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  • Author: James E. Misner x
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Jennie A. Gilbert and James E. Misner

This study examined the metabolic response to a 763-kcal mixed meal at rest and during 30 min of exercise at 50% maximal oxygen consumption (VO2max) in 8 aerobically trained (AT), 8 resistance trained (RT), and 8 untrained (UT) subjects. Oxygen consumption (VO,) was measured minute by minute during 30 min of exercise by indirect calorimetry on 2 nonconsecutive days (postabsorptive exercise, PA; and postprandial exercise, PP). Total VO, consumed and total caloric expenditure during the PA and PP conditions were similar for the three groups, indicating that prior food intake did not affect energy expenditure during exercise. Consequently, TEM during exercise did not differ significantly among the groups. Respiratory exchange ratio (R) differed significantly only during the PA condition, with the AT group exhibiting significantly lower R values compared to the RT group, and significantly lower R values compared to the UT group. These data suggest that the consumption of a meal 30 min prior to exercise does not increase TEM during exercise in AT, RT, and UT subjects.

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Jill A. Kanaley, Richard A. Boileau, Benjamin H. Massey and James E. Misner

Changes in muscular efficiency as it relates to age were examined during inclined submaximal treadmill walking in 298 boys ages 7–15 years. Furthermore, the changes in efficiency with increased work intensity (67–90% V̇O2max) were studied. Efficiency was expressed as submaximal oxygen consumption (V̇O2) and was calculated mathematically as energy out/energy in = (vertical distance) (wt of subject)/(V̇O2 L • min−1) (kcal equivalent). Efficiency, calculated mathematically, was found to significantly increase (p<.01) with age, with the younger children (<9 yrs) being less efficient than the older children (13–15 yrs). These values ranged from 12.8% for the youngest boys (<9 yrs) to 16.4% for the oldest boys (13–15 yrs). In addition, efficiency significantly increased in a linear fashion (p<.01) during submaximal workloads within each age group. No significant interactions (p>.05) between age and workload were found. These values are lower than gross efficiency values during cycling previously reported in the literature for adults; however, they support earlier findings that children increase in efficiency with age and work intensity, regardless if expressed as efficiency or V̇O2 (ml • kg−1 •min−1). These findings suggest that parameters associated with growth and development may influence muscular efficiency with age.