Not all the studies that investigated all the conditions in the triad , but the authors concluded that it seemed that athletes were in more severe stage of this disorder .
Bone mineral density in adolescent female athletes: relationship to exercise type and muscle strength.
PURPOSE This study investigated the influence of different exercise types and differences in anatomical distribution of mechanical loading patterns on bone mineral density ( BMD ) in elite female cyclists , runners , swimmers , triathletes , and controls ( N = 15 per group ) . Associations between leg strength and BMD were also examined . METHODS Areal BMD ( g x cm(-2 ) ) was assessed by duel-energy x-ray absorptiometry ( DXA ) ( total body ( TB ) , lumbar spine ( LS ) , femoral neck ( FN ) , legs , and arms ) . Right knee flexion and extension strength was measured using a Cybex Norm isokinetic dynamometer at 60 degrees x s(-1 ) . RESULTS Runners had significantly higher unadjusted TB , LS , FN , and leg BMD than controls ( P < 0.05 ) ; higher TB , FN , and leg BMD than swimmers ( P < 0.05 ) ; and greater leg BMD than cyclists ( P < 0.05 ) . Absolute knee extension strength was significantly ( P < 0.01 ) correlated ( 0.33 < or = r < or = 0.44 ) with TB , FN , LS , and leg BMD for all groups combined . Weaker but still significant correlations ( 0.28 < or = r < or = 0.33 ) existed for normalized ( per leg lean tissue mass ) knee extension strength and all BMD sites , except FN BMD . There were no significant correlations between absolute or normalized knee flexion strength and any of the BMD variables . Absolute knee extension strength was entered as the second independent predictor for LS and leg BMD in stepwise multiple linear regression analysis ( MLRA ) , accounting for increments of 4 % and 12 % , respectively , in total explained variation . CONCLUSION We conclude that running , a weight bearing exercise , is associated with larger site-specific BMD than swimming or cycling , that the generalized anatomical distribution of loads in triathlon appears not to significantly enhance total body BMD status , and that knee extension strength is only a weak correlate and independent predictor of BMD in adolescent females
Not all the studies that investigated all the conditions in the triad , but the authors concluded that it seemed that athletes were in more severe stage of this disorder .