High intensity knee extensor training, in patients with chronic heart failure: Major skeletal muscle improvement

Skeletal muscle adaptations to high intensity knee extensorstrength and/or endurance training in patients with chronicheart failure were investigated. Eleven patients with chronicheart failure were randomized into two groups and exercisedthe m. quadriceps femoris 3 days/week for 8 weeks. After training,the maximal exercise intensity tolerated on the ergometer cyclewas raised from 99 (32) to 114 (40) watts (W, P<0·05)for all 11 patients. Peak dynamic knee extensor work rate showedthe greatest increase after endurance training (40%, P<0·01).Maximal dynamic and isometric strength were elevated by 40–45%(P<0·05) after strength training. The cross-sectionalarea of m. quadriceps femoris was increased in the strength-trainedlegs (9%, P<0·05), and the capillary per fibre ratioof m. vastus lateralis was raised by 47 and 58% in the endurance-trainedlegs (P<0·05). The oxidative enzyme activity in m.vastus lateralis was significantly raised above 50% after endurancetraining, whereas glycolytic enzyme activity was unaltered.The peripheral skeletal musculature in patients with chronicheart failure adapts fairly quickly to high intensity knee extensortraining. This results in a marked rise in local, and a smallrise in total work capacity, indicating maintained plasticityof skeletal muscle in chronic heart failure patients.