Christopher J. Stevens, Daniel J. Plews, Paul B. Laursen, Aden B. Kittel, Lee Taylor

This investigation assessed the acute physiological and perceptual responses to wearing additional clothing during outdoor cycling to determine if this strategy could increase the heat load while training in temperate environments. Seven male cyclists (age: 32 ± 13 y, height: 179 ± 10 cm, body mass: 74 ± 10 kg, body fat percentage: 10.3 ± 1.0%) completed 2 randomized outdoor (∼17°C and ∼82% RH), 80 min cycling sessions at moderate-hard intensities (CR10 RPE = 3-5). They wore spandex shorts and a short sleeve top (CON) or additional clothing including full-length spandex pants and a 'winter' cycling jacket and gloves (AC). Core temperature, heart rate, sweat rate, thermal sensation and thermal comfort were measured across the trials. Moderate increases were observed in AC vs. CON for the change in mean core temperature (0.4 ± 0.3°C, effect size, ES = 1.16 ± 0.55), change in maximum core temperature (0.5 ± 0.3°C, ES = 1.07 ± 0.48) and sweat rate (0.24 ± 0.16 L . h-1, ES = 1.04 ± 0.59). A small increase in mean heart rate (3 ± 3 bpm, ES = 0.32 ± 0.28) was observed as well as a 'very likely' (percentage difference = 22.4 ± 7.1) and 'most likely' (percentage difference = 42.9 ± 11.9) increase in thermal sensation and thermal comfort, respectively, in AC vs. CON. Dressing in additional clothing while cycling outdoors in a temperate environment increased physiological strain and sensations of warmth and discomfort. Training in additional clothing during outdoor cycling represents a practical alternative to increasing the heat load of a training session.