COMPARISONS OF TECHNIQUES AND MODELS FOR ASSESSING BODY COMPOSITION CHANGES OVER 1 Y IN POSTMENOPAUSAL WOMEN:

2073 Techniques and models for assessing changes in body composition in healthy, previously sedentary postmenopausal women (40-66 y) in response to 1-y of exercise training (n=36) versus no training (n=40) were compared. Subjects were randomized to progressive resistance and weight-bearing exercise (E) versus no exercise (NE). E performed two sets of 8 high-intensity resistance exercises and 25 minutes of weight-bearing exercise 3 d/wk; NE was untreated. Changes in body mass (Wt), fat mass (FM), and fat free mass (FFM) after 1 y were assessed by a multicomponent model (MC), dual energy x-ray absorptiometry (DXA), and underwater weighing (UWW). Wt did not change (E, 0.5 kg; NE, 0.8 kg). In E, FFM increased significantly (p 0.001) as assessed by DXA (0.7″ 1.0 kg) but changes by MC (−0.1″ 4.2 kg) and UWW (−0.2″ 3.4 kg) were not significant. Changes in FM and %Fat in E were not significant. In NE, changes in FFM, FM and %Fat were significant (p ú 0.02) assessed by MC (FFM −1.5″ 3.7 kg, FM 2.3″ 4.1 kg; %Fat 2.8″ 4.7) and UWW (FFM −1.1″ 2.5 kg, FM 2.1″ 3.6 kg, %Fat 2.5″ 3.5), but changes by DXA were not significant (FFM 0.2″ 1.2 kg; FM 1.0″ 3.9 kg; %Fat 0.6″ 3.2). SDs for changes were smallest for the DXA method. DXA SDs for FM in E and NE were respectively 2.5 and 3.9 kg; for MC, 5.5 and 4.1 kg; and for UWW, 4.4 and 3.6 kg. DXA measurements showed a small and significant increase in FFM for E but not NE, and no change in FM for either E or NE. We conclude that DXA was the most sensitive method for assessing changes in body composition of postmenopausal women after 1 y of E or NE. Supported by AR39559