AGE AND EXCESS POSTEXERCISE OXYGEN CONSUMPTION 74

Abstract

It has been well-documented that metabolic rate both at rest and during maximal intensity exercise declines as one ages. However, energy expenditure during recovery from exercise has not been studied. We examined the magnitude and duration of excess postexercise oxygen consumption (EPOC) in three age groups, i.e., 18-25 yr (Y), 35-45 yr (M), and 55-67 yr (O). Volunteers were 45 men considered to be at low risk for cardiovascular disease according to ACSM(1995) guidelines and were evenly distributed among the age groups. They reported to the lab in the early morning after an overnight fast and refraining from strenuous physical activity for 36 h. Baseline VO2 was measured during the last 10 min of a 30 min seated rest. Subjects walked on a treadmill at 4.8 km h-1 until they expended 837 kJ (200 kcal). Grade was adjusted so that intensity was 60% of their measured VO2 max. Following a 1 min cool down at 2.7 km h-1 and 0% grade, subjects were seated until a 5 min average of VO2 was within ±.01 1 min-1 of the baseline value. ANOVA (Tukey post hoc) showed that VO2 max (ml kg-1 min-1) was higher (p<.001) in Y(X=53.7±7.2 SD) than M (45.5±8.6) and O (38.8±9.9). Baseline VO2 was significantly higher (p<.04) in Y (3.7±0.5) than O (3.2±0.6) but not M (3.3±0.5). EPOC duration (min) was similar among the groups (Y=24.9±10.4, M=23.3±9.9. O=21.3±11.8), however, Y had a greater (p<.03) EPOC magnitude(57.8±33.1 kJ) than M (39.3±19.3) and O (33.5±18.8). The findings indicate that the time it takes to recover from moderate intensity and duration exercise does not differ across age groups. However, energy expended during the EPOC period was diminished across the age span, implying that the rate of recovery energy expenditure may slow as one ages. Additionally, our results agree with what has been previously reported regarding the decrease in VO2 at rest and during maximal exercise across age groups. More work should be done to substantiate these findings.