Relationship between iron status and exercise in male and female growing rats

Weanling rats of both sexes were fed for 6 weeks diets containing 42, 17 or 7 ppm iron to produce adequate, moderately deficient and severely deficient iron status, respectively. At each level of iron, rats were either sedentary, trained regularly on a treadmill or housed in activity wheel cages. The moderately and severely deficient rats of both sexes which were exercised regularly had slightly greater liver non-heme iron stores and slightly higher hematologic values than sedentary rats. In the adequately nourished rats, exercise enhanced iron stores but had no effect on hematologic status. Rats were tested for physical work performance by a graded treadmill test every 2 weeks. Compared to adequately nourished rats, moderately iron-deficient rats had lower liver iron stores and slightly lower hematological values, but growth rate, heart size, spontaneous activity and treadmill performance were unaffected by the deficiency. Severely deficient rats, compared to adequately nourished rats, had depressed growth rate (82%), cardiac hypertrophy (14%) and lower hematologic values. Treadmill performance of male rats, in contrast to females, was more negatively affected by severe iron deficiency.