Muscle Adaptation During the Transition to Minimalist Running

Hopefully the title of this post is not misleading, as it is not about the results of a study, but about this press release from the University of Virginia about a study that researchers there are going to do. It is getting a bit of media attention.

Here are some snippets from the press release:

…people in running shoes strike first with the heel (because of all the cushioning), whereas barefoot and minimalist runners strike first with the forefoot. This difference affects how the muscles of the legs and feet respond and develop.

But, exactly, how do the muscles change when adapting to a new running style?
That is the question researchers at the University of Virginia are asking in a new one-of-a-kind study of runners who are transitioning from shoed running style to minimalist running.

“shoed” – that is a new word for my dictionary! I have always used the term ‘shod’.

“We want to know what happens to the muscles of the leg and foot when recreational runners make the switch to minimalist footwear,” said Geoffrey Handsfield, a U.Va. Ph.D. student in biomedical engineering who is leading the study. “Many minimalist shoe manufacturers make claims that their shoes will lead to strengthening the muscles of the calf and feet while avoiding common running injuries. However, there is little scientific evidence supporting these claims.”

There is not little scientific evidence supporting these claims, there is actually NO scientific evidence supporting these claims. There is actually more research supporting the opposite (see below). It is kind of paradoxical that the critics demanded that the more traditional running shoe companies produce evidence for the claims for their shoes, but were never demanding that the minimalist manufactures provide evidence for the claims that they were making … don’t figure! The making of unsupported health claims is what got the toning shoe companies into legal trouble and why Vibram is facing a class action.

The researchers aim to find out exactly which muscles get bigger or weaken, which elongate or shorten, and if some muscles do not change.

Different running techniques use different muscles differently. Some will get weaker and some will get stronger. The blanket rhetoric that “barefoot” strengthens the muscles is just that, rhetoric. Some muscles are used less when barefoot running, so lets see if those muscles get “weaker” in this study. Some muscles are used more when wearing shoes, so lets see if those muscles get “stronger” in this study.

Handsfield and his co-investigators, biomedical engineering professor Silvia Blemker (Handsfield’s adviser) and third-year undergraduate biomedical engineering student Natalie Powers, are using static and dynamic MRI with motion capture cameras and an instrumented treadmill to track the running technique and muscle tissue adaptations of recreational runners transitioning to minimalist running technique.

“Most studies and discussions have been about running form and the effects on bones and joints, but we’re taking a different approach,” Handsfield said. “We think it’s relevant to look at the muscles’ adaptations, which also affect the bones and joints in their interactions.”

He said this is among the first longitudinal studies of runners switching to a new running technique and using a minimalist shoe, and the first to use advanced imaging to study the effects on muscles of different running techniques.

A prospective study rather than an acute intervention is ideal. Some other prospective studies have shown differences between acute effects of a change in running technique and habituation to that technique (see my comments on this study).

The researchers are not attempting to prove one running style is better than the other; rather they are interested in the affects of the change on muscles. The eventual results could help runners make their own decisions regarding footwear and running styles.

Great; no agenda; just comparing the difference. This is how research should be done. The results will show which running technique do what to different muscles and further provide guidance to clinicians to determine which running technique can reduce the load in which tissues. See my speculation here: Which injuries are probably more common in which foot strike pattern? and also Do running shoes weaken muscles?

This study will also hopefully resolve the issue of just how much increase in muscle strength may occur with minimalism/barefoot vs the process just being one of the tissues adapting to the different loads. However, we know from this unpublished study presented at the 2012 ACSM mtg that there was NOT an increase in strength from barefoot running and this small one from the 2011 meeting, that there was also not an increase in strength. Even though both these studies were small and are not yet published in full for peer review and appraisal,  they are the only ones that have so far looked at it and both do not support the widely held contention that ‘minimalism’ does lead to an increase in strength. Even I am surprised at this, but we got to go with what the evidence says.

My only criticism of the above study reported in the press release is that I could find no reference to the study at any of the clinical trial registries, which would be helpful to increase transparency in the conduct and reporting of trials like this one. This is now an important prerequisite for trials. Many of the major journals are now not publishing the results of such studies that are not registered. See this statement on the obligation to register trials.

As always, I go where the evidence takes me until convinced otherwise, and I will look forward to the data from this study.

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