocities due to fatigue and correlations between HABD torque and hip- and knee-joint velocities highlight the need to consider not only the quantity of HABD strength but also the rate of eccentric control of HABDs.

The Influence of Sagittal Plane Hip Position on Lower-Extremity Muscle Activity and Torque Output

CONTEXT

Hip muscle strength has previously been evaluated in various sagittal plane testing positions. Altering the testing position appears to have an influence on hip muscle torque during hip extension, abduction, and external rotation. However, it is unknown how altering the testing position influences hip muscle activity during these commonly performed assessments.

OBJECTIVES

To evaluate how hip sagittal plane position influences hip muscle activation and torque output.

STUDY DESIGN

Cross-sectional.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 22 healthy females (age = 22.1 [1.4] y; mass = 63.4 [11.3] kg; height = 168.4 [6.2] cm) were recruited.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Participants completed isometric contractions with surface electromyography on the superior and inferior gluteus maximus; anterior, middle, and posterior gluteus medius; biceps femoris, semitendinosus, adductor longus, and tensor fascia latae. Extension and external rotation were tested in 0°, 45°, and 90° of hip flexion and abduction was tested in -5°, 0°, and 45° of hip flexion. Repeated-measures analysis of variances were used for statistical analysis (P ≤ .01).

RESULTS

Activation of gluteal (P < .007), semitendinosus (P = .002), and adductor longus (P = .001) muscles were lesser for extension at 90° versus less flexed positions. Adductor longus activity was greatest during 90° of hip flexion for external rotation torque testing (P < .001). Tensor fascia latae (P < .001) and gluteus maximus (P < .001) activities were greater in 45° of hip flexion. Significant differences in extension (P < .001) and abduction (P < .001) torque were found among positions.

CONCLUSIONS

Position when assessing hip extension and abduction torque has an influence on both muscle activity and torque output but only muscle activity for hip external rotation torque. Clinicians should be aware of the influence of position on hip extension, abduction, and external rotation muscle testing and select a position most in line with their clinical goals.

Gait Retraining Improves Running Impact Loading and Function in Previously Injured U.S. Military Cadets: A Pilot Study

INTRODUCTION

Running-related musculoskeletal injury (RRI) among U.S. military service members continues to negatively impact force readiness. There is a paucity of evidence supporting the use of RRI interventions, such as gait retraining, in military populations. Gait retraining has demonstrated effectiveness in altering running biomechanics and reducing running load. The purpose of this pilot study was to investigate the clinical effect of a gait retraining intervention on a military cadet population recovering from a lower-extremity RRI.

MATERIALS AND METHODS

The study design is a pilot study. Before study initiation, institutional approval was granted by the Keller Army Community Hospital Office of Human Research Protections. Nine rearfoot strike (RFS) runners recovering from a lower-extremity RRI at the U.S. Military Academy were prospectively enrolled and completed a gait retraining intervention. Participants followed-up with their assigned medical provider 6 times over 10 weeks for a clinical evaluation and running gait retraining. Gait retraining was provided utilizing verbal, visual, and audio feedback to facilitate a change in running foot strike pattern from RFS to non-rearfoot strike (NRFS) and increase preferred running step rate. At pre-intervention and post-intervention running ground reaction forces (GRF) [average vertical loading rate (AVLR), peak vertical GRF], kinematic (foot strike pattern) and temporospatial (step rate, contact time) data were collected. Participants self-reported their level of function via the Single Assessment Numeric Evaluation, Patient-Specific Functional Scale, and total weekly running minutes. Paired samples t-tests and Wilcoxon signed rank tests were used to compare pre- and post-intervention measures of interest. Values of P < .05 were considered statistically significant.

RESULTS

Nine patients completed the 10-week intervention (age, 20.3 ± 2.2 years; height, 170.7 ± 13.8 cm; mass, 71.7 ± 14.9 kg; duration of injury symptoms, 192.4 ± 345.5 days; running speed, 2.8 ± 0.38 m/s). All nine runners (100%) transitioned from RFS to NRFS. Left AVLR significantly decreased from 60.3 ± 17.0 bodyweight per second (BW/s) before intervention to 25.9 ± 9.1 BW/s after intervention (P = 0.008; effect size (d) = 2.5). Right AVLR significantly decreased from 60.5 ± 15.7 BW/s to 32.3 ± 12.5 BW/s (P < .001; d = 2.0). Similarly, step rate increased from 169.9 ± 10.0 steps per minute (steps/min) before intervention to 180.5 ± 6.5 steps/min following intervention (P = .005; d = 1.3). Single Assessment Numeric Evaluation scores improved significantly from 75 ± 23 to 100 ± 8 (P = .008; d = 1.5) and Patient-Specific Functional Scale values significantly improved from 6 ± 2.3 to 9.5 ± 1.6 (P = .007; d = 1.8) after intervention. Peak vertical GRF (left, P = .127, d = 0.42; right, P = .052, d = 0.53), contact time (left, P = 0.127, d = 0.42; right, P = 0.052, d = 0.53), and total weekly continuous running minutes (P = 0.095, d = 0.80) remained unchanged at post-intervention. All 9 patients remained injury free upon a 6-month medical record review.

CONCLUSIONS

In 9 military service members with a RRI, a 10-week NRFS gait retraining intervention was effective in improving running mechanics and measures of function. Patients remained injury-free 6 months following enrollment. The outcomes of this pilot study suggest that individuals recovering from certain lower-extremity RRIs may benefit from transitioning to an NRFS running pattern.