Footwear, orthoses affect leg muscle activity

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Biomechanics Magazine March 2007

http://www.biomech.com/showArticle.jhtml?articleID=197800586

Footwear, orthoses affect leg muscle activity

By: Lori Rochelle Roniger

Wearing footwear and orthoses while walking can significantly change

the electromyographic activity of leg muscles, according to a study

published in Clinical Biomechanics in December.

The investigators, who were from LaTrobe University in ,

Australia, used surface electromyography to evaluate the effects of

three levels of medial rearfoot wedging (0 degrees , 15 degrees ,

and 30 degrees ), also known as inverted foot orthoses, on EMG

amplitude. Fifteen people with pronated but otherwise healthy feet

served as subjects.

After four weeks of acclimatization to the various orthoses, EMG

data were measured under five conditions: barefoot, wearing shoes

only, and wearing shoes and each of the three orthoses.

Maximum EMG amplitude for the tibialis anterior increased

significantly while subjects wore shoes only and shoes with each of

the orthoses compared to walking barefoot. Peroneus longus maximum

EMG amplitude increased significantly (21%) with the 15 degrees

orthoses compared to barefoot.

No significant medial gastrocnemius or soleus EMG maximum amplitude

changes were found. Overall, the effects of wearing shoes and

orthoses in individual subjects were highly variable, the

researchers concluded.