The effect of changing mediolateral center of pressure on rearfoot eversion during treadmill running

IntroductionAtypical rearfoot eversion is an important kinematic risk factor in running-related injuries. Prominent interventions for atypical rearfoot eversion include foot orthoses, footwear, and taping, yet a running gait retraining is lacking. Therefore, the aim was to investigate the effects of changing mediolateral center of pressure (COP) on rearfoot eversion, subtalar pronation, medial longitudinal arch angle (MLAA), hip kinematics and vertical ground reaction force (vGRF).MethodsFifteen healthy female runners underwent gait retraining under three conditions. Participants were instructed to run normally, on the lateral (COP lateral) and medial (COP medial) side of the foot. Foot progression angle (FPA) was controlled using real-time visual feedback. 3D measurements of rearfoot eversion, subtalar pronation, MLAA, FPA, hip kinematics, vGRF and COP were analyzed. A repeated-measures ANOVA followed by pairwise comparisons was used to analyze changes in outcome between three conditions. Data were also analyzed using statistic parameter mapping.ResultsRunning on the lateral side of the foot compared to normal running and running on the medial side of the foot reduced peak rearfoot eversion (mean difference (MD) with normal 3.3°, p < 0.001, MD with COP medial 6°, p < 0.001), peak pronation (MD with normal 5°, p < 0.001, MD with COP medial 9.6°, p=<0.001), peak MLAA (MD with normal 2.3°, p < 0.001, MD with COP medial 4.1°, p < 0.001), peak hip internal rotation (MD with normal 1.8°, p < 0.001), and peak hip adduction (MD with normal running 1°, p = 0.011). Running on the medial side of the foot significantly increased peak rearfoot eversion, pronation and MLAA compared to normal running.SignificanceThis study demonstrated that COP translation along the mediolateral foot axis significantly influences rearfoot eversion, MLAA, and subtalar pronation during running. Running with either more lateral or medial COP reduced or increased peak rearfoot eversion, peak subtalar pronation, and peak MLAA, respectively, compared to normal running. These results might use as a basis to help clinicians and researchers prescribe running gait retraining by changing mediolateral COP for runners with atypical rearfoot eversion or MLAA.     

Kinematic gait characteristics associated with patellofemoral pain syndrome: A systematic review

Development of patellofemoral pain syndrome (PFPS) is considered to be multifactorial. The aims of this systematic review were to (i) summarise and critique the body of literature addressing kinematic gait characteristics associated with PFPS; and (ii) provide recommendations for future research addressing kinematic gait characteristics associated with PFPS. A comprehensive search of MEDLINE, EMBASE, CINAHL, and Current Contents revealed 561 citations for review. Each citation was assessed for inclusion and quality using a modified version of the ‘Quality Index’ and a novel inclusion/exclusion criteria checklist by two independent reviewers. A total of 24 studies were identified. No prospective studies with adequate data to complete effect size calculations were found. Quality of included case–control studies varied, with a number of methodological issues identified. Heterogeneity between studies made meta-analysis inappropriate. Reductions in gait velocity were indicated during walking, ramp negotiation, and stair negotiation in individuals with PFPS. Findings indicated delayed timing of peak rearfoot eversion and increased rearfoot eversion at heel strike transient during walking; and delayed timing of peak rearfoot eversion, increased rearfoot eversion at heel strike, reduced rearfoot eversion range, greater knee external rotation at peak knee extension moment, and greater hip adduction during running in individuals with PFPS. There is a clear need for prospective evaluation of kinematic gait characteristics in a PFPS population to distinguish between cause and effect. Where possible, future PFPS case–control studies should consider evaluating kinematics of the knee, hip and foot/ankle simultaneously with larger participant numbers. Completing between sex comparisons when practical and considering spatiotemporal gait characteristics during methodological design and data analysis is also recommended.     

The biomechanical variables involved in the aetiology of iliotibial band syndrome in distance runners – A systematic review of the literature

The aim of this literature review was to identify the biomechanical variables involved in the aetiology of iliotibial band syndrome (ITBS) in distance runners. An electronic search was conducted using the terms “iliotibial band” and “iliotibial tract”.The results showed that runners with a history of ITBS appear to display decreased rear foot eversion, tibial internal rotation and hip adduction angles at heel strike while having greater maximum internal rotation angles at the knee and decreased total abduction and adduction range of motion at the hip during stance phase. They further appear to experience greater invertor moments at their feet, decreased abduction and flexion velocities at their hips and to reach maximum hip flexion angles earlier than healthy controls. Maximum normalised braking forces seem to be decreased in these athletes. The literature is inconclusive with regards to muscle strength deficits in runners with a history of ITBS. Prospective research suggested that greater internal rotation at the knee joint and increased adduction angles of the hip may play a role in the aetiology of ITBS and that the strain rate in the iliotibial bands of these runners may be increased compared to healthy controls.A clear biomechanical cause for ITBS could not be devised due to the lack of prospective research.     

Effects of load carriage on biomechanical variables associated with tibial stress fractures in running

BackgroundMilitary personnel are required to run while carrying heavy body-borne loads, which is suggested to increase their risk of tibial stress fracture. Research has retrospectively identified biomechanical variables associated with a history of tibial stress fracture in runners, however, the effect that load carriage has on these variables remains unknown.Research questionWhat are the effects of load carriage on running biomechanical variables associated with a history of tibial stress fracture?MethodsTwenty-one women ran at 3.0 m/s on an instrumented treadmill in four load carriage conditions: 0, 4.5, 11.3, and 22.7 kg. Motion capture and ground reaction force data were collected. Dependent variables included average loading rate, peak absolute free moment, peak hip adduction, peak rearfoot eversion, and stride frequency. Linear mixed models were used to asses the effect of load carriage and body mass on dependent variables.ResultsA load x body mass interaction was observed for stride frequency only (p = 0.017). Stride frequency increased with load carriage of 22.7-kg, but lighter participants illustrated a greater change than heavier participants. Average loading rate (p < 0.001) and peak free moment (p = 0.015) were greater in the 22.7-kg condition, while peak rearfoot eversion (p ≤ 0.023) was greater in the 11.3- and 22.7-kg conditions, compared to the unloaded condition. Load carriage did not affect peak hip adduction (p = 0.67).SignificanceParticipants adapted to heavy load carriage by increasing stride frequency. This was especially evident in lighter participants who increased stride frequency to a greater extent than heavier participants. Despite this adaptation, running with load carriage of ≥11.3-kg increased variables associated with a history of tibial stress fracture, which may be indicative of elevated stress fracture risk. However, the lack of concomitant change amongst variables as a function of load carriage may highlight the difficulty in assessing injury risk from a single measure of running biomechanics.     

Kinematic gait characteristics associated with patellofemoral pain syndrome: A systematic review

Development of patellofemoral pain syndrome (PFPS) is considered to be multifactorial. The aims of this systematic review were to (i) summarise and critique the body of literature addressing kinematic gait characteristics associated with PFPS; and (ii) provide recommendations for future research addressing kinematic gait characteristics associated with PFPS. A comprehensive search of MEDLINE, EMBASE, CINAHL, and Current Contents revealed 561 citations for review. Each citation was assessed for inclusion and quality using a modified version of the ‘Quality Index’ and a novel inclusion/exclusion criteria checklist by two independent reviewers. A total of 24 studies were identified. No prospective studies with adequate data to complete effect size calculations were found. Quality of included case–control studies varied, with a number of methodological issues identified. Heterogeneity between studies made meta-analysis inappropriate. Reductions in gait velocity were indicated during walking, ramp negotiation, and stair negotiation in individuals with PFPS. Findings indicated delayed timing of peak rearfoot eversion and increased rearfoot eversion at heel strike transient during walking; and delayed timing of peak rearfoot eversion, increased rearfoot eversion at heel strike, reduced rearfoot eversion range, greater knee external rotation at peak knee extension moment, and greater hip adduction during running in individuals with PFPS. There is a clear need for prospective evaluation of kinematic gait characteristics in a PFPS population to distinguish between cause and effect. Where possible, future PFPS case–control studies should consider evaluating kinematics of the knee, hip and foot/ankle simultaneously with larger participant numbers. Completing between sex comparisons when practical and considering spatiotemporal gait characteristics during methodological design and data analysis is also recommended.     

Effects of medially wedged insoles on the biomechanics of the lower limbs of runners with excessive foot pronation and foot varus alignment

BackgroundExcessive foot pronation during running in individuals with foot varus alignment may be reduced by medially wedged insoles.Research questionThis study investigated the effects of a medially wedged insole at the forefoot and at the rearfoot on the lower limbs angles and internal moments of runners with excessive foot pronation and foot varus alignment.MethodsKinematic and kinetic data of 19 runners (11 females and 8 males) were collected while they ran wearing flat (control condition) and medially wedged insoles (insole condition). Both insoles had arch support. We used principal component analysis for data reduction and dependent t-test to compare differences between conditions.ResultsThe insole condition reduced ankle eversion (p = 0.003; effect size = 0.63); reduced knee range of motion in the transverse plane (p = 0.012; effect size = 0.55); increased knee range of motion in the frontal plane in early stance and had earlier knee adduction peak (p = 0.018; effect size = 0.52); reduced hip range of motion in the transverse plane (p = 0.031; effect size = 0.48); reduced hip adduction (p = 0.024; effect size = 0.50); reduced ankle inversion moment (p = 0.012; effect size = 0.55); and increased the difference between the knee internal rotation moment in early stance and midstance (p = 0.012; effect size = 0.55).SignificanceInsoles with 7˚ medial wedges at the forefoot and rearfoot are able to modify motion and moments patterns that are related to lower limb injuries in runners with increased foot pronation and foot varus alignment with some non-desired effects on the knee motion in the frontal plane.     

Kinematic classification of iliotibial band syndrome in runners

Several inconsistent causative biomechanical factors are considered to be crucial in the occurrence of iliotibial band syndrome (ITBS). The focus of this study was on assessing differences in the kinematic characteristics between healthy runners [control group (CO)] and runners with ITBS in order to recommend treatment strategies to deal with this injury. Three‐dimensional kinematics of barefoot running was used in the biomechanical setup. Both groups were matched with respect to gender, height and weight. After determining drop outs, the final population comprised 36 subjects (26 male and 10 female): 18 CO and 18 ITBS (13 male and five female, each). Kinematic evaluations indicate less hip adduction and frontal range of motion at the hip joint in runners with ITBS. Furthermore, maximum hip flexion velocity and maximum knee flexion velocity were lower in runners with ITBS. Lack of joint coordination, expressed as earlier hip flexion and a tendency toward earlier knee flexion, was found to be another discriminating variable in subjects with ITBS compared with CO subjects. We assume that an increase in range of motion at the hip joint, stretching of the hip abductors, as well as stretching the hamstrings, calf muscles and hip flexors will help treat ITBS.     

Stiffness of the iliotibial band and associated muscles in runner’s knee: Assessing the effects of physiotherapy through ultrasound shear wave elastography

ObjectivesTo test the hypothesis that Iliotibial Band Syndrome (ITBS) is caused by excessive iliotibial band (ITB) tension, promoted by hip abductor and external rotator weakness, and evaluate the influence of 6 weeks of physiotherapy on ITB stiffness.DesignInterventional study with control group.SettingClinical.Participants14 recreational runners with ITBS and 14 healthy controls of both sexes.Main outcome measuresUltrasound shear wave elastography, hip muscle strength, visual analog scale pain, subjective lower extremity function.ResultsNo statistical differences in ITB tension between legs as well as between patients suffering from ITBS and healthy controls were detected. Results showed significant strength deficits in hip abduction, adduction as well as external and internal rotation. Following six weeks of physiotherapy, hip muscle strength (all directions but abduction), pain and lower extremity function were significantly improved. ITB stiffness, however, was found to be increased compared to baseline measurements.ConclusionShear wave elastography data suggest that ITB tension is not increased in the affected legs of runners with ITBS compared to the healthy leg or a physical active control group, respectively. Current approaches to the conservative management of ITBS appear ineffective in lowering ITB tone.     

Do hip strength,flexibility and running biomechanics predict dynamic valgus in female recreational runners?

BackgoundDynamic valgus has been the focus of many studies to identify its association to an increased risk of running-related injuries. However, it is not known which physical and biomechanical variables are associated with this movement dysfunction. Research question: This study aimed to test the correlation between strength, flexibility and biomechanical variables and dynamic valgus in female runners.MethodsTwenty-nine healthy females ran on a treadmill at 2.92 m/s and performed strength, range of motion and endurance tests. Pelvic, hip and ankle kinematics were measured with a 3D motion analysis system. Six multiple linear regression models were used to identify the ability of physical and biomechanical variables to predict excursion and peak of contralateral pelvic drop, hip adduction and internal rotation.ResultsContralateral pelvic drop and hip adduction were positively correlated to ankle eversion and step cadence. Hip internal rotation had a negative correlation with ankle eversion. Despite significance, predictor variables explained less than 30% of dynamic valgus variance during running. No interest variable had significant correlation with the hip strength and hip and ankle passive range of motion.SignificanceThe results showed that distal joint kinematics and spatiotemporal variables should be considered during biomechanical running analysis to identify their possible relationship with joint overload caused by dynamic valgus. Caution should be taken when linking hip disorders during running to posterolateral hip strength and stiffness, core endurance, and ankle dorsiflexion range of motion since no correlation occurred amongstthese variables in this sample of female runners.     

Walking kinematics in individuals with patellofemoral pain syndrome: a case-control study

Patellofemoral pain syndrome (PFPS) development is considered to be multifactorial with various knee, hip and foot/ankle kinematic factors thought to be involved. A paucity of research evaluating kinematic factors throughout the lower limb kinematic chain simultaneously in individuals with PFPS was identified in a recent systematic review. The objective of this study was to compare kinematics at the knee, hip and foot/ankle in a group of individuals with PFPS to a group of asymptomatic controls. Twenty-six individuals with PFPS and 20 controls aged between 18 and 35 were recruited. Between-group comparisons were made for magnitude and timing of peak angles, and range of motion at the forefoot (dorsiflexion, abduction and supination), rearfoot (dorsiflexion, internal rotation and eversion), knee (flexion, abduction and internal rotation) and hip (adduction and internal rotation) during walking. The PFPS group demonstrated less peak hip internal rotation (7.0° versus 11.8°, p=0.024, p=0.024), earlier peak rearfoot eversion relative to the laboratory (30.4% versus 35.3% of the gait cycle, p=0.010) and tibia (32.7% versus 36.5% of the gait cycle, p=0.030), and greater rearfoot dorsiflexion range of motion relative to the laboratory (72.3° versus 68.2°, p=0.007). Additionally, a trend toward reduced gait velocity (p=0.070) was found in the PFPS group. Reduced peak hip internal rotation and gait velocity in individuals with PFPS may indicate compensation to reduce PFJ load during walking. However, earlier peak rearfoot eversion may be a factor related to the pathomechanical development of the condition.     

Effect of foot orthoses on magnitude and timing of rearfoot and tibial motions,ground reaction force and knee moment during running

Changes in magnitude and timing of rearfoot eversion and tibial internal rotation by foot orthoses and their contributions to vertical ground reaction force and knee joint moments are not well understood. The objectives of this study were to test if orthoses modify the magnitude and time to peak rearfoot eversion, tibial internal rotation, active ground reaction force and knee adduction moment and determine if rearfoot eversion, tibial internal rotation magnitudes are correlated to peak active ground reaction force and knee adduction moment during the first 60% stance phase of running. Eleven healthy men ran at 170 steps per minute in shod and with foot orthoses conditions. Video and force-plate data were collected simultaneously to calculate foot joint angular displacement, ground reaction forces and knee adduction moments. Results showed that wearing semi-rigid foot orthoses significantly reduced rearfoot eversion 40% (4.1°; p = 0.001) and peak active ground reaction force 6% (0.96 N/kg; p = 0.008). No significant time differences occurred among the peak rearfoot eversion, tibial internal rotation and peak active ground reaction force in both conditions. A positive and significant correlation was observed between peak knee adduction moment and the magnitude of rearfoot eversion during shod (r = 0.59; p = 0.04) and shod/orthoses running (r = 0.65; p = 0.02). In conclusion, foot orthoses could reduce rearfoot eversion so that this can be associated with a reduction of knee adduction moment during the first 60% stance phase of running. Finding implies that modifying rearfoot and tibial motions during running could not be related to a reduction of the ground reaction force.     

The influence of maturation and sex on pelvis and hip kinematics in youth distance runners

ObjectivesThis study aimed to investigate differences in stance phase pelvic and hip running kinematics based on maturation and sex among healthy youth distance runners.DesignCross-Sectional.Methods133 uninjured youth distance runners (M = 60, F = 73; age = 13.5 ± 2.7 years) underwent a three-dimensional running analysis on a treadmill at a self-selected speed (2.8 ± 0.6 m·s^?1). Participants were stratified as pre-pubertal, mid-pubertal, or post-pubertal according to the modified Pubertal Maturational Observation Scale. Stance phase pelvis and hip range of motion (RoM) and peak joint positions were extracted. Two-way ANCOVAs (sex, maturation; covariate of running velocity) were used with Bonferroni-Holm method to control for multiple comparisons with a target alpha level of 0.05.ResultsA two-way interaction between sex and maturation was detected (p = 0.009) for frontal plane pelvic obliquity RoM. Post-hoc analysis identified a maturation main effect only among females (p?0.008). Pelvic obliquity RoM was significantly greater among post-pubertal (p = 0.001) compared to pre-pubertal females. Significant main effects of sex (p = 0.02), and maturation (p = 0.01) were found for hip adduction RoM. Post-hoc analysis indicated a significant increase in hip adduction RoM from pre-pubertal to post-pubertal female runners (p = 0.001). A significant main effect of sex was found for peak hip adduction angle (p = 0.001) with female runners exhibiting greater maximum peak hip adduction compared to males.ConclusionsMaturation influences pelvic and hip kinematics greater in female than male runners. Sex differences became more pronounced during later stages of puberty. These differences may correspond to an increased risk for running-related injuries in female runners compared to male runners.     

Validity and reliability of a smartphone motion analysis app for lower limb kinematics during treadmill running

ObjectiveTo investigate the validity and reliability of a smartphone application for selected lower-limb kinematics during treadmill running.DesignValidity and reliability study.SettingBiomechanics laboratory.ParticipantsTwenty healthy female runners.Main outcome measure(s)Sagittal-plane hip, knee, and ankle angle and rearfoot eversion were assessed using the Coach’s Eye Smartphone application and a 3D motion capture system. Paired t-test and intraclass correlation coefficients (ICC) established criterion validity of Coach’s Eye; ICC determined test-retest and intrarater/interrater reliability. Standard error of measurement (SEM) and minimal detectable change (MDC) were also reported.ResultsSignificant differences were found between Coach’s Eye and 3D measurements for ankle angle at touchdown and knee angle at toe-off (p < 0.05). ICCs for validity of Coach’s Eye were excellent for rearfoot eversion at touchdown (ICC = 0.79) and fair-to-good for the other kinematics (range 0.51–0.74), except for hip at touchdown, which was poor (ICC = 0.36). Test-retest (range 0.80–0.92), intrarater (range 0.95–0.99) and interrater (range 0.87–0.94) ICC results were excellent for all selected kinematics.ConclusionCoach’s Eye can be used as a surrogate for 3D measures of knee and rearfoot in/eversion at touchdown, and hip, ankle, and rearfoot in/eversion at toe-off, but not for hip and ankle at touchdown or knee at toe-off. Reliable running kinematics were obtained using Coach’s Eye, making it suitable for repeated measures.     

Gait alterations in posterior tibial tendonitis: A systematic review and meta-analysis

BackgroundPosterior tibial tendon dysfunction (PTTD) is a common and debilitating tendinopathy that can lead to a profound decrease in gait function. While the clinical diagnosis and treatment of this disorder are well described, the pathomechanics have not been adequately characterized. The purpose of this systematic review and meta-analysis is to compare foot/ankle kinematics and kinetics in patients with PTTD with healthy controls during gait.MethodsRelevant articles were selected thought Medline (Pubmed), Scopus, CINAHL, and Web of Science. Studies focused on foot/ankle kinematics and kinetics in patients with PTTD were involved. Articles were included if they: 1) compared patients with PTTD to healthy controls, 2) utilized kinematics or kinetics as the primary outcome measure, 3) evaluated gait tasks, and 4) were written in English.ResultsEleven articles were included in this systematic review, and 8 studies were synthesized and analyzed. Our meta-analyses indicated increased dorsiflexion and abduction of the forefoot, as well as increased plantarflexion and eversion of hindfoot for patients with PTTD during stance of walking.ConclusionOur results from the meta-analysis showed more conclusive changes in the forefoot (increased dorsiflexion and abduction) and hindfoot (increased plantarflexion and eversion) kinematics during stance of walking, which may be associated with a pathological process of PTTD. This review provides an improved understanding of gait function in patients with PTTD and preliminary knowledge for future research.     

Frontal plane kinematics predict three-dimensional hip adduction during running

ObjectivesTo investigate if frontal plane kinematics are predictive of three dimensional (3D) hip adduction and hip internal rotation during running.Study designCross-sectional.SettingBiomechanics laboratory.ParticipantsThirty healthy male runners aged 18–45 years.Main outcome measuresTwo dimensional (2D) angles in the frontal plane (peak pelvic obliquity, peak hip adduction, peak femoral valgus, peak knee valgus and peak tibial valgus) and 3D hip adduction and hip internal rotation during stance phase of running were obtained.ResultsLinear regression modelling revealed that peak 2D pelvic obliquity (a drop towards the contralateral leg) and peak femoral valgus significantly predicted 88% of the variance in peak 3D hip adduction (p < 0.001). Frontal plane kinematics however, were not predictive of peak hip internal rotation in 3D (p > 0.05).ConclusionsFrontal plane kinematics, specifically contralateral pelvic drop and femoral valgus, predicted the vast majority of the variance in 3D hip adduction during the stance phase of running. This indicates that 2D video may have potential as a clinically feasible proxy for measurement of peak 3D hip adduction – a risk factor for patellofemoral pain.     

Runners with patellofemoral pain have altered biomechanics which targeted interventions can modify: A systematic review and meta-analysis

Patellofemoral pain (PFP) is the most prevalent running pathology and associated with multi-level biomechanical factors. This systematic review aims to guide treatment and prevention of PFP by synthesising prospective, observational and intervention studies that measure clinical and biomechanical outcomes in symptomatic running populations. Medline, Web of Science and CINAHL were searched from inception to April 2015 for prospective, case-control or intervention studies in running-related PFP cohorts. Study methodological quality was scored by two independent raters using the modified Downs and Black or PEDro scales, with meta-analysis performed where appropriate. 28 studies were included. Very limited evidence indicates that increased peak hip adduction is a risk factor for PFP in female runners, supported by moderate evidence of a relationship between PFP and increased peak hip adduction, internal rotation and contralateral pelvic drop, as well as reduced peak hip flexion. Limited evidence was also identified that altered peak force and time to peak at foot level is a risk factor for PFP development. Limited evidence from intervention studies indicates that both running retraining and proximal strengthening exercise lead to favourable outcomes in both pain and function, but only running retraining significantly reduces peak hip adduction, suggesting a possible kinematic mechanism. Put together, these findings highlight limited but coherent evidence of altered biomechanics which interventions can alter with resultant symptom change in females with PFP. There is a clear need for high quality prospective studies of intervention efficacy with measurement of explanatory mechanisms.     

Tibial rotation in running: Does rearfoot adduction matter?

ObjectiveTo quantify the magnitude of global rearfoot motion, in particular, rearfoot adduction and to investigate its relationship to tibial rotation.DesignOne hundred and four participants ran barefoot on an Ethylene Vinyl Acetate (EVA) foam. Global range of motion values for the shank, rearfoot and medial metatarsal segment as well as foot motion within the transverse plane were determined using an optoelectric motion capture system. Relationships between parameters were assessed using partial correlation analysis.ResultsGlobal rearfoot adduction amounts to 6.1° (±2.7). Furthermore global rearfoot adduction and rearfoot eversion were significantly related to internal tibial rotation (partial correlation: r = 0.37, p < 0.001 and r = −0.24, p = 0.015, respectively). Furthermore, a strong relationship between rearfoot adduction and transverse within foot motion (r = −0.65, p < 0.001) was found.ConclusionNext to rearfoot eversion, rearfoot adduction may be also important to the understanding of ankle joint coupling. Controlling rearfoot adduction and transverse within foot motion may be a mechanism to control excessive tibial rotation.     

Hip abductor weakness is not the cause for iliotibial band syndrome

Muscular deficits in the hip abductors are presumed to be a major factor in the development of Iliotibial Band Syndrome in runners. No definite relationship between muscular weakness of the hip abductors and the development of Iliotibial Band Syndrome or different ratios between hip adduction to abduction have been reported so far. Isokinetic measurements were taken from 10 healthy runners and 10 runners with Iliotibial Band Syndrome. Primary outcome variables were concentric, eccentric, and isometric peak torque of the hip abductors and adductors at 30 degrees/s, and a concentric endurance quotient at the same angle velocity. Differences in muscle strength of the hip abductors between healthy (CO) and injured runners (ITBS) were not statistically significant in any of the muscle functions tested. Both groups showed the same strength differences between hip adduction and abduction, and increased strength in hip adduction. Weakness of hip abductors does not seem to play a role in the etiology of Iliotibial Band Syndrome in runners, since dynamic and static strength measurements did not differ between groups, and differences between hip abduction and adduction were the same. Strengthening of hip abductors seems to have little effect on the prevention of Iliotibial Band Syndrome in runners.     

Major factors influencing rearfoot external eversion moment during barefoot walking

BackgroundExcessive rearfoot eversion motion during walking has been considered as a risk factor for lower limb chronic injuries. External moment due to ground reaction force (GRF) is the essential cause by which the rearfoot is passively everted during walking.Research questionThis study aims to identify the key factors influencing the rearfoot external eversion moments due to the GRF during walking.MethodsFrom 3-D foot coordinates and GRF data of 29 healthy participants during walking, the rearfoot external eversion moments due to the GRF and factors composing the moment (height of the ankle joint center, mediolateral GRF, mediolateral distance of the center of pressure relative to the ankle joint center in the transverse plane, vertical GRF) were computed.ResultsThe mediolateral GRF was a key factor influencing the magnitude of the rearfoot external eversion moment just after foot contact, with which pre-contact medial foot velocity was significantly correlated. During the subsequent support phase, the mediolateral distance of the center of pressure (the application point of the vertical GRF) relative to the ankle joint center was also found to be another determinant of the magnitude of the rearfoot external eversion moment.SignificanceWe succeeded in demonstrating the specific factors that most likely explain the magnitude of the rearfoot external eversion moment during initial contact and the subsequent support phase during walking. Based on the findings, specific measures to suppress the rearfoot external eversion moment could be proposed.