Iron supplementation improves endurance after training in iron-depleted, nonanemic women.
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.
Hinton
P S
PS
Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA.
Giordano
C
C
Brownlie
T
T
Haas
J D
JD
D000222:Adaptation, Physiological; D000328:Adult; D004311:Double-Blind Method; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007501:Iron / Q000008:administration & dosage*; D000090463:Iron Deficiencies; D019344:Lactic Acid / Q000097:blood; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D011659:Pulmonary Gas Exchange; D011990:Receptors, Transferrin / Q000097:blood; D012119:Respiration
D011990:Receptors, Transferrin; D019344:Lactic Acid; D005293:Ferritins; D007501:Iron