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% VO2max, in aerobically trained (AT, N = 8), resistance-trained (RT, N = 8), and untrained (UT, N = 8) subjects. Mean (+/- SEM) VO2max 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 (post-exercise PP VO2 minus post-exercise PA VO2) was 4.86 +/- 1.62, 5.22 +/- 1.80, and 9.36 +/- 5.08 I for the AT, RT, and UT groups, respectively. The TEM post-exercise was significantly lower (P less than 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 less than 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.(ABSTRACT TRUNCATED AT 250 WORDS)