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First published randomized controlled trial: minimalist vs maximalist running shoes

At last, the first randomized controlled trial on the risk of injury with relation to shoe type (minimalist vs. traditional/maximalist) has just been published!
Summary
A total of 103 runners used to wearing traditional/maximalist shoes were randomly assigned a neutral traditional/maximalist (Nike Pegasus 28), partial minimalist (Nike Free 3.0 V2), or full minimalist shoe (Vibram 5-Fingers Bikila). Runners started a 12-week training program in preparation for a 10 km event and progressively increased the proportion of their training time with the new shoes. The outcome measures included the number of injury events (23 in total) and running-related pain. The proportion of injured runners was significantly higher for the Nike Free compared with the two other conditions (Pegasus and 5-Fingers).
Conclusion of the Authors

This study started as a short paper published in Footwear Science entitled “Examining the potential role of minimalist footwear for the prevention of proximal lower-extremity injuries.” Their conclusions were as follows: “Running in minimalist footwear appears to increase the likelihood of experiencing an injury and running-related pain in runners otherwise new to this footwear category while training for a 10 km event (12 weeks). Using a full minimalist design; however, may reduce pain at the knee, hip and pelvis, and lower back suggesting there is merit in using a full minimalist design for injury prevention with appropriate pre-conditioning of soft-tissue in the shin and calf.” (Given the fact that the experience of pain was significantly more important in the case of the ultra-minimalist group.) This study was subsequently published once more in a more thorough format in the British Journal of Sports Medicine under a new title (Examining injury risk and pain perception in runners using minimalist footwear).

This time, the conclusions were as follows:
  • Both partial and full minimalist footwear designs resulted in a greater risk of injury compared with the neutral footwear group.
  • The partial minimalist shoe resulted in a greater overall injury rate.
  • Runners in the full minimalist shoe reported greater shin and calf pain than runners in both other footwear groups.
  • It is recommended that clinicians use caution when prescribing the use of minimalist running shoe designs in light of the greater risk of injury and pain with their use.

 

This study represents the best work published thus far on the subject. While the experimental protocol is not flawless, it is very well designed. What bugs me though is the lack of clarity in their clinical recommendations (text box highlighting what the majority of practitioners will remember).

 

After a careful reading of this study published in two parts, I would formulate their conclusion differently (for more accuracy):

 

Recreational runners used to wearing traditional shoes and who were assigned a new partial minimalist shoe (Nike Free 3.0, 10 minutes more per week for 12 weeks) showed a significantly higher risk of injury (more precisely at the calf and shin) ... AND

Recreational runners used to wearing traditional shoes and who were assigned a full minimalist shoe (5-Fingers, 10 minutes more per week during 12 weeks) did NOT show a significantly higher risk of injury, but rather a higher likelihood of developing pain at the calf and shin

 

Here are a few critical pointsFor research addicts:

 

  • Runners who already wore minimalist shoes before the study or with less than five years of running experience were excluded. Thus, this publication studied the risk associated with the integration of new running shoes, in runners used to traditional/maximalist footwear switching to two different types of minimalist shoe models, well before assessing the actual injury risk related to minimalism per se.
  • The statistical data relative to these studies as they stand right now do not allow us to conclude (as was stated in their first article) that the Free or 5F actually reduce pain at the knee, hip, and lower back. (Even though I do believe in this hypothesis.)
  • On the other hand, it is clear that in the case of such a transition (10 minutes more per day), the more minimalist the shoes, the more likely the pain at the shin and calf. (Is this transition still too aggressive in terms of time?)
  • We are surprised to see that the 5F have not caused more injuries.
  • The follow-up period was very short (12 weeks)… a longer follow-up would have been very interesting: once runners are well adapted to their new running shoes, is there a protective or deleterious effect of either footwear on the incidence of injuries?

 

For scientists:

 

  • The groups were too small to draw solid conclusions.
  • The confounding variables previously identified in order to ensure group homogeneity should not include useless anthropometric measures (Q angle and foot posture index), but rather specific kinetic and kinematic parameters (loading rate, cadence, foot strike pattern) as well as physiological parameters (VO2 max).
  • The risk of bias is summed up as follows: High risk of bias for blinding of participants and other sources of bias (industry partnership grant); Unclear risk of bias for allocation concealment and selective outcome reporting; Low risk of bias for sequence generation and incomplete outcome data.

Thanks to a wide range of studies (2013-RyanA, 2013-RyanB, 2013-Cauthon, 2013-Ridge, 2012-Salzler, 2011-Giuliani), we now know that a quick transition from a maximalist shoe model to a minimalist design represents a certain degree of risk.

 

Be that as it may, there are still two scientific issues that would need stronger evidence:

1. Should beginners start with minimalist or maximalist running shoes?

2. What is the incidence of injury for runners used to minimalist or maximalist running shoes? …

 

We have a few hypotheses in mind… do you? Blaise and Jean-Francois