Tissue iron deficiency without anemia impairs adaptation in endurance capacity after aerobic training in previously untrained women.
BACKGROUND
We previously showed that iron supplementation significantly improves iron status and maximal work capacity in previously untrained, marginally iron-deficient women with a baseline serum transferrin receptor concentration > 8.0 mg/L. However, the effect of transferrin receptor status on adaptation in endurance capacity after aerobic training in these subjects has not been fully explored.


OBJECTIVE
Our objective was to examine the effect of baseline serum transferrin receptor status on adaptations in endurance capacity.


METHODS
Forty-one untrained, iron-depleted, nonanemic women were randomly assigned to receive either 100 mg FeSO(4) or a placebo for 6 wk in a double-blind trial. All subjects trained on cycle ergometers 5 d/wk for the last 4 wk of the study. Endurance capacity was assessed at baseline and after treatment by using a 15-km time trial conducted on a cycle ergometer.


RESULTS
Significant treatment effects were observed for time to complete the 15-km time trial, work rate, and percentage of maximal oxygen uptake in subjects with a baseline serum transferrin receptor concentration > 8.0 mg/L. No significant treatment effects were observed in subjects with a normal baseline transferrin receptor concentration.


CONCLUSIONS
Our findings suggest that, in the presence of overt tissue iron deficiency, iron deficiency without anemia impairs adaptation in endurance capacity after aerobic training in previously untrained women. This impairment can be corrected with iron supplementation.
Brownlie
Thomas
T
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA. tb22@cornell.edu
Utermohlen
Virginia
V
Hinton
Pamela S
PS
Haas
Jere D
JD
D000222:Adaptation, Physiological; D000328:Adult; D015930:Diet Records; D019587:Dietary Supplements; D004311:Double-Blind Method; D005080:Exercise Test; D005260:Female; D005296:Ferrous Compounds / Q000627:therapeutic use*; D006801:Humans; D007501:Iron / Q000008:administration & dosage; D000090463:Iron Deficiencies; D009752:Nutritional Status; D010101:Oxygen Consumption; D010807:Physical Endurance; D011990:Receptors, Transferrin / Q000097:blood* / Q000378:metabolism; D012119:Respiration
D005296:Ferrous Compounds; D011990:Receptors, Transferrin; D007501:Iron