Effects of iron status on performance during maximal and submaximal cycle ergometry in trained women


Hinton, P.S.; Vetter, M.J.; Sinclair, L.M.; Wendtland, C.D.

Medicine & Science in Sports & Exercise 35(5 Suppl.): S128

2003


Purpose: To examine the relationships between indicators of iron status (hemoglobin [Hb], hematocrit [Hct], serum ferritin [sFer], serum transferrin receptor [sTfR], transferrin saturation [TS], serum iron [Fe]) and physical performance (VO2, HR, RER, energy expenditure) during maximal and submaximal cycle ergometry in trained women. Methods: Nineteen trained (VO2max=44±2 ml/kg/min; weekly energy expenditure=4528±618 kcal/wk) women between the ages of 20-41 years served as subjects. Blood drawn prior to the VO2max test was used to determine Hb, Hct, sFer, Fe, TS, and sTfR. Within 3-7 days after the VO2max test, subjects performed 60-minutes of submaximal (60.6±0.5% VO2max) cycle ergometry. Multiple linear regression analyses were used to examine the relationship between indicators of iron status and performance variables. Results: Four subjects met the criteria for nonanemic, iron-deficiency (Hb>12 g/dl, sFer<16 ng/ml) while two additional subjects met the criteria for anemia (Hb<12 g/dl). Significant correlations were found to exist between Hb and Hct (r2=0.72, p<0.05) and between Hb and sFer (r2=0.46, p<0.05) but not between sFer and sTfR. When intensity and time were controlled for, there was a significant positive association between Hb and total energy expenditure (partial r2=0.49, p<0.05) during the submaximal exercise test. Conclusion: These results suggest that, in trained females, differences in maximal and submaximal exercise performance cannot be attributed to differences in Hb or tissue iron status.