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

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 Delta 1 degrees C and Delta 2 degrees C using whole-body passive heating.Method: Eighteen female participants underwent a control trial (Con) and two progressive passive heating trials with Delta 1 degrees C and Delta 2 degrees C increase of oral temperature (T-Oral) using 45 degrees 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 Delta 1 degrees C but was different between Delta 1 degrees C and Delta 2 degrees C in an eye closed condition. Furthermore, Delta 2 degrees 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 Delta 2 degrees C compared to Delta 1 degrees 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 degrees C from baseline.