LOSS OF BONE-MINERAL DENSITY IN WOMEN ATHLETES DURING AGING

Total and regional bone mineral density (BMD) by dual-energy-X-ray abs orptiometry (DXA) and bone turnover were tested in 50 highly trained w omen athletes and 21 sedentary control women (18-69 years; BMI < 25 kg /m(2)). VO2max (ml.kg(-1).min(-1)) and lean tissue mass (DXA) were sig nificantly higher in the athletes versus controls (both P < 0.0001), T otal body BMD did not decline significantly with age in the athletes w hereas lumbar spine (L-2-L-4) BMD approached statistical significance (r = -0.26; P = 0.07), Significant losses of the femoral neck (r = - 0 .42), Ward's triangle (r = -0.53), and seater trochanter BMD (r = -0.3 3; all P < 0.05) occurred with age in the athletes. In the athletes, t otal body BMD, L-2-L-4 BMD, and BMD of all sites of the femur were ass ociated with lean tissue mass (r = 0.32 to r = 0.57, all P < 0.05) and VO2max (r = 0.29 to r = 0.48, all P < 0.05). Femoral neck and greater trochanter BMD were higher in the athletes than in controls (both P ( r 0.05) and lumbar spine and Ward's triangle BMD approached statistica l significance (both P = 0.07). Bone turnover was assessed by serum bo ne-specific alkaline phosphatase (B-ALP), urinary deoxypyridinoline cr osslinks (Dpd), and urinary aminoterminal cross-linked telopeptides MT X). There were no relationships between B-ALP or Dpd with age whereas NTX increased with age (r = 0.46, P < 0.05) in the entire group. Level s of B-ALP and NTX were negatively associated with total body, L-2-L-4 , femoral neck, Ward's triangle, and greater trochanter BMD (P < 0.05) . B-ALP and Dpd were not significantly different between athletes and controls whereas NTX was lower in the athletes than in controls (P < 0 .001). The high levels of physical activity observed in women athletes increase aerobic capacity and improve muscle mass but are not suffici ent to prevent the loss of bone with aging.