Article

During voluntary step initiation (SI), propulsive forces are generated during
anticipatory postural adjustments (APA) which displace the centre-of-gravity
(CoG) in the desired direction. These propulsive forces are implemented by ankle
synergy, bilateral soleus inhibition followed by activation of tibialis anterior
(TA). The aim of this study was to investigate the effect of fatigue applied to
ankle dorsiflexors on APA associated with SI and on related motor performance.
Eight young healthy participants initiated stepping before and after a protocol
designed to generate fatigue in ankle dorsiflexors. Fatigue was induced by series
of high-level isometric contractions performed until exhaustion. Results showed
that, with fatigue, the level of TA activation during APA, anticipatory postural
dynamics (backward centre-of-pressure displacement and forward CoG velocity) and
related motor performance (peak of CoG velocity) were attenuated, while APA
duration and total SI duration increased. These changes were interpreted as
reflecting a protective strategy aiming to preserve the integrity of the fatigued
muscles, rather than an impairment associated with muscle weakness.
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Langue : ANGLAIS