The purpose of this study was to determine whether aerobic fitness level would influence measurements of excess postexercise oxygen consumption (EPOC) and initial rate of recovery. Twelve trained [Tr; peak oxygen consumption (VO2 peak) = 53.3 +/- 6.4 ml . kg-1 . min-1] and ten untrained (UT; VO2 peak = 37.4 +/- 3.2 ml . kg-1 . min-1) subjects completed two 30-min cycle ergometer tests on separate days in the morning, after a 12-h fast and an abstinence from vigorous activity of 24 h. Baseline metabolic rate was established during the last 10 min of a 30-min seated preexercise rest period. Exercise workloads were manipulated so that they elicited the same relative, 70% VO2 peak (W70%), or the same absolute, 1.5 l/min oxygen uptake (VO2) (W1.5), intensity for all subjects, respectively. Recovery VO2, heart rate (HR), and respiratory exchange ratio (RER) were monitored in a seated position until baseline VO2 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 magnitude (Tr: W70% = 3.2 +/- 1.0 liters O2, 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 EPOC accumulation in the W70% trial is attributed to the parallel decline in absolute VO2 during most of the initial recovery period. Tr subjects had faster relative decline during the fast-recovery phase, however, when a correction for their higher exercise VO2 was taken. Postexercise VO2 was lower for Tr group for nearly all of the W1.5 trial and particularly during the fast phase. Recovery HR kinetics were remarkably similar for both groups in W70%, but recovery was faster for Tr during W1.5. RER values were 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 the same relative or same absolute work rate.
SummaryBody composition and resting metabolic rate (RMR) were measured in 4 spinal cord injured (SCI) paraplegic men. The level of lesion ranged from T4 to Ll, and the duration of disability averaged 7'4 ± 3'3 (SEM) years. Hydrodensitometry was used to determine percent body fat, fat mass and lean body mass (LBM). RMR was measured following a 12-hour fast and 24 hours post-exercise using a ventilated hood. RMR was also predicted from LBM values based on the equation of Cunningham (1980). Results of the body composition measurements indicated a greater than average amount of body fat for men of this age group. RMR and LBM were significantly correlated (r = 0'98, P < 0'02). However, measured RMR values were lower than predicted in 3 of the 4 subjects, especially when LBM was relatively low. Further investigation into the relationship between LBM and RMR in SCI individuals is warranted using a larger sample size and with subjects representing a wide range of lesion level.Key words: Spinal cord injury; Paraplegia; Resting metabolic rate; Body composition.Results of extensive epidemiological research have led to the identification of several factors which increase the risk of developing coronary heart disease. One of these factors is obesity (Hubert et al., 1983). Increased levels of stored body fat are the result of a positive energy balance, which occurs when energy intake exceeds energy expenditure. Whereas energy intake is dependent on food ingestion, the major components of energy expenditure include resting metabolic rate (RMR), dietary induced thermogenesis, and physical activity. Recent evidence shows that, in many cases, increasing levels of body fat are more closely related to decreases in energy expenditure rather than to increased energy intake (Keen et al., 1979; Stunkard and Penick, 1979).In sedentary popUlations, RMR is the greatest contributor to energy expenditure, estimated by some to account for up to 80% of the total daily energy requirement (Tremblay et al., 1985). Because of the extremely sedentary lifestyle of spinal cord
Exercise prevented a decline in TBBMC seen in the nonexercisers. On the other hand, exercise in oral contraceptive users prevented the increase observed in the spine of the nonexercise plus OCont group.
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