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Unstable shoes provide more activation of selected lower extremity muscles and increased postural sway WHILE STANDING. Does this really surprise us?  “ …it was shown that standing in the unstable shoe increased activity of the flexor di…

Unstable shoes provide more activation of selected lower extremity muscles and increased postural sway WHILE STANDING. Does this really surprise us?

 “ …it was shown that standing in the unstable shoe increased activity of the flexor digitorum longus, peroneal (PR) and anterior compartment (AC) muscles of the lower leg. No activity differences for the larger soleus (SOL) were identified between the stable and unstable shoe conditions.”. In English that means the muscles on the front, back and outside of your lower leg.

It goes on to say “Postural sway was greater while standing in the unstable shoe compared to barefoot and the stable control shoe.” and “Postural sway while standing in the unstable MBT shoe also decreased over the 6-week accommodation period.” Postural sway is one way of measuring proprioception or body position awareness. 

The key words here are “WHILE STANDING”. It DOES NOT SAY WALKING. We have talked about rockered shoes in numerous previous posts and we have always maintained that in the right circumstances, it can be a good thing, but not necessarily something you should go do your grocery shopping or gym workout in.

Gait Posture. 2010 Jun;32(2):215-9. doi: 10.1016/j.gaitpost.2010.04.018. Epub
2010 May 23.

Standing in an unstable shoe increases postural sway and muscle activity of
selected smaller extrinsic foot muscles.

Landry SC, Nigg BM, Tecante KE.

Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500
University Drive N.W., Calgary, Alberta, Canada T2N 1N4. scott.landry@acadiau.ca

Inactivity or the under-utilization of lower limb muscles can lead to strength
and functional deficits and potential injury. Traditional shoes with stability
and support features can overprotect the foot and potentially contribute to the
deterioration of the smaller extrinsic foot muscles. Healthy subjects (n=28)
stood in an unstable MBT (Masai Barefoot Technology) shoe during their work day
for a 6-week accommodation period. A two-way repeated measures ANOVA was used to 
determine (i) if unstable shoe wear increased electromyographic (EMG) activity of
selected extrinsic foot muscles and increased postural sway compared to standing 
barefoot and in a stable control shoe and (ii) if postural sway and muscle
activity across footwear conditions differed between a pre- and
post-accommodation testing visit. Using an EMG circumferential linear array, it
was shown that standing in the unstable shoe increased activity of the flexor
digitorum longus, peroneal (PR) and anterior compartment (AC) muscles of the
lower leg. No activity differences for the larger soleus (SOL) were identified
between the stable and unstable shoe conditions. Postural sway was greater while 
standing in the unstable shoe compared to barefoot and the stable control shoe.
These findings suggest that standing in the unstable MBT shoe effectively
activates selected extrinsic foot muscles and could have implications for
strengthening and conditioning these muscles. Postural sway while standing in the
unstable MBT shoe also decreased over the 6-week accommodation period.

Copyright 2010 Elsevier B.V. All rights reserved.