Despite reported benefits of exercise training in men with chronic congestive heart failure (CHF) and in both men and women with coronary artery disease, the effects of training in women with CHF have not been throughly investigated. Therefore, 16 women (62 +/- 10 years [mean +/- SD]) with stable, moderate, chronic CHF (left ventricular ejection fraction 28 +/- 8%) were studied in a randomized crossover trial with 8 weeks of knee extensor endurance training and 8 weeks of nontraining. The effects of the exercise-based rehabilitation were assessed in skeletal muscle metabolic capacity, exercise tolerance, and quality of life. The compliance rate in training was 98% and no adverse events occurred during the study period. Training increased the activity of citrate synthase (44%, p <0.0001) and lactate dehydrogenase (23%, p <0.002) in the trained muscles, and an improved oxidative capacity in relation to the glycolytic capacity (23%, p <0.002) was found. Peak oxygen uptake (14%, p <0.0005) and peak work rate (43%, p <0.0001) during incremental exercise increased, and blood lactate concentration during standardized submaximal exercise and during the recovery phase decreased (17%, p <0.05). The distance ambulated during 6 minutes (p <0.03), and the overall (p <0.01), physical (p <0.05), and psychosocial (p <0.03) health-related quality of life improved. Because the skeletal muscle endurance training improved peripheral oxidative capacity, exercise tolerance, and the health-related quality of life without any adverse events, this mode of training can be recommended for women with chronic heart failure.