BONE-MINERAL DENSITY AND LONG-TERM EXERCISE - AN OVERVIEW OF CROSS-SECTIONAL ATHLETE STUDIES

Evidence in human studies of the association of long term habitual exe rcise with bone mineral content (BMC) and density (BMD) largely comes from studies in athletes. In young adults, the highest BMC and BMD val ues have been found in strength and power-trained athletes, while endu rance activities such as long distance running and swimming seem less effective with regard to peak bone density. Intensive endurance traini ng may even be associated with amenorrhoea and decreased trabecular bo ne density in young female. However, after menopause female athletes s how greater bone mass indicating that they do not share the accelerate d decline in BMC observed in a nonathletic population. Middle-aged and elderly male athletes from various sports have significantly higher B MC and BMD than controls, especially in trabecular bone sites, but hig her cortical BMC has also been found in the dominant/nondominant arm c omparisons with unilateral exercises such as tennis. The differences f ound between female athletes and controls have generally been less pro nounced that those among men, but a number of studies suggest in a wom en long term physical training may counteract the low BMC and BMD asso ciated with reduced bone mass. Although the interpretation of results of cross-sectional studies should be treated with caution, studies in athletes serve as an economical alternative approach to experimental t rials with their long term follow-up and exercise compliance problems. The difference found in BMD between those who have devoted themselves to life-long training and those who have been much less active should not be underestimated.