Resistance training and inter-interindividual response differences on cardiorespiratory fitness in older adults: An ancillary meta-analysis of randomized controlled trials

Abstract

Examine true inter-individual response differences (IIRD) as a result of resistance training on cardiorespiratory fitness in older adults. Data from a recent meta-analysis of 22 randomized controlled trials representing 552 men and women (292 resistance training, 260 control) ≥ 60 years of age were included. The primary outcome was cardiorespiratory fitness (VO2max) in ml.kg−1.min−1. Using the inverse variance heterogeneity (IVhet) model, statistically significant treatment effect (resistance training minus control) increases in VO2max in ml.kg−1.min−1 were found (mean, 1.8, 95% CI, 0.4 to 3.3 ml.kg−1.min−1, p = 0.01; Q = 82.8, p < 0.001; I2  = 74.6%, 95% CI, 61.6 to 83.3%; [Formula: see text] =1.1). The 95% prediction interval (PI) was −0.8 to 4.5 ml.kg−1.min−1. However, no statistically significant IIRD was observed (mean, 0.6, 95% CI, −1.1 to 1.4 ml.kg−1.min−1; [Formula: see text] =1.5). The 95% PI was −1.8 to 2.0 ml.kg−1.min−1. In conclusion, while progressive resistance training may increase VO2max in ml.kg−1.min−1, a lack of true resistance-training-associated IIRD exist.