Influence of exercise intensity and regional differences in the sudomotor recruitment pattern in exercising...

We investigated the influence of exercise intensities and regional differences in the sudomotor recruitment pattern in boys. Six prepubertal boys (age 11 ± 1 yr) cycled at light, moderate, and high exercise intensity (35%, 50%, and 65% VO₂max) for 30 min in a temperate condition (28 °C, 40% relative humidity). Local sweat rate (ventilated capsule) and number of activated sweat glands (starch-iodine technique) at five body sites were assessed and sweat gland output was calculated. Responses in boys were compared with those in nine young men (23 ± 1 yr) tested under identical conditions. The forehead, chest, back, and forearm, but not thigh, sweat rate increased from light to moderate and at high intensities in boys (all p ≤ 0.005) but not from moderate to high (all p ≥ 0.071). The sweat rate on the forehead was relatively higher (p ≤ 0.045) and thigh was lower (p ≤ 0.050) than other sites in boys at moderate and high intensities. Exercise intensity-dependent sweating was associated with activating more sweat glands but not increasing glandular output in boys. The sweat rate in boys was attenuated versus men heterogeneously across body sites concurrent to low glandular outputs (all p ≤ 0.027). We conclude that exercise intensity modulates the sweat rate in boys by changing the number of activated sweat glands heterogeneously among skin sites. Age-related differences in the sudomotor pattern are evident at higher exercise intensities. Development of glandular output per gland occurring from boys to young men may play a key role in modulating sweat rate with respect to exercise intensity and regional differences.