Abstract
The lumbar spine and femoral neck densities of 123 and 141 normal adult women (50±10
years), respectively, measured by dual photon absorptiometry, were correlated with
the number of hours of walking per day associated with their regular daily activities.
This measure of exercise, obtained by detailed questionnaire and interview, was analyzed
because it is regular, seasonally stable, and quantifiable. Both lumbar spine and
femoral neck densities were significantly correlated with walking, with 0.8% and 1.9%
increases in average bone density per hour of daily walking, respectively. This increase
in density is substantial, considering that the age-related rate of bone loss in the
same population is 0.7% and 0.5% per year of lumbar spine and femoral neck, respectively.
This means that, on the average, a woman walking one additional hour per day has a
femoral neck bone density comparable to that of a women 4 years younger who does not
pursue this additional activity. This physical activity-associated enhancement of
bone density may be critical at old age when osteoporosis is clinically manifested.
Key words
Bone density - physical activity - lumbar spine - femoral neck - dual photon absorptiometry
