WORK CAPACITY, HEART-RATE AND BLOOD LACTATE RESPONSES TO IRON TREATMENT

Changes in Hb, work performance, heart rate and post-exercise blood lactate were studied in Fe-deficient, anemic subjects for 16 days following total dosage infusion of Fe dextran, i.v. (30-50 ml). Six adult men and 14 women were subjects with initial Hb levels of 6.6 .+-. 0.6 g/dl (mean .+-. SEM [standard error of the mean]) for the Fe treatment group (n = 10) and 8.0 .+-. 0.7 for the placebo group (saline infusion, n = 10). Serum Fe levels were 0.51 .+-. 0.15 and 0.67 .+-. 0.12 mg/l for the 2 groups, respectively. Hb and maximal work time increased significantly within 4 days after Fe treatment and continued to increase up to 16 days. No changes were found in the placebo subjects. Heart rates at a given exercise intensity were lower in the Fe treatment group than in control subjects who had the same Hb levels but were not treated with Fe. Post-exercise venous blood lactate was similar on succeeding days after Fe treatment even though the subjects reached higher work loads. Treatment of Fe-deficient, anemic subjects with Fe dextran results in improved work capacity within 4 days and a lower heart rate at a given work load after treatment which cannot be accounted for totally by the elevation of Hb concentration.