Changes in phase angle and body composition induced by resistance training in older women.

Abstract

Resistance training (RT) has selective effects on body composition that may counteract the deleterious effects of aging. Changes in phase angle (PhA) may serve to monitor the influence of RT in older people. To describe the effect of RT in training, detraining and retraining on body composition, including PhA in older women. Thirty-three older women (⩾60 years old) participated. The RT program was carried out over 12 weeks for each stage (training, detraining and retraining). Whole-body fat-free mass and fat mass (FM) and appendicular lean soft tissue (ALST) measurements were carried out using a dual energy X-ray absorptiometry. Bioimpedance spectroscopy was used to estimate total body water (TBW), intra (ICF) and extracellular (ECF) fluids, whole-body resistance (R) and reactance (Xc) and PhA. Upper and lower body muscle strength were also assessed. From baseline to after training muscle strength, ALST and PhA significantly (P<0.05) increased. In detraining, significant (P<0.05) reductions in muscle strength, TBW, ECF, ICF and PhA along with significant (P<0.05) increases in R were observed, with the greatest magnitude observed for PhA (Δ=-7.6%). From detraining to retraining a significant reduction in FM along with increases in Xc, PhA and muscle strength were observed. Although an increase was observed from detraining to retraining in PhA, the values were still lower than baseline PhA. In untrained older women, a RT is associated with increases in PhA, whereas detraining results in a marked decrease in PhA, and more time may be required in retraining to counteract the negative influence of absence of exercise stimulus.