Abstract
This study examined the effects of an acute bout of exercise of low-intensity on food intake and energy expenditure over four days in women taking oral contraceptives. Twenty healthy, active (n = 10) and inactive (n = 10) pre-menopausal women taking oral contraceptives completed two conditions (exercise and control), in a randomised, crossover fashion. The exercise experimental day involved cycling for one hour at an intensity equivalent to 50% of maximum oxygen uptake and two hours of rest. The control condition comprised three hours of rest. Participants arrived at the laboratory fasted overnight; breakfast was standardised and an ad libitum pasta lunch was consumed on each experimental day. Participants kept a food diary to measure food intake and wore an Actiheart to measure energy expenditure for the remainder of the experimental days and over the subsequent 3 days. There was a condition effect for absolute energy intake (exercise vs. control: 3363 ± 668 kJ vs. 3035 ± 752 kJ; p = 0.033, d = 0.49) and relative energy intake (exercise vs. control: 2019 ± 746 kJ vs. 2710 ± 712 kJ; p < 0.001, d = −1.00) at the ad libitum lunch. There were no significant differences in energy intake over the four days in active participants and there was a suppression of energy intake on the first day after the exercise experimental day compared with the same day of the control condition in inactive participants (mean difference = −1974 kJ; 95% CI −1048 to −2900 kJ, p = 0.002, d = −0.89). There was a group effect (p = 0.001, d = 1.63) for free-living energy expenditure, indicating that active participants expended more energy than inactive participants during this period. However, there were no compensatory changes in daily physical activity energy expenditure. These results support the use of low-intensity aerobic exercise as a method to induce a short-term negative energy balance in inactive women taking oral contraceptives.
Highlights
MethodsParticipantsWith institutional ethics approval, twenty-nine healthy women were recruited
Regular exercise is prophylactic and promotes metabolic adaptations that improve physical and mental health
Post hoc analysis did not show any differences in the active group and inactive participants had only a decrease in energy intake on the first day after the exercise experimental day compared with the same day of the control condition
Summary
ParticipantsWith institutional ethics approval, twenty-nine healthy women were recruited. The mean score for the SPAF for the active and inactive groups were 16.8 ± 6.8 and 17.6 ± 5.8, respectively with no participant scoring greater than 28 (scores greater than 30 are indicative of moderate premenstrual symptoms) (Allen et al, 1991). Participants’ mean score for cognitive restraint based on the revised version of the Three-Factor Eating Questionnaire (Karlsson, Persson, Sjöström, & Sullivan, 2000) was 11.6 ± 3.1 for the active and 10.5 ± 3.3 for the inactive group with all participants having a cognitive restraint score lower than 18. Veracity of selfreported measures of physical activity was confirmed with a posteriori analysis of the Actiheart data. These data calculated individual Physical Activity Level (PAL) by dividing participants’ total energy expenditure in a 24-hour period by their basal metabolic rate. The active group had a mean PAL of 1.79 ± 0.13 and the inactive 1.56 ± 0.15, which according to the classification of lifestyles in relation to PAL in adults (WHO, 2004) identified them as having an active to moderately active lifestyle (1.70–1.99) and a sedentary to light activity lifestyle (1.40–1.69), respectively
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