Miller EE, et al., The effect of minimal shoes on arch structure and intrinsic foot muscle strength, Journal of Sport and Health
Science (2014), http://dx.doi.org/10.1016/j.jshs.2014.03.011
Journal Abstract
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The purpose of the following study was to investigate the differences of running in minimal versus conventional shoes on intrinsic foot muscle development and longitudinal arch function. It was hypothesised that the comfort features of conventional running shoes reduce the workload of the foot’s intrinsic muscles – potentially inferring with the function and development of the arch.
33 healthy runners were randomised into a control group and an experimental group, wearing conventional and minimal support footwear respectively. All participants completed a 12-week training regime, in which an MRI was taken pre- and post-training of their feet.
Whilst both groups demonstrated an increase in cross-sectional area of flexor digitorum brevis, only the experimental group exhibited an increase in volume and area of abductor digiti minimi – along with significant increases in longitudinal arch stiffness.
These findings support the hypothesis that minimalist shoes exploits the spring-like function of the longitudinal arch, leading to greater demands of the intrinsic muscles supporting the arch, essentially strengthening the foot.
Abstract
Background
This prospective study explored the effects of endurance running (ER) in minimal versus standard running shoes on the foot’s superficial layer intrinsic muscles and the function of the longitudinal arch. Our hypothesis was that running in minimal shoes would cause hypertrophy in these muscles and lead to higher, stronger, stiffer arches.
Methods
The hypothesis was tested using a sample of 33 healthy runners randomized into two groups, a control group shod in traditional running footwear and an experimental group shod in minimal support footwear, whose feet were scanned in an MRI before and after a 12-week training regime. Running kinematics as well as arch stiffness and height were also assessed before and after the treatment period.
Results
Analysis of anatomical cross-sectional areas and muscle volumes indicate that the flexor digitorum brevis muscle became larger in both groups by 11% and 21%, respectively, but only the minimally shod runners had significant areal and volumetric increases of the abductor digiti minimi of 18% and 22%, respectively, and significantly increased longitudinal arch stiffness (60%).
Conclusion
These results suggest that endurance running in minimal support footwear with 4 mm offset or less makes greater use of the spring-like function of the longitudinal arch, thus leading to greater demands on the intrinsic muscles that support the arch, thereby strengthening the foot.