Lack of exercise leads to significant and reversible loss of scale invariance in both aged and young mice

Abstract

In healthy humans and other animals, behavioral activity exhibits scale invariance over multiple timescales from minutes to 24 h, whereas in aging or diseased conditions, scale invariance is usually reduced significantly. Accordingly, scale invariance can be a potential marker for health. Given compelling indications that exercise is beneficial for mental and physical health, we tested to what extent a lack of exercise affects scale invariance in young and aged animals. We studied six or more mice in each of four age groups (0.5, 1, 1.5, and 2 y) and observed an age-related deterioration of scale invariance in activity fluctuations. We found that limiting the amount of exercise, by removing the running wheels, leads to loss of scale-invariant properties in all age groups. Remarkably, in both young and old animals a lack of exercise reduced the scale invariance in activity fluctuations to the same level. We next showed that scale invariance can be restored by returning the running wheels. Exercise during the active period also improved scale invariance during the resting period, suggesting that activity during the active phase may also be beneficial for the resting phase. Finally, our data showed that exercise had a stronger influence on scale invariance than the effect of age. The data suggest that exercise is beneficial as revealed by scale-invariant parameters and that, even in young animals, a lack of exercise leads to strong deterioration in these parameters.

Sleep, recovery, and metaregulation: explaining the benefits of sleep

“…Rodent studies have also shown that access to running wheels can substantially affect the distribution, amount, and architecture of vigilance states and activity across 24 hours, 151 , 152 as well as EEG SWA. 98 Notably, frontal predominance of SWA was enhanced after a period of waking without running wheel activity leading the authors to hypothesize that more diverse waking behaviors and activity led to a higher need for local or global “recovery”.…”

Stereotypic wheel running decreases cortical activity in mice

“…In this study, we performed continuous recordings of neuronal activity from two cortical regions in mice given free access to running wheels (RWs). Previously, it has been shown that spontaneous wheel running is associated with distinct changes in the architecture and distribution of vigilance states across 24 h, and leads to regional changes in waking and sleep EEG 27 28 29 30 . On the other hand, several studies performed in head-fixed animals showed that locomotion affects neuronal activity in a cortical region, and cell type-specific manner 6 7 8 9 13 .…”

Locomotor exercise and circadian rhythms in mammals

“…2). Indeed, locomotor activity has also been reported to improve rhythms both in aged mice [38] and in mutant strains with disrupted SCN intercellular synchrony [8], whilst a lack of exercise has been reported to reduce scale invariance of behavioural rhythms, a marker of general health [55]. Further, the timing of exercise within a lightdark cycle has been shown to be important for the degree of protection offered by exercise against weight gain on a high fat diet [56], and simulated shift-work desynchronises liver gene expression, disrupting metabolism [47].…”