ANALYSIS OF BODY-COMPOSITION TECHNIQUES AND MODELS FOR DETECTING CHANGE IN SOFT-TISSUE WITH STRENGTH TRAINING

The purpose of this study was to compare the ability of various body-c omposition assessment techniques to detect changes in soft tissue in o lder, weight-stable women (50-70 y of age) completing a 1-y randomized , controlled trial of progressive resistance training. The interventio n group (n = 20) performed high-intensity strength-training 2 d/wk wit h five different exercises; the control group (n = 19) was untreated. Hydrostatic weighing, 24-h urinary creatinine, computed tomography of thigh sections, total body potassium, and tritium dilution techniques were used to measure increases in total fat-free mass (FFM) and the mu scle and water components of FFM. A decrease in fat mass (by hydrostat ic weighing) was seen in the strength-trained women compared with the control subjects (P = 0.01-0.0001). Anthropometry, bioelectric impedan ce, dual-energy X-ray absorptiometry, and total body nitrogen and carb on did not measure any significant change in soft tissue. The choice o f a body-composition technique is important when designing a study exp ected to affect soft tissue, because not all techniques available are precise enough to detect small changes.