The effect of weight-bearing exercise on bone mineral density: A study of female ex-elite athletes and the general population

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Abstract
The aim of this retrospective cohort study was to estimate the changes in bone mineral density (BMD) as a consequence of exercise in female ex‐athletes and age‐matched controls. Eighty‐three ex‐elite female athletes (67 middle and long distance runners, 16 tennis players, currently aged 40–65) were recruited from the original records of their sporting associations. Controls were 585 age‐matched females. The main outcome measures were BMD of lumbar spine (LS), femoral neck (FN), and forearm, estimated by dual‐energy X‐ray absorptiometry (DXA) scan. Levels of physical activity were assessed using a modified Allied Dunbar Fitness Survey scale and classified as (a) ex‐athletes, (b) active controls (≥1 h of vigorous physical activity currently and in the past), (c) low activity controls with inconsistent or intermediate levels of activity, and (d) inactive controls (< 15 minutes of exercise per week). After adjustment for differences in age, weight, height, and smoking, athletes had greater BMDs than controls: 8.7% at the LS (95% confidence interval [CI] 5.4‐12.0; p < 0.001) and 12.1% at FN (CI 9.0‐15.3; p < 0.001). The benefits of exercise appeared to persist after cessation of sporting activity. Active controls (n = 22) had greater BMDs than the inactive group (n = 347): 7.9% LS (CI 2.0‐13.8; p = 0.009) and 8.3% FN (CI 2.7‐13.8; p = 0.004). The low activity controls (n = 216) had an intermediate BMD. Tennis players had greater BMDs compared with runners: 12.0% LS (CI 5.7‐18.2; p = 0.0004) and 6.5% FN (CI −0.2‐13.2; p = 0.066). The BMD of tennis players' dominant forearms were greater than their nondominant forearms. In conclusion, regular vigorous weight‐bearing exercise of 1 h or more per week is associated with an increase in BMD within a normal population. This study confirms long‐term weight‐bearing exercise as an important factor in the regulation of bone mass and fracture prevention.
Funding Information
  • Oliver Bird Fund of the Nuffield Trust
  • Lawn Tennis Association, the Internatoinal Athletics Association