Journal of Applied Physiology, Vol 80, Issue 2 491-495, Copyright © 1996 by American Physiological Society
Responses of sweating and body temperature to sinusoidal exercise in physically trained men
F. Yamazaki, N. Fujii, R. Sone and H. Ikegami
Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan.
The effect of physical training on the dynamic responses of sweating to
transient exercise is still controversial. We determined the phase response
and amplitude response (delta) of sweating rate and body temperature to
sinusoidal exercise in physically trained and untrained subjects. Eight
trained and seven untrained male subjects exercised on a cycle ergometer
with a constant load for 30 min; for the next 28 min, they exercised with a
sinusoidal load. The sinusoidal load variation ranged from approximately 10
to 60% of peak O2 uptake with a 4-min period. The ambient temperature and
the relative humidity during exercise were 25 degrees C and 35%,
respectively. There was no difference between the groups in the phase lags
of esophageal temperature (Tes) and mean skin temperature (Tsk), whereas
the phase lags of sweating rates for the chest and forearm were
significantly shorter in the trained group (P < 0.05). The delta of Tes
and Tsk per 1 W of exercise load in the trained group was significantly
smaller than that in the untrained group (both, P < 0.05), whereas there
was no difference between the groups in the delta of sweating rate for the
chest and forearm. We conclude that subjects who have undergone long-term
physical training show prompter dynamic characteristics of sweating
response compared with untrained subjects and have a higher capacity to
maintain constant body temperature during exercise at transient load.
