Thermoregulatory Burden from Using Respirators and Performing Composite Movement-Based Exercises of Varying Metabolic Demand

Abstract

Using a fitting respirator in exercises of heavy metabolic demand may increase the user’s thermal burden, as the metabolic heat typically relieved via respiration is baffled by the mask and less exchanged into the environment. This study investigated the increase in thermoregulatory burden as manifested in skin physiological changes from using N95 filtering-facepiece respirators and simultaneously performing composite movement-based exercises of varying metabolic demand. As the results show, when the participants exercised the transepidermal water loss (TEWL) and skin moisture in the forearm and in the cheek immediately outside the N95 mask rose in accordance with the metabolic intensity of the activity, particularly in the first 10 min (TEWL: 26.9–40.4% increase from the level determined at 0 min; skin moisture: 28.1–250.2% increase). Under high metabolic rate, throughout the entire 30 min of exercise the skin capillary blood flow (SCBF) of the participants increased steadily in both the forearm and cheek (6.4–12.3% increase), signaling a continuous requirement for release of excess metabolic heat. These findings indicated that the respirators and the conditions under which they were used should both be considered when the thermoregulatory burden the users of respirators sustained was evaluated. To prevent potential heat stress in the workplace, it is essential to include in the respirator safety program an ergonomic assessment of workload.