title: 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.
authors: Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; gu_changgui@163.com hes@bu.edu J.H.Meijer@lumc.nl.
authors: Changgui
authors: C
authors: Gu
authors: Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands;
authors: Claudia P
authors: CP
authors: Coomans
authors: Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115; and.
authors: Kun
authors: K
authors: Hu
authors: Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115; and.
authors: Frank A J L
authors: FA
authors: Scheer
authors: Departments of Physics, Chemistry, Biomedical Engineering, and Physiology, Boston University, Boston, MA 02215 gu_changgui@163.com hes@bu.edu J.H.Meijer@lumc.nl.
authors: H Eugene
authors: HE
authors: Stanley
authors: Department of Molecular Cell Biology, Laboratory for Neurophysiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; gu_changgui@163.com hes@bu.edu J.H.Meijer@lumc.nl.
authors: Johanna H
authors: JH
authors: Meijer
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010805:Physical Conditioning, Animal; D013997:Time Factors
keywords: aging; behavioral activity; circadian rhythms; multiple timescales; wheel running