Iron supplementation improves endurance after training in iron-depleted, nonanemic women

J Appl Physiol (1985). 2000 Mar;88(3):1103-11. doi: 10.1152/jappl.2000.88.3.1103.

Abstract

Our objective was to investigate the effects of iron depletion on adaptation to aerobic exercise, assessed by time to complete a 15-km cycle ergometer test. Forty-two iron-depleted (serum ferritin <16 microg/l), nonanemic (Hb >12 g/dl) women (18-33 yr old) received 100 mg of ferrous sulfate (S) or placebo (P) per day for 6 wk in a randomized, double-blind trial. Subjects trained for 30 min/day, 5 days/wk at 75-85% of maximum heart rate for the final 4 wk of the study. There were no group differences in baseline iron status or in 15-km time. Iron supplementation increased serum ferritin and decreased transferrin receptors in the S compared with the P group. The S and P groups decreased 15-km time and respiratory exchange ratio and increased work rate during the 15-km time trial after training. The decrease in 15-km time was greater in the S than in the P group (P = 0.04) and could be partially attributed to increases in serum ferritin and Hb. These results indicate that iron deficiency without anemia impairs favorable adaptation to aerobic exercise.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptation, Physiological
  • Adult
  • Double-Blind Method
  • Energy Metabolism
  • Exercise Test
  • Female
  • Ferritins / blood
  • Humans
  • Iron / administration & dosage*
  • Iron Deficiencies*
  • Lactic Acid / blood
  • Oxygen Consumption
  • Physical Endurance / drug effects*
  • Physical Endurance / physiology
  • Pulmonary Gas Exchange
  • Receptors, Transferrin / blood
  • Respiration

Substances

  • Receptors, Transferrin
  • Lactic Acid
  • Ferritins
  • Iron