Endurance training increases aerobic capacity but does not affect isokinetic leg muscle strength in chronic heart failure

Background: In patients with CHF, physical reconditioning improves exercise tolerance and endurance capacity. However, there is no evidence that endurance training programs affect skeletal muscle strength in such patients.

Design: The present study investigates the effects of endurance training on isokinetic skeletal muscle strength and on aerobic capacity in chronic heart failure (CHF) patients.

Methods: Eleven stable CHF patients (8 men, mean aged 54.3 yr and women, mean aged 49.3 yr) participated in a classical controlled inhospital 8-week endurance training program. Progressive incremental exercise tests with gas exchange analysis and isokinetic strength measurements of knee flexors and extensors were conducted in all subjects before and after training at different angular velocities (60, 180, 240°/s ).

Results: After training, peak � O $_2$ improved significantly (from 16.3 ± 3.3 to 20.7 ± 4.0 ml/kg/min; p < 0.002) as did New York Heart Association (NYHA) functional class (2.2 ± 0.4 to 1.5 ± 0.5; p < 0.001). Conversely, isokinetic strength at all angular velocities studied was unchanged after the training program.

Conclusion: Isokinetic muscle strength was not improved in CHF patients participating in a endurance training program. A combined endurance and resistance protocol might be helpful for these patients whose frequently altered muscle strength undoubtedly contributes to their poor quality of life for everyday activities.