Blood Volume, Hemoglobin Mass, and Peak Oxygen Uptake in Older Adults: The Generation 100 Study

Abstract

Purpose: To investigate the association between blood volume, hemoglobin mass (Hb mass ), and peak oxygen uptake (VO 2peak ) in healthy older adults. Methods: Fifty fit or unfit participants from the prospective randomized Generation 100 Study ( n = 1,566) were included (age- and sex-specific VO 2peak above or below average values). Blood, plasma, and erythrocyte volume and Hb mass were tested using the carbon monoxide rebreathing method within 1 week after VO 2peak testing. Results: Mean age, BMI, Hb mass , blood volume, and VO 2peak were 73.0 ± 2.1 years, 24.8 ± 3.3 kg·m 2 , 10.0 ± 1.7 g·kg −1 , 76.4 ± 11.8 mL·kg −1 , and 33.5 ± 8.4 mL·kg −1 ·min −1 . VO 2peak in fit and unfit participants and women and men were 38.6 ± 6.5 and 25.8 ± 3.8 mL·kg −1 ·min −1 , 30.7 ± 7.6 mL·kg −1 ·min −1 , and 35.5 ± 8.5 mL·kg −1 ·min −1 , respectively. Women were shorter (Δ14 cm), leaner (Δ13 kg), and with less muscle mass (Δ9%) than men ( P < 0.05). Relative erythrocyte volume and Hb mass were lower in women, and blood and erythrocyte volume and Hb mass were higher in the fit participants ( P < 0.05). Hb mass and erythrocyte volume explained 40 and 37%, respectively, of the variability in VO 2peak , with a limited effect of physical-activity adjustment (40 and 38%, respectively). Blood and plasma volume explained 15 and 25%, respectively, of VO 2peak variability, and the association was strengthened adjusting for physical activity (25 and 31%, respectively), indicating a training-dependent adaptation in plasma but not erythrocyte volume ( p ≤ 0.006). Conclusions: Blood and plasma volumes were moderately associated with VO 2peak in healthy older men and women, and the association was strengthened after adjustment for physical activity. Hb mass and erythrocyte volume were strongly associated with VO 2peak but unrelated to physical activity.

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