Background: Physical inactivity (PIA) can negatively impact health and maybe development. Less is understood regarding the impact of physical inactivity during key stages of skeletal muscle development on adult health. Purpose: We propose that exposure to PIA early in life will impair growth rate, muscular function and tissue composition in adulthood. Methods: We exposed postnatal mice to 2 weeks of PIA in the form of hindlimb unloading (HU, N=10), small mouse cage (SMC, N=17) or standard mouse cage activity (CON, N=18) and followed their recovery for 4 months until adulthood at 5 months of age. Growth, grip strength and body composition were assessed once per month during the 4 mo recovery and physical function (grip strength, aerobic capacity on a treadmill), metabolic function (GTT) and muscle size were tested once at 5 mo of age. Results: Growth rate was similar at 17.24±0.67 g, 17.83±4.31 g, and 17.28±3.62 g for CON, SMC and HU, respectively. Final lean mass was identical at 20.77±0.52 g, 20.88±1.07 g, and 20.75±0.99 g for CON, SMC and HU, respectively. Max grip strength was similar with 283±14, 321±26, and 356±30 g of force for CON, SMC and HU, respectively. Area under the curve and 2hr glucose during the GTT and muscle and liver weights were similar. Time to exhaustion on the treadmill was similar with 18.2±1.4 min, 16.8±1.3 min, and 17.5±2.6 min for CON, SMC and HU, respectively. Conclusion: Early postnatal mice subjected to PIA displayed similar growth rates, max grip strength, treadmill time, GTT responses and lean mass compared to control mice as adults. Mice exposed to early life inactivity are able to recover muscle and metabolic function in adulthood. Data are Mean± SEM.
Author(s): *Jevnikar E., Ben; *Bagg, M. Alexandra; *Kachulkin A., Anthony; *Richards E., Katie; Binion A., Rachael; Smith D., Austin; Schaab D., Ty; Reidy T., Paul
Advisor(s): Paul Reidy, Department of Kinesiology, Nutrition and Health
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