Submitted on July 5, 2007
Accepted on January 16, 2008
Stability of hemoglobin mass over 100 days in active men
Annette Eastwood1*, Will G Hopkins2, Pitre C. Bourdon3, Robert T. Withers4, and Christopher J. Gore5
1 Sport Science, South Australian Sports Institute, Adelaide, South Australia, Australia; Exercise Physiology, Flinders University, Adelaide, South Australia, Australia
2 Institute of Sport and Recreation Research, AUT University, Auckland, New Zealand
3 Sport Science, South Australian Sports Institute, Adelaide, South Australia, Australia; Adelaide, South Australia, Australia
4 Exercise Physiology Laboratory, Flinders University, Adelaide, South Australia, Australia
5 Department of Physiology, Australian Institute of Sport, Bruce, Australian Capital Territory, Australia
* To whom correspondence should be addressed. E-mail: eastwood.annette{at}saugov.sa.gov.au.
PURPOSE: To investigate the suggestion in a recent meta-analysis that variability in hemoglobin mass increases when time between measurements increases from days to months. METHODS: Hemoglobin mass of six active men was measured with the carbon-monoxide method every 1-6 d for 100-114 d (42 ± 3 measurements, mean ± SD). Measurement error for each individual's series was estimated from the standard deviation of consecutive pairwise changes and compared with his total error (standard deviation of all values). Linear trends and periodicities in each series were quantified by regression and spectral analysis. Series with known random error and periodicity were also simulated and analyzed. RESULTS: There were clear differences in the pairwise error of measurement between subjects (range 1.4-2.7%). For five men there was little difference between the total and pairwise errors; their mean ratio (1.06, 90% confidence limits 0.96 to 1.17) was less than ratios for simulated sinusoidal series with random error of 2%, amplitude of 2% and periods of 20-100 d (ratios 1.13-1.21). Spectral analysis clearly revealed such periodicities in the simulated series but not in the series of these subjects. The sixth man, who had donated blood 12 d before commencing measurements, showed errors, trend and periodicity consistent with gradual restoration of hemoglobin mass. CONCLUSION: Measurement error of hemoglobin mass does not increase over 100 days. Consequently, hemoglobin mass may be suitable for long-term monitoring of small changes that might occur with training or erythropoietin abuse, taking into consideration the small differences between athletes in errors and trends.
