Effect of cooling on static postural balance while wearing firefighter’s protective clothing in a hot environment

Abstract

Objectives. Postural imbalance can result from hyperthermia-mediated muscular fatigue and is a major factor contributing to injuries from falling. The objective of this study was to investigate the effect of exercise-induced hyperthermia and the impact of cooling on postural balance while wearing firefighters’ protective clothing (FPC) in a hot environment. Methods. A portable force platform measured postural balance characterized by postural sway patterns using center of pressure metrics. Twelve healthy, physically fit males were recruited to stand on the force platform once with eyes open and once with eyes closed before and after treadmill exercise (40% $\dot{V}{\text{O}}_{2\text{max}}$) inside an environmental chamber under hot and humid conditions (30 °C and 70% relative humidity) while wearing FPC. Subjects participated in two randomly assigned experimental phases: control and cooling intervention. Results. A significant increase in physiological responses and postural balance metrics was observed after exercising in the heat chamber while wearing FPC. Cooling resulted in a significant effect only on postural sway speed after exercise-induced hyperthermia. Conclusions. Hyperthermia can negatively alter postural balance metrics, which may lead to an increased likelihood of falling. The utilization of body cooling reduced the thermal strain but had limited impact on postural balance stability.

KEYWORDS:

• firefighters
• personal protective equipment
• postural balance
• hyperthermia
• heat stress
• active cooling

Acknowledgements

The data used in this study are a subset of a larger study derived from Dr Aljaroudi’s PhD dissertation work at the University of Cincinnati conducted during his pre-doctoral research at the National Personal Protective Technology Laboratory (NPPTL). The authors thank the subjects for their time and participation. The authors also thank Aitor Coca, PhD, Jung-Hyun Kim, PhD and Tianzhou Wu, MS for their support during the data collection. The authors also thank Ms Lorenna Altman and Ms Cyndi Cox from the University of Cincinnati for their technical support. Finally, the authors thank Raymond J. Roberge, MD for his medical screening and monitoring of the subjects during the data collection.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded in part from the National Institute for Occupational Safety and Health (NIOSH) ERC University of Cincinnati [Grant #T420H008432]; NIOSH/National Personal Protective Technology Laboratory (NPPTL) internal discretionary funding.