Journal of Applied Physiology, Vol 79, Issue 1 47-54, Copyright © 1995 by American Physiological Society
Climate-related corrections for improved estimation of energy expenditure from heart rate in children
H. Hebestreit, O. Bar-Or, C. McKinty, M. Riddell and P. Zehr
Children's Exercise and Nutrition Centre, Chedoke Hospital, McMaster University, Hamilton, Ontario, Canada.
The purpose of this study was to determine the relationship between
children's heart rate (HR) and climatic heat stress at several O2 uptake
(Vo2) levels and to construct equations and nomograms for an improved
estimation of energy expenditure (EE) from HR monitoring. On four occasions
12 boys and 8 girls (8-11 yr) cycled for 5 min each at 35, 55, and 75% of
peak Vo2 (random order), with rest periods in between, in a climatic
chamber. The randomly assigned conditions were 22 degrees C dry bulb
temperature, 50% relative humidity (RH); 28 degrees C, 55% RH; 32 degrees
C, 52% RH; or 35 degrees C, 58% RH. HR and Vo2 were determined during the
final 2 min of rest and exercise bouts. HR measured at a dry bulb
temperature (T) (HRmeas) was then related to a HR at 22 degrees C that
would have been expected to occur at an identical Vo2 (HRcalc22) by using
individual 22 degrees C HR-Vo2 regression lines. HRcalc22 could be
estimated from HRmeas.[1.175032-(0.007956.T)], with a mean error of
prediction for the entire group < 1.5 beats/min for each temperature.
The following conclusions were drawn: 1) children's HR at a given Vo2
increases linearly with ambient temperature at 22-35 degrees C, 50-60% RH;
and 2) HR can be corrected for the influence of climate in groups of
children resting and exercising at the above conditions, thereby reducing
the error of estimating EE from HR.
