Combined aerobic and strength training for fitness outcomes in heart failure: meta-analysis and meta-regression

Purpose To compare the effects of combined training (CT) versus aerobic training (AT) or versus control on VO2 peak and quadriceps muscle strength in patients with heart failure (HF). Materials and methods Major electronic databases were searched, from inception to November 2020, for randomized clinical trials comparing the effects of CT against AT or control on VO2 peak and/or quadriceps muscle strength in patients with HF. Random effects meta-analyses were conducted, calculating the standardized mean difference (SMD). Results Twenty-eight articles were included. An increase on VO2 peak (SMD = 0.77, 95%CI 0.39-1.14, I (2)=80.1%) and quadriceps muscle strength (SMD = 0.67, 95%CI 0.18-1.16, I (2)=0%) was found in CT compared to control. CT increased quadriceps muscle strength, versus AT (SMD = 0.44, 95%CI 0.15-0.74, I (2)=0%). There were no differences between CT and AT on VO2 peak (SMD=-0.01, 95%CI -0.36 to 0.34, I (2)=65%). Time of session and training duration moderate the effects of CT over control on VO2 peak. Conclusions CT promotes increases on quadriceps muscle strength and aerobic capacity over control and provides additional gains on quadriceps muscle strength, having the same effects on VO2 peak compared to AT. A longer time of session is associated with greater benefits to aerobic capacity.