Whole-body passive heating at moderate hyperthermic state impairs static and dynamic balance in healthy females

Abstract

Background: Whether static and dynamic balances can be impaired with increasing core temperature in female participants remains unknown.

Purpose: We tested the hypothesis that static and dynamic balances can be further impaired with systematic increases of core temperature by Δ1 °C and Δ 2 °C using whole-body passive heating.

Method: Eighteen female participants underwent a control trial (Con) and two progressive passive heating trials with Δ 1 °C and Δ 2 °C increase of oral temperature (T_Oral) using 45 °C water bath. In each trial, we assessed static balance with both eye open and closed and assessed dynamic balance using obstacle crossing at 10 %, 20 % and 30 % of the participant's leg length.

Results: Static balance was not different between Con and Δ1 °C but was different between Δ1 °C and Δ 2 °C in an eye closed condition. Furthermore, Δ 2 °C greatly impaired both static and dynamic balances when compared to Con. The joint angles and toe clearance increased while leading heel-obstacle distance decreased during crossing obstacles at the height of 20 % and 30 % leg length with leading limbs in the Δ2 °C compared to Δ 1 °C and Con (All P < 0.05). However, no differences in joint kinematics and toe clearance with trailing limbs were observed (All P > 0.05).

Conclusion: In female participants, static and dynamic balances only became impaired when T_Oral increased 2 °C from baseline.

Keywords: Center of pressure; Crossing obstacles; Oral temperature; Proprioception; Visual feedback.