Endurance training-induced increases in peak oxygen uptake were preserved (11% increase) despite removing the training-induced increases in hemoglobin mass and blood volume by phlebotomy.
Does 10 weeks of endurance training improve peak oxygen uptake independently of blood volume expansion in untrained adults?
Endurance training increases peak oxygen uptake primarily through elevated peak cardiac output and widened arteriovenous O2 difference, independent of blood volume expansion.
p-value: p=≤0.005
Abstract Purpose The endurance training (ET) -induced increases in peak oxygen uptake (V̇ V˙ O 2peak) and cardiac output (Q̇ Q˙ peak) during upright cycling are reversed to pre-ET levels after removing the training-induced increase in blood volume (BV). We hypothesised that ET-induced improvements in V̇ V˙ O 2peak and Q̇ Q˙ peak are preserved following phlebotomy of the BV gained with ET during supine but not during upright cycling. Arteriovenous O 2 difference (a- v v¯ O 2 diff; V̇ V˙ O 2 / Q̇ Q˙), cardiac dimensions and muscle morphology were studied to assess their role for the V̇ V˙ O 2peak improvement. Methods Twelve untrained subjects (V̇ V˙ O 2peak: 44 ± 6 ml kg −1 min −1) completed 10 weeks of supervised ET (3 sessions/week). Echocardiography, muscle biopsies, haemoglobin mass (Hb mass) and BV were assessed pre- and post-ET. V̇ V˙ O 2peak and Q̇ Q˙ peak during upright and supine cycling were measured pre-ET, post-ET and immediately after Hb mass was reversed to the individual pre-ET level by phlebotomy. Results ET increased the Hb mass (3. 3 ± 2. 9%; P = 0. 005), BV (3. 7 ± 5. 6%; P = 0. 044) and V̇ V˙ O 2peak during upright and supine cycling (11 ± 6% and 10 ± 8%, respectively; P ≤ 0. 003). After phlebotomy, improvements in V̇ V˙ O 2peak compared with pre-ET were preserved in both postures (11 ± 4% and 11 ± 9%; P ≤ 0. 005), as was Q̇ Q˙ peak (9 ± 14% and 9 ± 10%; P ≤ 0. 081). The increased Q̇ Q˙ peak and a- v v¯ O 2 diff accounted for 70% and 30% of the V̇ V˙ O 2peak improvements, respectively. Markers of mitochondrial density (CS and COX-IV; P ≤ 0. 007) and left ventricular mass (P = 0. 027) increased. Conclusion The ET-induced increase in V̇ V˙ O 2peak was preserved despite removing the increases in Hb mass and BV by phlebotomy, independent of posture. V̇ V˙ O 2peak increased primarily through elevated Q̇ Q˙ peak but also through a widened a- v v¯ O 2 diff, potentially mediated by cardiac remodelling and mitochondrial biogenesis.
Skattebo et al. (Sat,) conducted a other in Healthy untrained subjects (n=12). Endurance training followed by phlebotomy vs. Pre-training baseline was evaluated on Change in peak oxygen uptake (VO2peak) during upright cycling after phlebotomy compared to pre-training (p=≤0.005). Endurance training-induced increases in peak oxygen uptake were preserved (11% increase) despite removing the training-induced increases in hemoglobin mass and blood volume by phlebotomy.
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