Skeletal muscle contractile characteristics and fatigue resistance in patients with chronic heart failure

Whole muscle contractile characteristics and fatigue resistancewere studied in male patients with chronic heart failure (n=6)and in healthy control subjects (n=6). Maximum voluntary isometricstrength in the major muscle groups of leg (plantar flexorsand knee extensors) and arm (elbow extensors and elbow flexors),was found to be similar for both groups of subjects. However,a faster isometric twitch time course was observed in the plantarflexor and knee extensor muscles of heart failure chronic patients.The poor resistance to fatigue in the knee extensors of chronicheart failure patients was confirmed in the present study, butusing twitch interpolation this was shown not to be due to pooractivation. The plantar flexors of chronic heart failure patientsalso showed a tendency to be less resistance to fatigue, evenwhen the muscle was activated by direst electrical stimulation. The present study shows that independent of muscle strength,patients with chronic heart failure may possess muscles thatare faster to contract and less resistant to fatigue. However,it seems this increased fatigability is not due to poor muscleactivation.