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

Results

Characteristics of the 10 subjects completing the study are summarized in Table 1. The young adult males in this study varied widely in body mass index, body composition, and aerobic fitness, and all successfully completed the total 47-min cycle ergometry exercise in the metabolic chamber.

Table 2 reports average workload, HR, oxygen consumption, and energy expenditure data for all subjects during the exercise bout. The relative HR and oxygen consumption data indicate that this exercise bout set at 57% Wmax was at a vigorous level, as defined by the American College of Sports Medicine.[1] Energy expenditure during the exercise bout was 6.1-fold greater than the corresponding energy expenditure on the rest day.

Table 3 summarizes the energy and macronutrient intakes and energy expenditure data during 24 h on rest and exercise days. A significantly higher energy intake occurred on the exercise compared with the rest day, with a mean increase of 659 ± 104 kcal·d−1 (P < 0.001). The percent of energy consumed as CHO and fat was slightly different on the exercise day; however, this difference corresponds to <0.6%. Total energy expenditure was greater on the exercise versus the rest day by 750 ± 121 kcal·d−1 (P < 0.001). On the rest day, energy intake was slightly below energy expenditure, with a mean difference of 38.0 ± 89.3 kcal·d−1. On the exercise day, energy intake was also slightly below energy expenditure by 129 ± 123 kcal·d−1.

Figure 1 contrasts energy expenditure for the exercise and rest days. The exercise bout resulted in a net energy expenditure of 519 ± 60.9 kcal (contrast in area under the curve, P < 0.001). Hour-by-hour analysis showed that energy expenditure was significantly elevated on the exercise day for 14.2 h after exercise, corresponding to an increase of 190 ± 71.4 kcal compared with the rest day. This increase in resting energy expenditure included 3.5 h of the early sleep period, accounting for 32.0 ± 39.3 kcal (P = 0.030).

Immediately after exercise, subjects sat quietly for 40 min, and the net energy expenditure during this period was 15.4 ± 12.8 kcal (P = 0.001). Subjects next were allowed to change clothes and clean themselves with a towel, and the net increase in energy expenditure during this period was 19.3 ± 16.0 kcal (P = 0.004). From this point in time to bedtime (a total of 9.7 h), the net increase in energy expenditure was 144 ± 49.9 kcal (P < 0.001). Preexercise periods did not differ between rest and exercise days, and subject movement recorded with the metabolic chamber infrared monitor was not different between exercise and rest days during this 9.7-h period (data not shown, P = 0.83).

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