Effect of hyperthermia on simulated muscle activation in female when crossing obstacle

TL;DR

This study found that higher body heat increases muscle activation in women when crossing obstacles of moderate height or higher.

Contribution

The study reveals how increasing hyperthermia affects muscle activation in females during obstacle crossing.

Findings

Greater hyperthermia (Δ2°C) increased lower limb muscle activation for obstacle heights of 20% and 30% leg length.

Muscle activation was not significantly different between mild hyperthermia (Δ1°C) and control conditions.

Higher muscle activation at Δ2°C suggests a compensatory mechanism for safety and stability during obstacle crossing.

Abstract

It is well known that hyperthermia greatly impairs neuromuscular function and dynamic balance. However, whether a greater level of hyperthermia could potentially alter the lower limb simulated muscle activation when crossing an obstacle in female participants remains unknown. Therefore we examined the effect of a systematic increase in oral temperature on lower limb simulated muscle activation when crossing an obstacle in female participants. Eighteen female participants were recruited where they underwent a control trial (Con) and two progressive passive heating trials with Δ 1°C and Δ 2°C increase of oral temperature (Toral) using a 45°C water bath. In each trial, we assessed lower limb simulated muscle activation when crossing an obstacle height of 10%, 20%, and 30% of the participant’s leg length and toe-off, toe-above-obstacle and heel-strike events were identified and analyzed. In all events, the lower limb simulated muscle activation were greater in Δ2°C than Δ1°C and Con when both leading and trailing limbs crossed the obstacle height of 20% and 30% leg length (all p < 0.001). However, the lower limb simulated muscle activation were not different between Δ1°C and Con across all obstacle heights (p > 0.05). This study concluded that a greater level of hyperthermia resulted in a greater lower limb simulated muscle activation to ensure safety and stability when females cross an obstacle height of 20% leg length or higher.

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