Yi. Zhu et Jd. Haas, IRON DEPLETION WITHOUT ANEMIA AND PHYSICAL PERFORMANCE IN YOUNG-WOMEN, The American journal of clinical nutrition, 66(2), 1997, pp. 334-341
Studies in laboratory animals found that iron deficiency without anemi
a decreased oxidative capacity and increased reliance on carbohydrate
as the substrate for energy, thereby causing impaired endurance. The p
urpose of this cross sectional study was to investigate the relation b
etween iron deficiency without anemia and physical performance in heal
thy active women aged 19-36 y. Iron-status assessment included determi
nation of hemoglobin, hematocrit, transferrin saturation, and serum fe
rritin values. Dietary iron intake was assessed by frequency questionn
aires and physical activity level was estimated by frequency questionn
aires and 2-wk records. Fifteen women with normal iron status and 15 w
omen with iron depletion (serum ferritin < 12 mu g/L) were chosen rand
omly from a group of 69 nonanemic women and given physical-performance
tests, including determinations of maximum oxygen consumption (VO(2)m
ax), ventilatory threshold, and delta-efficiency. There were Ilo signi
ficant differences between the two groups in body size, body compositi
on, physical activity level, dietary iron intake, delta-efficiency, or
ventilatory threshold. Compared with the iron-depleted group, the iro
n-sufficient group had significantly higher hemoglobin, transferrin sa
turation, and serum ferritin values and a significantly greater tenden
cy to use iron supplements. When physical activity level and fat-free
mass were controlled for, the iron-depleted group had a significantly
lower VO(2)max. The difference in VO(2)max was significantly associate
d with serum ferritin concentration; hemoglobin value was not a signif
icant confounder. Therefore, reduction of VO(2)max in nonanemic women
with iron depletion was likely caused by factors related to reduced bo
dy iron storage but was unrelated to decreased oxygen-transport capaci
ty of the blood.