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

Am J Physiol. 1985 Sep;249(3 Pt 1):E306-11. doi: 10.1152/ajpendo.1985.249.3.E306.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Body Weight
  • Eating
  • Electron Transport Complex IV / metabolism
  • Hemoglobins / analysis
  • Iron / pharmacology
  • Iron Deficiencies*
  • Male
  • Muscles / anatomy & histology
  • Muscles / drug effects
  • Muscles / metabolism
  • Organ Size / drug effects
  • Oxygen Consumption / drug effects
  • Physical Education and Training
  • Physical Exertion*
  • Rats
  • Rats, Inbred Strains
  • Succinate Dehydrogenase / metabolism
  • Time Factors


  • Hemoglobins
  • Iron
  • Succinate Dehydrogenase
  • Electron Transport Complex IV