The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)


Skeletal effects of physical activity differ between populations

IAN J. WALLACE1, STEFAN JUDEX2 and BRIGITTE DEMES3.

1Anthropology, Stony Brook University, 2Biomedical Engineering, Stony Brook University, 3Anatomical Sciences, Stony Brook University

March 26, 2015 3:15, Grand Ballroom E/F/G Add to calendar

The effects of physical activity on skeletal structure and strength are frequently observed to vary from one individual to the next. Here, we examine whether such variation also exists at the population level. An experiment was conducted involving mice from two outbred stocks that have been reproductively isolated for >100 generations (Hsd:ICR, Crl:CD1). Growing females from each stock were either treated with a treadmill-running regimen for 1 month or served as controls. Home-cage activity of all animals was monitored during the experiment. Limb forces were recorded to verify that they were similar in the two stocks. After the experiment, micro-CT was used to quantify cortical and trabecular bone structure in the tibial mid-diaphysis and proximal metaphysis, respectively, and mechanical testing was used to determine diaphyseal strength. Among Hsd:ICR mice, running led to significant improvements in diaphyseal bone quantity, structural geometry, and mechanical strength, as well as enhanced trabecular bone morphology. In contrast, among Crl:CD1 mice, the same running regimen had little effect on tibial structure and strength. In neither stock was body mass, muscle mass, or cage activity different between runners and controls. Given that most environmental variables were controlled in the study, we suggest that the differential effects of exercise on the bones of Hsd:ICR and Crl:CD1 mice were due to genetic differences between stocks. Based on these results, when analyzing skeletal structure among past humans, it should be kept in mind that the ‘functional signal’ in bones from different populations could vary despite similar activity patterns during life.

Funded primarily by the L.S.B. Leakey Foundation.