A 45-minute Vigorous Exercise Bout Increases Metabolic Rate for 14 Hours

Amy M. Knab; R. Andrew Shanely; Karen D. Corbin; Fuxia Jin; Wei Sha; David C. Nieman

Disclosures

Med Sci Sports Exerc. 2011;43(9):1643-1648. 

In This Article

Abstract and Introduction

Abstract

Introduction: The magnitude and duration of the elevation in resting energy expenditure after vigorous exercise have not been measured in a metabolic chamber. This study investigated the effects of inserting a 45-min vigorous cycling bout into the daily schedule versus a controlled resting day on 24-h energy expenditure in a metabolic chamber.
Methods: Ten male subjects (age = 22–33 yr) completed two separate 24-h chamber visits (one rest and one exercise day), and energy balance was maintained for each visit condition. On the exercise day, subjects completed 45 min of cycling at 57% W max (mean ± SD = 72.8% ± 5.8% V̇O2max) starting at 11:00 a.m. Activities of daily living were tightly controlled to ensure uniformity on both rest and exercise days. The area under the energy expenditure curve for exercise and rest days was calculated using the trapezoid rule in the EXPAND procedure in the SAS and then contrasted.
Results: The 45-min exercise bout resulted in a net energy expenditure of 519 ± 60.9 kcal (P < 0.001). For 14 h after exercise, energy expenditure was increased 190 ± 71.4 kcal compared with the rest day (P < 0.001).
Conclusions: In young male subjects, vigorous exercise for 45 min resulted in a significant elevation in postexercise energy expenditure that persisted for 14 h. The 190 kcal expended after exercise above resting levels represented an additional 37% to the net energy expended during the 45-min cycling bout. The magnitude and duration of increased energy expenditure after a 45-min bout of vigorous exercise may have implications for weight loss and management.

Introduction

Measurement of the various components of energy expenditure including the resting metabolic rate (RMR) has improved our understanding of energy balance as it relates to human obesity. Accurate assessment of RMR requires sophisticated methodologies including direct and indirect calorimetry. Open-circuit indirect calorimetry Douglas bag systems and metabolic carts are most commonly used when measuring RMR, but measurement time is typically limited to 15–30 min and then extrapolated to 24-h periods. Whole-room indirect calorimeters (i.e., metabolic chambers) allow extended measurement of energy expenditure with tight control of energy intake and the daily schedule.

Studies using Douglas bag systems and metabolic carts have shown that 15–30 min of moderate to vigorous exercise causes a small increase in RMR that persists for a short time after exercise.[25] One study of 10 male triathletes, for example, showed that three separate cycling bouts of 20-, 30-, and 60-min duration and 75%, 50%, and 50% maximum aerobic capacity, respectively, resulted in 12–30 net calories expended more than 20–33 min after exercise.[25] Others report an extended increase in postexercise energy expenditure after just 20 min of cycling at 70% maximum aerobic capacity,[3] and differences between studies may be related to control of subject energy intake and daily activities. Several investigators emphasize that elevations in postexercise energy expenditure depend on the degree of homeostatic disturbance and that RMR is elevated especially after high-intensity long-duration exercise.[6,23] For example, rates for postexercise energy expenditure were elevated for 0.3, 3.3, and 10.5 h in six males cycling for 80 min at 29%, 50%, and 75% of maximum aerobic capacity.[4] Methods using indirect calorimetry have suggested that the magnitude of the elevation in energy expenditure after exercise is dependent on the intensity of the exercise;[15] thus, resolving the issue of the duration and magnitude of the increase in energy expenditure after exercise bouts is important when considering the potential effect on total 24-h energy expenditure.

Metabolic chambers have been used to investigate the effects of physical activity on substrate utilization[18,19,26] and 24-h energy expenditure.[21,24] However, few studies to date have analyzed the effects of physical activity on postexercise net energy expenditure during a 24-h period. Dionne et al.[9] investigated the effect of moderate-intensity exercise (50% V̇O2max for 60 min) on 24-h energy expenditure and substrate utilization in eight young healthy males and reported no difference in 24-h energy expenditure or respiratory quotient (RQ) between control and exercise sessions. Subjects exercised in the middle of the afternoon outside of the chamber and immediately ingested a milk shake that equaled the energy expended during exercise. These research design characteristics and the moderate intensity of the exercise bout may explain the reported results. Treuth et al.[29] reported an increase in 24-h energy expenditure when contrasting high- and low-intensity exercise bouts, but the research design did not include a rest day for the determination of the magnitude and duration of postexercise net energy expenditure.

This study investigated the effect of 45 min of vigorous cycling (57% W max or ~70% V̇O2max) on postexercise RMR as measured in a metabolic chamber, under tightly controlled conditions of daily living. The exercise session was conducted late in the morning and contrasted with a rest day to determine both the magnitude and duration of vigorous exercise on postexercise energy expenditure.

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