Page 109 - JSOM Fall 2021

An Ongoing Series

Update on Minimalist Running Shoes

Joseph J. Knapik, ScD*; Robin Orr, PhD; Rodney Pope, PhD

ABSTRACT
This article provides updated information comparing min- this type is closer to barefoot running, which humans are natu-
imalist running shoes (MRS) to conventional running shoes rally adapted for through years of evolution. Opponents argue
(CRS). Our previous review found that, compared with that the foot is better protected by the stability, support, and
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running in CRS, transitioning to MRS resulted in lower en- superior cushioning provided by modern CRS. Our review
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ergy cost and less ground contact occurring at the forefoot, indicated that running in MRS resulted in a lower energy cost,
resulting in lower impact forces. There was some increased likely because of their lower weight. Biomechanically, those
risk of injury with MRS, although data were conflicting. A running in CRS often strike the ground with the heel first,
more recent 26-week study involved 30 trained runners using resulting in higher ground impact forces. Those running in
CRS and 31 using MRS. The proportion of training time in MRS generally strike the ground with the forefoot or mid-
the assigned shoes increased by 5% each week. After the first foot, resulting in lower ground impact forces. Better-designed
6 weeks of transition (35% of training time in the assigned prospective studies suggested that bone stress injuries and the
shoe), energy cost was lower and 5-km running time faster in overall injury incidence tended to be higher when running in
MRS compared with CRS. No further improvement occurred MRS during 10 to 12 weeks of transition to this type of foot-
4,5
from weeks 6 to 26. There were no significant differences in wear ; however, other, less well-designed studies generally
injury incidence in the two groups (CRS = 37%, MRS = 52%; suggested there is no difference in injury rates between shoe
p = .24). Running-related pain was higher in the MRS group in types or higher injury rates among CRS users. 7
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the knee, shin, calf, and ankle and increased at these locations
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as running mileage increased. Risk of injury in MRS increased In our previous paper, we noted that longer-term investiga-
as participant body weight increased. These more recent data tions were needed in which runners were followed not only
suggest that MRS can improve performance, but most runners during the transition period to MRS but also for periods in
should limit running in MRS to 35% of training time and in which they are fully adapted to MRS. We mentioned one long-
situations where optimal performance is desired (e.g., races, term study at the University of South Australia–Adelaide that
fitness tests). was ongoing at the time. This study has now been completed,
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and several articles reporting data from this investigation have
Keywords: energy cost; running economy; injuries been published. These studies address energy cost, perfor-
mance, and running-related pain and injury incidence while
running in CRS and MRS. 9-11 The purpose of this paper is to
review the new information from this investigation.
Introduction
In the Spring 2016 edition of this journal, we reviewed data
on the physiological, biomechanical, and medical aspects of Long-Term Study on Adaptations
running in CRS and MRS. A minimalist shoe is one that “pro- to Minimalist Shoes
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vides minimal interference with the natural movement of the The University of South Australia study was 26 weeks in du-
foot due to its high flexibility, low heel to toe drop, weight and ration. Participants were selected if they (1) had no prior ex-
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stack height, and the absence of motion control and stability perience with MRS, (2) used a rearfoot ground strike pattern,
devices.” Advocates of MRS argue that running in shoes of (3) trained at least 9 miles per week, and (4) could run 5-km
2
*Correspondence to joseph.j.knapik.civ@mail.mil
MAJ (Ret) Joseph J. Knapik served 50 years with the US military as a wheel vehicle mechanic, medic, Medical Service Corps officer, contrac-
tor, and Department of Defense civilian. He is currently a research physiologist at the United States Army Research Institute of Environmental
Medicine (Natick, MA) and an adjunct professor at Uniformed Services University (Bethesda, MD) and Bond University (Robina, Queensland,
Australia). Dr Robin Orr served in the Australian Regular Army for more than 23 years as an infantry soldier, Physical Training Instructor, phys-
iotherapist, and human performance officer. Still serving in the reserves, he leads the Tactical Research Unit headquartered at Bond University.
Dr Rodney Pope is Professor of Physiotherapy at Charles Sturt University (New South Wales, Australia) and honorary adjunct professor with the
Tactical Research Unit at Bond University. He has spent much of his 30-year career researching, practicing, and advising on injury risk manage-
ment in military and other tactical populations.

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