High bone mineral density in loaded skeletal regions of former professional football (soccer) players: what is the effect of time after active career?

Objectives: Physical exercise is an important factor in the acceleration and maintenance of bone mineral density (BMD). Football is an impact loading sport and some studies demonstrate its site specific, bone mass increasing effect. We compared BMD at different skeletal regions in a group of former professional football players and in normal control subjects and evaluated the effect of demographic factors and time after active career on BMD. Methods: Twenty four former football players <70 years old who had retired from professional football at least 10 years previously and 25 non-athletic controls were recruited. The demographic characteristics, activity levels, and dietary habits of all subjects and the chronological history of the footballers' professional careers were noted. BMD was measured by DEXA at the calcaneus and distal tibia and at the lumbar spine, proximal femur, and distal and proximal radius, and compared between groups. Stepwise multiple linear regression analysis was used to determine the probable predictors of BMD in former football players. Results: In former players BMD values were found to be significantly higher at the lumbar spine, femur neck, femur trochanter, distal tibia, and calcaneus, but not at Ward's triangle (femur) or the distal and proximal radius regions compared with controls. Time after active career was the only independent predictor of BMD at the lumbar spine, proximal femur (neck, trochanter, and Ward's triangle), and distal tibia. Conclusions: Former footballers had higher BMD at weight loaded sites and time after active career seemed to be an important factor in determining BMD.