THERMOREGULATORY RESPONSES TO CYCLING WITH AND WITHOUT A HELMET

This study examined the effects of wearing a helmet on selected body t emperatures and perceived heat sensation of the head and body while cy cling in a hot-dry (D) (35 degrees C, 20% relative humidity (RH) and h ot-humid (H) (35 degrees C, 70% RH) environment. Ten male and four fem ale cyclists (mean +/- SD: males = age 27 +/- 7 yr, peak O-2 uptake (( V) over dot O-2) 4.10 +/- 0.54 L . min(-1); females = age 26 +/- 3 yr, peak O-2 uptake ((V) over dot O-2) 3.08 +/- 0.49 L . min(-1)) perform ed four randomized 90-min cycling trials at 60% of peak (V) over dot O -2 both with (HE) and without (NH) a commercially available cycling he lmet in both D and H environments. (V) over dot O-2, core (T-c), skin (T-sk), and head skin temperatures, heart rate (HR), rating of perceiv ed exertion (RPE), and perceived thermal sensation of head (TSH) and b ody (TSB) were measured throughout exercise. For all measured variable s, no significant difference was evident between HE and NH. However, T -c, T-sk, and mean head skin temperatures were higher (P < 0.001) in H than D. Likewise, RPE, TSH, TSB (P < 0.001), and sweat rates (H = 1.3 3 +/- 0.32, D = 1.14 +/- 0.23 L . h(-1)) (P < 0.01) were higher in H v ersus D. Results indicate that use of a commercially available cycling helmet while riding in a hot-dry or hot-humid environment does not ca use the subjects to become more hyperthermic or increase perceived hea t sensation of the head or body.