Journal of Applied Physiology, Vol 54, Issue 2 355-360, Copyright © 1983 by American Physiological Society
Human frontal sweat rate and lactate concentration during heat exposure and exercise
N. Fellmann, G. Grizard and J. Coudert
Output (Qsweat) and lactate concentration ( [L]sweat) in frontal sweat and
blood lactate concentration ( [L]blood) were monitored in three male
volunteers: one sedentary (S), one fit (F), and one very fit (VF).
Measurements were made under three sweating conditions: 1) heat exposure to
infrared radiation (IR) at rest for 25 min at 45 degrees C; 2) bicycle
exercise at constant relative maximal aerobic power (87 +/- 2% MAP) for 25
min (Cst EX) at 23 degrees C; and 3) bicycle exercise at increasing work
loads (from 60-95% MAP) in four or five successive 5-min steps (Incr EX) at
23 degrees C. Comparison of these data showed that under the above three
conditions 1) Qsweat of S was lower than that of F and VF; and 2) changes
in [L]sweat were different: in IR and Cst EX, [L]blood remained constant,
and [L]sweat decreased with heat load duration similarly in the three
subjects (the slopes of the two curves were not significantly different);
at Incr Ex, [L]blood increased and [L]sweat remained constant in S, F, and
VF (21.71 +/- 0.85, 16.75 +/- 0.99, 12.83 +/- 0.45 (SE) mM, respectively).
It was suggested that the high [L]blood and increased adrenergic
stimulation observed in Incr Ex could act on [L]sweat in relation to the
physical fitness level.
