Translational Science: How experimental research has contributed to the understanding of spontaneous Physical Activity and Energy Homeostasis

Abstract — Spontaneous physical activity (SPA) consists of all daily living activities other than volitional exercise (e.g. sports and fitness-related activities). SPA is an important component of energy expenditure and may protect from overweight and obesity. Little is known about the biological regulation of SPA, but animal research has contributed significantly to expand our knowledge in this field. Studies in rodents have shown that SPA is influenced by nutrients and volitional exercise. High-fat diet seems to decrease SPA, which contributes to weigh gain. Volitional exercise may also reduce SPA, helping to explain the commonly reported low efficiency of exercise to cause weight loss, and highlighting the need to find a volume/intensity of exercise to maximize total daily energy expenditure. Animal studies have also allowed for the identification of some brain areas and chemical mediators involved in SPA regulation. These discoveries could enable the development of new therapeutics aiming to enhance SPA.Keywords: energy balance, free-living activity, volitional exercise, sedentary behavior.