Synergy between time-restricted feeding and time-restricted running is necessary to shift the muscle clock in male...

Circadian disruption is an important factor driving the current-day high prevalence of obesity and type-2 diabetes. While the impact of incorrect timing of caloric intake on circadian disruption is widely acknowlegded, the contribution of incorrect timing of physical activity remains relatively understudied. Here, we modeled the incorrect timing of physical activity in nightshift workers in male Wistar rats, by restricting running wheel access to the innate inactive (light) phase (LR). Controls included no wheel access (NR); access only during the innate active (dark) period (DR); or unrestricted (ad libitum) access (ALR). LR did not shift the phase of the muscle or liver clock, but dampened the muscle clock amplitude. As our previous study demonstrated that light-phase restricted feeding did shift the liver clock, but made the muscle clock arrhythmic, we next combined the time restriction of wheel and food access to either the light phase (LRLF) or dark phase (DRDF). LRLF produced a ∼12 h shift in the majority of clock gene rhythms in both skeletal muscle and liver. On the other hand, DRDF was most effective in reducing body weight and the accumulation of fat mass. Therefore, in order to shift the muscle clock in male Wistar rats, synergy between the timing of feeding and physical activity is necessary. These findings may contribute to further improve the design of lifestyle strategies that try to limit metabolic misalignment caused by circadian disruption.