Clothing and thermoregulation during sub maximal cycling: effects of heat, humidity and fabric

The investigation evaluated if wearing a specialised under garment, termed base layer, could significantly alter physiological or thermoregulatory responses to sub maximal cycling. Twelve males completed a 60 minute continuous cycling protocol ( 60% \TO 2max) twice within three environmental conditions (ambient (20 °C, 35% relative humidity) (RH)), hot/dry (30 °C, 35% RH) and hot/humid (30 °C, 80% RH)). Protocols were completed in a repeated measures counterbalanced design within a controlled environmental chamber at the same time of day. Participants wore the same cotton shorts, socks and running trainers alongside either a 100% cotton or a base layer t-shirt for each trial. Values for core temperature (T c), mean skin temperature (Tsk), heat rate (HR), oxygen uptake ( VO 2), rate of perceived exertion (RPE), thermal comfort and sweating sensation were recorded at 15, 30, 45 and 60 minutes whilst sweat loss (SLoss) was calculated post exercise. All variables were calculated into delta values (A) (cotton -base layer) and analysed using a two-way analysis of variance (ANOV A) excluding A SLoss which was analysed using a One-way ANOVA. Where necessary Bonferroni correct T-tests were implemented to further investigate any significant effects. Results showed base layers significantly reduced VO 2 (P = 0.038) whilst increasing SLoss (P < 0.001) within the hot/dry condition. Further Bonferroni corrected T-test revealed base layers reduced \102 between 15 and 45 (P = 0.048), 15 and 60 (P = 0.017), and 45 and 60 minutes (P = 0.049) within the hot/dry condition. No significant differences were detected in any other variables. The investigation reports that a specialised base layer may provide both a thermoregulatory and physiological advantage during sub maximal cycling within hot/dry environmental conditions