Increased reflex activation of the peroneus longus following application of an ankle brace declines over time

Two experiments were performed to document the time-dependent characteristics of the peroneus longus short latency stretch reflex amplitude following application of an ankle brace. In Experiment 1, stretch reflexes were induced in 15 weightbearing subjects during an unbraced condition and braced condition. In Experiment 2, stretch reflexes were induced in 15 weightbearing subjects before and after 3 h of wearing the brace. In Experiment 1. the amplitude of the stretch reflex increased in the braced condition by about 25% relative to the non-braced condition (p = 0.006). In Experiment 2 the amplitude of the stretch reflex increased about 18% immediately after application of the brace relative to the non-braced condition (p = 0.037). After 3 h, the stretch reflex amplitude was not different from that of initial non-braced condition. Given the importance of the peroneus longus muscle in ankle complex stability, further attention should be directed to whether the increased stretch reflex gain can be exploited during rehabilitation from ankle complex injuries. The findings provide a framework by which the effect of ankle braces on ankle joint proprioception, muscle activation profiles and balance may be physiologically interpreted.