EXCESS POSTEXERCISE OXYGEN-CONSUMPTION AND RECOVERY RATE IN TRAINED AND UNTRAINED SUBJECTS

The purpose of this study was to determine whether aerobic fitness lev el would influence measurements of excess postexercise oxygen consumpt ion (EPOC) and initial rate of recovery. Twelve trained [TT; peak oxyg en consumption ((V) over dot O-2 peak) = 53.3 +/- 6.4 ml.kg(-1).min(-1 )] and ten untrained (UT; (V) over dot O-2 peak = 37.4 +/- 3.2 ml.kg(- 1).min(-1)) subjects completed two 30-min cycle ergometer tests on sep arate days in the morning, after a 12-h fast and an abstinence from vi gorous activity of 24 h. Baseline metabolic rate was established durin g the last 10 min of a 30-min seated preexercise rest period. Exercise workloads were manipulated so that they elicited the same relative, 7 0% (V) over dot O-2 peak (W70%), or the same absolute, 1.5 l/min oxyge n uptake ((V) over dot O-2) (W1.5), intensity for all subjects, respec tively. Recovery (V) over dot O-2, heart rate (HR), and respiratory ex change ratio (RER) were monitored in a seated position until baseline (V) over dot O-2 was reestablished. Under both exercise conditions, Tr had shorter EPOC duration (W70% = 40 +/- 15 min, W1.5 = 21 +/- 9 min) than UT (W70% = 50 +/- 14 min; W1.5 = 39 +/- 14 min), but EPOC magnit ude (Tr: W70% = 3.2 +/- 1.0 liters O-2, W1.5 = 1.5 +/- 0.6 liters O-2; UT: W70% = 3.5 +/- 0.9 liters O-2, W1.5 = 2.4 +/- 0.6 liters O-2) was not different between groups. The similarity of Tr and UT EPOC accumu lation in the W70% trial is attributed to the parallel decline in abso lute (V) over dot O-2 during most of the initial recovery period. Tr s ubjects had faster relative decline during the fast-recovery phase, ho wever, when a correction for their higher exercise (V) over dot O-2 wa s taken. Postexercise (V) over dot O-2 was lower for Tr group far near ly all of the W1.5 trial and particularly during the fast phase. Recov ery HR kinetics were remarkably similar for both groups in W70%, but r ecovery was faster for Tr during W1.5. RER values were at or below bas eline throughout much of the recovery period in both groups; with UT e xperiencing larger changes than Tr in both trials. These findings indi cate that Tr individuals have faster regulation of postexercise metabo lism when exercising at either the same relative or same absolute work rate.