The longer-term effects of minimalist running shoes on lower limb structure and function, running performance, and injury risk

Abstract

The effects of transitioning to minimalist running shoes are a topic of interest for runners and scientists. However, relatively few studies have investigated longer-term effects of running in minimalist shoes. This paper will report preliminary findings from a planned 20-week follow-up of runners who participated in a 6-week randomised controlled trial of minimalist shoes and had successfully transitioned to using minimalist or control shoes for 35% of weekly training. Runners continued to transition to their allocated shoes throughout the planned 20-week follow-up by increasing minimalist or control shoe use by 5% each week. The allocated shoes were used for 100% of weekly running during the final 6 weeks of the follow-up. Training volume, shoe use, running-related pain and injury were monitored weekly. Time trial performance, running economy, stride rate, stride length, shoe comfort, ankle plantar flexor muscle strength, and bone mineral density in the tibia, calcaneus, and metatarsals were assessed at the end of the 20-week follow-up. Early published findings from this trial demonstrate that risk of sustaining a running-related injury increased for heavier runners using minimalist shoes compared to control shoes. Additionally, greater weekly calf, ankle, and shin pain severity were experienced by runners completing high weekly running distance using minimalist shoes compared to control shoes. This paper will expand on these published findings by (1) discussing the longer-term effects of transitioning to minimalist shoes on time trial performance, running economy, muscle strength and bone mineral density, and (2) use a series of example cases from the study to explore potential moderating factors (shoe comfort, running biomechanics, and training volume) that might influence the effects of minimalist shoes on running performance, muscle strength, bone mineral density, pain and injury. The clinical and research implications of the findings from this planned follow-up study and case series investigation will be discussed.