EFFECT OF EXERCISE TRAINING ON SKELETAL-MUSCLE HISTOLOGY AND METABOLISM IN PERIPHERAL ARTERIAL-DISEASE

Patients with symptomatic peripheral arterial occlusive disease have a claudication-limited peak exercise performance that is improved with exercise training. The effects of training on skeletal muscle metaboli sm were evaluated in 26 patients with claudication, randomized into a 12-wk program of treadmill training (enhances muscle metabolic activit y in normal subjects), strength training (stimulates muscle hypertroph y in normal subjects), or a nonexercising control group. Gastrocnemius muscle biopsies were performed at rest and before and after training. After 12 wk, only treadmill training improved peak exercise performan ce and peak oxygen consumption. Treadmill training did not alter type I or type II fiber area and did not increase citrate synthase activity but was associated with an increase in the percentage of denervated f ibers (from 7.6 +/- 5.4 to 15.6 +/- 7.5%, P < 0.05). Improvement in ex ercise performance with treadmill training was associated with a corre lative decrease in the plasma (r = -0.67) and muscle (r = -0.59) short -chain acylcarnitine concentrations (intermediates of oxidative metabo lism). Patients in the strength and control groups had no changes in m uscle histology or carnitine metabolism, but strength-trained subjects had a decrease in citrate synthase activity. Thus treadmill training increased peak exercise performance, but this benefit was associated w ith skeletal muscle denervation and the absence of a ''classic'' mitoc hondrial training response (increase in citrate synthase activity). Th e present study confirms the relationship between skeletal muscle acyl carnitine content and function in peripheral arterial occlusive diseas e, demonstrating that the response to treadmill training was associate d with parallel improvements in intermediary metabolism.