Barefoot running: an evaluation of current hypothesis, future research and clinical applications

Isolated effects of footwear structure and cushioning on running mechanics in habitual mid/forefoot runners

The true differences between barefoot and shod running are difficult to directly compare because of the concomitant change to a mid/forefoot footfall pattern that typically occurs during barefoot running. The purpose of this study was to compare isolated effects of footwear structure and cushioning on running mechanics in habitual mid/forefoot runners running shod (SHOD), barefoot (BF), and barefoot on a foam surface (BF+FOAM). Ten habitually shod mid/forefoot runners were recruited (male = 8, female = 2). Repeated measures ANOVA (α = 0.05) revealed differences between conditions for only vertical peak active force, contact time, negative and total ankle joint work, and peak dorsiflexion angle. Post hoc tests revealed that BF+FOAM resulted in smaller vertical active peak magnitude and instantaneous vertical loading rate than SHOD. SHOD resulted in lower total ankle joint work than BF and BF+FOAM. BF+FOAM resulted in lower negative ankle joint work than either BF or SHOD. Contact time was shorter with BF than BF+FOAM or SHOD. Peak dorsiflexion angle was smaller in SHOD than BF. No other differences in sagittal joint kinematics, kinetics, or ground reaction forces were observed. These overall similarities in running mechanics between SHOD and BF+FOAM question the effects of footwear structure on habituated mid/forefoot running described previously.

Can the "Appropriate" Footwear Prevent Injury in Leisure-Time Running? Evidence Versus Beliefs

Leisure-time running is one of the most popular forms of physical activity around the world. It can be practiced almost everywhere and requires mainly a pair of "appropriate" running shoes. However, the term appropriate is ambiguous, and the properties of running footwear have always generated hot debates among clinicians, coaches, and athletes, whatever the level of practice. As the main interface between the runner's foot and the ground, the shoe potentially plays an important role in managing repetitive external mechanical loads applied to the musculoskeletal system and, thus, in injury prevention. Consequently, over the last decades, running shoes have been prescribed based on matching shoe features to foot morphology. This strategy aligns with the popular belief that footwear is one of the main extrinsic factors influencing running-related injury risk. Despite a seemingly sound strategy for shoe prescription and constant progress in running-footwear technology, the injury rate remains high. Therefore, our aim in this narrative literature review is to clarify whether the prescription of appropriate footwear to prevent injury in running is evidence based, the result of logical fallacy, or just a myth. The literature presented in this review is based on a nonsystematic search of the MEDLINE database and focuses on work investigating the effect of shoe features on injury risk in runners. In addition, key elements for a proper understanding of the literature on running footwear and injury risk are addressed. In this literature review, we outline (1) the main risk factors and the mechanisms underlying the occurrence of running-related injury, (2) important methodologic considerations for generating high-level evidence, (3) the evidence regarding the influence of running-shoe features on injury risk, (4) future directions for research, and (5) final general recommendations.

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

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

Foot Loading Associated with Barefoot, Shod, and Minimalist Running in Male Rearfoot Strikers

BACKGROUND

We aimed to determine the center of pressure (COP) trajectories and regional pressure differences in natural rearfoot strikers while running barefoot, running with a minimalist shoe, and running with a traditional shoe.

METHODS

Twenty-two male natural rearfoot strikers ran at an imposed speed along an instrumented runway in three conditions: barefoot, with a traditional shoe, and with a minimalist shoe. Metrics associated to the COP and regional plantar force distribution, captured with a pressure platform, were compared using one-way repeated-measures analysis of variance.

RESULTS

The forefoot contact phase was found to be significantly shorter in the barefoot running trials compared with the shod conditions (P = .003). The initial contact of the COP was located more anteriorly in the barefoot running trials. The mediolateral position of the COP at initial contact was found to be significantly different in the three conditions, whereas the final mediolateral position of the COP during the forefoot contact phase was found to be more lateral in the barefoot condition compared with both shod conditions (P = .0001). The metrics associated with the regional plantar force distribution supported the clinical reasoning with respect to the COP findings.

CONCLUSIONS

The minimalist shoe seems to provide a compromise between barefoot running and running with a traditional shoe.

Sports bra but not sports footwear decreases breast movement during walking and running

Running is a modality that has a large number of adepts, including women. Therefore, it is important to understand how sportswear can help women, with special attention to the breast movement. The aim of this study was to analyse the effect of different combinations of breast support and footwear on the breast movement during walking and running. Twenty women performed treadmill walking (5 km/h) and running (7 and 10 km/h) combining different footwear (barefoot, minimalist, and traditional) and breast support conditions (bare breast, everyday bra, and sports bra). Three-dimensional data from breast and trunk markers were tracked for 10 stride cycles. Relative breast displacement was calculated and derived for velocity. An interaction effect was observed between support, footwear, and speed conditions. The bare breast conditions presented differences from the other conditions in the majority of the kinematic variables, presenting higher breast displacement and velocity values. On the other hand, the sports bra conditions presented the lowest values for the kinematics variables. In the vertical component of breast displacement during running (10 km/h) we verified that the sports bra presented reductions of 56% and 43% in relation to the bare breast and everyday bra conditions, respectively. Despite this, no differences were found between footwear within each breast support condition. A sports bra is efficient to decrease breast movement. In addition, neither of the tested footwear was able to decrease these movements.

Acute responses to barefoot 5 km treadmill running involve changes in landing kinematics and delayed onset muscle soreness

BACKGROUND

Barefoot running has gained popularity among physical activity practitioners, but there is a lack of information regarding the acute adaptations to this running technique without supervision. Information about acute adaptations can help to define the best way to insert barefoot running in the routine of runners willing to, and also provide orientation for those people who want to experience this technique.

RESEARCH QUESTION

What acute adaptations can be observed among recreational runners exposed to barefoot running?

METHODS

Sagittal 2D kinematics, plantar pressure, foot sensitivity and delayed onset muscle soreness were compared between conditions of shod and barefoot running in 13 recreational runners who performed two trials of 5 km treadmill running.

RESULTS

We found an acute effect of barefoot running on foot landing that changes from a rearfoot strike to a forefoot strike pattern. This change most likely contributed to the increase in neuromuscular recruitment of calf muscles (i.e. gastrocnemius and soleus) resulting in higher perception of delayed onset muscle soreness. Barefoot running also elicited higher stride cadence. Plantar pressure before and after running revealed higher pressure in the different foot regions after barefoot running. Foot sensitivity increased after running regardless of the footwear condition.

CONCLUSION

Barefoot running has acute effects on running technique including higher perception of delayed onset muscle soreness in the 48 h following the exercise.

SIGNIFICANCE

Our results highlight the importance of following participants for days after a first session of barefoot running in order to properly manage the acute adaptation periods as well provide precise advices for those trying the barefoot technique.

Effects of sports bra and footwear on vertebral posture during walking and running

Little attention has been given to factors which affects women running, such as proper footwear and breast support and their effects on spine. The objective of study was to analyse the influence of different breast support and footwear on vertebral posture during walking and running. Seventeen women (x¯ = 23.51; SD = 3.70 years) performed a treadmill walking (5 km/h) and running (7 and 10 km/h) with different footwear (barefoot, minimalist and traditional) and breast support (bare breast, everyday bra and sports bra) conditions. Spine movements were analyzed using three cameras in grayscale video mode, positioned behind the participant to register reflective markers fixed in the vertebrae. From the 3D coordinates of the trunk markers we computed, for the whole gait cycle (C) and for the average gait posture (neutral curve-NC) the maximal (M) thoracic (T) kyphosis and lateral flexion, and the maximal lumbar (L) lordosis and lateral flexion. Frontal plane: bare breast presented higher lumbar NC than the everyday bra and sports bra, higher MLC than the sports bra and lower MTC than the everyday bra and sports bra. Barefoot presented higher MTC than minimalist. Sagittal plane: bare breast presented lower MTC than the sports bra. Barefoot presented higher lumbar NC than the minimalist and traditional footwear and higher MLC than the minimalist and traditional ones. The sports bra increased curvatures in the thoracic spine that were rectified during bare breast conditions. In addition, both footwears were able to maintain the natural curvatures of the spine in the lumbar.

Effects of 12 weeks of barefoot running on foot strike patterns, inversion-eversion and foot rotation in long-distance runners

PURPOSE

The purpose of this study was to determine the effects of 12 weeks of barefoot running on foot strike patterns, inversion-eversion and foot rotation in long-distance runners.

METHODS

Thirty-one endurance runners with no experience in barefoot running were randomized into a control group and an experimental group who received barefoot training. At pre-test and post-test, all subjects ran at low and high self-selected speeds on a treadmill. Data were collected by systematic observation of lateral and back recordings at 240 Hz.

RESULTS

McNemar's test indicated significant changes (p < 0.05) in the experimental group at both high and low speed running in foot strike patterns, reducing the percentage of high rearfoot strikers and increasing the number of midfoot strikers. A significant increase (p < 0.05) of external rotation of the foot and a decrease of inversion occurred at comfortable speed in the experimental group.

CONCLUSION

Twelve weeks of barefoot running, applied progressively, causes significant changes in foot strike pattern with a tendency toward midfoot or forefoot strikes, regardless of running speed and significant changes in foot rotation at low speed, while the inversion was reduced in left foot at low speed with a tendency toward centered strike.

Morphology-Related Foot Function Analysis: Implications for Jumping and Running

Barefoot and shod running has received increased attention in recent years, however, the influence of morphology-related foot function has not been explored. This study aimed to investigate morphology-related jumping and running biomechanical functions in habitually barefoot and shod males. A total of 90 barefoot males (Indians) and 130 shod males (Chinese), with significant forefoot and toe morphology differences, participated in a vertical jump and running test to enable the collection of kinematic and kinetic data. The difference of pressure distribution in the hallux and forefoot was shown while jumping and running. The unrestricted forefoot and toes of the barefoot group presented flexible movement and leverage functions to expand the forefoot loading area during performance of the two tasks. Findings related to morphology functions, especially in the forefoot and toe may provide useful information for footwear design.

Adaptation of Running Biomechanics to Repeated Barefoot Running: A Randomized Controlled Study

BACKGROUND

Previous studies have shown that changing acutely from shod to barefoot running induces several changes to running biomechanics, such as altered ankle kinematics, reduced ground-reaction forces, and reduced loading rates. However, uncertainty exists whether these effects still exist after a short period of barefoot running habituation.

PURPOSE/HYPOTHESIS

The purpose was to investigate the effects of a habituation to barefoot versus shod running on running biomechanics. It was hypothesized that a habituation to barefoot running would induce different adaptations of running kinetics and kinematics as compared with a habituation to cushioned footwear running or no habituation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Young, physically active adults without experience in barefoot running were randomly allocated to a barefoot habituation group, a cushioned footwear group, or a passive control group. The 8-week intervention in the barefoot and footwear groups consisted of 15 minutes of treadmill running at 70% of VO₂ max (maximal oxygen consumption) velocity per weekly session in the allocated footwear. Before and after the intervention period, a 3-dimensional biomechanical analysis for barefoot and shod running was conducted on an instrumented treadmill. The passive control group did not receive any intervention but was also tested prior to and after 8 weeks. Pre- to posttest changes in kinematics, kinetics, and spatiotemporal parameters were then analyzed with a mixed effects model.

RESULTS

Of the 60 included participants (51.7% female; mean ± SD age, 25.4 ± 3.3 years; body mass index, 22.6 ± 2.1 kg·m^-2), 53 completed the study (19 in the barefoot habituation group, 18 in the shod habituation group, and 16 in the passive control group). Acutely, running barefoot versus shod influenced foot strike index and ankle, foot, and knee angles at ground contact (P < .001), as well as vertical average loading rate (P = .003), peak force (P < .001), contact time (P < .001), flight time (P < .001), step length (P < .001), and cadence (P < .001). No differences were found for average force (P = .391). After the barefoot habituation period, participants exhibited more anterior foot placement (P = .006) when running barefoot, while no changes were observed in the footwear condition. Furthermore, barefoot habituation increased the vertical average loading rates in both conditions (barefoot, P = .01; shod, P = .003) and average vertical ground-reaction forces for shod running (P = .039). All other outcomes (ankle, foot, and knee angles at ground contact and flight time, contact time, cadence, and peak forces) did not change significantly after the 8-week habituation.

CONCLUSION

Changing acutely from shod to barefoot running in a habitually shod population increased the foot strike index and reduced ground-reaction force and loading rates. After the habituation to barefoot running, the foot strike index was further increased, while the force and average loading rates also increased as compared with the acute barefoot running situation. The increased average loading rate is contradictory to other studies on acute adaptations of barefoot running.

CLINICAL RELEVANCE

A habituation to barefoot running led to increased vertical average loading rates. This finding was unexpected and questions the generalizability of acute adaptations to long-term barefoot running. Sports medicine professionals should consider these adaptations in their recommendations regarding barefoot running as a possible measure for running injury prevention.

REGISTRATION

DRKS00011073 (German Clinical Trial Register).

The relationship between static and dynamic foot posture and running biomechanics: A systematic review and meta-analysis

BACKGROUND

Medial longitudinal arch characteristics are thought to be a contributing factor to lower limb running injuries. Running biomechanics associated with different foot types have been proposed as one of the potential underlying mechanisms. However, no systematic review has investigated this relationship.

RESEARCH QUESTION

The aim of this study was to conduct a systematic literature search and synthesize the evidence about the relationship between foot posture and running biomechanics.

METHODS

For this systematic review and meta-analysis different electronic databases (Pubmed, Web of Science, Cochrane, SportDiscus) were searched to identify studies investigating the relationship between medial longitudinal arch characteristics and running biomechanics. After identification of relevant articles, two independent researchers determined the risk of bias of included studies. For homogenous outcomes, data pooling and meta-analysis (random effects model) was performed, and levels of evidence determined.

RESULTS

Of the 4088 studies initially identified, a total of 25 studies were included in the qualitative review and seven in the quantitative analysis. Most studies had moderate and three studies a low risk of bias. Moderate evidence was found for a relationship between foot posture and subtalar joint kinematics (small pooled effects: -0.59; 95%CI -1.14 to - 0.003) and leg stiffness (small pooled effect: 0.59; 95%CI 0.18 to 0.99). Limited or very limited evidence was found for a relationship with forefoot kinematics, tibial/leg rotation, tibial acceleration/shock, plantar pressure distribution, plantar fascia tension and ankle kinetics as well as an interaction of foot type and footwear regarding tibial rotation.

SIGNIFICANCE

While there is evidence for an association between foot posture and subtalar joint kinematics and leg stiffness, no clear relationship was found for other biomechanical outcomes. Since a comprehensive meta-analysis was limited by the heterogeneity of included studies future research would benefit from consensus in foot assessment and more homogenous study designs.

Online multifactorial prevention programme has no effect on the number of running-related injuries: a randomised controlled trial

Objective

To examine the effect of a multifactorial, online injury prevention programme on the number of running-related injuries (RRIs) in recreational runners.

Methods

Adult recreational runners who registered for a running event (distances 5 km up to 42.195 km) were randomised into the intervention group or control group. Participants in the intervention group were given access to the online injury prevention programme, which consisted of information on evidence-based risk factors and advices to reduce the injury risk. Participants in the control group followed their regular preparation for the running event. The primary outcome measure was the number of self-reported RRIs in the time frame between registration for a running event and 1 month after the running event.

Results

This trial included 2378 recreational runners (1252 men; mean [SD] age 41.2 [11.9] years), of which 1196 were allocated to the intervention group and 1182 to the control group. Of the participants in the intervention group 37.5% (95% CI 34.8 to 40.4) sustained a new RRI during follow-up, compared with 36.7% (95% CI 34.0 to 39.6) in the control group. Univariate logistic regression analysis showed no significant difference between the intervention and control group (OR 1.08; 95% CI 0.90 to 1.30). Furthermore, the prevention programme seemed to have a negative impact on the occurrence of new RRIs in the subgroup of runners with no injuries in the 12 months preceding the trial (OR 1.30; 95% CI 0.99 to 1.70).

Conclusion

A multifactorial, online injury prevention programme did not decrease the total number of RRIs in recreational runners.

Trial registration number

NTR5998.

Force-generating capacity of the toe flexor muscles and dynamic function of the foot arch in upright standing

The muscle and tendon complex of the foot helps to support the foot arch and generates the muscle force of the foot. The present study investigated the force-generating capacity of the toe flexor muscles and the dynamic function of the foot arch when standing upright, and the relationships between these indices. The maximum toe flexor force and foot arch height in the sitting and standing positions were studied in the left and right feet of 224 healthy young individuals. To measure the maximum isometric force of the toe flexor muscles, the subjects exerted maximum force on a toe grip dynamometer. Measurements were repeated three times with at least a 1-min rest period between bouts, and the maximum value among the measurements for each foot was used for further analysis. The absolute value of the toe flexor strength was normalised by body mass. The foot arch height was measured the distance between the tuberosity of the navicular bone and the floor, and normalised by height. The relative foot arch height difference between the sitting and standing positions was evaluated as the foot arch dynamics. The maximum isometric toe flexor strength was 42% higher in the standing position than in the sitting position. There was no relationship between the relative toe flexor strength and the relative foot arch height in either the sitting or standing positions; however, the relative increase in toe flexor strength from sitting to standing (the force amplification factor) was related to the foot arch dynamics, and the flexible foot arch showed a greater increase in the toe flexor strength from sitting to standing compared with the strength in the stiff foot arch. The results of this study suggest that the force-generating capacity of the toe flexor muscles is augmented by bodyweight bearing in upright standing. Additionally, the force amplification mechanism is mechanically regulated by the dynamic function of the foot arch in conjunction with the stretching of the muscle-tendon complex of the foot.

The Influence of the Improvement of Calf Strength on Barefoot Loading

The purpose of this study was to determine whether enhancement of calf muscular strength can produce influence on plantar pressure in barefoot running. Ten healthy male subjects (age:22±2.5 years, height: 1.76±0.4m, body mass: 65±2.5kg) participate this experiment enduring 8-week strength training adopting by calf raise movement on calf muscle. A medical ultrasonic instrument (Q6, China) was used to observe the variation of calf muscular morphology. A plantar pressure plate ( Novel Emed, Germany) was used to collect the variation of 8-region plantar pressure. After 8-week strength training, a significant increasing trend between pre-and post-strength training in subject`s pinnation angle (PA) of the gastrocnemius was found. Under strength training, there are some significant variations between pre-and post-plantar pressure. The start point of center of pressure (COP) gradually forward (middle foot 80%, forefoot 20%); the peak pressure of subject`s heel foot (HF) significantly lower; the maximal force in second-third metatarsal (M 2-3), medial foot (MF) and HF significantly decrease; the contact area in other toe (OT) significantly increase as well as MF and HF significantly decrease; the time-force integral in M2-3 and HF significantly lower and in MF significantly enhance. These results suggest, the enhancement of calf muscular strength may produce positively influence on beginning transitional process from shod running to barefoot running and is also worth to as a feasible way to recommend. However, the effects of strength straining on plantar pressure do not fully explore and still need to deeply explore own to existing limitations.

Differential effects of speed on two-dimensional foot strike pattern during barefoot and shod running in recreationally active men

The majority of barefoot running studies have not considered speed as an influential factor on foot strike pattern. The aim of this study was to investigate differences in foot strike pattern and spatiotemporal characteristics between barefoot and shod overground running at varying speeds. We first determined maximal running speed (Vm) over 50 m in 15 recreationally active men who self-reported as habitual rearfoot strikers. Participants then completed shod and barefoot running trials at different speeds equivalent to approximately 90%, 80%, 70% and 60% of Vm. Sagittal plane two-dimensional (2D) foot-ground contact angle, ankle plantar-dorsi flexion angle, contact time, flight time, step length and step rate variables for each trial were recorded. A significant interaction effect of running speed and footwear condition (p < 0.05) on foot-ground contact angle, ankle plantar-dorsi flexion angle and contact time was observed. There was a main effect of running speed (p < 0.01) on flight time, step length and step rate. There was a main effect of footwear condition on step length (p < 0.01). Participants were more inclined to plantarflex the ankle and contact the ground with the forefoot at higher percentages of Vm, especially when running barefoot.

Non-linear growth trends of toe flexor muscle strength among children, adolescents, and young adults: a cross-sectional study

PURPOSE

There are only a few studies on the muscular strength of the foot in children and adolescents; thus, the developmental pattern and normative data of these populations during growth are unclear. We sought to elucidate the developmental pattern of the foot muscle strength among children, adolescents, and young adults compared with that of the hand.

METHODS

A total of 747 children, adolescents, and young adults participated in this study, and their maximum isometric toe flexor strength (TFS), hand grip strength (HGS), and foot length were measured.

RESULTS

TFS was correlated with HGS (r = 0.785), age (r = 0.659), height (r = 0.757), body mass (r = 0.737), and foot length (r = 0.594). Multiple regression analyses revealed that TFS was correlated with age (β = 0.243 in boys; β = 0.461 in girls), squared value of age (age²; β = - 0.296 in boys; β = - 0.260 in girls), and body mass (β = 0.256 in boys; β = 0.311 in girls) in both sexes, indicating a non-linear relationship between age and TFS development. In a regression model for HGS, age was a significant variable, but not age². HGS increased linearly from childhood until young adulthood, whereas TFS increased from childhood until adolescence and then levelled off.

CONCLUSION

Our results demonstrate that TFS has a different developmental pattern compared with HGS.

Heel impact forces during barefoot versus minimally shod walking among Tarahumara subsistence farmers and urban Americans

Despite substantial recent interest in walking barefoot and in minimal footwear, little is known about potential differences in walking biomechanics when unshod versus minimally shod. To test the hypothesis that heel impact forces are similar during barefoot and minimally shod walking, we analysed ground reaction forces recorded in both conditions with a pedography platform among indigenous subsistence farmers, the Tarahumara of Mexico, who habitually wear minimal sandals, as well as among urban Americans wearing commercially available minimal sandals. Among both the Tarahumara (n = 35) and Americans (n = 30), impact peaks generated in sandals had significantly (p < 0.05) higher force magnitudes, slower loading rates and larger vertical impulses than during barefoot walking. These kinetic differences were partly due to individuals' significantly greater effective mass when walking in sandals. Our results indicate that, in general, people tread more lightly when walking barefoot than in minimal footwear. Further research is needed to test if the variations in impact peaks generated by walking barefoot or in minimal shoes have consequences for musculoskeletal health.

Foot Strike Patterns Differ Between Children and Adolescents Growing up Barefoot vs. Shod

Effects of early and permanent footwear use are not well understood. The aim of this study was to investigate the effects of habituation to footwear on foot strike patterns of children and adolescents. Healthy habitually barefoot and shod participants (aged 6–18 years) from South Africa (n=288) and Germany (n=390) performed multiple 20-m jogging and running trials with and without shoes. Each foot strike was captured using a high-speed camera to determine a rearfoot or non-rearfoot strike. The probability of a rearfoot strike in both cohorts and each age was analyzed by using a mixed-effects logistic regression adjusted for possible confounders. Habitually barefoot children showed a higher probability of using rearfoot strikes than habitually shod children (p<0.001). The probability was age-dependent and decreased in habitually barefoot children with age (OR _{barefoot-jogging} =0.82, 95% CI, 0.71 to 0.96, p=0.014; OR _{barefoot-running} =0.58, 95% CI, 0.50 to 0.67, p<0.001 and OR _shod-running =0.68, 95% CI, 0.59 to 0.79, p<0.001). In habitually shod children, the probability increased significantly for shod jogging (OR=1.19, 95% CI, 1.05 to 1.35, p=0.006). To conclude, foot strike patterns of children are influenced by habituation to footwear. Younger habitually barefoot children show higher rates of rearfoot strikes for shod and barefoot running, and it converges in later adolescence.

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.

Acute fatigue negatively affects risk factors for injury in trained but not well-trained habitually shod runners when running barefoot

INTRODUCTION

Many factors may contribute to running-related injury. These include fatigue and footwear, the combination of which has rarely been studied, in particular with reference to barefoot running, recently advocated as a method to reduce injury risk.

METHODS

Twenty-two runners (12 well-trained and 10 trained) participated in a 10 km fatiguing trial. Knee and ankle joint kinematics and kinetics and electromyography were assessed during overground running in the barefoot and shod condition. This was performed pre- and post-fatigue using a motion capture system and force platforms.

RESULTS

Initial loading rate increased in the trained runners when barefoot but not shod. Shod knee stiffness increased in both groups after fatigue, whereas barefoot knee stiffness decreased only in the trained group. A reduction in barefoot bicep femoris pre-activation was found in both groups. During stance, a reduction in vastus lateralis and biceps femoris and an increase in tibialis anterior activity were found over time in both groups and conditions. Trained runners decreased gluteus medius and increased lateral gastrocnemius median frequency for both conditions after fatigue.

CONCLUSION

When fatigued, gait adjustments in habitually shod runners may increase injury risk when running barefoot. Training status may be a risk factor for injury, as less-trained runners experience muscular fatigue changes that may compromise ground reaction force attenuation. Caution is recommended when transitioning to pure barefoot running.

Growing-up (habitually) barefoot influences the development of foot and arch morphology in children and adolescents

The development of the human foot is crucial for motor learning in children and adolescents as it ensures the basic requirements for bipedal locomotion and stable standing. Although there is an ongoing debate of the advantages and disadvantages of early and permanent footwear use, the influence of regular barefootness on foot characteristics in different stages of child development has not been extensively evaluated. A multicenter epidemiological study was conducted to compare the foot morphology between habitually barefoot children and adolescents (N = 810) to age-, sex- and ethnicity-matched counterparts that are used to wearing shoes. While controlling for confounders, we found that habitual footwear use has significant effects on foot-related outcomes in all age groups, such as a reduction in foot arch and hallux angles. The results indicate an impact of habitual footwear use on the development of the feet of children and adolescents. Therefore, growing up barefoot or shod may play an important role for childhood foot development, implying long-term consequences for motor learning and health later in life.

The effect of minimalist footwear and instruction on running: an observational study

Background

It is not known whether the effects on altered running style which are attributed to minimalist footwear can be achieved by verbal instructions in standard running shoes (SRS).

Aim

To explore the effect of Vibram FiveFingers (VFF) versus SRS plus running instruction on lower extremity spatiotemporal parameters and lower limb joint kinematics.

Methods

35 healthy subjects (mean=30 years, 18 females) were assessed on two occasions with 3D motion analysis. At each session subjects ran on a treadmill (3.58 m/s) for 2 min in either VFF or SRS (randomised order); with and without running instruction. Differences between spatiotemporal parameters and lower limb joint kinematics between conditions were assessed using a 2x2 repeated-measures ANOVA.

Results

Wearing VFF significantly increased cadence (p<0.001) and reduced stride length (p<0.01). Prior to initial contact, both instruction and VFF significantly increased foot (p<0.001 and p=0.02, respectively) and ankle (p<0.001 and p=0.02, respectively) plantarflexion, while wearing VFF significantly increased knee extension (p=0.04). At initial contact, instruction significantly increased knee flexion (p=0.04), and foot (p=0.001) and ankle (p=0.03) plantarflexion. At mid-stance and toe-off, instruction significantly increased knee flexion (p=0.048 and p<0.001, respectively) and foot plantarflexion (p<0.001 and p=0.01, respectively). Instruction had a greater effect on increasing knee flexion (p=0.007) and plantarflexion angle (p<0.001) when subjects wore SRS and VFF, respectively.

Conclusion

Alterations in spatiotemporal parameters observed when running in VFF are likely to be attributable to the minimalist footwear. However, the kinematic adaptations observed following instruction suggests that changes in joint angles previously attributed to minimalist footwear alone may be similarly achieved with instruction.

Conceptualizing minimalist footwear: an objective definition

Running has been plagued with an alarmingly high incidence of injury, which has resulted in the exploration of interventions aimed at reducing the risk of running-related injury. One such intervention is the introduction of footwear that mimics barefoot running. These have been termed minimalist shoes. Minimalist footwear aims to reduce the risk of injury by promoting adaptations in running biomechanics that have been linked to a reduction in both impact and joint forces. However, some studies have found that minimalist footwear may be beneficial to the runner as they promote favourable biomechanical adaptations, whilst other studies have found the opposite to be true. Reasons for these conflicting results could be attributed to the lack of a definition for minimalist footwear. The aim of this review article is to provide a structural definition for minimalist footwear based on studies that have examined the influence of footwear on biomechanical variables during running. Based on current literature, we define minimalist footwear as a shoe with a highly flexible sole and upper that weighs 200g or less, has a heel stack height of 20mm or less and a heel-toe differential of 7mm or less.

Transition from shod to barefoot alters dynamic stability during running

INTRODUCTION

Barefoot running recently received increased attention, with controversial results regarding its effects on injury risk and performance. Numerous studies examined the kinetic and kinematic changes between the shod and the barefoot condition. Intrinsic parameters such as the local dynamic stability could provide new insight regarding neuromuscular control when immediately transitioning from one running condition to the other. We investigated the local dynamic stability during the change from shod to barefoot running. We further measured biomechanical parameters to examine the mechanisms governing this transition.

METHODS

Twenty habitually shod, young and healthy participants ran on a pressure plate-equipped treadmill and alternated between shod and barefoot running. We calculated the largest Lyapunov exponents as a measure of errors in the control of the movement. Biomechanical parameters were also collected.

RESULTS

Local dynamic stability decreased significantly (d=0.41; 2.1%) during barefoot running indicating worse control over the movement. We measured higher cadence (d=0.35; 2.2%) and total flight time (d=0.58; 19%), lower total contact time (d=0.58; -5%), total vertical displacement (d=0.39; -4%), and vertical impulse (d=1.32; 11%) over the two minutes when running barefoot. The strike index changed significantly (d=1.29; 237%) towards the front of the foot.

CONCLUSIONS

Immediate transition from shod to the barefoot condition resulted in an increased instability and indicates a worst control over the movement. The increased instability was associated with biomechanical changes (i.e. foot strike patterns) of the participants in the barefoot condition. Possible reasons why this instability arises, might be traced in the stance phase and particularly in the push-off. The decreased stability might affect injury risk and performance.

Preventing running-related injuries using evidence-based online advice: the design of a randomised-controlled trial

Introduction

Running-related injuries (RRIs) are frequent and can lead to cessation of health promoting activities. Several risk factors for RRIs have been identified. However, no successful injury prevention programme has been developed so far. Therefore, the aim of the present study is to investigate the effect of an evidence-based online injury prevention programme on the number of RRIs.

Methods and analysis

The INSPIRE trial is a randomised-controlled trial with a 3-month follow-up. Both novice and more experienced runners, aged 18 years and older, who register for a running event (distances 5 km up to 42.195 km) will be asked to participate in this study. After completing the baseline questionnaire, participants will be randomised into either the intervention group or control group. Participants in the intervention group will get access to the online injury prevention programme. This prevention programme consists of information on evidence-based risk factors and advices to reduce the injury risk. The primary outcome measure is the number of self-reported RRIs in the time frame between registration for a running event and 1 month after the running event. Secondary outcome measures include the running days missed due to injuries, absence of work or school due to injuries, and the injury location.

Ethics and dissemination

An exemption for a comprehensive application is obtained by the Medical Ethical Committee of the Erasmus University Medical Centre Rotterdam, Netherlands. The results of the study will be published in peer-reviewed journals and presented on international congresses.

Trial registration number

NTR5998. Pre-results

Dynamic loading and kinematics analysis of vertical jump based on different forefoot morphology

Purpose

This study examined differences in ankle motion and plantar pressure between habitually barefoot male (HBM) and habitually shod male (HSM) during vertical jump.

Methods

Eighteen habitually barefoot males and twenty habitually shod males volunteered to join the test. Distance between hallux and second toe was measured with Easy-Foot-Scan. Plantar pressure and ankle kinematics were measured with EMED force platform and Vicon motion analysis system respectively. T test was taken to analyse the significant differences using Stata 12.0 software.

Results

The distance between hallux and other toes in HBM was greater than it in HSM. HBM showed larger plantar loading under hallux and medial forefoot, while HSM showed lager plantar loading under medial and central forefoot. HBM had smaller ankle plantarflexion, eversion and external rotation than HSM.

Conclusion

Findings of this study provide basic information for further studies on different hallux/toe function in motion control between habitually shod and barefoot populations.

Injuries observed in a prospective transition from traditional to minimalist footwear: correlation of high impact transient forces and lower injury severity

OBJECTIVES

Minimalist running is increasing in popularity based upon a concept that it can reduce impact forces and decrease injury rates. The purpose of this investigation is to identify the rate and severity of injuries in runners transitioning from traditional to minimalist footwear. The secondary aims were to identify factors correlated with injuries.

METHODS

Fourteen habitually shod (traditional running shoes) participants were enrolled for this prospective study investigating injury prevalence during transition from traditional running shoes to 5-toed minimalist shoes. Participants were uninjured, aged between 22-41 years, and ran at least twenty kilometers per week in traditional running shoes. Participants were given industry recommended guidelines for transition to minimalist footwear and fit with a 5-toed minimalist running shoe. They completed weekly logs for identification of injury, pain using Visual Analogue Scale (VAS), injury location, and severity. Foot strike pattern and impact forces were collected using 3D motion analysis at baseline, 4 weeks, and 12 weeks. Injuries were scored according to a modified Running Injury Severity Score (RISS).

RESULTS

Fourteen runners completed weekly training and injury logs over an average of 30 weeks. Twelve of 14 (86%) runners sustained injuries. Average injury onset was 6 weeks (range 1-27 weeks). Average weekly mileage of 23.9 miles/week prior to transition declined to 18.3 miles/week after the transition. The magnitude of the baseline impact transient peak in traditional shoes and in minimalist shoes negatively correlated with RISS scores (r = -0.45, p = 0.055 and r = -0.53, p = 0.026, respectively).

CONCLUSION

High injury rates occurred during the transition from traditional to minimalist footwear. Non-compliance to transition guidelines and high injury rates suggest the need for improved education. High impact transient forces unexpectedly predicted lower modified RISS scores in this population.

The effects of being habitually barefoot on foot mechanics and motor performance in children and adolescents aged 6-18 years: study protocol for a multicenter cross-sectional study (Barefoot LIFE project)

Background

Barefoot locomotion has evoked an increasing scientific interest with a controversial debate about benefits and limitations of barefoot and simulated barefoot walking and running. While most current knowledge comes from cross sectional laboratory studies, the evolutionary perspective suggests the importance of investigating the long-term effects. Observing habitually barefoot populations could fill the current gap of missing high quality longitudinal studies. Therefore, the study described in this design paper aims to investigate the effects of being habitually barefoot on foot mechanics and motor performance of children and adolescents.

Methods

This study has a cross-sectional, binational design and is part of the “Barefoot Locomotion for Individual Foot- and health Enhancement (Barefoot LIFE)” project. Two large cohorts (n_(total) = 520) of healthy children and adolescents between 6 and 18 years of age will be included respectively in Germany and South Africa. A barefoot questionnaire will be used to determine habitually barefoot individuals. The testing will be school-based and include foot mechanical (static arch height index, dynamic arch index, foot pliability) and motor performance (coordination, speed, leg power) outcomes. Gender, BMI and level of physical activity will be considered for confounding.

Discussion

The strength of this study is the comparison of two large cohorts with different footwear habits to determine long-term effects of being habitually barefoot on foot mechanics and motor performance.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-016-0166-1) contains supplementary material, which is available to authorized users.

Effects of training in minimalist shoes on the intrinsic and extrinsic foot muscle volume

BACKGROUND

Minimalist shoes have gained popularity recently because it is speculated to strengthen the foot muscles and foot arches, which may help to resist injuries. However, previous studies provided limited evidence supporting the link between changes in muscle size and footwear transition. Therefore, this study sought to examine the effects of minimalist shoes on the intrinsic and extrinsic foot muscle volume in habitual shod runners. The relationship between participants' compliance with the minimalist shoes and changes in muscle õvolume was also evaluated.

METHODS

Twenty habitual shod runners underwent a 6-month self-monitoring training program designed for minimalist shoe transition. Another 18 characteristics-matched shod runners were also introduced with the same program but they maintained running practice with standard shoes. Runners were monitored using an online surveillance platform during the program. We measured overall intrinsic and extrinsic foot muscle volume before and after the program using MRI scans.

FINDINGS

Runners in the experimental group exhibited significantly larger leg (P=0.01, Cohen's d=0.62) and foot (P<0.01, Cohen's d=0.54) muscle after transition. Foot muscle growth was mainly contributed by the forefoot (P<0.01, Cohen's d=0.64) but not the rearfoot muscle (P=0.10, Cohen's d=0.30). Leg and foot muscle volume of runners in the control group remained similar after the program (P=0.33-0.95). A significant positive correlation was found between participants' compliance with the minimalist shoes and changes in leg muscle volume (r=0.51; P=0.02).

INTERPRETATION

Habitual shod runners who transitioned to minimalist shoes demonstrated significant increase in leg and foot muscle volume. Additionally, the increase in leg muscle volume was significantly correlated associated with the compliance of minimalist shoe use.

Minimalist Running Shoes and Injury Risk Among United States Army Soldiers

BACKGROUND

Minimalist running shoes (MRS) are lightweight, are extremely flexible, and have little to no cushioning. It has been thought that MRS will enhance running performance and decrease injury risk.

PURPOSE

To compare physical characteristics, fitness performance, and injury risks associated with soldiers wearing MRS and those wearing traditional running shoes (TRS).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Participants were men in a United States Army brigade (N = 1332). Physical characteristics and Army Physical Fitness Test data were obtained by survey. Fitness performance testing was administered at the brigade, and the types of footwear worn were identified by visual inspection. Shoe types were categorized into 2 groups: TRS (stability, cushioning, and motion control) and MRS. Injuries from the previous 12 months were obtained from the Defense Medical Surveillance System. A t test was used to determine mean differences between personal characteristics, training, and fitness performance metrics by shoe type. Hazard ratios and 95% CIs were calculated to determine injury risk by shoe type, controlling for other risk factors.

RESULTS

A majority of soldiers wore cushioning shoes (57%), followed by stability shoes (24%), MRS (17%), and motion control shoes (2%). Soldiers wearing MRS were slightly younger than those wearing TRS (P < .01); performed more push-ups, sit-ups, and pull-ups (P < .01); and ran faster during the 2-mile run (P = .01). When other risk factors were controlled, there was no difference in injury risk for running shoe type between soldiers wearing MRS compared with TRS.

CONCLUSIONS

Soldiers who chose to wear MRS were younger and had higher physical performance scores compared with soldiers wearing TRS. When these differences are controlled, use of MRS does not appear to be associated with higher or lower injury risk in this population.

The influence of shoe drop on the kinematics and kinetics of children tennis players

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12 mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p = .004) and the ankle was less dorsiflexed at foot strike (p = .037). In D0 compared with D12, the peak impact force was reduced by 17% (p = .049), the ankle was less dorsiflexed at foot strike (p = .045) and the knee was more flexed at foot strike (p = .007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p = .658) or the peak ankle plantarflexor moment (p = .071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.

Loading rate increases during barefoot running in habitually shod runners: Individual responses to an unfamiliar condition

The purpose of this study was to examine the effect of barefoot running on initial loading rate (LR), lower extremity joint kinematics and kinetics, and neuromuscular control in habitually shod runners with an emphasis on the individual response to this unfamiliar condition. Kinematics and ground reaction force data were collected from 51 habitually shod runners during overground running in a barefoot and shod condition. Joint kinetics and stiffness were calculated with inverse dynamics. Inter-individual initial LR variability was explored by separating individuals by a barefoot/shod ratio to determine acute responders/non-responders. Mean initial LR was 54.1% greater in the barefoot when compared to the shod condition. Differences between acute responders/non-responders were found at peak and initial contact sagittal ankle angle and at initial ground contact. Correlations were found between barefoot sagittal ankle angle at initial ground contact and barefoot initial LR. A large variability in biomechanical responses to an acute exposure to barefoot running was found. A large intra-individual variability was found in initial LR but not ankle plantar-dorsiflexion between footwear conditions. A majority of habitually shod runners do not exhibit previously reported benefits in terms of reduced initial LRs when barefoot. Lastly, runners who increased LR when barefoot reduced LRs when wearing shoes to levels similar seen in habitually barefoot runners who do adopt a forefoot-landing pattern, despite increased dorsiflexion.

Lower limb mechanics during moderate high-heel jogging and running in different experienced wearers

The aim of this study is to investigate the differences in lower limb kinematics and kinetics between experienced (EW) and inexperienced (IEW) moderate high-heel wearers during jogging and running. Eleven experienced female wearers of moderate high-heel shoes and eleven matched controls participated in jogging and running tests. A Vicon motion analysis system was used to capture kinematic data and a Kistler force platform was used to collect ground reaction force (GRF). There were no significant differences in jogging and running speed respectively. Compared with IEW, EW adopted larger stride length (SL) with lower stride frequency (SF) at each corresponding speed. During running, EW enlarged SL significantly while IEW increased both SL and SF significantly. Kinematic data showed that IEW had generally larger joint range of motion (ROM) and peak angles during stance phase. Speed effect was not obvious within IEW. EW exhibited a significantly increased maximal vertical GRF (Fz2) and vertical average loading rate (VALR) during running, which was potentially caused by overlong stride. These suggest that both EW and IEW are at high risk of joint injuries when running on moderate high heels. For wearers who have to do some running on moderate high heels, it is crucial to control joint stability and balance SL and SF consciously.

Peroneal tendinosis as a predisposing factor for the acute lateral ankle sprain in runners

PURPOSE

A painful episode in the region of the peroneal tendons, within the retromalleolar groove, is a common precipitating event of an acute lateral ankle sprain. A forefoot striking pattern is suspected to cause peroneal tendinosis. The aim of this study is to analyse the role of peroneal tendinosis as a predisposing factor for ankle sprain trauma in runners.

METHODS

Fifty-eight runners who had experienced acute ankle sprain trauma, with pre-existing pain episodes for up to 4 weeks in the region of the peroneal tendons, were assessed clinically. Fractures were excluded by conventional radiography. An magnetic resonance imaging (MRI) scan had been performed within 14 days after the traumatic event and was subsequently evaluated by two experienced radiologists.

RESULTS

MRI revealed peroneal tendinosis in 55 patients (95% of the total study population). Peroneus brevis (PB) tendinosis was found in 48 patients (87% of all patients with peroneal tendinosis), and peroneus longus (PL) tendinosis was observed in 42 cases (76%). Thirty-five patients (64%) had combined PB and PL tendinosis. A lesion of the anterior talofibular ligament was found to be the most common ligament injury associated with peroneal tendinosis (29 cases; 53%), followed by a lesion of the calcaneofibular ligament (16 cases; 29%) and a lesion of the posterior tibiofibular ligament (13 cases; 24%).

CONCLUSION

The results of this study reflect the correlation between peroneal tendinosis and ankle sprain trauma. Injuries of one or more ligaments are associated with further complications. A period of rest or forbearance of sports as well as adequate treatment of the peroneal tendinosis is essential to prevent subsequent ankle injuries, especially in runners. Modification of the running technique would also be beneficial.

LEVEL OF EVIDENCE

IV.

Individual Responses to a Barefoot Running Program: Insight Into Risk of Injury

BACKGROUND

Barefoot running is of popular interest because of its alleged benefits for runners, including reduced injury risk and increased economy of running. There is a dearth in understanding whether all runners can gain the proposed benefits of barefoot running and how barefoot running may affect long-term injury risk.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine whether runners can achieve the proposed favorable kinematic changes and reduction in loading rate after a progressive training program that included barefoot running. It was hypothesized that not all individuals would experience a decrease in initial loading rate facilitated by increased ankle plantar flexion after a progressive barefoot running program; it was further hypothesized that relationships exist between changes in initial loading rate and sagittal ankle angle.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 26 habitually shod runners completed an 8-week, progressively introduced barefoot running program. Pre- and postintervention barefoot and shod kinematics, electromyography, and ground-reaction force data of the lower limb were collected. Ankle and knee kinematics and kinetics, initial loading rates, spatiotemporal variables, muscle activity during preactivation, and ground contact were assessed in both conditions before and after the intervention. Individual responses were analyzed by separating runners into nonresponders, negative responders, and positive responders based on no change, increase, and decrease in barefoot initial loading rate, respectively.

RESULTS

No biomechanical changes were found in the group after the intervention. However, condition differences did persist during both preactivation and ground contact. The positive-responder group had greater plantar flexion, increased biceps femoris and gluteus medius preactivation, and decreased rectus femoris muscle activity between testing periods. The negative responders landed in greater barefoot dorsiflexion after the intervention, and the nonresponders did not change. An overall change in ankle flexion angle was associated with a change in initial loading rate (r(2) = 0.345, P = .002) in the barefoot but not shod condition.

CONCLUSION

Eight weeks of progressive barefoot running did not change overall group biomechanics, but subgroups of responders (25% of the entire group) were identified who had specific changes that reduced the initial loading rate. It appears that changes in initial loading rate are explained by changes in ankle flexion angle at initial ground contact.

CLINICAL RELEVANCE

Uninstructed barefoot running training does not reduce initial loading rate in all runners transitioning from shod to barefoot conditions. Some factors have been identified that may assist sports medicine professionals in the evaluation and management of runners at risk of injury. Conscious instruction to runners may be required for them to acquire habitual barefoot running characteristics and to reduce risk of injury.

Medical and Disaster Preparedness of US Marathons

BACKGROUND

Despite the events that occurred at the 2013 Boston Marathon (Boston, Massachusetts USA), there are currently no evidence-based guidelines or published data regarding medical and disaster preparedness of marathon races in the United States. Purpose To determine the current state of medical disaster preparedness of marathons in the US and to identify potential areas for improvement.

METHODS

A cross-sectional, questionnaire-based study was conducted from January through May of 2014. The questionnaire was distributed to race directors of US road and trail marathons, as identified by a comprehensive internet database.

RESULTS

One hundred twenty-three questionnaires were available for analysis (19% usable response rate). Marathon races from all major regions of the US were represented. Runner medical information was not listed on race bibs in 53% of races. Only 45% of races held group training and planning sessions prior to race day. Automated external defibrillators (AEDs) were immediately available on 50% of courses, and medications such as albuterol (30%), oxygen (33%), and IV fluids (34%) were available less frequently. Regarding medical emergencies, 55% of races did not have protocols for the assessment of dehydration, asthma, chest pain, syncope, or exercise-induced cramping. With regard to disaster preparedness, 50% of races did not have protocols for the management of disasters, and 21% did not provide security personnel at start/finish lines, aid stations, road crossings, and drop bag locations.

CONCLUSIONS

Areas for improvement in the preparedness of US marathons were identified, such as including printed medical information on race bibs, increasing pre-race training and planning sessions for volunteers, ensuring the immediate availability of certain emergency equipment and medications, and developing written protocols for specific emergencies and disasters.

Foot Morphological Difference between Habitually Shod and Unshod Runners

Foot morphology and function has received increasing attention from both biomechanics researchers and footwear manufacturers. In this study, 168 habitually unshod runners (90 males whose age, weight & height were 23±2.4 years, 66±7.1 kg & 1.68±0.13 m and 78 females whose age, weight & height were 22±1.8 years, 55±4.7 kg & 1.6±0.11 m) (Indians) and 196 shod runners (130 males whose age, weight & height were 24±2.6 years, 66±8.2 kg & 1.72±0.18 m and 66 females whose age, weight & height were 23±1.5 years, 54±5.6 kg & 1.62±0.15 m) (Chinese) participated in a foot scanning test using the easy-foot-scan (a three-dimensional foot scanning system) to obtain 3D foot surface data and 2D footprint imaging. Foot length, foot width, hallux angle and minimal distance from hallux to second toe were calculated to analyze foot morphological differences. This study found that significant differences exist between groups (shod Chinese and unshod Indians) for foot length (female p = 0.001), width (female p = 0.001), hallux angle (male and female p = 0.001) and the minimal distance (male and female p = 0.001) from hallux to second toe. This study suggests that significant differences in morphology between different ethnicities could be considered for future investigation of locomotion biomechanics characteristics between ethnicities and inform last shape and design so as to reduce injury risks and poor performance from mal-fit shoes.

Comparison of minimalist footwear strategies for simulating barefoot running: a randomized crossover study

Possible benefits of barefoot running have been widely discussed in recent years. Uncertainty exists about which footwear strategy adequately simulates barefoot running kinematics. The objective of this study was to investigate the effects of athletic footwear with different minimalist strategies on running kinematics. Thirty-five distance runners (22 males, 13 females, 27.9 ± 6.2 years, 179.2 ± 8.4 cm, 73.4 ± 12.1 kg, 24.9 ± 10.9 km.week^-1) performed a treadmill protocol at three running velocities (2.22, 2.78 and 3.33 m.s^-1) using four footwear conditions: barefoot, uncushioned minimalist shoes, cushioned minimalist shoes, and standard running shoes. 3D kinematic analysis was performed to determine ankle and knee angles at initial foot-ground contact, rate of rear-foot strikes, stride frequency and step length. Ankle angle at foot strike, step length and stride frequency were significantly influenced by footwear conditions (p<0.001) at all running velocities. Posthoc pairwise comparisons showed significant differences (p<0.001) between running barefoot and all shod situations as well as between the uncushioned minimalistic shoe and both cushioned shoe conditions. The rate of rear-foot strikes was lowest during barefoot running (58.6% at 3.33 m.s^-1), followed by running with uncushioned minimalist shoes (62.9%), cushioned minimalist (88.6%) and standard shoes (94.3%). Aside from showing the influence of shod conditions on running kinematics, this study helps to elucidate differences between footwear marked as minimalist shoes and their ability to mimic barefoot running adequately. These findings have implications on the use of footwear applied in future research debating the topic of barefoot or minimalist shoe running.

Effects of footwear on treadmill running biomechanics in preadolescent children

While recent research debates the topic of natural running in adolescents and adults, little is known about the influence of footwear on running patterns in children. The purpose of this study was to compare shod and barefoot running gait biomechanics in preadolescent children. Kinematic and ground reaction force data of 36 normally developed children aged 6-9 years were collected during running on an instrumented treadmill. Running conditions were randomized for each child in order to compare barefoot running with two different shod conditions: a cushioned and a minimalistic running shoe. Primary outcome was the ankle angle at foot strike. Secondary outcomes were knee angle, maximum and impact ground reaction forces, presence of rear-foot strike, step width, step length and cadence. Ankle angle at foot strike differed with statistical significance (p < 0.001) between conditions. Running barefoot reduced the ankle angle at foot strike by 5.97° [95% CI, 4.19; 7.75] for 8 kmh(-1) and 6.18° [95% CI, 4.38; 7.97] for 10 kmh(-1) compared to the cushioned shoe condition. Compared to the minimalistic shoe condition, running barefoot reduced the angle by 1.94° [95% CI, 0.19°; 3.69°] for 8 kmh(-1) and 1.38° [95% CI, -3.14°; 0.39°] for 10 kmh(-1). Additionally, using footwear significantly increased maximum and impact ground reaction forces, step length, step width and rate of rear-foot strike. In conclusion, preadolescent running biomechanics are influenced by footwear, especially by cushioned running shoes. Health professionals and parents should keep this in mind when considering footwear for children.

Running with a minimalist shoe increases plantar pressure in the forefoot region of healthy female runners

OBJECTIVES

Minimalist running shoes have been proposed as an alternative to barefoot running. However, several studies have reported cases of forefoot stress fractures after switching from standard to minimalist shoes. Therefore, the aim of the current study was to investigate the differences in plantar pressure in the forefoot region between running with a minimalist shoe and running with a standard shoe in healthy female runners during overground running.

DESIGN

Randomized crossover design.

METHODS

In-shoe plantar pressure measurements were recorded from eighteen healthy female runners. Peak pressure, maximum mean pressure, pressure time integral and instant of peak pressure were assessed for seven foot areas. Force time integral, stride time, stance time, swing time, shoe comfort and landing type were assessed for both shoe types. A linear mixed model was used to analyze the data.

RESULTS

Peak pressure and maximum mean pressure were higher in the medial forefoot (respectively 13.5% and 7.46%), central forefoot (respectively 37.5% and 29.2%) and lateral forefoot (respectively 37.9% and 20.4%) for the minimalist shoe condition. Stance time was reduced with 3.81%. No relevant differences in shoe comfort or landing strategy were found.

CONCLUSIONS

Running with a minimalist shoe increased plantar pressure without a change in landing pattern. This increased pressure in the forefoot region might play a role in the occurrence of metatarsal stress fractures in runners who switched to minimalist shoes and warrants a cautious approach to transitioning to minimalist shoe use.