Article

This study investigated the influence of long-term wearing of unstable
shoes (WUS) on compensatory postural adjustments (CPA) to an external
perturbation. METHODS: Participants were divided into two groups: one wore
unstable shoes while the other wore conventional shoes for 8 weeks. The ground
reaction force signal was used to calculate the anterior-posterior (AP)
displacement of the centre of pressure (CoP) and the electromyographic signal of
gastrocnemius medialis (GM), tibialis anterior (TA), rectus femoris (RF) and
biceps femoris (BF) muscles was used to assess individual muscle activity,
antagonist co-activation and reciprocal activation at the joint (TA/GM and
RF/(BF+GM) pairs) and muscle group levels (ventral (TA+RF)/dorsal (GM+BF) pair)
within time intervals typical for CPA. The electromyographic signal was also used
to assess muscle latency. The variables described were evaluated before and after
the 8-week period while wearing the unstable shoes and barefoot. RESULTS:
Long-term WUS led to: an increase of BF activity in both conditions (barefoot and
wearing the unstable shoes); a decrease of GM activity; an increase of antagonist
co-activation and a decrease of reciprocal activation level at the TA/GM and
ventral/dorsal pairs in the unstable shoe condition. Additionally, WUS led to a
decrease in CoP displacement. However, no differences were observed in muscle
onset and offset. CONCLUSION: Results suggest that the prolonged use of unstable
shoes leads to increased ankle and muscle groups' antagonist co-activation levels
and higher performance by the postural control system.
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Langue : ANGLAIS