Previous studies have suggested that submaximal energy expenditure relative to body
mass during weight-bearing exercise may be greater in boys compared to girls. This
two-part study examined a) gender-related five-year longitudinal changes in submaximal
walking economy and b) gross, net,, and delta muscle work efficiency during submaximal
cycle exercise in a cross-sectional analysis of boys and girls. In the longitudinal
study, the influence of pre-exercise metabolic expenditure, stride frequency, and
substrate utilization (by RER) on changes in economy were examined. During the five
years, mean VO2 per kg during submaximal treadmill walking (measured at 8 % slope, 3.25 mph) decreased
16 % in girls and 13 % in boys (p>0.05 for gender). Likewise, no significant gender
differences were observed in decline of stride frequency over time. RER values were
similar between sexes except in the final two years when girls had significantly greater
values than the boys. No gender-related differences were observed in any measure of
muscle work efficiency. This study failed to reveal significant gender differences
in utilization of energy during submaximal exercise in children.
Key words
Exercise economy - treadmill testing
