Abstract
To assess the effects of starting or stopping leg cooling on the thermoregulatory
responses during exercise, 60 min of cycling exercise at 30% of maximal oxygen uptake
was performed under 4 conditions using tube trouser perfused with water at 10°C; no
leg cooling (NC), starting of leg cooling after 30 min of exercise (delayed cooling,
DC), continuous leg cooling (CC), and stopping of continuous leg cooling after 30 min
of exercise (SC) at an environmental temperature of 28.5°C. During exercise under
the DC conditions, an instantaneous increase in the esophageal temperature (Tes), a suppression of the cutaneous vascular conductance at the forearm (%CVC), and
a decrease in the mean skin temperature (Tsk) were observed after leg cooling. The total sweat loss (Δm
sw,tot) was lower under the DC than the NC condition. In the SC study, however, the Tes remained constant, while the %CVC increased gradually after leg cooling was stopped,
and the Δm
sw,tot was greater than that under the CC condition. These results suggest that during exercise,
rapid skin cooling of the leg may cause an increase in core temperature, while also
enhancing thermal stress. However, stopping skin cooling did not significantly affect
the core temperature long-term, because the skin blood flow and sweat rate subsequently
increased.
Key words
water-perfused trouser - body cooling - cutaneous vascular conductance - sweat loss
