The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

The effects of physical activity and health status on bone strength development


Department of Anthropology, University of Tennessee, Knoxville

Saturday 4:15-4:30, Galleria North Add to calendar

Cortical bone adapts to environmental influences by altering its mass and shape at both macroscopic and microscopic scales. These alterations, in turn, influence bone strength. Biological anthropologists often examine cortical bone to infer either biomechanical loading (caused by physical activity) or metabolic status (an indicator of health) from human skeletal remains. However, this methodological approach is problematic, because these factors do not act independently but rather interact in shaping bone morphology and strength. Although the existence of such an interaction is acknowledged in theory, it has yet to be thoroughly assessed in humans. An understanding of this interaction is critical for the proper interpretation of behavior from the archaeological record.

A juvenile (0-18 years) archaeological sample (n=140) from a Roman Egyptian cemetery (Kellis 2) was utilized, as bone is most responsive to environmental influences during growth. Macroscopic and microscopic bone morphology was assessed in three skeletal elements under different levels of biomechanical loading (i.e., femora, humeri, ribs) and compared among individuals with varying amounts of metabolic stress (inferred from skeletal stress markers). It was hypothesized that as biomechanical loading demands increase among the three elements, systemic reductions in bone mass due to metabolic stress are increasingly attenuated to maintain proper bone strength.

Results generally support this hypothesis. Ribs exhibit significant reductions in macroscopic bone mass with metabolic stress, while femora demonstrate minimal reductions, and humeri are intermediate. Likewise, ribs possess the most significant microscopic loss relative to long bones, as expected; however, femora and humeri have similar microscopic bone mass.

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