The effect of footwear and footfall pattern on running stride interval long-range correlations and distributional variability

The presence of long-range correlations (self-similarity) in the stride-to-stride fluctuations in running stride interval has been used as an indicator of a healthy adaptable system. Changes to footfall patterns when running with minimalist shoes could cause a less adaptable running gait. The purpose of this study was to investigate stride interval variability and the degree of self-similarity of stride interval in runners wearing minimalist and conventional footwear. Twenty-six trained habitual rearfoot footfall runners, unaccustomed to running in minimalist footwear, performed 6-min sub-maximal treadmill running bouts at 11, 13 and 15 km·h⁻¹ in minimalist and conventional shoes. Force sensitive resistors were placed in the shoes to quantify stride interval (time between successive foot contacts). Footfall position, stride interval mean and coefficient of variation (CV), were used to assess performance as a function of shoe type. Long-range correlations of stride interval were assessed using detrended fluctuation analysis (α). Mean stride interval was 1-1.3% shorter (P = 0.02) and 27% of runners adopted a midfoot footfall (MFF) in the minimalist shoe. There was a significant shoe effect on α and shoe*speed*footfall interaction effect on CV (P < 0.05). Runners that adopted a MFF in minimalist shoes, displayed reduced long-range correlations (P < 0.05) and CV (P < 0.06) in their running stride interval at the 15 km·h⁻¹ speed. The reduced variability and self-similarity observed for runners that changed to a MFF in the minimalist shoe may be suggestive of a system that is less flexible and more prone to injury.     

Biomechanical effects following footstrike pattern modification using wearable sensors

ObjectivesThis study sought to examine the biomechanical effects of an in-field sensor-based gait retraining program targeting footstrike pattern modification during level running, uphill running and downhill running.DesignQuasi-experimental design.MethodsSixteen habitual rearfoot strikers were recruited. All participants underwent a baseline evaluation on an instrumented treadmill at their preferred running speeds on three slope settings. Participants were then instructed to modify their footstrike pattern from rearfoot to non-rearfoot strike with real-time audio biofeedback in an 8-session in-field gait retraining program. A reassessment was conducted to evaluate the post-training biomechanical effects. Footstrike pattern, footstrike angle, vertical instantaneous loading rate (VILR), stride length, cadence, and knee flexion angle at initial contact were measured and compared.ResultsNo significant interaction was found between training and slope conditions for all tested variables. Significant main effects were observed for gait retraining (p-values ≤ 0.02) and slopes (p-values ≤ 0.01). After gait retraining, 75% of the participants modified their footstrike pattern during level running, but effects of footstrike pattern modification were inconsistent between slopes. During level running, participants exhibited a smaller footstrike angle (p ≤ 0.01), reduced VILR (p ≤ 0.01) and a larger knee flexion angle (p = 0.01). Similar effects were found during uphill running, together with a shorter stride length (p = 0.01) and an increased cadence (p ≤ 0.01). However, during downhill running, no significant change in VILR was found (p = 0.16), despite differences found in other biomechanical measurements (p-values = 0.02–0.05).ConclusionAn 8-session in-field gait retraining program was effective in modifying footstrike pattern among runners, but discrepancies in VILR, stride length and cadence were found between slope conditions.     

Biomechanical analysis of gait waveform data: exploring differences between shod and barefoot running in habitually shod runners

The aim of this study was to utilise one-dimensional statistical parametric mapping to compare differences between biomechanical and electromyographical waveforms in runners when running in barefoot or shod conditions.Fifty habitually shod runners were assessed during overground running at their current 10-km race running speed. Electromyography, kinematics and ground reaction forces were collected during these running trials. Joint kinetics were calculated using inverse dynamics. One-dimensional statistical parametric mapping one sample t-test was conducted to assess differences over an entire gait cycle on the variables of interest when barefoot or shod (p < 0.05).Only sagittal plane differences were found between barefoot and shod conditions at the knee during late stance (18–23% of the gait cycle) and swing phase (74–90%); at the ankle early stance (0–6%), mid-stance (28–38%) and swing phase (81–100%). Differences in sagittal plane moments were also found at the ankle during early stance (2, 4–5%) and knee during early stance (5–11%). Condition differences were also found in vertical ground reaction force during early stance between (3–10%).An acute bout of barefoot running in habitual shod runners invokes temporal differences throughout the gait cycle. Specifically, a co-ordinative responses between the knee and ankle joint in the sagittal plane with a delay in the impact transient peak; onset of the knee extension and ankle plantarflexion moment in the shod compared to barefoot condition was found. This appears to affect the delay in knee extension and ankle plantarflexion during late stance. This study provides a glimpse into the co-ordination of the lower limb when running in differing footwear.     

There is no difference in footstrike pattern distribution in recreational runners with or without anterior knee pain

BackgroundThere are no studies comparing footstrike pattern distribution between recreational runners with or without anterior knee pain.ObjectiveThe aim of this study was to investigate if there was any difference in footstrike pattern between recreational runners with or without anterior knee pain.MethodsThis cross-sectional study involved 62 runners without anterior knee pain and 60 runners with anterior knee pain. We recruited runners in public parks and amateur road running competitions. A 2D record was made using a high-speed camera with an acquisition frequency of 300 Hz and shutter speed of 300^s−1. Also, demographic information, running characteristics, knee pain characteristics, and running biomechanics variables were collected. Besides the footstrike pattern, running step length, mean velocity, footstrike angle, and ankle push-off were evaluated.ResultsThe distribution of rearfoot strike pattern was similar between groups, observed in 96.6 % of the subjects with anterior knee pain and in 93.5 % of the subjects without it. In the secondary analysis, a logistic regression was conducted, and none of the demographic information, running training characteristics, and running biomechanics variables evaluated in this study were associated with runners presenting knee pain.ConclusionRunners with or without anterior knee pain do not differ in regard to footstrike pattern. Both groups had predominantly rearfoot strike patterns, and none of the collected variables were associated with anterior knee pain on runners.     

The effects of foot orthosis and low-dye tape on lower limb joint angles and moments during running in individuals with pes planus

BackgroundPes Planus or Flat feet is one of the most common lower limb abnormalities. When runners with this abnormality participate in recreational running, interventional therapies could help in pain alleviation and enhance performance. To determine the most effective treatment, however, a biomechanical examination of the effects of each treatment modality is required.Research questionThe aim of the present study was to investigate the effects of Foot Orthoses (FOs) and Low-Dye Tape (LDT) on lower limb joint angles and moments during running in individuals with pes planus.Methodskinematic and kinetic data of 20 young people with pes planus were measured during running in three conditions: (1) SHOD (2) with shoes and FOs (3) with shoes and LDT. One-way repeated measure ANOVA was used to investigate the impacts of the FOs and LDT on the lower limb joint angles and moments throughout the stance phase of the running cycle.ResultsThe results showed that FOs reduced ankle eversion compared to SHOD and LDT (P < 0.001) and decreased the dorsiflexion angle (P = 0.005) and the plantarflexor moment compared to the SHOD (P < 0.001). FOs increased knee adduction angle (P = 0.021) and knee external rotator moment (P < 0.001) compared to both conditions and increased knee extensor and abductor moments compared to SHOD (P < 0.001). At the hip joint, FOs only increased hip external rotation compared with the LDT condition (P = 0.031); and LDT increased hip extensor moment compared to SHOD and FOs (P = 0.037) and also increased hip adduction angle compared to SHOD (P = 0.037).SignificanceFOs with a medial wedge appears to increase the external knee adduction moment and knee adduction angles, which are risk factors for the development and progression of knee osteoarthritis. Further, usage of FOs seems to reduce the ankle joint role in propulsion as it impacts the ankle sagittal angles and moments.     

What differentiates rearfoot strike runners with low and high vertical load rates?

BackgroundRunners with a rearfoot strike pattern typically show high vertical ground reaction force loading rates (LRs), that are associated with injuries, compared with forefoot strikers. However, some runners with a rearfoot strike pattern run in a way that reduces LRs. Our purpose was to identify differences in running mechanics between rearfoot strike runners with high and low vertical LRs.Methods42 healthy runners, 21 with high (≥ 80.5 BW/s) and 21 with low (≤ 46.3 BW/s) LRs, were included in the current study. Lower extremity kinematic and kinetic data were then collected while participants ran along a 30 m runway. Running mechanics were calculated, including sagittal plane knee stiffness during early stance, the components of knee stiffness (Δ knee flexion and flexion moment), sagittal joint angles at initial contact, as well as cadence. The two LR groups were compared for differences in outcome variables using independent t-tests or Mann Whitney U tests.FindingsKnee stiffness was significantly lower in the low LR group (p < 0.01, d = 0.87), due to higher knee flexion excursion (p < 0.01, d = 1.38). At initial contact, the low LR group showed lower hip and knee flexion, but greater ankle and foot dorsiflexion (p = 0.01–0.04, d = 0.64–0.93). No differences were found in cadence.InterpretationThese results provide potential targets, related to gait kinematics and kinetics, for gait retraining aimed at reducing LRs in rearfoot strike runners.     

Effects of a foot strengthening program on foot muscle morphology and running mechanics: A proof-of-concept,single-blind randomized controlled trial

ObjectivesTo investigate the effects of a foot training program on muscle morphology and strength as well as running biomechanics in healthy recreational runners.DesignProof-of-concept, single-blind randomized controlled trial.SettingsRunners were allocated to a control (CG) or an intervention (IG) group. The intervention focused on strengthening the intrinsic foot muscles and their activation during weight-bearing activities. All participants were assessed at baseline and after 8-weeks.ParticipantsTwenty-eight healthy recreational long-distance runners not habituated to minimalist running shoes or barefoot running.Main outcomes measuresOutcomes were hallux and toes strength; foot function, cross-sectional area and volume of the abductor hallucis (ABH), abductor digiti minimi (ABV), flexor digitorum brevis (FDB), and flexor hallucis brevis; medial longitudinal arch range of motion and stiffness; vertical and antero-posterior propulsive impulses during running.ResultsCompared to the CG, an increase was found in the IG for the volume of all muscles investigated and for vertical propulsive impulse during running. Correlations were found between vertical propulsive impulse and volume of ABH(r = 0.40), ABV(r = 0.41), and FDB(r = 0.69).ConclusionThe foot exercise protocol effectively increased intrinsic foot muscle volume and propulsive forces in recreational runners. This shows that intrinsic muscle strengthening affects running mechanics and suggests that it may improve running performance.     

Short-term effects of a trunk modification program on patellofemoral joint stress in asymptomatic runners

ObjectivesTo evaluate short-term effects of a four-week gait retraining program using visual feedback on trunk flexion angle, patellofemoral joint (PFJ) stress, lower extremity biomechanics and motor skill automaticity.DesignLongitudinal interventional study.SettingsUniversity research laboratory.ParticipantsTwelve asymptomatic recreational runners (seven male and five female).Main outcome measuresTrunk kinematics as well as lower extremity kinematics and kinetics were assessed prior to training at week 1 (baseline) and week 2, 3, 4 and 8 (retention). PFJ stress was computed using a sagittal plane model. A dual-task procedure was performed to examine automaticity.ResultsAt week 8, runners demonstrated 10.1° increase in trunk flexion angle (p < .001) and 17.8% reduction in peak PFJ stress (p < .001) compared to baseline. This is associated with a 16.8% decrease in knee extensor moment and less than 2.5° change in knee flexion angle. Participants also showed 33.3% increase in peak hip extensor moment and small reduction in peak ankle plantar flexor moment. Lastly, runners demonstrated automaticity of the modified skill with a dual-task cost of less than 3%.ConclusionThe gait retraining program is effective to elicit short term changes in trunk position, PFJ stress, and automaticity of the new motor skill.     

Effects of wobble board training on single‐leg landing neuromechanics

Balance training programs have been shown to reduce ankle sprain injuries in sports, but little is known about the transfer from this training modality to motor coordination and ankle joint biomechanics in sport‐specific movements. This study aimed to investigate the effects of wobble board training on motor coordination and ankle mechanics during early single‐leg landing from a lateral jump. Twenty‐two healthy men were randomly assigned to either a control or a training group, who engaged in 4 weeks of wobble board training. Full‐body kinematics, ground reaction force, and surface electromyography (EMG ) from 12 lower limb muscles were recorded during landing. Ankle joint work in the sagittal, frontal, and transverse plane was calculated from 0 to 100 ms after landing. Non‐negative matrix factorization (NMF ) was applied on the concatenated EMG Pre‐ and Post‐intervention. Wobble board training increased the ankle joint eccentric work 1.2 times in the frontal (P  <  .01) and 4.4 times in the transverse plane (P  <  .01) for trained participants. Wobble board training modified the modular organization of muscle recruitment in the early landing phase by separating the activation of plantar flexors and mediolateral ankle stabilizers. Furthermore, the activation of secondary muscles across motor modules was reduced after training, refocusing the activation on the main muscles involved in the mechanical main subfunctions for each module. These results suggest that wobble board training may modify motor coordination when landing from a lateral jump, focusing on the recruitment of specific muscles/muscle groups that optimize ankle joint stability during early ground contact in single‐leg landing.     

Subclassification of recreational runners with a running-related injury based on running kinematics evaluated with marker-based two-dimensional video analysis

ObjectivesTo explore whether homogeneous subgroups could be discriminated within a population of recreational runners with a running-related injury based on running kinematics evaluated with marker-based two-dimensional video analysis.DesignCross-sectional.SettingResearch laboratory.ParticipantsFifty-three recreational runners (15 males, 38 females) with a running-related injury.Main outcome measuresFoot and tibia inclination at initial contact, and hip adduction and knee flexion at midstance were measured in the frontal and sagittal plane with marker-based two-dimensional video analysis during shod running on a treadmill at preferred speed. The four outcome measures were clustered using K-means cluster analysis (n = 2–10). Silhouette coefficients were used to detect optimal clustering.ResultsThe cluster analysis led to the classification of two distinct subgroups (mean silhouette coefficient = 0.53). Subgroup 1 (n = 39) was characterized by significantly greater foot inclination and tibia inclination at initial contact compared to subgroup 2 (n = 14).ConclusionThe existence of different subgroups demonstrate that the same running-related injury can be represented by different kinematic presentations. A subclassification based on the kinematic presentation may help clinicians in their clinical reasoning process when evaluating runners with a running-related injury and could inform targeted intervention strategy development.     

Gait variability between younger and older adults: An equality of variance analysis

BackgroundTo estimate gait variability, several methods have been routinely used which provide a measure of global variability. A recent study introduced a group waveform variability method which provides a point-by-point measurement of data variance equality. This can identify where in the gait cycle the significant differences in variability exist.Research questionDo waveform differences exist in equality of variance and group means in lower limb biomechanical variables between healthy younger and older adults during a gait task?MethodsTwenty healthy younger (19–44 years old, age=29.9(7.0) years, body mass index= 24.6(3.2)kg/m², females= 10) and 20 healthy older (55–79 years old, age=63.6(5.5) years, body mass index= 25.9(2.7)kg/m², females= 10) adults who were free from lower limb injuries and had no musculoskeletal or neurological disorders. Temporospatial outcomes, sagittal and frontal lower limb joint angles and moments, along with joint powers were examined as participants walked at a self-selected pace. Waveform patterns were normalized to the gait cycle and compared using equality of variance and statistical parametric mapping techniques.ResultsNo difference in walking speed existed between the younger or older groups (P > .05). The older group had greater variability (P < .05) in sagittal hip angles, as well as greater frontal ankle angle and moment variability. The younger group had significantly greater mean (P < .05) ankle power generation prior to toe-off.SignificanceThis study provided a baseline of temporal differences in variance between healthy younger and older individuals. Its findings warrant the use of the equality of variance test to compare temporal differences for a variety of populations and tasks. Older adults generally had more variability than the younger adults, with many differences occurring near the transition from double- to single-limb support. The statistical parametric mapping analysis showed that the older adults could not generate as much ankle power as the younger adults prior to toe-off.     

Does running speed affect the response of joint level mechanics in non-rearfoot strike runners to footwear of varying longitudinal bending stiffness?

BackgroundModifying the longitudinal bending stiffness (LBS) of footwear has become a popular method to improve sport performance. It has been demonstrated to influence running economy by altering lower extremity joint level mechanics. Previous studies have only examined within-participant effects at one running speed.Research questionDo joint level mechanics differ in response to varying footwear LBS at a range of running speeds?MethodsThis study utilized a cross-sectional repeated measure study design using a convenience sample. Ten well trained non-rearfoot strike male distance runners ran at 3.89, 4.70, and 5.56 m/s (14, 17, 20 km/hr) in footwear of three different LBS levels. Mechanics and energetics of the metatarsophalangeal joint (MTPJ), ankle, knee, and hip joints during stance phase were assessed using an 8-camera optical motion capture system (f_s = 200 Hz), a force instrumented treadmill (f_s = 1000 Hz) and standard inverse dynamics theory.ResultsRange of motion and negative work decreased and angular stiffness increased for the MTPJ with increasing LBS at all speeds (p < .001). Peak MTPJ moment did not change at any speed in response to increased LBS. Negative work at the ankle decreased in the stiff shoe at 17 km/hr (p = .036). Peak ankle plantar flexion velocity decreased with increasing LBS at all speeds (p < .05).SignificanceWhile changes in MTPJ mechanics were consistent across speeds, decreased negative ankle work was only observed at 17 km/hr in the stiff shoe, suggesting that perhaps tuned footwear LBS may need to focus primarily on metabolically beneficial changes in ankle plantar flexor mechanical behavior to improve performance in distance runners. Tuning footwear stiffness may also be beneficial to clinical populations, as clinicians seek to optimize their patients’ locomotion economy.     

Foot contact angle variability during a prolonged run with relation to injury history and habitual foot strike pattern

Foot strike pattern and movement variability have each been associated with running injuries. Foot contact angle (FCA) is a common measure of strike pattern. Thus, variability in FCA could be an important running injury risk factor. The purposes of this study were to compare (a) foot contact angle (FCA) and its variability between runners with and without injury history and, (b) FCA variability between habitual rearfoot strike (RFS) and non-RFS runners during a prolonged run. Twenty-three runners with and 21 without injury history participated. Motion capture was used to collect kinematic data during a 40 min treadmill run. Average FCA and its variability were compared between injury groups and among four time points. FCA and its variability were not different between runners with and without injury history or among time points during the run. FCA variability was lower in non-RFS compared to RFS runners (P < 0.001). Lower FCA variability in non-RFS runners may have implications for higher injury risks due to repeated localized tissue loading. Prospective analyses on the effects of lower FCA variability on injury risk are needed.     

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.     

Immediate effects of foot orthoses on lower limb biomechanics,pain, and confidence in individuals with patellofemoral osteoarthritis

BackgroundFoot orthoses are a recommended treatment for patellofemoral (PF) pain and a number of lower limb osteoarthritic (OA) conditions. However, their mechanism of effect is poorly understood.Research questionTo compare the immediate effects of foot orthoses and flat inserts on lower limb biomechanics, knee pain and confidence in individuals with PFOA.MethodsTwenty-one participants (14 females; mean ± SD age 58 ± 8 years) with PFOA underwent three-dimensional motion analysis during level-walking, stair ascent, and stair descent under three footwear conditions: (i) their own shoes; (ii) prefabricated foot orthoses; and (iii) flat shoe inserts. Participants reported their average levels of knee pain and confidence after each task. Data were analysed with repeated-measures analysis of variance (ANOVA), effect sizes (partial eta squared), and Bonferroni post-hoc tests.ResultsDuring level-walking, there was a significant main effect of foot orthoses on peak ankle dorsiflexion angle (F₂ = 0.773, p < 0.001, ƞ² = 0.773) and peak ankle external dorsiflexion moment (F₂ = 0.356, p = 0.046, ƞ² = 0.356). Foot orthoses decreased the peak ankle dorsiflexion angle compared to the flat insert and shoe conditions, and decreased the peak ankle external dorsiflexion moment relative to flat inserts. During stair descent, there was a significant main effect of foot orthoses on peak ankle external dorsiflexion moment (F₂ = 0.823, p = 0.006, ƞ² = 0.738), with a trend towards lower peak dorsiflexion moment for foot orthoses compared to the flat insert and shoe conditions. No significant main effects were observed during stair ascent. No other lower limb biomechanical changes were observed across all three conditions. Knee pain and confidence scores were not significantly different across the three conditions.SignificancePrefabricated foot orthoses altered sagittal plane biomechanics of the ankle during level-walking and stair descent in individuals with PFOA. Further research is required to determine whether these changes are clinically beneficial.     

Increased use of stepping strategy in response to medio-lateral perturbations in the elderly relates to altered reactive tibialis anterior activity

BackgroundThe influence of aging on reactive control of balance during walking has been mainly investigated in the sagittal plane, whereas balance control in response to frontal plane perturbations is largely unexplored in the elderly. This is remarkable, given that walking mainly requires active control in the frontal plane. An extensive gait perturbation protocol was used to test whether reactive control of walking balance changes with aging and whether these changes are more pronounced in the frontal than in the sagittal plane.Research questionDo alterations in reactive muscle activity cause an age-related shift in stepping strategy in response to perturbations in the frontal and sagittal planes during walking?MethodA treadmill-based perturbation protocol imposed frontal and sagittal plane perturbations of different magnitudes during different phases of the gait cycle. Motion capture and electromyography measured the response to the different perturbations in a group of eighteen young and ten older adults.ResultsOnly for a small subset of the perturbations, reactive muscle activity and kinematic strategies differed between young and older subjects. When perturbation magnitude increased, the older adults relied more on a stepping strategy for inward directed frontal plane perturbations and for sagittal plane perturbation just before heelstrike. Tibialis anterior activity increased less in the older compared to the young subjects. Using simulations, we related tibialis anterior activity to backward and outward movement of the center of pressure in the stance foot and confirmed its contribution to the ankle strategy. We concluded that deficient tibialis anterior activity predisposes elderly to use stepping rather than lateral ankle strategies to control balance.SignificanceRehabilitation targets for fall prevention in elderly need to also focus on ankle muscle reactivity.     

A step towards dynamic foot classification: Functional grouping using ankle joint frontal plane motion in running

BackgroundThe premise behind static foot classification suggests structure dictate’s function. However, the validity of this has been challenged, as weak association between static foot type and dynamic motion exists. This has led to calls for dynamic assessments and classification of feet based on functional motion, yet methods to do this have been seldom explored.Research questionWithin a group of runners do homogenous sub-groups of ankle joint complex (AJC) frontal plane motion exist?MethodsA k means clustering analysis was conducted on the frontal plane AJC motion patterns of a group of healthy adults running barefoot (n = 42) to identify functional movement groups. Once identified, statistical parametric mapping was employed to determine the differences between clusters across stance. The identified clusters were used to determine dynamic foot type; an agreement analysis was conducted between the newly defined foot types and the Foot Posture Index (FPI-6).ResultsTwo distinct clusters were identified. Waveform analysis identified that cluster 1 displayed significantly (p < 0.001) less AJC eversion between 0% and 97% of the stance phase compared to cluster 2, with the differences between clusters associated with large effect sizes (g > 1). Based on the displayed kinematic profiles, cluster 1 was defined as a Neutral Dynamic Foot Type (Neutral_DFT), and cluster 2 a Pronated Dynamic Foot Type (Pronated Dynamic_DFT). The newly defined foot type measure had only a slight agreement (κ = 0.08) with the FPI-6.SignificanceWe demonstrated a protocol to classify a runner’s foot type derived directly from AJC motion during running. Poor agreement between the dynamic and static classification measures further evidence that these assessments are not analogous. Our results question the validity of static classification when looking to characterise the foot during running, suggesting dynamic assessments are more appropriate to reflect the foots functional response.     

Efficacy of motion control shoes for reducing excessive rearfoot motion in fatigued runners

ObjectivesExcessive foot pronation and fatigue in running are possible risk factors for injuries. Motion control footwear was designed to limit excessive foot motion in runners, but its clinical efficacy has not been well reported. This study investigated the rearfoot kinematics in runners when running with different footwear before and after fatigue of the lower leg muscles.DesignWithin subjects repeated measures.SettingUniversity gait laboratory.Participants25 female recreational runners.Main outcome measuresA Vicon three-dimensional motion analysis system was used to capture the rearfoot motions of 25 recreational runners who had excessive foot pronation, when running with motion control shoes and neutral shoes before and after fatigue of the lower leg muscles.ResultsThe findings with neutral shoe testing revealed a significant increase in rearfoot angle of 6.5° (95% CI 4.7–8.2°) (p<0.01) when the muscles were fatigued. However, the findings with motion control shoes revealed that rearfoot angle was marginally insignificant (p=0.06) in subjects before and after muscle fatigue. Moreover, rearfoot motion when running with neutral shoes was higher than that with motion control shoes in both pre- (p<0.01) and post-fatigue states (p<0.01).ConclusionsMotion control shoes can control excessive rearfoot movements in runners with over-pronation regardless of the state of leg muscle fatigue.     

Relationship between lower limb EMG activity and knee frontal plane projection angle during a single-legged drop jump

ObjectivesTo assess a relationship between lower limb muscle activity and the frontal plane knee kinematics during a single-legged drop jump.DesignCorrelation study;SettingFunctional Anatomy Laboratory.Participants35 healthy collegiate male athletes.Main outcome measuresMuscle activity (%MVIC) of gluteus maximus, gluteus medius, biceps femoris, semitendinosus, vastus medialis quadriceps, vastus lateralis quadriceps, medial gastrocnemius and lateral gastrocnemius; peak knee frontal plane projection angle; and Pearson's correlation coefficients between muscle activity and peak knee frontal plane projection angle. All outcomes were assessed for both dominant and non-dominant limbs.ResultsSignificant correlations (r = 0.46–0.60, P < 0.05) were found between the muscle activities of the gluteus maximus, gluteus medius, biceps femoris, and semitendinosus, when compared to the knee frontal plane projection angle.ConclusionGluteal muscles and hamstring muscles are associated with the peak knee frontal plane projection angle during a single-legged drop jump test. Thus, gluteal and hamstring muscle activities should be considered when developing rehabilitation or injury prevention programs.