Exercise-induced local sweating: Greater reduction in women than men with sunscreen use

Sunscreens may affect thermoregulation and sweating during exercise in warm climates. In this study, we compared the effects of three sunscreens on local sweating rate (LSR) during exercise under controlled conditions (32°C, relative humidity 55%). Fifteen subjects (8 men, 7 women) underwent 20-min cycles in four randomized conditions: control (CON), sunscreen A (SSA), sunscreen B (SSB) and sunscreen C (SSC). LSR was measured by a patch on the scapular region (p < .001). CON showed higher LSR (182.21 μL/min·dm², CI95% 168 to 195 μL/min·dm²) compared to SSA (142.10 μL/min·dm², CI95% 128 to 155 μL/min·dm²), SSB (158.06 μL/min·dm², CI95% 144 to 171 μL/min·dm²), and SSC (159.00 μL/min·dm², CI95% 145 to 172 μL/min·dm²). In men, SSA showed lower LSR compared to CON, SSB, and SSC (p < .05). On the other hand, no statistically significant differences were found in LSR between SSB, SSC, and CON conditions. In women, CON was superior to all sunscreens in LSR (p < .001), and there was no difference between them (SSA, SSB, SSC, p > .05). Sunscreen reduced LSR during moderate exercise in a hot and moderate humidity environment compared to CON, especially SSA in men and all sunscreens in women.