Temperature effects on ventilatory rate, heart rate, and preferred
pedal rate during cycle ergometry.
Leweke, Frank, Kurt Br[umlaut]uck, and Horst Olschewski.
Institute of Physiology, Justus Liebig University Giessen, D-35392
Giessen, Germany
APStracts 2:0167A, 1995.
According to the most customary exercise protocols core temperature
rises in parallel with work load (WL) and experimental time (TIME).
Physiological variables, however, may be related to each of these
factors. In order to investigate effects of WL independent of TIME
and body temperature (TEMP) we employed four moderate work loads in
4-min steps between 35 and 65% VO2peak in randomized order. In order
to investigate independent effects of TEMP the same work protocol was
performed both after resting in comfortable ambient temperature
(CONT) and after a double cold exposure (precooling test, PRET) where
core temperature (Tc) and the temperature set point are decreased by
approximately 0.6 and 0.3 degrees C, respectively. Eight male
subjects (24 +/- 1.9 yr, VO2peak 4.9 +/- 0.5 l/min) worked on a cycle
ergometer in a climatic chamber. Heart rate (HR) and breathing
frequency (BF) but not preferred pedal rate (PR) were positively
correlated to (Tc), the slopes amounting to 17 and 3.75 min-1/
degrees C for HR and BF, respectively. The regression appeared linear
over the whole temperature range and the regression lines were not
shifted by precooling. PR was increased by TIME, but PRET-CONT
differences of PR and Tc were inversely correlated (r = -0.50,
p<0.01). The effects of WL were highly significant on HR, VO2 and
rating of perceived exertion (RPE) but not on BF, PR and sweat rate.
The relation of RPE to HR was shifted by precooling. In conclusion,
during moderate cycle exercise, heart rate and breathing frequency
are linearly correlated to core temperature, whereas pedal rate is
increased by a thermoregulatory response to cold obscuring an opposed
temperature effect.
Received 17 May 1994; accepted in final form 18 April 1995.
APS Manuscript Number A476-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 2 May 1995.