Reduced Non-Exercise Activity Attenuates Negative Energy Balance in Mice Engaged in Voluntary Exercise.
AUTHORS
- PMID: 29511026 [PubMed].
ABSTRACT
Exercise alone is often ineffective for treating obesity despite the associated increase in metabolic requirements. Decreased non-exercise physical activity has been implicated in this resistance to weight loss, but the mechanisms responsible are unclear. We quantified the metabolic cost of non-exercise, or “off-wheel”, activity (OWA) and voluntary wheel running (VWR) and examined whether changes in OWA during VWR altered energy balance in chow-fed C57BL/6J mice (n=12). Energy expenditure (EE), energy intake, and behavior (VWR and OWA) were continuously monitored for four days with locked running wheels followed by nine days with unlocked running wheels. Unlocking the running wheels increased EE as a function of VWR distance. Metabolic cost of exercise (MCE; kcal per meter traveled) was negatively associated with VWR. Unlocking the wheel led to a negative energy balance, but also decreased OWA, which was predicted to mitigate the expected change in energy balance by ∼45%. A novel behavioral circuit involved repeated bouts of VWR and roaming was discovered. Repeated bouts of VWR and MCE together explained 80% of the variance in VWR distance between individual mice. The integrated analysis described here reveals that weight loss effects of voluntary exercise can be countered by a reduction in non-exercise activity.
Exercise alone is often ineffective for treating obesity despite the associated increase in metabolic requirements. Decreased non-exercise physical activity has been implicated in this resistance to weight loss, but the mechanisms responsible are unclear. We quantified the metabolic cost of non-exercise, or “off-wheel”, activity (OWA) and voluntary wheel running (VWR) and examined whether changes in OWA during VWR altered energy balance in chow-fed C57BL/6J mice (n=12). Energy expenditure (EE), energy intake, and behavior (VWR and OWA) were continuously monitored for four days with locked running wheels followed by nine days with unlocked running wheels. Unlocking the running wheels increased EE as a function of VWR distance. Metabolic cost of exercise (MCE; kcal per meter traveled) was negatively associated with VWR. Unlocking the wheel led to a negative energy balance, but also decreased OWA, which was predicted to mitigate the expected change in energy balance by ∼45%. A novel behavioral circuit involved repeated bouts of VWR and roaming was discovered. Repeated bouts of VWR and MCE together explained 80% of the variance in VWR distance between individual mice. The integrated analysis described here reveals that weight loss effects of voluntary exercise can be countered by a reduction in non-exercise activity.
Tags: 2018