Effect of resistance training on phase angle in older women: A randomized controlled trial

Phase angle (PhA) is an angular-derived bioelectrical impedance parameter based on resistance and reactance that has been widely used in different populations as an objective indicator of cellular health. The purpose of this study was to analyze the effect of resistance training (RT) on PhA in older women. Forty-one older women (67.2 ± 4.5 years, 64.0 ± 12.3 kg, 154.7 ± 5.2 cm, and 26.6 ± 4.8 kg/m² ) were randomly assigned to one of two groups: a training group (TG, n = 19) that underwent progressive RT for 12 weeks (eight exercises, three sets of 10-15 repetitions maximum, three times per week) or a control group (CG, n = 22) that did not perform any type of exercise during the intervention period. Resistance, reactance, PhA, total body water (TBW), intracellular (ICW) and extracellular (ECW) water were assessed by spectral bioelectrical impedance. There was a significant group by time interaction (P < 0.05) for PhA, TBW, and ICW in which only the TG increased their scores after the intervention period (PhA = +6.5%, TBW = +2.8%, and ICW = +5.1%). The results suggest that progressive RT promotes an increase in PhA in older women. Therefore, the PhA seems to be a good parameter to assess changes in cellular health during RT intervention.