Study: Intense Exercise Episode Reduces Physical Activity and Body Temperature, Leading to Weight Gain
Exercise is often recommended for weight loss, yet a recent animal study from the University of Tsukuba suggests that intense exercise sessions might reduce subsequent physical activity and body temperature, potentially leading to weight gain. This effect may be due to disruptions in the circadian rhythm of the stress hormone corticosterone, affecting the synchronization between physical activity and body temperature.
While exercise offers many health benefits, its impact on weight loss can sometimes be less effective than anticipated. This might be due to reduced physical activity following exercise, though the underlying mechanism is not yet fully understood.
Corticosterone, a stress hormone, follows a circadian rhythm, with low levels at bedtime and peaks upon waking, regulating physical and mental activity levels. Researchers hypothesized that even a single high-intensity exercise session could disrupt this rhythm, reducing physical activity and heat production, thus diminishing weight loss effects.
To test this, mice were divided into three groups: high-intensity exercise, moderate-intensity exercise, and rest. Researchers monitored the mice’s physical activity and core body temperature—an index of heat production—before and after exercise. The study, published in Medicine & Science in Sports & Exercise, found that the high-intensity exercise group showed significant reductions in physical activity and core body temperature post-exercise, despite no changes in food intake, leading to weight gain.
Additionally, the researchers noted a disruption in the synchrony between physical activity and body temperature. They confirmed a positive correlation: relatively low corticosterone levels during wake times were associated with decreased physical activity.
The findings suggest that a single session of high-intensity exercise can disrupt the circadian rhythm of corticosterone, resulting in reduced physical activity, lower body temperature, and weight gain.
This study underscores the importance of considering not only the calories burned during exercise but also the subsequent activity levels and circadian rhythm when designing effective weight loss exercise regimens.
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