ARTICLES
Effect of duration of exercise on excess postexercise O2 consumption
R. Bahr, I. Ingnes, O. Vaage, O. M. Sejersted and E. A. Newsholme
[SIZE=-1][/SIZE]This study was undertaken to determine the effect of exercise duration on the time course and magnitude of excess postexercise O2 consumption (EPOC). Six healthy male subjects exercised on separate days for 80, 40, and 20 min at 70% of maximal O2 consumption on a cycle ergometer. A control experiment without exercise was performed. O2 uptake, respiratory exchange ratio (R), and rectal temperature were monitored while the subjects rested in bed 24 h postexercise. An increase in O2 uptake lasting 12 h was observed for all exercise durations, but no increase was seen after 24 h. The magnitude of 12-h EPOC was proportional to exercise duration and equaled 14.4 +/- 1.2, 6.8 +/- 1.7, and 5.1 +/- 1.2% after 80, 40, and 20 min of exercise, respectively. On the average, 12-h EPOC equaled 15.2 +/- 2.0% of total exercise O2 consumption (EOC). There was no difference in EPOC:EOC for different exercise durations. A linear decrease with exercise duration was observed in R between 2 and 24 h postexercise. No change was observed in recovery rectal temperature. It is concluded that EPOC increases linearly with exercise duration at a work intensity of 70% of maximal O2 consumption.
: Med Sci Sports Exerc. 1992 Jan;24(1):66-71.
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Effect of supramaximal exercise on excess postexercise O2 consumption.[/SIZE]
Bahr R,
Gronnerod O,
Sejersted OM.
Department of Physiology, National Institute of Occupational Health, Oslo, Norway.
This study was undertaken to determine the effect of high intensity exercise on the time course and magnitude of excess postexercise O2 consumption (EPOC). Six healthy male subjects performed three intermittent 2-min exercise bouts on a cycle ergometer at 108% of VO2max with 3-min rest periods (3 x 2 min). O2 uptake, blood lactate, plasma catecholamines, and rectal temperature were measured while the subjects rested in bed for 14 h postexercise, and the results were compared with those of an identical control experiment without exercise. In addition, they were studied on two separate days for 2 h after only two (2 x 2 min) or one (1 x 2 min) exercise bout. O2 uptake was significantly increased for 4 h after 3 x 2 min exercise, for 60 min after 2 x 2 min, and for 30 min after 1 x 2 min exercise. EPOC was 5.6 +/- 0.41 (1 x 2 min), 6.7 +/- 0.41 (2 x 2 min), and 16.3 +/- 3.01 (3 x 2 min), respectively. Over the first hour postexercise, EPOC was linearly related to the change in blood lactate and plasma norepinephrine. However, after exhaustive supramaximal exercise O2 consumption was significantly increased for 4 h, whereas blood lactate and plasma norepinephrine concentrations were significantly increased for only 2 h.
Sports Med. 2003;33(14):1037-60.
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Effect of exercise intensity, duration and mode on post-exercise oxygen consumption.[/SIZE]
Borsheim E,
Bahr R.
Norwegian University of Sport and Physical Education, Oslo, Norway.
[email protected]
In the recovery period after exercise there is an increase in oxygen uptake termed the 'excess post-exercise oxygen consumption' (EPOC), consisting of a rapid and a prolonged component. While some studies have shown that EPOC may last for several hours after exercise, others have concluded that EPOC is transient and minimal. The conflicting results may be resolved if differences in exercise intensity and duration are considered, since this may affect the metabolic processes underlying EPOC. Accordingly, the absence of a sustained EPOC after exercise seems to be a consistent finding in studies with low exercise intensity and/or duration. The magnitude of EPOC after aerobic exercise clearly depends on both the duration and intensity of exercise. A curvilinear relationship between the magnitude of EPOC and the intensity of the exercise bout has been found, whereas the relationship between exercise duration and EPOC magnitude appears to be more linear, especially at higher intensities. Differences in exercise mode may potentially contribute to the discrepant findings of EPOC magnitude and duration. Studies with sufficient exercise challenges are needed to determine whether various aerobic exercise modes affect EPOC differently. The relationships between the intensity and duration of resistance exercise and the magnitude and duration of EPOC have not been determined, but a more prolonged and substantial EPOC has been found after hard- versus moderate-resistance exercise. Thus, the intensity of resistance exercise seems to be of importance for EPOC. Lastly, training status and sex may also potentially influence EPOC magnitude, but this may be problematic to determine. Still, it appears that trained individuals have a more rapid return of post-exercise metabolism to resting levels after exercising at either the same relative or absolute work rate; however, studies after more strenuous exercise bouts are needed. It is not determined if there is a sex effect on EPOC. Finally, while some of the mechanisms underlying the more rapid EPOC are well known (replenishment of oxygen stores, adenosine triphosphate/creatine phosphate resynthesis, lactate removal, and increased body temperature, circulation and ventilation), less is known about the mechanisms underlying the prolonged EPOC component. A sustained increased circulation, ventilation and body temperature may contribute, but the cost of this is low. An increased rate of triglyceride/fatty acid cycling and a shift from carbohydrate to fat as substrate source are of importance for the prolonged EPOC component after exhaustive aerobic exercise. Little is known about the mechanisms underlying EPOC after resistance exercise.
