Thermoregulatory responses of junior lifesavers wearing protective clothing

Abstract

This study investigated the influence of protective clothing worn to prevent marine stinger envenomation on the thermoregulatory responses of pre-pubescent surf lifesavers exercising in situ under hot and humid conditions (27 °C, 78% relative humidity). Participants performed beach and water activities typically associated with junior surf lifesaving competition in a randomised cross-over design on two separate occasions 7 days apart: one wearing a full-length Lycra stinger suit (S) and one wearing normal swimwear (SW). Skin (TSK) and core (TC) body temperatures, skin blood flow (SKBF), heart rate (HR), body mass, thermal comfort and perceived effort were assessed pre-, mid- (following beach activities) and post-exercise (following water activities). Sweat rates were compared between S and SW. TC was greater following beach activities for S (37.78 °C ± 0.06) compared to SW (37.60 °C ± 0.07; p < 0.05) and male participants experienced greater TC (37.97 °C ± 0.09) than their female counterparts (37.71 °C ± 0.07 °C). TSK following both the beach and water activities were lower than pre-exercise (p < 0.05). SKBF was significantly increased for calf across time (p < 0.01). Male participants experienced a higher HR for S compared to female participants (p < 0.01) while the opposite applied to SW (p < 0.01). There were no gender or between-condition differences for sweat rate or perceived effort. There was evidence of heat storage while stinger suits were worn during beach activities in the absence of any differences in exercise intensity or sweat rate. The results of the present study suggest that the stinger suits should be limited to water-based activities.