Effects of a 12 -week endurance exercise training program on resting metabolic rate, thermic effect of a meal, and excess post -exercise oxygen consumption
The purpose of the present study was to examine the effects of a 12-week endurance exercise training on resting metabolic rate (RMR), thermic effect of a meal (TEM), and excess post-exercise oxygen consumption (EPOC), and to provide insights into mechanisms by determining several blood hormones and substrates responsible for metabolic alterations consequent to exercise training. Nineteen untrained male subjects, aged 18–32 yrs, were randomly assigned to one of two groups, i.e., exercise training group (EX) or control group (CON). All subjects participated in a 45-min RMR test, a 180-min TEM test, and a EPOC test following an exercise for 30 min at 70% VO2max at pre-intervention test, followed by 12 weeks of intervention. Upon the completion of intervention, RMR, TEM, and EPOC were measured. Subjects in the EX group completed two EPOC sessions at post-intervention test, i.e., same absolute intensity trials and same relative intensity trials. Epinephrine, norepinephrine, total and free thyroxine, insulin (INS), cortisol, free fatty acids (FFA), blood glucose and/or blood lactate were determined during RMR, TEM, and EPOC tests. No significant change in RMR was found in the EX group, whereas RMR decreased significantly in the CON group. The mechanism for the decreased RMR in the CON group was uncertain. The results suggest that 12 weeks of endurance exercise training program failed to increase RMR; however, exercise training might have prevented a decline in RMR. TEM increased significantly following the 12-week exercise training as post-prandial INS sensitivity and/or glucose absorption may have increased with training. The magnitude of EPOC decreased during the same absolute intensity trial following 12 weeks of exercise training, indicating that exercise training improved control of metabolic stress during recovery from a bout of exercise. During the same relative intensity trial, no significant change in the EPOC response was found, suggesting that EPOC varies as a function of relative intensity. It was concluded that 12 weeks of endurance exercise training increased post-absorptive and post-prandial thermogenesis and improved metabolic efficiency during recovery from a bout of exercise.
Sedlock, Purdue University.
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