Lower thermic effect of a meal post-exercise in aerobically trained and resistance-trained subjects

Despite the abundance of literature concerning the thermic effect of a test meal (TEM) at rest in trained and untrained subjects, there is little information available concerning the TEM post-exercise. Therefore, it was the purpose of this study to examine the metabolic response to a 763-kcal meal prior to 30 min of exercise at 50% VO_2max, in aerobically trained (AT, N = 8), resistance-trained (RT, N= 8), and untrained (UT, N = 8) subjects. Mean (±SEM) VO_2max was 60.7 ± 2.3 ml.kg^-1 ·min^-1, 52.9 ± 2.2 ml·kg^-1·min^-1, and 51.1 ± 2.2 ml.kg^–1.min^-1, for the AT, RT, and UT groups, respectively. Mean (±SEM) percent fat was 13.7 ± 1.2, 12.7 ± 1.9, and 16.9 ± 1.4 for the AT, RT, and UT groups, respectively. Post-exercise VO₂ was measured by indirect calorimetry every half hour, on two nonconsecutive days (post-absorptive (PA) post-exercise and post-prandial (PP) post-exercise) for 3 h. The total TEM (postexercise PP VO₂ minus post-exercise PA VO₂) was 4.86 ± 1.62, 5.22 ± 1.80, and 9.36 ± 5.081 for the AT, RT, and UT groups, respectively. The TEM post-exercise was significantly lower (P < 0.05) for the AT and RT groups compared with the UT group. Respiratory exchange ratio (R) differed significantly only during the PA post-exercise condition, with the AT group exhibiting significantly lower (P < 0.01) values compared with the RT and UT groups. PA post-exercise R for the RT group was not significantly different (P = 0.09) from the UT group. These data suggest that the consumption of a meal 30 min prior to exercise results in a lower TEM post-exercise in AT and RT subjects. However, the AT group may utilize a higher percentage of fat as substrate following post-absorptive exercise.