TY - JOUR
T1 - Changes In Heart Rate Variability Following Acclimation To Heat
AU - Frank, A.
AU - Belokopytov, M.
AU - Moran, D.
AU - Shapiro, Y.
AU - Epstein, Y.
PY - 2001
Y1 - 2001
N2 - We studied the sympatho-vagal balance during acclimation to heat in eight healthy individuals. The subjects, dressed in shorts and tennis shoes, underwent a 10 d procedure of acclimation. Daily exposure lasted 115 min—5 min rest followed by 2 bouts of 50 min exercise (walking on a treadmill at a work load of ~350 watt) separated by 10 min rest—at 40°C and 40% relative humidity. We analyzed the time and frequency domains of 256 R-R intervals, toward the end of the second bout of exercise, on the first and tenth days of acclimation. Typical changes for heat acclimation (a reduction in rectal temperature and heart rate, an increase in sweat rate) were observed. Concomitant to a decrease in the final heart rate on the tenth day, sympathetic tone increased. We suggest that, except for the chronotropic response, changes in the sympatho-vagal balance may reflect several adaptive mechanisms of the cardiovascular system. Peripheral factors rather than intrinsic cardiac factors are of relatively greater importance in the direct control of cardiac function.
AB - We studied the sympatho-vagal balance during acclimation to heat in eight healthy individuals. The subjects, dressed in shorts and tennis shoes, underwent a 10 d procedure of acclimation. Daily exposure lasted 115 min—5 min rest followed by 2 bouts of 50 min exercise (walking on a treadmill at a work load of ~350 watt) separated by 10 min rest—at 40°C and 40% relative humidity. We analyzed the time and frequency domains of 256 R-R intervals, toward the end of the second bout of exercise, on the first and tenth days of acclimation. Typical changes for heat acclimation (a reduction in rectal temperature and heart rate, an increase in sweat rate) were observed. Concomitant to a decrease in the final heart rate on the tenth day, sympathetic tone increased. We suggest that, except for the chronotropic response, changes in the sympatho-vagal balance may reflect several adaptive mechanisms of the cardiovascular system. Peripheral factors rather than intrinsic cardiac factors are of relatively greater importance in the direct control of cardiac function.
KW - HRV
KW - acclimation
KW - exercise heat stress
KW - sympatho-vagal balance
UR - http://www.scopus.com/inward/record.url?scp=0034972985&partnerID=8YFLogxK
U2 - 10.1515/JBCPP.2001.12.1.19
DO - 10.1515/JBCPP.2001.12.1.19
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C2 - 11414505
AN - SCOPUS:0034972985
SN - 0792-6855
VL - 12
SP - 19
EP - 32
JO - Journal of Basic and Clinical Physiology and Pharmacology
JF - Journal of Basic and Clinical Physiology and Pharmacology
IS - 1
ER -