Moderate-intensity resistance exercise training in patients with chronic heart failure improves strength, endurance, heart rate variability, and forearm blood flow

Background: Resistance exercise training was applied to patients with chronic heart failure (CHF) on the basis that it may partly reverse deficiencies in skeletal muscle strength and endurance, aerobic power (VO2peak), heart rate variability (HRV), and forearm blood flow (FBF) that are all putative factors in the syndrome. Methods and results: Thirty-nine CHF patients (New York Heart Association Functional Class = 2.3 +/- 0.5; left ventricular ejection fraction 28% +/- 7%; age 65 +/- 11 years; 33:6 male:female) underwent 2 identical series of tests, I week apart, for strength and endurance of the knee and elbow extensors and flexors, VO2peak, HRV, FBF at rest, and FBF activated by forearm exercise or limb ischemia. Patients were then randomized to 3 months of resistance training (EX, n = 19), consisting of mainly isokinetic (hydraulic) ergometry, interspersed with rest intervals, or continuance with usual care (CON, n = 20), after which they underwent repeat endpoint testing. Combining all 4 movement patterns, strength increased for EX by 21 +/- 30% (mean +/- SD, P < .01) after training, whereas endurance improved 21 +/- 21% (P < .01). Corresponding data for CON remained almost unchanged (strength P < .005, endurance P < .003 EX versus CON). VO2peak improved in EX by 11 +/- 15% (P < .01), whereas it decreased by 10 +/- 18% (P < .05) in CON (P < .001 EX versus CON). The ratio of low-frequency to high-frequency spectral power fell after resistance training in EX by 44 +/- 53% (P < .01), but was unchanged in CON (P < .05 EX versus CON). FBF increased at rest by 20 +/- 32% (P < .01), and when stimulated by submaximal exercise (24 +/- 32%, P < .01) or limb ischemia (26 +/- 45%, P < .01) in EX, but not in CON (P < .01 EX versus CON). Conclusions: Moderate-intensity resistance exercise training in CHF patients produced favorable changes to skeletal muscle strength and endurance, VO2peak, FBF, and HRV.