Gait Retraining as an Intervention for Patellofemoral Pain

The Relationships between Patellofemoral Bone Remodeling, Cartilage Composition, and Vertical Loading Rate: PET/MRI in Isolated Patellofemoral Osteoarthritis

OBJECTIVE

Loading is invariably an important factor of consideration for understanding the causality flow and parallel existence of articular cartilage and subchondral bone changes. The goal of this study was to investigate the patterns of subregional 18NaF-SUV vs. T1p-T2 associations and vertical ground reaction force loading rates; in isolated patellofemoral-joint-osteoarthritis (PFJ-OA) patients.

METHOD

Thirty-five isolated PFJ-OA patients, with no tibiofemoral involvement, underwent simultaneous scans in a 3.0T whole-body hybrid PET-MRI scanner. MRI WORMS assessments were performed to identify/confirm isolated PFJ-OA knees from bilateral scans. T1p-T2 relaxation and SUV values were automatically computed for both trochlear and patellar cartilage and subchondral bone subregions (deep, superficial, lateral, and medial). Maximum vertical impact loading rates (Loading-RateNorm) were calculated from walking trials. Relationships were explored between SUV uptake, T1p-T2 values, and Loading-RateNorm via linear mixed-effects modeling.

RESULTS

Significant and complex association patterns were noted between medial and lateral bone 18NaF-SUV uptakes vs. medial and lateral cartilage sub-regional T1p and T2. SUVMean and SUVMax were positively associated with deep cartilage subregional T1pand T2 values; and negatively associated with superficial cartilage subregional T1p-T2 values in both medial and lateral regions. Both medial and lateral bone 18NaF-SUVMean and SUVMax uptakes remained positively associated with the individual gait characteristics, i.e., peak vertical impact loading rates (Loading-RateNorm).

CONCLUSION

Evidence of simultaneous, complementary, cross-sectional associations between T1p-T2 values and peak vertical loading rates with 18NaF-SUV, have been rare in the isolated PFJ-OA cohort. The clinical implications of such novel associations remain of utmost importance from a gait retraining perspective.

Exploring the use of bimodal transcranial direct current stimulation to enhance movement in individuals with patellofemoral pain-A sham-controlled double blinded pilot study

Introduction

In individuals with patellofemoral pain (PFP), addressing increased knee valgus during weight-bearing activities typically involves strengthening weak hip muscles. However, recent literature highlights the role of altered descending central control in abnormal movements associated with PFP. While transcranial direct current stimulation (tDCS) has demonstrated the capacity to enhance neuroplasticity, its application targeting the corticomotor function of gluteal muscles in PFP remains unexplored. This study aimed to investigate the effects of combining bimodal tDCS with exercise on frontal plane kinematics in individuals with PFP. The hypothesis was that bimodal tDCS, specifically targeting the corticomotor function of the gluteal muscles, would augment the effectiveness of exercise interventions in improving frontal plane kinematics compared to sham stimulation.

Methods

Ten participants with PFP participated in two sessions involving either bimodal tDCS or sham stimulation, concurrently with hip strengthening exercises. Weight-bearing tasks, including single leg squat, single leg landing, single leg hopping, forward step-down, and lateral step-down, were performed and recorded before and after each session. Pain visual analog scale (VAS) scores were also documented. A one-way ANOVA with repeated measures was employed to compare kinematics, while a Friedman test was used to compare VAS across the three conditions (pre-test, post-tDCS, and post-Sham).

Results

We observed no significant differences in trunk lean angle, hip and knee frontal plane projection angles, or dynamic valgus index among the three conditions during the five weight-bearing tasks. VAS scores did not differ across the three conditions.

Discussion and conclusion

A single session of tDCS did not demonstrate immediate efficacy in enhancing frontal plane kinematics or relieving pain in individuals with PFP. Considering observed positive outcomes in other neurological and orthopedic populations with multi-session tDCS applications, suggesting potential cumulative effects, further research is essential to explore the effects of multi-session tDCS on weight-bearing movement and underlying neurophysiology in individuals with PFP.

Enhancing running injury prevention strategies with real-time biofeedback: A systematic review and meta-analysis

The number of runners and the incidence of running-related injuries (RRIs) are on the rise. Real-time biofeedback gait retraining offers a promising approach to RRIs prevention. However, due to the diversity in study designs and reported outcomes, there remains uncertainty regarding the efficacy of different forms of feedback on running gait biomechanics. Three databases: MEDLINE, PUBMED, and SPORTDiscus were searched to identify relevant studies published up to March 2024, yielding 4646 articles for review. The quality of the included studies was assessed using the Downs and Black Quality checklist. Primary outcomes, including Peak Tibial Acceleration (PTA), Vertical Average Loading Rate (VALR), and Vertical Instantaneous Loading Rate (VILR), were analysed through meta-analysis. 24 studies met the inclusion criteria and were analysed in this review.17 used visual biofeedback (VB) while 14 chose auditory biofeedback (AB). The meta-analysis revealed a reduction in loading variables both immediately following the intervention and after extended training, with both visual and auditory feedback. Notably, the decrease in loading variables was more pronounced post-training and VB proved to be more effective than AB. Real-time biofeedback interventions are effective in lowering loading variables associated with RRIs. The impact is more substantial with sustained training, and VB outperforms AB in terms of effectiveness.

Patellofemoral pain syndrome in children and adolescents: A cross-sectional study

OBJECTIVES

To assess the prevalence and associated factors of Patellofemoral Pain Syndrome (PFPS) in children and adolescents.

METHOD

A population-based cross-sectional study was conducted with children and adolescents aged 10 to 18 years, who presented a history of peripatellar and/or retropatellar pain, attending elementary or high school in urban public schools in Natal, Brazil. The sample size was calculated based on a minimum outcome prevalence of 22%.

RESULTS

A prevalence of 24.7% of PFPS was found. There was a positive association of PFPS with active students (p < 0.01; PR: 2.5; CI: 1.4-4.5), low functional capacity (p < 0.01; PR: 8.0; CI: 5.0-12.8), and those classified as pubertal (p < 0.03; PR: 1.8; CI: 1.0-3.2).

CONCLUSION

There was a considerable prevalence of PFPS in children and adolescents, as well as an association between the level of sexual maturation and adjustable determinants, such as the level of physical activity and low functional capacity in this group.

Running Gait Training Improves Outcomes at United States Air Force Basic Military Training

INTRODUCTION

The aim is to investigate the impact of large-group, motor learning-based running gait training on injury risk in United States Air Force (USAF) Basic Military Training (BMT).

DESIGN

A prospective quasi-experimental program evaluation is used.

MATERIALS AND METHODS

Medical providers taught running gait form to groups of trainees in the first week of training of BMT from August 2020 to March 2021. The main outcome measures included risk ratio of reported injuries, removal from training because of injury, and separation from service because of injury.

RESULTS

Of BMT trainees, 2,205 underwent group, motor learning-based running gait training; this was compared with two intake groups (nA = 3,941 and nB = 2,041) who were only given introductions to sports medicine staff in a classroom setting. Reported pain complaints increased (χ2 = 27.4A and 20.83B, P < .001). Risk ratios for more severe injuries necessitating time out of training or separation from USAF were reduced, although these were statistically not significant (13%, P = .48 and 22%, P = .29, respectively). Leadership implemented gait training across BMT, and data from the following 8 weeks of intake (n = 6,223) demonstrated similar trends in increases in patient reports of pain (χ2 = 67.25, P < .001) but significantly reduced risk ratios of removal from training (32%, χ2 = 16.35, P < .001) or separation (32%, χ2 = 12.54, P < .001).

CONCLUSIONS

While not previously shown to mitigate injury, large-group, running gait training was associated with a significant reduction in injury severity defined by training delays and separation from service in USAF BMT.

A framework based on subject-specific musculoskeletal models and Monte Carlo simulations to personalize muscle coordination retraining

Excessive loads at lower limb joints can lead to pain and degenerative diseases. Altering joint loads with muscle coordination retraining might help to treat or prevent clinical symptoms in a non-invasive way. Knowing how much muscle coordination retraining can reduce joint loads and which muscles have the biggest impact on joint loads is crucial for personalized gait retraining. We introduced a simulation framework to quantify the potential of muscle coordination retraining to reduce joint loads for an individuum. Furthermore, the proposed framework enables to pinpoint muscles, which alterations have the highest likelihood to reduce joint loads. Simulations were performed based on three-dimensional motion capture data of five healthy adolescents (femoral torsion 10°-29°, tibial torsion 19°-38°) and five patients with idiopathic torsional deformities at the femur and/or tibia (femoral torsion 18°-52°, tibial torsion 3°-50°). For each participant, a musculoskeletal model was modified to match the femoral and tibial geometry obtained from magnetic resonance images. Each participant's model and the corresponding motion capture data were used as input for a Monte Carlo analysis to investigate how different muscle coordination strategies influence joint loads. OpenSim was used to run 10,000 simulations for each participant. Root-mean-square of muscle forces and peak joint contact forces were compared between simulations. Depending on the participant, altering muscle coordination led to a maximum reduction in hip, knee, patellofemoral and ankle joint loads between 5 and 18%, 4% and 45%, 16% and 36%, and 2% and 6%, respectively. In some but not all participants reducing joint loads at one joint increased joint loads at other joints. The required alteration in muscle forces to achieve a reduction in joint loads showed a large variability between participants. The potential of muscle coordination retraining to reduce joint loads depends on the person's musculoskeletal geometry and gait pattern and therefore showed a large variability between participants, which highlights the usefulness and importance of the proposed framework to personalize gait retraining.

Foot Strike Run Retraining for Patients With Patellofemoral Chondral Defects: A Case Series

Military service members (SMs) demonstrate high rates of patellofemoral chondral defects (PFCDs) that are difficult to diagnosis and, if untreated, result in a cascade of events eventually leading to osteoarthritis. Running is an essential occupational task for SMs; however, there is little evidence regarding techniques to maintain running ability in individuals with cartilage defects. The purpose of this case series was to assess the clinical application of foot strike run retraining in patients with PFCDs. This case series included two active duty U.S. Marine Corps SMs who presented to outpatient physical therapy with PFCD, diagnosed via MRI. Both patients attended eight foot strike run retraining sessions. Running mechanics and patient-reported outcomes were recorded pre-training, post-training, and at a 1-month follow-up visit. Both patients successfully converted their strike pattern from a rearfoot to a non-rearfoot strike pattern with training and retained this strategy at 1-month follow-up. Post-intervention, both patients demonstrated increased running tolerance, and improvements in Numeric Pain Rating Scale and Lower Extremity Functional Scale scores. Biomechanical analysis showed that both patients demonstrated a 63% to 70% reduction in average and peak vertical ground reaction force loading rates post-treatment. Modification of foot strike pattern from rear to non-rearfoot strike during running for individuals with PFCD can reduce the magnitude of impact loading, which potentially limits disease progression. These findings suggest that foot strike run retraining may be a feasible strategy to reduce pain and improve function in SMs with PFCD who are required to run for occupational responsibilities.

Effects of two gait retraining programs on pain, function, and lower limb kinematics in runners with patellofemoral pain: A randomized controlled trial

BACKGROUND

Patellofemoral Pain (PFP) is one of the main injuries in runners. Consistent evidence support strengthening programs to modulate symptoms, however, few studies investigated the effects of gait retraining programs.

OBJECTIVE

To investigate the effects of two different two-week partially supervised gait retraining programs on pain, function, and lower limb kinematics of runners with PFP.

METHODS

Randomized controlled trial. Thirty runners were allocated to gait retraining groups focusing on impact (n = 10) or cadence (n = 10), or to a control group (n = 10). Impact group received guidance to reduce tibial acceleration by 50%, while cadence group was asked to increase cadence by 7.5-10%. The control group did not receive any intervention. Usual and running pain, knee function, and lower limb kinematics (contralateral pelvic drop, hip adduction, knee flexion, ankle dorsiflexion, tibia inclination, and foot inclination) were evaluated before (T0), immediately after the intervention (T2), and six months after the protocol (T24).

RESULTS

A significant group x time interaction was found for running pain (p = 0.010) and knee function (p = 0.019). Both programs had greater improvements in running pain compared to no intervention at T24 (Impact x Control-mean difference (MD) -3.2, 95% CI -5.1 to -1.3, p = 0.001; Cadence x Control-MD -2.9, 95% CI -4.8 to -1.0, p = 0.002). Participants of the impact group had greater improvements in knee function compared to no intervention at T2 (Impact x Control-MD 10.8, 95% CI 1.0 to 20.6, p = 0.027). No between-group differences in usual pain and lower limb kinematics were found (p>0.05).

CONCLUSION

Compared to no intervention, both programs were more effective in improving running pain six months after the protocol. The program focused on impact was more effective in improving knee function immediately after the intervention. Clinical trial registry number: RBR-8yb47v.

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 accuracy of commercially available instrumented insoles (ARION) for measuring spatiotemporal running metrics

Spatiotemporal metrics such as step frequency have been associated with running injuries in some studies. Wearables can measure these metrics and provide real-time feedback in-field, but are often not validated. This study assessed the validity of commercially available wireless instrumented insoles (ARION) for quantifying spatiotemporal metrics during level running at different speeds (2.78-5.0 m s-1 ,) and slopes (3° and 6° up/downhill) to an instrumented treadmill. Mean raw, percentage and absolute percentage error, and limits of agreement (LoA) were calculated. Agreement was statistically quantified using four thresholds: excellent, <5%; good, <10%; acceptable, <15%; and poor, >15% error. Excellent agreement (<5% error) was achieved for stride time across all conditions, and for step frequency across all but one condition with good agreement. Contact time and swing time generally showed at least good agreement. The mean difference across all conditions was -0.95% for contact time, 0.11% for stride time, 0.6% for swing time, -0.11% for step frequency, and -0.09% when averaged across all outcomes and conditions. The accuracy at an individual level was generally good to excellent, being <10% for all but two conditions, with these conditions being <15%. Additional experiments among four runners showed that step length could also be measured with an accuracy of 1.76% across different speeds with an updated version of the insoles. These findings suggests that the ARION wearable may not only be useful for large-scale in-field studies investigating group differences, but also to quantify spatiotemporal metrics with generally good to excellent accuracy for individual runners.

The Relationship between Patellofemoral Pain Syndrome and Hip Biomechanics: A Systematic Review with Meta-Analysis

(1) Background and purpose: Muscular control and motor function in a patient with Patellofemoral pain syndrome (PFPS) have not yet been investigated systematically. Therefore, this review synthesis the previous results about the association of PFPS with gluteus muscle activation, hip strength, and kinematic characteristic of the hip and knee joint, to deepen understanding of the PFPS etiology and promote the establishment of an effective treatment strategy. (2) Methods: A literature search was conducted from January 2000 to July 2022 in four electronic databases: Medline, Embase, Google scholar, and Scopus. A total of 846 articles were initially identified, and after the screening process based on the inclusion criteria, 12 articles were eventually included. Means and SDs of gluteus medius (GMed), gluteus maximus (GMax), hip strength, and kinematic variation of hip and knee were retrieved from the present study. (3) Results and conclusion: Regarding kinematic variation, moderate evidence indicates that an increased peak hip adduction was found in PFPS groups during running and single leg (SL) squat activities. There is no difference in the GMed and GMax activation levels between the two groups among the vast majority of functional activities. Most importantly, strong evidence suggests that hip strength is weaker in individuals with PFPS, showing less strength of hip external rotation and hip abduction compared to the control group. However, without prospective studies, it is difficult to determine whether hip strength weakness is a cause or a result of PFPS. Therefore, further research is needed to evaluate the hip strength level in identifying individuals most likely to associated with PFPS development is needed.

Effect of Flat Running Shoes on Hip Kinematics in Male Recreational Runners

Patellofemoral joint pain and iliotibial band syndrome are very common running-related injuries. Excessive contralateral pelvic drop, hip adduction, and hip internal rotation have been suggested to be associated with the two injuries. The purpose of this repeated measures and the cross-sectional study was to investigate the effect of flat running shoes on these kinematic variables compared with that of conventional running shoes with a 10 mm drop. Eighteen male recreational runners were recruited to run in flat shoes and conventional shoes with a 10 mm drop, in random order. Impact force data and lower extremity kinematics were synchronously obtained using two Kistler force plates and eight motion infrared cameras, whereas differences in the impact force and hip kinematics were compared using statistical parametric mapping. Regarding hip kinematics, the hip flexion (p = 0.004) and adduction angles (p = 0.004) decreased significantly at 30-70% and 62-85% of the stance phase, respectively, while wearing flat running shoes; the contralateral pelvic drop angle (p = 0.001) decreased significantly at 31-75% of the stance phase while wearing flat running shoes. The knee internal rotation angle (p = 0.035) decreased significantly at 8-17% of the stance phase while wearing flat running shoes compared with conventional running shoes. Given that these kinematic variables are associated with patellofemoral joint pain and iliotibial band syndrome, flat running shoes may have potential benefits for the prevention or treatment of knee injuries.

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.

Reduced Vastus Medialis/Lateralis EMG Ratio in Volleyballers with Chronic Knee Pain on Sports-Specific Surfaces: A Pilot Study

BACKGROUND

Even though chronic knee pain is common in volleyball, neuromuscular imbalance as a potential risk factor has not been investigated in volleyball-specific tasks. The aim of the study was to compare neuromuscular control between healthy and injured players in a clinical jump test and a volleyball-specific jump task in real field conditions.

METHODS

Six athletes with knee pain and nine controls were included. Surface electromyographic data were recorded from the mm. vastus medialis (VM) and lateralis (VL) of both legs. VM/VL activation ratio was calculated from countermovement jump (CMJ) and volleyball spike indoors and on two beach surfaces.

RESULTS

All subjects had pain in the leading leg. Mann-Whitney U Test (M-W-U Test) revealed a significantly lower VM/VL ratio of the leading leg (always affected) of the injured compared with that of the healthy control group for the CMJ and spike jump on all three grounds. Bland-Altman analysis revealed low bias and low difference in standard deviation for the injured leg but high values for the uninvolved leg and healthy controls between tasks and grounds. These results could indicate that neuromuscular control might not adapt too well to different movement tasks and grounds in the injured leg.

CONCLUSION

Athletes with chronic knee pain might have lower VM/VL ratios than controls independent from movement task and ground. Neuromuscular control in injured athletes might be less adaptable to new circumstances. The results of neuromuscular control in laboratory settings might be applicable to field conditions in injured legs but not healthy ones.

PIMP Your Stride: Preferred Running Form to Guide Individualized Injury Rehabilitation

Despite the wealth of research on injury prevention and biomechanical risk factors for running related injuries, their incidence remains high. It was suggested that injury prevention and reconditioning strategies should consider spontaneous running forms in a more holistic view and not only the injury location or specific biomechanical patterns. Therefore, we propose an approach using the preferred running form assessed through the Volodalen^® method to guide injury prevention, rehabilitation, and retraining exercise prescription. This approach follows three steps encapsulated by the PIMP acronym. The first step (P) refers to the preferred running form assessment. The second step (I) is the identification of inefficiency in the vertical load management. The third step (MP) refers to the movement plan individualization. The answers to these three questions are guidelines to create individualized exercise pathways based on our clinical experience, biomechanical data, strength conditioning knowledge, and empirical findings in uninjured and injured runners. Nevertheless, we acknowledge that further scientific justifications with appropriate clinical trials and mechanistic research are required to substantiate the approach.

Linking Gait Biomechanics and Daily Steps After ACL Reconstruction

PURPOSE

Aberrant biomechanics and altered loading frequency are associated with poor knee joint health in osteoarthritis development. After anterior cruciate ligament reconstruction (ACLR), individuals demonstrate underloading (lesser vertical ground reaction force (vGRF)) with stiffened knee gait biomechanics (lesser knee extension moment (KEM) and knee flexion angle) and take fewer daily steps as early as 6 months after surgery. The purpose of this cross-sectional laboratory study is to compare gait biomechanics throughout stance between individuals 6-12 months after ACLR who take the lowest, moderate, and highest daily steps.

METHODS

Individuals with primary, unilateral history of ACLR between the ages of 16 and 35 yr were included (n = 36, 47% females; age, 21 ± 5 yr; months since ACLR, 8 ± 2). Barefoot gait biomechanics of vGRF (body weight), KEM (body weight × height), and knee flexion angle during stance were collected and time normalized. Average daily steps were collected via a waist-mounted accelerometer in free-living settings over 7 d. Participants were separated into tertiles based on lowest daily steps (3326-6042 daily steps), moderate (6043-8198 daily steps), and highest (8199-12,680 daily steps). Biomechanical outcomes of the ACLR limb during stance were compared between daily step groups using functional waveform gait analyses.

RESULTS

There were no significant differences in sex, body mass index, age, or gait speed between daily step groups. Individuals with the lowest daily steps walk with lesser vGRF and lesser KEM during weight acceptance, and lesser knee flexion angle throughout stance in the ACLR limb compared with individuals with highest and moderate daily steps.

CONCLUSIONS

After ACLR, individuals who take the fewest daily steps also walk with lesser vGRF during weight acceptance and a stiffened knee strategy throughout stance. These results highlight complex interactions between joint loading parameters after ACLR.

Clinicians' experience of the diagnosis and management of patellofemoral pain: A qualitative exploration

BACKGROUND

Patellofemoral pain (PFP) is common and has a poor long-term prognosis. There is a lack of clarity about the clinical reasoning of recognised inter-disciplinary experts in the published literature.

OBJECTIVES

To help identify best practice by exploring the clinical reasoning of a range of inter-disciplinary experts that regularly diagnose and treat PFP.

DESIGN

Qualitative study with semi-structured interviews.

METHOD

Recruitment resulted in a convenience sample for semi-structured interview, which were recorded and transcribed verbatim. Data were analysed until theoretical saturation, as determined by multiple investigators.

FINDINGS

Interviews with 19 clinical experts (15 men, 4 women; mean experience 18.6 years ± 8.6) from four broad professions yielded four themes. Firstly, the assessment and diagnosis process should include a thorough history and examination to rule in PFP. Secondly, information provision should aim to increase patients' understanding, aid in controlling symptoms, and facilitate behaviour change. Thirdly, active rehabilitation, which was a salient theme and included advocacy of combined hip and knee exercise that is adapted to the individual. Finally, treatment adjuncts, which can be used selectively to modify symptoms, may include running retraining, taping, or foot orthoses.

CONCLUSIONS

PFP should be diagnosed clinically, and tailored treatment programmes should be prescribed for people with PFP. Exercise was considered the most effective treatment and underlying psychological factors should be addressed to improve prognosis.

The Effectiveness of Gait Retraining on Running Kinematics, Kinetics, Performance, Pain, and Injury in Distance Runners: A Systematic Review With Meta-analysis

OBJECTIVE

To evaluate the effectiveness of running gait retraining on kinematics, kinetics, performance, pain, and injury in distance runners.

DESIGN

Intervention systematic review with meta-analysis.

LITERATURE SEARCH

Seven electronic databases from inception to March 2021.

TRIAL SELECTION CRITERIA

Randomized controlled trials that (1) evaluated running gait retraining compared to no intervention, usual training, placebo, or standard care and (2) reported biomechanical, physiological, performance, or clinical outcomes.

DATA SYNTHESIS

Random-effects metaanalyses were completed, and the certainty of evidence was judged using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. We categorized interventions into step rate, non-rearfoot footstrike, impact, ground contact time, and multiparameter subgroups.

RESULTS

We included 19 trials (673 participants). Moderate-certainty evidence indicated step rate gait retraining increased step rate (SMD 1.03 [95% confidence interval {CI}: 0.63, 1.44]; number of trials (N): 4; I²: 0%) and reduced average vertical loading rate (SMD -0.57 [95% CI, -1.05 to -0.09], N: 3; I²: 0%). Low-certainty evidence indicated non-rearfoot footstrike retraining increased knee flexion at initial contact (SMD 0.74 [95% CI, 0.11 to 1.37]; N: 2; I²: 0%), but did not alter running economy (SMD 0.21 [95% CI, -1.11 to 1.52]; N: 3; I²: 19%).). Low-certainty evidence indicated multiparameter retraining did not alter running economy (SMD 0.32 [-0.39, 1.02]; N: 3; I²: 19%) or performance (SMD 0.14 [95% CI, -4.87 to 4.58]; N: 2; I²: 18%). Insufficient trials reported on pain outcomes. Two trials demonstrated reduced 1-year injury incidence following gait retraining.

CONCLUSIONS

Gait retraining interventions altered step rate and knee kinematics, lowered vertical loading rates, and did not affect running performance. J Orthop Sports Phys Ther 2022;52(4):192-206. Epub 05 Feb 2022. doi:10.2519/jospt.2022.10585.

Prehabilitation for Recreational Runners: Motivators, Influencers, and Barriers to Injury Prevention Strategies for Running-Related Injury

CONTEXT

Injury prevention programs are effective when implemented in team sports, but many recreational runners have less access to such focused interventions or peer support and often seek other sources to learn about injury reduction strategies.

OBJECTIVE

This study aimed to explore runners' motivations in attending a prehabilitation (prehab) for runners workshop, establish their comprehension of prehab, and identify barriers to ongoing engagement with injury prevention.

DESIGN

Qualitative study using focus groups.

PARTICIPANTS AND SETTING

Twenty-two runners participating in prehab for runners workshops took part in one of 4 focus groups, each recorded, transcribed, and analyzed using Grounded Theory to create codes, subthemes, and themes.

RESULTS

Four themes emerged: (1) Participation was influenced by experience of previous injury and worry of cessation of running. As the workshop ran weekly for 4 weeks, opportunity to see someone more than once who was also a physiotherapist influenced participation. (2) Runners welcomed clarification for online exercises and advice suggested for runners. They were surprised by the difficulty of single-leg neuromuscular facilitation exercises and reported benefit from most or all information especially non-exercise-based approaches such as load management, pain monitoring, and running cues. (3) Participants were empowered by a structured, holistic, and evidence-based approach that embraced autonomy for exercise self-selection and progression. Confidence to engage in open discussion was due to small group size. (4) Barriers to prehab were personal responsibility, equipment, time, lack of supervision, and peer influence.

CONCLUSION

A composite approach to strategies for injury risk reduction during prehab, combining progressive exercises with educational resources, can address runners' individual needs. Early discussion of motivational tools on commencement of prehab with guidance from runners on how to incorporate prehab independently into running training is recommended. Providing these tools allows runners to self-identify the approach best suited to their personal running profile at that given time.

Brain and Spinal Cord Adaptations Associated With Patellofemoral Pain: A Systematic Review and Meta-Analysis

Objective

To evaluate the evidence for altered cortical and spinal cord functions in individuals with patellofemoral pain (PFP).

Methods

We conducted a comprehensive search of databases to appraise and analyze the studies published prior to December 10, 2021 that examined spinal reflex excitability measured using Hoffmann reflex (H-reflex) amplitudes, corticospinal excitability measured using transcranial magnetic stimulation (TMS)-elicited motor evoked potential (MEP) amplitudes, motor threshold (MT), or stimulus-response (SR) curves, cortical reorganization assessed using TMS cortical mapping or structural magnetic resonance imaging (MRI), or functional changes of the brain assessed using functional MRI (fMRI) in individuals with PFP.

Results

Eight studies were eligible for analyses. While an earlier study showed that pain had no effect on the H-reflex amplitude of the quadriceps muscle, more recent evidence reported a decrease in vastus medialis (VM) H-reflex amplitude in participants with PFP. VM H-reflex amplitude was correlated with pain, chronicity, physical function, and isometric knee extensor torque production in participants with PFP. Altered corticospinal excitability was reported in participants with PFP, observed as increased MT in the VM and vastus lateralis (VL) muscles. In addition, cortical reorganization has been observed, where decreased number of cortical peaks, shifts and reduced volumes, and increased overlap of motor cortex representations for the VM, VL, and rectus femoris (RF) muscles were reported in participants with PFP.

Conclusion

There is emerging evidence on altered cortical and spinal cord functions in individuals with PFP, however, solid conclusions cannot be drawn due to limited literature available. Further research is needed to better understand the adaptations of the brain and spinal cord in this population.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42020212128.

Utility of Gait Biofeedback Training to Improve Walking Biomechanics in Patients With Chronic Ankle Instability: A Critically Appraised Topic

Clinical Scenario: Chronic ankle instability (CAI) is a condition that involves feelings of the ankle “giving way,” pain, and decreased self-reported function. Individuals with CAI often demonstrate persistent biomechanical impairments during gait that are associated with repetitive lateral ankle sprains (LAS) and the development of early onset ankle posttraumatic osteoarthritis (OA). Traditional rehabilitation strategies have not successfully improved these reported aberrant gait biomechanics; thus, traditional rehabilitation may not effectively reduce the risk of recurrent LAS and ankle OA among individuals with CAI. Conversely, targeted gait training with biofeedback may be effective at decreasing the risk of recurring LAS and ankle OA if these rehabilitation strategies can promote individuals with CAI to develop a gait strategy that protects against subsequent LAS and ankle OA. Clinical Question: Can targeted gait biofeedback interventions cause individuals with CAI to implement a walking gait pattern that is not associated with recurrent LAS and ankle OA? Summary of Findings: Five studies assessed gait biofeedback interventions targeting plantar pressure and/or ankle kinematics involving visual biofeedback (n = 3), auditory biofeedback (n = 1), and haptic biofeedback (n = 1). Plantar pressure was medially shifted during a single session while receiving biofeedback (n = 2), immediately after biofeedback (n = 1), and 5 minutes after receiving biofeedback (n = 1) in 3 studies. One study demonstrated reduced ankle inversion after 8 sessions of biofeedback training. One study did not substantially improve plantar pressure while receiving visual feedback. Clinical Bottom Line: Targeted gait training strategies appear effective in acutely altering gait biomechanics in individuals with CAI while receiving, and immediately after, biofeedback has been removed. Long-term outcomes are not currently established for gait training strategies in those with CAI. Strength of Recommendation: Limited evidence (grade B) suggests that targeted gait biofeedback strategies can alter specific CAI gait biomechanics to a strategy not associated with recurrent LAS, and ankle OA immediately, and after, multiple sessions of gait training.

Extensor mechanism tendinopathy in patients with lateral patellar maltracking

OBJECTIVE

Patellar maltracking is an important subset of patellofemoral pain syndrome. We hypothesize that maltracking patients have an increased incidence of extensor mechanism dysfunction due to repetitive attempts at stabilization of the patella. Our purpose is to delineate imaging features to identify maltracking patients at risk for extensor mechanism tendinopathy.

MATERIALS AND METHODS

Retrospective review of knee MRIs performed for anterior knee pain over a year was conducted to identify 218 studies with imaging findings of maltracking. The cases were evaluated for the presence and degree of patellar and quadriceps tendinopathy, tibial tuberosity-trochlear groove distance (TT-TG) and the distribution and grade of patellofemoral chondrosis. Cases were compared to 100 healthy, age-matched control knee MRIs.

RESULTS

The mean age of maltracking patients with either patellar or quadriceps tendinosis was 41.2 years versus 48.2 years in the control population (p = 0.037). The TT-TG was significantly higher in maltracking patients with either patellar or quadriceps tendinosis at 16.49 mm versus 14.99 mm (p = 0.006). Maltrackers with isolated lateral patellofemoral chondrosis had a higher mean TT-TG at 17.4 mm versus 15.4 mm (p = 0.007). Extensor mechanism tendinosis was increased in the maltracking population compared to the controls at 57.8% versus 27.3% (p = 0.004).

CONCLUSION

Extensor mechanism tendinosis is more common in the maltracking population and occurs at a younger age. TT-TG distance is significantly increased in patients with extensor mechanism dysfunction and in patients with isolated lateral patellofemoral chondrosis. TT-TG measurement can be used independently to identifying maltrackers who may be at risk for future complications.

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.

Neurophysiological changes of brain and spinal cord in individuals with patellofemoral pain: a systematic review and meta-analysis protocol

INTRODUCTION

Reduced neuromuscular control due to altered neurophysiological functions of the central nervous system has been suggested to cause movement deficits in individuals with patellofemoral pain (PFP). However, the underlying neurophysiological measures of brain and spinal cord in this population remain to be poorly understood. The purpose of this systematic review is to evaluate the evidence for altered cortical and spinal cord functions in individuals with PFP.

METHODS AND ANALYSIS

The protocol for conducting the review was prepared using the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines. We will systematically search the literature that examines cortical and spinal cord functions in individuals with PFP, aged 18-45 years. The studies for cross-sectional, prospective, longitudinal, case-control and randomised control trial designs will be included from the following databases: PubMed (MEDLINE), EMBASE and Web of Science. Only studies published in English prior to 1 February 2021 will be included. The risk of bias and quality assessment will be performed using National Institutes of Health's Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. We will conduct meta-analysis of the data where appropriate. Narrative synthesis will be taken if a meta-analysis is not possible.

ETHICS AND DISSEMINATION

This is a systematic review from the existing literature and does not require ethical approval. The results of this study will be published in a peer-reviewed journal in the field of rehabilitation medicine, sports/orthopaedic medicine or neurology, regardless of the outcome.

PROSPERO REGISTRATION NUMBER

CRD42020212128.

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.

Effects of gait retraining with focus on impact versus gait retraining with focus on cadence on pain, function and lower limb kinematics in runners with patellofemoral pain: Protocol of a randomized, blinded, parallel group trial with 6-month follow-up

Patellofemoral pain (PFP) is one of the most prevalent injuries in runners. Unfortunately, a substantial part of injured athletes do not recover fully from PFP in the long-term. Although previous studies have shown positive effects of gait retraining in this condition, retraining protocols often lack clinical applicability because they are time-consuming, costly for patients and require a treadmill. The primary objective of this study will be to compare the effects of two different two-week partially supervised gait retraining programs, with a control intervention; on pain, function and lower limb kinematics of runners with PFP. It will be a single-blind randomized clinical trial with six-month follow-up. The study will be composed of three groups: a group focusing on impact (group A), a group focusing on cadence (group B), and a control group that will not perform any intervention (group C). The primary outcome measure will be pain assessed using the Visual Analog Pain scale during running. Secondary outcomes will include pain during daily activities (usual), symptoms assessed using the Patellofemoral Disorders Scale and lower limb running kinematics in the frontal (contralateral pelvic drop; hip adduction) and sagittal planes (foot inclination; tibia inclination; ankle dorsiflexion; knee flexion) assessed using the MyoResearch 3.14-MyoVideo (Noraxon U.S.A. Inc.). The study outcomes will be evaluated before (t0), immediately after (t2), and six months (t24) after starting the protocol. Our hypothesis is that both partially supervised gait retraining programs will be more effective in reducing pain, improving symptoms, and modifying lower limb kinematics during running compared with the control group, and that the positive effects from these programs will persist for six months. Also, we believe that one gait retraining group will not be superior to the other. Results from this study will help improve care in runners with PFP, while maximizing clinical applicability as well as time and cost-effectiveness.

Eccentric exercise in the prevention of patellofemoral pain in high-volume runners: A rationale for integration

Patellofemoral pain (PFP) is a common overuse condition seen in high-volume runners, such as military recruits. Exercise is commonly prescribed, with benefit, for the rehabilitation of individuals with PFP. However, a substantial number of individuals with the condition do not achieve an optimal outcome, suggesting the condition can be difficult and complex. Given the challenging nature of the condition, and the risk of developing PFP in high-volume runners, it seems logical to investigate options for injury prevention. Eccentric exercise has been useful in the prevention of some pathologies so its utility in preventing PFP should be explored. Current evidence regarding prevention programs for PFP are limited. Preventative exercise programs for PFP have not been well described or reported, and questions remain regarding their effectiveness. Based on available evidence or lack thereof, and known physiological and clinical effects of eccentric exercise, suggestions for integration of eccentric exercise into PFP prevention programs are offered. Eccentric exercise may be useful for PFP prevention from a theoretical framework however additional longitudinal cohort studies would be useful in determining its utility.

Characteristics of Injuries Occurring During Cross-Country: A Report from the Athletic Training Practice-Based Research Network

CONTEXT

Cross-country is a popular sport activity, particularly in adolescent populations. Although epidemiologic investigations have provided insight into patient and injury characteristics associated with running injuries, little is known about how these injuries are managed at the point of care.

OBJECTIVE

To describe injury and treatment characteristics of injuries sustained during cross-country.

DESIGN

Cross-sectional study.

SETTING

High school athletic training clinics within the Athletic Training Practice-Based Research Network.

PATIENTS OR OTHER PARTICIPANTS

Patient cases were included if the patient was diagnosed with an injury that occurred during interscholastic cross-country participation. All patients received usual care by an athletic trainer.

MAIN OUTCOME MEASURE(S)

We used summary statistics to describe injury (sex, age, participation level, time of injury, mechanism of injury, body part, injury type, diagnosis) and treatment (type, amount, duration, number of services) characteristics.

RESULTS

Most cross-country injuries occurred to the lower extremity and were musculotendinous or ligamentous in nature. The most common injury types were sprain/strain (43.8%), tendinopathy (18.5%), and general pain (9.5%). Injured body parts and diagnoses were typically similar between sexes. The most frequently used treatment was therapeutic exercises or activities (28.7%), and patients received an average of 7.4 ± 17.4 total athletic training services during 5.5 ± 15.1 episodes of care over 27.8 ± 87.5 days.

CONCLUSIONS

Adolescent cross-country student-athletes frequently sustained non-time-loss injuries that required up to 1 month of treatment and management. These findings will generate awareness surrounding the role of athletic trainers in providing care for cross-country athletes.

An exploratory investigation of patellofemoral joint loadings during directional lunges in badminton

Anterior knee pain is a commonly documented musculoskeletal disorder among badminton players. However, current biomechanical studies of badminton lunges mainly report kinetic profiles in the lower extremity with few investigations of in-vivo loadings. The objective of this study was to evaluate tissue loadings in the patellofemoral joint via musculoskeletal modelling and Finite Element simulation. The collected marker trajectories, ground reaction force and muscle activation data were used for musculoskeletal modelling to compute knee joint angles and quadricep muscle forces. These parameters were then set as boundary conditions and loads for a quasistatic simulation using the Abaqus Explicit solver. Simulations revealed that the left-forward (LF) and backward lunges showed greater contact pressure (14.98-29.61%) and von Mises stress (14.17-32.02%) than the right-forward and backward lunges; while, loadings in the left-backward lunge were greater than the left-forward lunge by 13-14%. Specifically, the stress in the chondral layer was greater than the contact interface, particularly in the patellar cartilage. These findings suggest that right-side dominant badminton players load higher in the right patellofemoral joint during left-side (backhand) lunges. Knowledge of these tissue loadings may provide implications for the training of badminton footwork, such as musculature development, to reduce cartilage loading accumulation, and prevent anterior knee pain.

Patient-Reported Outcomes and Knee Mechanics Correlate With Patellofemoral Deep Cartilage UTE-T2* 2 Years After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Patellofemoral joint degeneration and dysfunction after anterior cruciate ligament reconstruction (ACLR) are increasingly recognized as contributors to poor clinical outcomes.

PURPOSE

To determine if greater deep cartilage matrix disruption at 2 years after ACLR, as assessed by elevated patellofemoral magnetic resonance imaging (MRI) ultrashort echo time-enhanced T2* (UTE-T2*), is correlated with (1) worse patient-reported knee function and pain and (2) gait metrics related to patellofemoral tracking and loading, such as greater external rotation of the tibia at heel strike, reduced knee flexion moment (as a surrogate of quadriceps function), and greater knee flexion angle at heel strike.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

MRI UTE-T2* relaxation times in patellar and trochlear deep cartilage were compared with patient-reported outcomes and ambulatory gait metrics in 60 patients with ACLR at 2 years after reconstruction. ACLR gait metrics were compared with those of 60 uninjured reference patients matched by age, body mass index, and sex. ACLR UTE-T2* values were compared with those of 20 uninjured reference patients.

RESULTS

Higher trochlear UTE-T2* values were associated with worse Knee injury and Osteoarthritis Outcome Scores (KOOS) Sport/Recreation subscale scores (rho = -0.32; P = .015), and showed a trend for association with worse KOOS Pain subscale scores (rho = -0.26; P = .045). At 2 years after ACLR, greater external rotation of the tibia at heel strike was associated with higher patellar UTE-T2* values (R = 0.40; P = .002); greater knee flexion angle at heel strike was associated with higher trochlear UTE-T2* values (rho = 0.39; P = .002); and greater knee flexion moment showed a trend for association with higher trochlear UTE-T2* values (rho = 0.30; P = .019). Patellar cartilage UTE-T2* values, knee flexion angle at heel strike, and external rotation of the tibia at heel strike were all elevated in ACLR knees as compared with reference knees (P = .029, .001, and .044, respectively).

CONCLUSION

Patellofemoral deep cartilage matrix disruption, as assessed by MRI UTE-T2*, was associated with reduced sports and recreational function and with gait metrics reflective of altered patellofemoral loading. As such, the findings provide new mechanistic information important to improving clinical outcomes related to patellofemoral dysfunction after ACLR.

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.

Normative measures of hip strength and relation to previous injury in collegiate cross-country runners

CONTEXT

Running related injury occurs frequently in collegiate cross-country runners. Hip strength is one factor that may be important in the rehabilitation and training of cross-country runners. However, no normative values exist to inform these strategies.

OBJECTIVE

Establish normative values for hip abduction and external rotation isometric strength in collegiate cross-country runners and explore the association between strength and previous injury.

DESIGN

Mixed methods using descriptive epidemiology and retrospective cross-sectional designs.

SETTING

University Laboratory Patients or Other Participants: Eighty-two NCAA Division III cross-country runners (38 males, 44 females) participated in this study.

MAIN OUTCOME MEASURE(S)

Isometric hip strength and reported injury Results: Males demonstrated greater absolute hip strength than females. Measures of hip strength were not different between sexes when normalized to height and mass. Hip abduction asymmetry was associated with previous injury in males. A combination of at least one leg with hip abduction weakness and bilateral external rotation weakness was associated with previous injury in females.

CONCLUSIONS

Knowledge of normative values of hip strength may help inform rehabilitation strategies in collegiate cross-country runners. Males and females may demonstrate differing strength profiles following running related injury.

Running barefoot leads to lower running stability compared to shod running - results from a randomized controlled study

Local dynamic running stability is the ability of a dynamic system to compensate for small perturbations during running. While the immediate effects of footwear on running biomechanics are frequently investigated, no research has studied the long-term effects of barefoot vs. shod running on local dynamic running stability. In this randomized single-blinded controlled trial, young adults novice to barefoot running were randomly allocated to a barefoot or a cushioned footwear running group. Over an 8-week-period, both groups performed a weekly 15-min treadmill running intervention in the allocated condition at 70% of their VO2 max velocity. During each session, an inertial measurement unit on the tibia recorded kinematic data (angular velocity) which was used to determine the short-time largest Lyapunov exponents as a measure of local dynamic running stability. One hundred running gait cycles at the beginning, middle, and end of each running session were analysed using one mixed linear multilevel random intercept model. Of the 41 included participants (48.8% females), 37 completed the study (drop-out = 9.7%). Participants in the barefoot running group exhibited lower running stability than in the shod running group (p = 0.037) with no changes during the intervention period (p = 0.997). Within a single session, running stability decreased over the course of the 15-min run (p = 0.012) without differences between both groups (p = 0.060). Changing from shod to barefoot running reduces running stability not only in the acute phase but also in the longer term. While running stability is a relatively new concept, it enables further insight into the biomechanical influence of footwear.

Agreement Between the OptoGait and Instrumented Treadmill System for the Quantification of Spatiotemporal Treadmill Running Parameters

The measurement of spatiotemporal gait parameters is commonly utilized to assess gait in healthy and injured individuals. The OptoGait system is a portable system and can be mounted to a treadmill to collect data in a clinical, training, or research setting. The purpose of this method comparison study was to examine the agreement of spatiotemporal gait parameters calculated by the OptoGait compared to an instrumented treadmill system during running. Thirty healthy runners ran on an instrumented treadmill with the OptoGait 1-m system mounted along the treadmill platform. Spatiotemporal running variables of step rate, step length, and contact time were calculated during the final minute of treadmill running. The level of agreement between the OptoGait and treadmill was analyzed using intraclass correlation coefficients [ICC (2,3)] for step rate, step length, and contact time. Step rate and step length demonstrated excellent agreement. Contact time demonstrated good agreement. Intraclass correlation coefficients for spatiotemporal parameters ranged from 0.83 to 0.99. The OptoGait demonstrated good to excellent agreement in the evaluation of running step rate, step length, and contact time and should be considered for use in clinical, training, or research settings.

Osteopathic Manipulative Treatment Versus Exercise Program in Runners With Patellofemoral Pain Syndrome: A Randomized Controlled Trial

CONTEXT

The effects of an exercise program (EP) for the treatment of patellofemoral pain syndrome (PFPS) are well known. However, the effects of osteopathic manipulative treatment (OMT) are unclear.

OBJECTIVE

To evaluate the effects of OMT versus EP on knee pain, functionality, plantar pressure in middle foot (PPMF), posterior thigh flexibility (PTF), and range of motion of hip extension in runners with PFPS.

DESIGN

This is a randomized controlled trial.

SETTING

Human performance laboratory.

PARTICIPANTS

A total of 82 runners with PFPS participated in this study.

INTERVENTIONS

The participants were randomized into 3 groups: OMT, EP, and control group. The OMT group received joint manipulation and myofascial release in the lumbar spine, hip, sacroiliac joint, knee, and ankle regions. The EP group performed specific exercises for lower limbs. The control group received no intervention.

MAIN OUTCOME MEASURES

The main evaluations were pain through the visual analog scale, functionality through the Lysholm Knee Scoring Scale, dynamic knee valgus through the step-down test, PPMF through static baropodometry, PTF through the sit and reach test, and range of motion through fleximetry. The evaluations were performed before the interventions, after the 6 interventions, and at 30-day follow-up.

RESULTS

There was a significant pain decrease in the OMT and EP groups when compared with the control group. OMT group showed increased functionality, decreased PPMF, and increased PTF. The range of motion for hip extension increased only in the EP group.

CONCLUSION

Both OMT and EP are effective in treating runners with PFPS.

A Random Forest Machine Learning Framework to Reduce Running Injuries in Young Triathletes

Background: The running segment of a triathlon produces 70% of the lower limb injuries. Previous research has shown a clear association between kinematic patterns and specific injuries during running. Methods: After completing a seven-month gait retraining program, a questionnaire was used to assess 19 triathletes for the incidence of injuries. They were also biomechanically analyzed at the beginning and end of the program while running at a speed of 90% of their maximum aerobic speed (MAS) using surface sensor dynamic electromyography and kinematic analysis. We used classification tree (random forest) techniques from the field of artificial intelligence to identify linear and non-linear relationships between different biomechanical patterns and injuries to identify which styles best prevent injuries. Results: Fewer injuries occurred after completing the program, with athletes showing less pelvic fall and greater activation in gluteus medius during the first phase of the float phase, with increased trunk extension, knee flexion, and decreased ankle dorsiflexion during the initial contact with the ground. Conclusions: The triathletes who had suffered the most injuries ran with increased pelvic drop and less activation in gluteus medius during the first phase of the float phase. Contralateral pelvic drop seems to be an important variable in the incidence of injuries in young triathletes.

Relationship among maximum hip isometric strength, hip kinematics, and peak gluteal muscle force during running

OBJECTIVE

To determine if there is a relationship among isometric hip strength, hip kinematics, and peak gluteal muscle forces in cross-country runners during running.

DESIGN

Cross Sectional.

SETTING

University Biomechanics Laboratory.

PARTICIPANTS

Forty-six NCAA Division III collegiate cross-country runners (18 males, 28 females).

MAIN OUTCOME MEASURES

Pearson correlation coefficients were used to describe relationships among isometric hip strength, hip kinematics, and peak gluteal muscle forces during the stance phase of running. Strength of correlations were interpreted as little to no relationship (r < 0.25), fair relationship (0.25 ≤ r < 0.5), moderate relationship (0.5 ≤ r < 0.75), and strong relationship (r ≥ 0.75). Correlations were considered significant if p < 0.05.

RESULTS

Little to no relationships were found among isometric hip strength and gluteal muscle forces during running (r < 0.25). A fair relationship was present between prone external rotation isometric hip strength and peak hip adduction (0.25 <r < 0.5). Little to no relationship was shown between gluteus medius force and hip internal rotation. Moderate relationships were present among peak gluteus medius and minimus muscle forces and peak hip adduction (0.5 <r < 0.75).

CONCLUSION

Isometric hip strength does not appear to be related to gluteal muscle forces and hip kinematics during the stance phase of running while gluteal muscle force was moderately related to hip adduction. Factors other than strength may be related to muscle force production and hip kinematics during running.