The relationship between bone mineral density (BMD) and swimming has been thoroughly researched. The aim of this study was to determine the effects of breath-hold diving on the BMD in the proximal femurs of women divers.

A case-control observational study was carried out using health-checks of divers and control subjects at a hospital in Jeju City, South Korea. Women divers (N=61) were matched individually with non-diver controls (N=61) by age, weight, and postmenopausal year. The bone mineral densities of their proximal femurs (total hip, femoral neck) were assessed by dual-energy X-ray absorptiometry.

The average diving year of women divers was 34±13 years. The BMD of divers was higher than that of controls in the total hip and femur neck area (P<0.05). On multiple linear regression analysis, age and body weight were predictors of proximal femur bone mineral densities in divers. On linear regression analysis of the proximal femur BMD according to age in divers and controls, the bone mineral densities of divers tend to decrease more rapidly than those of controls in all two areas of the proximal femurs.

Our study results may suggest that diving in a high-pressure environment is an osteogenic stimulus. However, the weight-supported environment in diving exerts an effect that reduces BMD proportionately to the time spent in the water.