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Work performance in the iron-deficient rat: improved endurance with exercise training

1985; American Physiological Society; Volume: 249; Issue: 3 Linguagem: Inglês

10.1152/ajpendo.1985.249.3.e306

1522-1555

Mikko Perkkiö, Lennart Jansson, S Henderson, Canio J. Refino, George A. Brooks, P. R. Dallman,

Iron Metabolism and Disorders

The effect of an endurance training regimen on muscle oxidative enzymes and work performance was studied in iron-deficient and -sufficient rats. Three-week-old male Sprague-Dawley rats (n = 40) were randomly assigned to diets containing either 6 mg iron/kg (iron deficient) or 50 mg iron/kg (iron sufficient). After 2 wk, each group of rats was further divided into untrained or endurance-trained subgroups. Training consisted of daily treadmill running of gradually increasing duration for a 1-mo period. After the training period, sedentary and endurance-trained iron-deficient rats were anemic (Hgb approximately 8 g/dl compared with 16 g/dl in the 2 control groups) and had significantly lower skeletal muscle cytochrome c concentration, cytochrome oxidase activity, and succinic oxidase activity compared with the iron-sufficient groups. In response to training iron-deficient rats also generally had a substantial increase in skeletal muscle oxidative enzymes (P less than 0.05), in contrast to iron-sufficient animals, in which there was little or no training effect. Work performance in response to training in the iron-deficient rats improved more than sixfold in an endurance type of exercise (P less than 0.05), but maximal oxygen consumption during a brief, intense type of exercise was not significantly affected. The results suggest that endurance training of iron-deficient rats results in a milder anemia and less drastic reduction of skeletal muscle oxidative enzymes which in turn allows better performance in an endurance type of exercise.