Excess postexercise oxygen consumption and recovery rate in trained and untrained subjects

Short, Kevin R., and Darlene A. Sedlock. Excesspostexercise oxygen consumption and recovery rate in trained anduntrained subjects. J. Appl. Physiol.83(1): 153-159, 1997.The purpose of this study was todetermine whether aerobic fitness level would influence measurements ofexcess postexercise oxygen consumption (EPOC) and initial rate ofrecovery. Twelve trained [Tr; peak oxygen consumption(O_{2 peak}) = 53.3 ± 6.4 ml · kg¹ · min¹]and ten untrained (UT;O_{2 peak} = 37.4 ± 3.2 ml · kg¹ · min¹)subjects completed two 30-min cycle ergometer tests on separate days inthe morning, after a 12-h fast and an abstinence from vigorous activityof 24 h. Baseline metabolic rate was established during the last 10 minof a 30-min seated preexercise rest period. Exercise workloads weremanipulated so that they elicited the same relative, 70%O_{2 peak} (W70%), orthe same absolute, 1.5 l/min oxygen uptake(O₂) (W1.5), intensity forall subjects, respectively. RecoveryO₂, heart rate (HR), andrespiratory exchange ratio (RER) were monitored in a seated positionuntil baseline O₂ wasreestablished. Under both exercise conditions, Tr had shorter EPOCduration (W70% = 40 ± 15 min, W1.5 = 21 ± 9 min) than UT(W70% = 50 ± 14 min; W1.5 = 39 ± 14 min), but EPOC magnitude(Tr: W70% = 3.2 ± 1.0 litersO₂, W1.5 = 1.5 ± 0.6 liters O₂; UT: W70% = 3.5 ± 0.9 liters O₂, W1.5 = 2.4 ± 0.6 liters O₂) was not different between groups. The similarity of Tr and UT EPOCaccumulation in the W70% trial is attributed to the parallel declinein absolute O₂ during mostof the initial recovery period. Tr subjects had faster relative declineduring the fast-recovery phase, however, when a correction for theirhigher exerciseO₂ was taken.Postexercise O₂ was lowerfor Tr group for nearly all of the W1.5 trial and particularly duringthe fast phase. Recovery HR kinetics were remarkably similar for bothgroups in W70%, but recovery was faster for Tr during W1.5. RER valueswere at or below baseline throughout much of the recovery period in both groups, with UT experiencing larger changes than Tr in both trials. These findings indicate that Tr individuals have faster regulation of postexercise metabolism when exercising at either thesame relative or same absolute work rate.