Background: Physical inactivity has many detrimental effects on health, yet the impact of physical inactivity in early life on muscle health in adulthood remains unknown. Early postnatal malnutrition has prolonged effects into adulthood and we propose that early postnatal physical inactivity would have similar effects. Methods: To test this hypothesis we exposed postnatal mice (3-4 weeks old), to 14 days of physical inactivity (PIA) via hindlimb unloading (HU) and small mouse cage (SMC). Grip strength and body composition were assessed before and after the inactivity period. Muscle weights were collected after completing PIA or 7 day recovery period. Results: Body weights and lean mass in SMC and HU mice were significantly reduced compared to controls immediately after PIA. Fat mass was significantly higher in control and SMC mice compared to HU after PIA. Absolute maximum grip strength between weeks 3 and 5 was significantly reduced in SMC and HU mice after PIA. Aside from the tricep, all muscle weights collected among both SMC and HU mice was significantly less than control mice following PIA. Conclusion: Mice exposed to PIA demonstrated lower body weights, maximum grip strength, lean mass, and fat mass compared to control mice. HU mice demonstrated lower body weight, grip strength, and lean mass than SMC mice. Alterations in muscle and body composition, and grip strength suggest significant impairments in long term physical health.
Authors: Ben E. Jevnikar, Austin D. Smith, Alexandra M. Bagg, Katie E. Richards, Ty D. Schaab
Advisor: Paul Reidy, Kinesiology, Nutrition and Health
Austin Smith, Kinesiology, Nutrition & Health
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