Physical activity is known to decline with aging. We investigated the influence of genetic background on the declining physical activity level throughout the lifespan in four inbred strains of mice.
PURPOSE: To determine if genetic background significantly influences physical activity patterns throughout the lifespan, from seven to 90 weeks, in four inbred mouse strains.
METHODS: Forty-one, seven-week old male and female mice from four inbred strains (C57Bl/6J, CBA/J, DBA/2J, and SWR/J) were individually housed with a running wheel and provided water and standard chow ad libitum. Daily physical activity, as assessed by voluntary running wheel activity, was measured with a sensor and digital odometer.
RESULTS: Daily duration, distance, and average running speed were different between strains across the lifespan (p<0.0001). Daily duration and distance decreased from seven to 90 weeks of age (p<0.01). SWR/J mice averaged greater activity durations than the C57Bl/6J and DBA/2J mice, and greater activity distances compared to DBA/2J mice (p<0.0001). C57Bl/6J mice averaged greater daily running speeds compared to the other strains (p<0.0001). Broad-sense heritability estimations for the strains across the 84-week lifespan increased significantly for each activity variable from seven weeks to mid-life then significantly declined to the end of life (p<0.05).
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CONCLUSIONS : Broad-sense heritability estimations differed significantly across the lifespan, peaking at midlife for each physical activity variable. Our findings suggest genetic background varies as it significantly influences the decline in physical activity throughout the lifespan.
Supported by National Institutes of Health Grant AG-022417 (M.J. Turner) and UNC Charlotte Faculty Grant Program (Turner, Hubbard-Turner, Wikstrom).
