Physical activity (PA) is a vital behavior to maximize health and wellness. Less is understood regarding the impact of physical inactivity on children, specifically during key stages of skeletal muscle development. We previously demonstrated that 2 weeks of extreme muscle tissue during 4-6 weeks of age causes a reduction in grip strength in adults (5 month mice). It remains unknown if a less extreme type of physical inactivity would have the same effect. We propose that, similar to malnutrition, exposure to a less extreme form of reduced activity early in life will impact function in adulthood. We exposed postnatal mice (1 month old) to physical inactivity in the form of reduced activity in a small mouse cage (SMC) shortly after weaning, and then let them age to adulthood (5 months of age). They were then tested for physical function (grip strength and aerobic capacity on a treadmill) and muscle size. Compared to similar aged controls, the mice in the small mouse cage during their period of physical inactivity (PIA) had significant differences in body weight during the last four days of PIA. There was no significant differences between control mice to SMC mice when looking at max grip strength, lean mass, fat mass, and weight of gastroc, triceps, TS, TA/EDL, Live, Soleus, and plantaris muscles relative to their body weight. A significant difference of a reduced total treadmill running time of the SMC mice vs. control mice was noted. Since treadmill testing is a strong predictor of health status, reduced functionality, and early mortality these findings of low aerobic capacity as a result of this minimal early life physical inactivity are concerning.
Author: Bagg, M. Alexandra; Jevnikar E., Ben; Richards E., Katie; Schaab D., Ty;
Advisor: Reidy T., Paul
Graduate Advisor: Smith D., Austin
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