[Effects of aerobic exercise on exercise tolerance in patients with chronic heart failure]

OBJECTIVE: To explore the effects of aerobic exercise on exercise tolerance in patients with chronic heart failure (CHF).

METHODS: A total of 50 CHF patients with left ventricular ejection fraction (LVEF) < 49% by echocardiography were enrolled. And they were randomly divided into exercise group (n = 25) and non-exercise group (n = 25). Cardiopulmonary exercise testing (CPET) was performed. The patients of exercise group underwent an aerobic exercise program in which exercise intensity was decided by anaerobic threshold (AT) before 10 J/s while those of non-exercise group performed daily activities. After 6 sessions of supervised aerobic exercise, the home-based aerobic exercise training began. CPET was re-examined 3 months later.

RESULTS: The VO(2) AT, VO(2) peak, Load AT, Load peak, peak VO(2)/HR and VE/VCO(2) slope at baseline were similar between exercise group and non-exercise group (P > 0.05). The VO(2) AT, VO(2) peak, Load AT, Load peak and peak VO(2)/HR in patients of exercise group were increased compared with baseline, The differences between baseline and 3 months later expressed as ΔVO(2) AT, ΔVO(2) peak, ΔLoad AT, ΔLoad peak, Δpeak VO(2)/HR and ΔVE/VCO(2) slope, The differences of ΔVO(2) AT, ΔVO(2) peak, ΔLoad AT, ΔLoad peak and Δpeak VO(2)/HR between two groups were statistically significant [ΔVO(2) AT: 2.8 (1.2 - 3.5) ml×kg(-1)×min(-1) vs -0.3 (-2.8 - 0.1) ml×kg(-1)×min(-1), P < 0.01; ΔVO(2) peak: 3.4 (1.8 - 4.6) ml×kg(-1)×min(-1) vs -0.5 (-1.4 - 0.3) ml×kg(-1)×min(-1), P < 0.01; ΔLoad AT:15.0 (2.5 - 22.5) J/s vs 0.5(-4.2 - 3.8) J/s, P < 0.01; ΔLoad peak: 15.0 (1.3 - 25.0) J/s vs 0.0 (-8.8 - 15.0) J/s, P < 0.05; Δpeak VO(2)/HR: 2.3 (0.0 - 4.0) ml×kg(-1)×beat(-1) vs -0.1 (-0.7 - 1.2) ml×kg(-1)×beat(-1), P < 0.01]. The difference of ΔVE/VCO(2) slope was not statistically significant [-2.3 (-12.2 - 1.8) vs 1.0 (-0.4 - 2.6), P > 0.05].

CONCLUSION: After 3 months of aerobic exercise, exercise capacity may improve in the CHF patients.