Muscoskeletal and Spatio-temporal Gait Changes in Walking After an Eight Weeks Minimalist Footwear Intervention

INTRODUCTION Manufacturers have now developed minimalist shoes to alleviate the obvious surface hazards that are present while barefoot (Willy & Davies). To date, the minimalist footwear option, that is now readily available, has received limited scientific investigation concerning chronic wear. This intermediate option has inspired many to transition to minimalist footwear or go barefoot through the use of training programs (Warne et al. 2013). Most training interventions regarding the transition to barefoot running commence with walking, yet no scientific rational exists for this decision. Therefore the aim of this study was to compare spatio-temporal walking gait parameters, and peak musculoskeletal torque values of the ankle joint after an 8 week minimalist footwear habituation period. METHODS Fourteen healthy male participants were randomly allocated to a control (CG) or intervention group (IG). The IG were provided with a pair of minimalist shoes (2.5 mm sole thickness; Feelmax Osma 2, Feelmax®) to be worn ≥6 hrs a day, 5 days a week over an 8 wk habituation period. Spatio-temporal and lower limb strength data were obtained both before and after the 8 wk period for all participants, in three different footwear conditions, barefoot, minimalist shoe, and traditional shoe. A 16 camera 3D motion capture system (Vicon) was used to collect data, which was subsequently processed and modelled analysed (Workstation, Bodybuilder, Vicon). Peak musculoskeletal torque values of the ankle joint were assessed through isokinetic dynamometry (Humac Norm Isokinetic dynamometer). Five repetitions of bilateral concentric and eccentric strength assessments were made during ankle plantar flexion and ankle dorsiflexion. Paired t-tests were utilised to determine group differences between baseline and post intervention spatio-temporal, and isokinetic force measures. Pearson’s correlation coefficient was used to assess relationships between the spatio-temporal and strength data. RESULTS The IG had an increase in stride length (4.2%; p = 0.44), and walking speed (5.2%; p = 0.04) during the barefoot condition. There was a similar increase in barefoot stride length observed in the CG (3.65%; p = 0.11). However, only the IG showed an improvement in eccentric plantar flexion strength of the left limb (18%; p = 0.021). No improvement in lower limb strength was observed in the CG. DISCUSSION Participants in the IG walked faster due to an increased stride length, as these spatiotemporal parameters are interrelated. This increase in stride length following the intervention differs to previous reports concerning barefoot gait during running (Kaplan 2014). This may be due to the extended time period the participants habituated to the footwear, or that the footwear worn was considerably more minimal than footwear investigated elsewhere. As significant differences were only observed in the barefoot condition, it can be suggested that the minimalist shoe worn during the 8 week period acted as a suitable transition to barefoot walking. Small improvements in peak torque values suggest that habitual walking in minimalist footwear resulted in increased lower limb strength. CONCLUSION To conclude, significant differences in gait parameters were only observed in the barefoot condition. This would suggest the minimalist shoe acted as a suitable training device for those transitioning to barefoot running. REFERENCES Kaplan, Y. (2014). Barefoot versus shoe running: from the past to the present. The Physician and sportsmedicine. 42 (1): 30-35. Warne, J., Kilduff, S., Gregan, B., Nevill, A., Moran, K., & Warrington, G. (2013). A 4Ǧweek instructed minimalist running transition and gaitǦretraining changes plantar pressure and force. Scandinavian journal of medicine & science in sports. Willy, R. & Davis, I. (2013). Kinematic and kinetic comparison of running in standard and minimalist shoes. Applied Sciences. 46 (2): 318-323.