PHYSICAL DECONDITIONING MAY BE A MECHANISM FOR THE SKELETAL-MUSCLE ENERGY PHOSPHATE-METABOLISM ABNORMALITIES IN CHRONIC HEART-FAILURE

The aim of our study was to investigate the contribution of physical d econditioning in skeletal muscle metabolic abnormalities in patients w ith chronic heart failure (CHF). Phosphate metabolism was studied in t he leg muscle at rest and during exercise by using phosphate 31 nuclea r magnetic resonance spectroscopy in a group of 14 patients with New Y ork Heart Association class II and III CHF and left ventricular ejecti on fraction <40% and in two groups of age-matched healthy volunteers: one group of 7 sedentary and another of 7 trained subjects. Phosphocre atine depletion rate, intracellular pH, and adenosine diphosphate leve ls in the muscle during exercise were not statistically different in t he CHF patients and in the sedentary healthy subjects, but both groups were statistically different from the trained healthy subjects, who h ad slower phosphocreatine depletion rates, as well as less intracellul ar acidosis and lower adenosine diphosphate levels during exercise (p = 0.02; analysis of variance). Our results suggest that metabolic chan ges occurring in the skeletal muscle of patients with CHF may contribu te to the limitation of exercise capacity and are most likely to be a consequence of physical deconditioning because they are very similar t o what is observed in sedentary and otherwise healthy subjects as comp ared with trained subjects.