Substrate oxidation and energy expenditure during and one hour after isocaloric exercise bouts of different intensity

Raul Y Zubia, University of Texas at El Paso

Abstract

A healthy body weight and percentage body fat are important to reduce the risk of obesity-related diseases. Physical activity contributes to weight loss and fat mass reduction. Research indicates that total energy expenditure and the percent contribution of fat to total energy expenditure during and after exercise (recovery) is similar when moderately trained individuals perform an isocaloric bout of exercise at 45% or 65% of maximal oxygen uptake (VO2max); however, this has not been investigated for sedentary overweight individuals. The purpose of this investigation was to compare the effects of two isocaloric exercise bouts of different intensity on total energy expenditure and percent contribution of fat and carbohydrates (CHO) to total energy expenditure during and one hour after exercise in sedentary, healthy, overweight (BMI 25-29.9 kg/m2) males. Fifteen males (age: 24.9 ± 1.2 y; mass: 83.5 ± 2.4 kg; BMI: 27.2 ± 0.5 kg/m 2) performed treadmill walking at 45% (moderate intensity) and 65% VO2max (high intensity) equivalent to 300 kcal followed by one hour of recovery in a recumbent position. Expired gases were measured continuously during exercise and recovery, and substrate utilization was determined using respiratory exchange ratio (RER). A two-way ANOVA with repeated measures was used to assess RER, fat and CHO oxidation as well as total energy expenditure before, during, and after exercise. Statistical significance was set at α = 0.05. The mean exercise RER was significantly lower (P < 0.05) during the moderate intensity trial (0.86 ± 0.01) than the high intensity trial (0.92 ± 0.01). Recovery, mean RER values were similar between trials (0.85 ± 0.01 and 0.84 ± 0.01 for moderate and high intensity, respectively; P > 0.05). Total energy expenditure (exercise and recovery combined) was significantly (P < 0.05) lower for the moderate intensity trial (382.0 ± 2.5 kcal) than the high intensity trial (391.2 ± 2.6 kcal). However, combined exercise and recovery calories derived from fat were significantly greater for the moderate than the high intensity trial (179.5 ± 10.7 kcal and 122.2 ± 10.4 kcal, respectively, P < 0.001). It was concluded that for sedentary overweight males, exercising at moderate intensities may produce greater fat mass reduction benefits than exercising at higher intensities. ^

Subject Area

Health Sciences, Recreation|Biology, Physiology

Recommended Citation

Zubia, Raul Y, "Substrate oxidation and energy expenditure during and one hour after isocaloric exercise bouts of different intensity" (2008). ETD Collection for University of Texas, El Paso. AAI1457846.
http://digitalcommons.utep.edu/dissertations/AAI1457846

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