Rearfoot Inversion Research Articles

Impact of chronic ankle instability on gait loading strategy in individuals with chronic ankle instability: a comparative study

BackgroundLateral ankle sprains rank among the most prevalent musculoskeletal injuries, while chronic ankle instability (CAI) is its most common cascade. In addition to the conflicting results of the previous studies and their methodological flaws, the specific gait loading strategy is still not well studied.PurposeThe study aimed to investigate the fluctuations in gait loading strategy in people with chronic ankle instability compared to health control.MethodsA total of 56 male subjects participated in this study and were allocated into two groups: (A) CAI group: 28 subjects with unilateral CAI (age 24.79 ± 2.64 and BMI 26.25 ± 3.50); and (B) control group: 28 subjects without a history of ankle sprains (age 24.57 ± 1.17 and BMI 26.46 ± 2.597). Stance time, weight acceptance time, and load distribution were measured to investigate gait loading strategy.ResultsThe study findings revealed that the CAI group had a significant higher load over the lateral rearfoot. However, MANOVA indicates that there was no overall significant difference in gait loading strategy between the CAI and control groups. Furthermore, in terms of stance time, time of weight acceptance phase, load over medial foot, and load over lateral foot, CAI and healthy controls seemed to walk similarly.ConclusionsThe findings revealed that individuals with CAI had the significant alteration in the lateral rearfoot loading, suggesting a potential compensatory mechanism to address instability during the weight acceptance phase. This could manifest a laterally deviated center of pressure and increased frontal plane inversion during the early stance phase. However, it is acknowledged that these alterations could be both the result and the origin of CAI. The study highlights the vulnerability of CAI during the early stance phase, emphasizing the need for gait reeducation as individuals return to walking as healthcare clinicians should focus on treatment modalities aimed at reducing rearfoot inversion in individuals with CAI.

Whipping or tearing? The biomechanics of Achilles tendinopathy in rearfoot strike runners

BackgroundTwo biomechanical mechanisms for the development of Achilles tendinopathy in runners have been proposed: A whipping mechanism characterized by prolonged and excessive rearfoot eversion, and a tearing mechanism characterized by high eccentric plantar flexor forces. The purpose of this pilot study was to determine if runners with and without a history of Achilles tendinopathy exhibited gait biomechanics consistent with either of these mechanisms. MethodsSeven male runners with previous or current Achilles tendinopathy and seven healthy male control runners were evaluated by three-dimensional gait analysis. Peak rearfoot eversion angle, rearfoot eversion excursion, duration of rearfoot eversion, and peak rearfoot inversion angle were compared between groups to evaluate the whipping mechanism of injury. Peak dorsiflexion angle, peak dorsiflexion velocity, and peak ankle power absorption were compared between groups to evaluate the tearing mechanism. Additionally, rearfoot eversion angle and sagittal plane ankle power waveforms were compared between groups using statistical parametric mapping. FindingsThere were no differences in any rearfoot eversion, inversion, or dorsiflexion variables or waveforms during running in the Achilles tendinopathy group compared to controls. InterpretationRearfoot strike runners with Achilles tendinopathy do not exhibit running biomechanics consistent with either the whipping or tearing mechanisms of injury.

Crossover gait in running and measuring foot inversion angle at initial foot strike: a front-view video analysis approach.

Introduction: Foot inversion angle at initial foot strike is associated with various running-related injuries. Traditionally, video analysis of foot inversion angle has been accomplished by positioning a camera to record from the back view, but complications arise when a crossover gait obscures the area of measurement. This study aims to investigate the viability of measuring foot inversion angles at initial foot strike of running from the front view as an alternative to using the back view in 2D video analysis. Methods: Forty-four healthy runners (20 females, 24 males) ran at their self-selected speeds on a treadmill with their gait recorded from front and back camera views. Foot inversion angles at initial foot strike were analyzed using Kinovea. A 2 × 2 (Camera × Foot) ANOVA with repeated measures was performed on the foot inversion angle data. Subsequently, correlation and linear regression were performed to determine the relationship between the back and front-view measurements. Results: Thirteen runners (29.5%) displayed crossover gait within 18 gait cycles. ANOVA revealed a significant main effect on Camera (p < .001) only, where foot inversion angle was greater from the front camera view. Correlation analysis showed a significant positive correlation between the front and back camera views (r = 0.388, p < .001). Regression analyses yielded an equation, = 0.42 + 0.53 , where and were the foot inversion angle measured from the back and front camera views, respectively. Discussion: With a linear regression conversion equation, front-view foot inversion angles at initial foot strike can be used to determine rearfoot inversion angles when crossover gait obstructs the back camera view.

Effects of midsole thickness on ground reaction force, ankle stability, and sports performances in four basketball movements

ABSTRACT Changes in midsole thickness can influence cushioning and rearfoot stability in running, but no information has been established in basketball. This study aimed to investigate whether midsole thickness would alter ground reaction force, ankle stability and performance-related indicators in four basketball manoeuvres. Fifteen university basketball athletes performed lateral shuffle, forward sprint, counter-movement jump (CMJ) and drop landing in basketball shoes of five midsole thicknesses (Thinnest, Thin, Medium, Thick, Thickest). One-way repeated-measures ANOVA was performed on each of the biomechanics and performances variables and Friedman test was performed on comfort perceptions. Our findings found a significant midsole thickness effect on the lower extremity biomechanics (p < 0.05), with better traction (p = 0.019) and greater plantarflexion (p = 0.019) while sprinting with thinner shoe conditions. Thicker basketball shoes led to greater rearfoot inversion (p = 0.004) and a more significant inversion velocity peak (p = 0.019) during lateral shuffling. No significant difference in peak impact force or peak loading rate was observed between shoes during drop landing. These findings suggest that participants wearing basketball shoes with thicker midsole may lead to ankle instability during lateral shuffling manoeuvres. Wearing basketball shoes with thinner midsoles may be beneficial for sprint and jump performances.

Can orthotic wedges change the lower-extremity and multi-segment foot kinematics during gait in people with plantar fasciitis?

BackgroundOrthotic wedges with medial posting of the forefoot and rearfoot have been shown to be effective in controlling excessive foot pronation in people with plantar fasciitis (PF), however the best prescription remains unclear. Research questionThe aim of this study was to determine the biomechanical effects of two designs of orthotic wedges within a shoe on the hip, knee, rearfoot, and forefoot kinematics in individuals with PF. MethodsThirty-five participants with PF were recruited. They were asked to walk under three randomized conditions; shod, shod with orthotic wedges with foot assessment technique 1 (W1), and shod with orthotic wedges from a new assessment technique (W2). Biomechanical outcomes included lower limb and multi-segment foot kinematics in each subphase of the stance gait, including contact phase, midstance phase, and propulsive phase. ResultsCompared with shod, the W1 significantly increased rearfoot dorsiflexion, decreased peak forefoot dorsiflexion, and peak rearfoot eversion during the contact phase. In addition, W1 increased rearfoot inversion, decreased hallux dorsiflexion, and peak hallux dorsiflexion during the propulsive phase. For W2, the wedge significantly decreased peak knee internal rotation, decreased forefoot abduction, peak forefoot dorsiflexion, and peak rearfoot eversion during the contact phase. In addition, W2 increased rearfoot inversion, decreased hallux dorsiflexion, and decreased peak hallux dorsiflexion during the propulsive phase. When comparing W1 and W2, W1 showed greater rearfoot dorsiflexion during the contact phase. SignificanceThese findings suggest that the use of forefoot varus wedges, and the combination of forefoot and rearfoot varus wedges, can change the lower limb kinematics, the multi-segment foot kinematics estimated using markers fixed to the shoe, and the relative length of the plantar fascia which can be associated with a reduction in pain and symptoms during walking.

Does the Foot and Ankle Alignment Impact the Patellofemoral Pain Syndrome? A Systematic Review and Meta-Analysis.

Background: A convincing association between the foot and ankle alignment (FAA) and patellofemoral pain syndrome (PFPS) remains debatable in the literature. Therefore, all studies investigating the role of FAA in patients with PFPS were systematically reviewed. Methods: A systematic literature search was performed on the databases PubMed, Embase, Cochrane Library, and Web of Science. Inclusion criteria were all studies investigating static and/or dynamic FAA factors and PFPS. Studies with less than 20 patients or with patellofemoral osteoarthritis were excluded. The quality assessment was based on Cochrane study criteria, and the maximum score was set at eight. Results: Of 2246 articles, only 13 case-control studies were eligible. Considering static FAA factors, two studies found an association with rearfoot eversion and one with rearfoot inversion. While examining dynamic FAA characteristics, one study found an association with rearfoot eversion range of motion and three with gait kinematics. No further associations were reported. The quality assessment mean score was 5.5 (SD = 0.97) corresponding to moderate quality. Conclusions: In contrast to our expectations, a limited number of studies were founded supporting an association between FAA and PFPS. At present, the quality of the literature is still poor and conflicting, thus the need for further studies to determine any association between FAA and PFPS.

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

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

Comparison of Transverse Plane Tibial and Frontal Plane Rearfoot Motion and Movement Coordination Between Runners With Medial Tibial Stress Syndrome and Healthy Controls.

Medial tibial stress syndrome (MTSS) is a common running-related injury. Alterations in movement patterns and movement coordination patterns have been linked to the development of overuse injuries. The aim of this study was to compare transverse plane tibial and frontal plane rearfoot motion and the coordination of these movements between runners with MTSS and healthy controls. A total of 10 recreational runners with MTSS and 10 healthy controls ran at 11km/h on a treadmill. A 3-camera motion analysis system operating at 200Hz was used to calculate tibia and rearfoot motion. Stance phase motion patterns were compared between groups using multivariate analysis, specifically, Hotelling T2 test with statistical parametric mapping. A modified vector coding technique was used to classify the coordination of transverse plane tibial and frontal plane rearfoot motion. The frequency of each coordination pattern displayed by each group was compared using independent samples t tests. Individuals with MTSS displayed significantly (P = .037, d = 1.00) more antiphase coordination (tibial internal rotation with rearfoot inversion) despite no significant (P > .05) differences in stance phase kinematics. The increased antiphase movement may increase the torsional stress placed upon the medial aspect of the tibia, contributing to the development of MTSS.

Mechanical character of lower limb for table tennis cross step maneuver

The agile footwork is a basic but important skill, how to efficiently grasp and improve its performance has always interested coaches and athletes, beginners particularly. The purpose of this study was to investigate the differences in kinetics and kinematics of the cross step between professional athletes and novice athletes using the Oxford foot model. Twenty-two male participants (professional athletes, 11; novice athletes, 11) with dominant right feet participated in the table tennis cross step test. A Vicon motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematic and kinetic data, respectively. Professional athletes showed significantly smaller forefoot plantarflexion and abduction, but larger hallux dorsiflexion at the cross step ending. In addition, they also showed significantly larger forefoot dorsiflexion and adduction but smaller forefoot eversion as well as rearfoot inversion than novice athletes at the forward-end of the step. In the entire motion, professional athletes performed significantly smaller joints range of motion, especially the hindfoot with respect to tibia angles. Concerning plantar relative load, professional athletes were significantly greater than that of novice athletes in the other toes, lateral forefoot and rear foot. Professional athletes possessed higher footwork agility and greater foot motor technique. The findings on the internal mechanisms of the cross step could help coaches and novice athletes understand the mechanical efficiencies in stroke finishing leading to improvements in performance.

Comparison of the rigidity and forefoot – Rearfoot kinematics from three forefoot tracking marker clusters during walking and weight-bearing foot pronation-supination

Due to the relative motion among the foot rays, the present study aimed to compare the rigidity as well as the forefoot – rearfoot kinematics obtained from three forefoot tracking marker clusters during walking and foot pronation-supination (PROSUP). Nineteen healthy adults performed six walking trials and ten cycles of foot PROSUP movements recorded by an optoelectronic system. Rearfoot's and forefoot's coordinate system were equal for all setups, only the forefoot's tracking markers locations varied among them, which were: (1st) a typical cluster, focusing on the proximal forefoot, (2nd) a second typical cluster, focusing on the distal forefoot and outer metatarsals, and (3rd) a new cluster proposition, focusing on the distal forefoot and central metatarsals. Cluster rigidity was the normalized intra-markers residual, and forefoot – rearfoot angles were the forefoot motion relative to the rearfoot at the peak of each plane of motion. Repeated-measures ANOVA with pairwise comparisons (α=0.05) revealed that the 3rd cluster had the smallest residual (p < 0.001) in comparison with the other clusters for both walking and PROSUP. Differences between forefoot – rearfoot angles were found in the sagittal plane for walking (p < 0.001), but not for PROSUP (p > 0.686). In the frontal and transverse planes, all clusters showed different forefoot – rearfoot angles (p < 0.001) for both walking and PROSUP. The 1st cluster showed smaller ROM in the three planes during walking, and the 3rd cluster was the only that showed forefoot – rearfoot inversion during maximum pronation. Therefore, the new forefoot tracking marker cluster proposition (3rd cluster) captured different forefoot – rearfoot kinematics and can be recommended when the objective is to maximize the cluster rigidity.

Effects of a foot orthosis inspired by the concept of a twisted osteoligamentous plate on the kinematics of foot-ankle complex during walking: A proof of concept

It has been suggested that the foot acts as a twisted osteoligamentous plate to control pronation and facilitate supination during walking. The aim of this study was to investigate the effect of an orthosis inspired by the concept of a foot’s twisted osteoligamentous plate on the kinematics of foot-ankle complex. Thirty-five subjects underwent a kinematic assessment of the foot-ankle complex during walking using three different orthoses: (1) Twisted Plate Spring (TPS) orthosis: inspired by the concept of a twisted osteoligamentous plate shape and made with a spring-like material (carbon fiber); (2) Flat orthosis: control orthosis made of a non-elastic material with a non-inclined surface; and (3) Rigid orthosis: control orthosis made of a non-elastic material, with the same shape of the TPS. Repeated measures analyses of variance demonstrated that the TPS reduced the duration and magnitude of rearfoot eversion (p ≤ 0.03), increased rearfoot inversion relative to shank (p < 0.01), increased forefoot eversion relative to rearfoot (p < 0.01), and increased peak of plantar flexion of forefoot relative to rearfoot during the propulsive phase (p = 0.01) compared to Flat orthosis. The effects of the TPS were different from the Rigid orthosis, demonstrating that, alongside shape, material properties were a determinant factor for the obtained results. The findings of this study help clarify the role of a mechanism similar to a twisted osteoligamentous plate on controlling foot pronation and facilitating supination during the stance phase of walking.

Multisegmented ankle-foot kinematics during gait initiation in ankle sprains and chronic ankle instability

BackgroundIndividuals with lateral ankle sprain and chronic ankle instability have impaired postural control and altered motor strategies during walking. However, little is known regarding foot mechanics during gait. The purpose of this study was to compare three-dimensional multisegmented ankle-foot kinematics during stance phase following gait-initiation in acute lateral ankle sprain (Ankle-sprain), chronic ankle instability (Chronic-instability), Coper, and Control groups. Methods80 recreationally-active individuals (Control: n = 22, Coper: n = 21, Ankle-sprain: n = 17, Chronic-instability: n = 20) participated. Three-dimensional kinematics of the hallux, medial forefoot, lateral forefoot, medial midfoot, lateral midfoot, and rearfoot on shank were collected during the stance phase following gait initiation using an electromagnetic motion capture system. The average joint excursions of 10 steps were normalized to 101 points and analyzed using Statistical Parametric Mapping ANOVA and post hoc t-tests comparing Coper, Ankle-sprain, or Chronic-instability versus Control groups. Secondary analysis was performed comparing Chronic-instability versus Coper groups. FindingsThe Ankle-sprain group had up to 4.1° more rearfoot inversion during midstance (mean difference: 3.1°) from 42 to 49% of stance phase compared to healthy controls. The Chronic-instability group had up to 5.3° more rearfoot inversion (mean difference: 3.6°) from 34% to 91% of stance phase compared to controls. There were no further statistical differences found between Chronic-instability and Copers, other planes, or segments of the ankle-foot complex. InterpretationAnkle-sprain and Chronic-instability groups demonstrated more rearfoot inversion compared to controls with no differences in midfoot or forefoot mechanics. Clinicians and researchers should include interventions that control inversion and increase eversion following lateral ankle sprain.

Ankle Joint and Rearfoot Biomechanics During Toe-In and Toe-Out Walking in People With Medial Compartment Knee Osteoarthritis.

Toe-in and toe-out walking are 2 strategies that have been shown to be effective in reducing the knee adduction moment in people with knee osteoarthritis. However, despite a positive biomechanical impact on the knee, altering foot rotation may impart unintended forces or joint positions on the ankle that could impact joint health. The kinematic and kinetic changes at the ankle during toe-in or toe-out walking have yet to be examined. To examine ankle/rearfoot biomechanics during toe-in and toe-out walking in those with knee osteoarthritis. Single-session repeated measures design to compare ankle biomechanics during walking with 4 different foot rotations. University motion analysis laboratory. A convenience sample (N = 15) of males and females with a diagnosis of medial knee osteoarthritis confirmed by radiographs. Participants walked in 4 conditions guided by real-time biofeedback: (1) toe-in (+10°), (2) zero rotation (0°), (3) toe-out (-10°), and (4) toe-out (-20°). Ankle and rearfoot kinematics and kinetics were examined during barefoot over-ground walking. Ankle joint angles, moments, moment impulses, and foot rotation. Overall, toe-in compared to toe-out walking decreased (P = .03) peak rearfoot eversion (toe-in = -1.6°; 10° toe-out = -3.7°; 20° toe-out = -4.1°). Toe-in compared to toe-out walking also increased rearfoot inversion at initial contact (7.4° vs 3.1° at 10° toe-out and 1.9° at 20° toe-out; P < .001) and frontal plane rearfoot angle excursion (9.0° vs 6.8° at 10° toe-out and 6.0° at 20° toe-out; P < .006). Toe-in compared to all other conditions increased peak external ankle inversion moments (0.04 Nm/kg vs 0.02 Nm/kg at 0°, 0.02 Nm/kg at 10° toe-out, and 0.01 Nm/kg at 20° toe-out; P < .003). Toe-in and toe-out walking require different ankle/rearfoot biomechanics, though no differences in discomfort were observed. Longer-term studies are required to properly assess these relationships in knee osteoarthritis populations. IV.

Understanding the Effect of High-Cut Shoes, Running Shoes and Prophylactic Supports on Ankle Stability When Performing a “V”-Cut Movement

Ankle inversion injury is extremely common in basketball, whereby rearfoot inver- sion and ankle plantar flexion is greater in those with injury. The current study analysed the response of recreational basketball players to three different footwear conditions; high-cut bas- ketball shoe, low-cut running shoe and low-cut running shoe with ankle brace. Ten recreational male basketball players performed 45° v-cut movements at an approach speed of 4.5m/s. Dependent variables included peak initial rearfoot inversion and ankle plantar flexion. Peak impact force was also measured due to the potential difference in cushioning provided by the footwear. Repeated measures ANOVA were used to compare dependent variables with statisti- cal significance accepted at p 0.05; Partial η 2 = 0.25) and impact force (F = 3.189, p > 0.05, Partial η 2 = 0.26).On the other hand, comparison of peak initial rearfoot inversion showed that there were significant differences between footwear conditions. Pairwise comparisons with Bonferroni adjustments showed significantly larger peak initial rearfoot inversion values for the high-cut basketball shoe compared to both the low-cut running shoe (p = 0.001) and the low-cut running shoe with brace condition (p = 0.001). Findings indicate the potential for using low-cut running shoes for recreational basketball without an increased injury risk.

A-11 キャンバー角が走動作に及ぼす影響(走動作)

Recently, trail running on various surface conditions, i.e. uphill, downhill, wet, rock and so on, is getting popular year by year. In these surface conditions, it is predicted that load applied to the lower-extremity becomes higher during running on camber, which demonstrates the condition to run across sloped surface laterally. However, there are few studies that have discussed relationship between footwear stability and kinematics of lower-extremity in camber running. The purpose of this kinematics in camber running, motion analyses on three surface conditions (flat, CM: Medial side of the foot gets higher than lateral and CL: Lateral side of the foot gets higher than medial) were carried out. As a result, rearfoot eversion angle (β) in CL running and knee varus angle (ζ) in CM running become higher than those in flat running at foot flat phase. It was also confirmed that knee varus angle has a high correlation with rearfoot inversion angle in CM running. Furthermore, the influence of sole structures on β and ζ was also discussed.

Forefoot midsole stiffness affects forefoot and rearfoot kinematics during the stance phase of gait.

The forefoot midsole stiffness of the shoe may affect the kinematics of the foot segments. We evaluated the effects of two different levels of forefoot midsole stiffness on the angular displacement of the forefoot and rearfoot in the three planes of motion during the stance phase of gait. Thirty-six participants walked on a 10-m walkway at their self-selected speed wearing shoes having either low or high forefoot midsole stiffness. Three-dimensional kinematic data of the foot segments were obtained during the stance phase of gait using an eight-camera motion analysis system synchronized with a force platform. The dependent variables were forefoot and rearfoot total range of motion and maximum and minimum angle values in the sagittal, frontal, and transverse planes of motion. Reduced forefoot midsole stiffness produced significantly greater forefoot total range of motion in the sagittal plane (1.59°). The low-stiffness condition also increased the magnitude of the forefoot dorsiflexion angles (4.14°). Furthermore, the low-stiffness condition increased the magnitude of the rearfoot inversion (1.21°) and adduction (11.38°) angles and reduced the rearfoot abduction angle (12.1°). It is likely that reduced stiffness of the forefoot midsole stretched the plantar fascia, increasing rearfoot stability during the stance phase of gait. Increased muscular contraction may also explain increases in rearfoot stability. Therefore, the integrity of the plantar fascia and ankle muscles' force and resistance should be considered when choosing a shoe with reduced or increased forefoot midsole stiffness for walking.

Foot orthoses for adults with flexible pes planus: a systematic review.

BackgroundFoot orthoses are widely used in the management of flexible pes planus, yet the evidence to support this intervention has not been clearly defined. This systematic review aimed to critically appraise the evidence for the use of foot orthoses for flexible pes planus in adults.MethodsElectronic databases (Medline, CINAHL, Cochrane, Web of science, SportDiscus, Embase) were systematically searched in June 2013 for randomised controlled, controlled clinical and repeated measure trials where participants had identified flexible pes planus using a validated and reliable measure of pes planus and the intervention was a rigid or semi-rigid orthoses with the comparison being a no-orthoses (shoes alone or flat non-posted insert) condition. Outcomes of interest were foot pain, rearfoot kinematics, foot kinetics and physical function.ResultsOf the 2,211 articles identified by the searches, 13 studies met the inclusion criteria; two were randomised controlled trials, one was a controlled trial and 10 were repeated measure studies. Across the included studies, 59 relevant outcome measures were reported with 17 calculated as statistically significant large or medium effects observed with use of foot orthoses compared to the no orthoses condition (SMD range 1.13 to -4.11).ConclusionsNo high level evidence supported the use of foot orthoses for flexible pes planus. There is good to moderate level evidence that foot orthoses improve physical function (medial-lateral sway in standing (level II) and energy cost during walking (level III)). There is low level evidence (level IV) that foot orthoses improve pain, reduce rearfoot eversion, alter loading and impact forces; and reduce rearfoot inversion and eversion moments in flexible pes planus. Well-designed randomised controlled trials that include appropriate sample sizes, clinical cohorts and involve a measure of symptom change are required to determine the efficacy of foot orthoses to manage adult flexible pes planus.

Changing step width alters lower extremity biomechanics during running

Step width is a spatiotemporal parameter that may influence lower extremity biomechanics at the hip and knee joint. The purpose of this study was to determine the biomechanical response of the lower extremity joints to step width changes during running. Lower extremity data from 30 healthy runners, half of them male, were collected during running in three step width conditions: preferred, wide, and narrow. Dependent variables and step width were analyzed using a mixed model ANOVA and pairwise t-tests for post hoc comparisons. Step width was successfully altered in the wide and narrow conditions. Generally, frontal plane peak values decreased as step width increased from narrow to preferred to wide. Peak hip adduction and rearfoot eversion angles decreased as step width increased from narrow to wide. Peak knee abduction moment and knee abduction impulse also decreased as step width increased from narrow to wide. Although men and women ran differently, gender only influenced the effect of step width on peak rearfoot inversion moment. In conclusion, step width influences lower extremity biomechanics in healthy runners. When step width increased from narrow to wide, peak values of frontal plane variables decreased. In addition to previously reported changes at the rearfoot, the hip and knee joint biomechanics were also influenced by changes in step width.

Effect of Shoe Heel Height and Total-Contact Insert on Muscle Loading and Foot Stability While Walking

Women wearing high-heeled shoes often complain of foot instability and low-back pain. Previous studies have demonstrated that using total-contact inserts (TCIs) in running shoes reduces impact on leg muscles and alters rearfoot motion. This study investigated how shoe heel height and use of TCIs in high-heeled shoes affect the wearer's rearfoot complex, muscle loading, and subjective comfort. Fifteen inexperienced high heel wearers walked under 6 test conditions formed by the cross-matching of shoe insert (with and without TCI) and heel height (1.0, 5.1, and 7.6 cm) at a speed of 1.3 m/s. The measures of interest were rearfoot kinematics; muscle activities by electromyography (EMG) of the tibialis anterior (TA), medial gastrocnemius (MG), quadriceps (QUA), hamstrings (HAM), and erector spinae (ES); and subjective comfort rating by visual analogue scale for each test condition. The statistical results showed that elevated heel height significantly increased plantar flexion (P < .001) and inversion (P < .01) at heel strike, prolonged TA-MG co-contraction (P < .001) and QUA activation period (P < .001), and increased root mean square (RMS) EMG in all measured muscles (TA, MG, QUA, ES: P < .001; HAM: P < .01). The use of TCIs reduced the rearfoot inversion angle (P < .01) and RMS EMG in both QUA and ES muscles (P < .01) and increased comfort rating (P < .001). These findings suggest that wearing high-heeled shoes adversely affects muscle control and reduces loads in QUA and ES muscles. The use of a TCI may improve comfort rating and foot stability.

Forefoot angle determines duration and amplitude of pronation during walking

The biomechanical mechanisms that link foot structure to injuries of the musculoskeletal system during gait are not well understood. This study had two parts. The purpose of part one was to determine the relation between clinical rearfoot and forefoot angles and foot angles as they make contact with the ground. The purpose of part two was to determine the effects of large vs. moderate values of both forefoot and rearfoot inversion angles at foot contact on foot kinematics. Clinical foot angle, the relationship between the foot and an axis extrinsically defined relative to the ground, was calculated from digital photographs taken in a prone position. During three speeds of over-ground walking, we measured frontal plane rearfoot and forefoot angle relative to the ground at foot contact, and the following stance phase kinematic measures: amplitude of rearfoot and forefoot eversion, duration of rearfoot and forefoot eversion, and duration between heel-off and onset of rearfoot and forefoot inversion. We found that the clinical forefoot angle predicted the forefoot angle at foot contact. Individuals with a large inversion forefoot angle at contact also had greater amplitude of forefoot eversion and everted longer during stance. We discuss the possible mechanisms for the increased risk of injury to the hip reported for individuals that have a large clinical forefoot angle in non-weight bearing. Equally important is the finding that rearfoot angle at contact did not predict the motions of the rearfoot or forefoot during stance.