TY - JOUR
T1 - Phlebotomy eliminates the maximal cardiac output response to six weeks of exercise training
AU - Bonne, Thomas Christian
AU - Doucende, Gregory
AU - Flück, Daniela
AU - Jacobs, Robert A
AU - Nordsborg, Nikolai Baastrup
AU - Robach, Paul
AU - Walther, Guillaume
AU - Lundby, Carsten
N1 - CURIS 2014 NEXS 094
PY - 2014/5/15
Y1 - 2014/5/15
N2 - With this study we tested the hypothesis that 6 wk of endurance training increases maximal cardiac output (Q̇max) relatively more by elevating blood volume (BV) than by inducing structural and functional changes within the heart. Nine healthy but untrained volunteers (V̇O2max 47 ± 5 ml·min-1·kg-1) underwent supervised training (60 min; 4 times weekly at 65% V̇O2max for 6 wk), and Q̇max was determined by inert gas rebreathing during cycle ergometer exercise before and after the training period. After the training period, blood volume (determined in duplicates by CO rebreathing) was reestablished to pretraining values by phlebotomy and Q̇max was quantified again. Resting echography revealed no structural heart adaptations as a consequence of the training intervention. After the training period, plasma volume (PV), red blood cell volume (RBCV), and BV increased (P < 0.05) by 147 ± 168 (5 ± 5%), 235 ± 64 (10 ± 3%), and 382 ± 204 ml (7 ± 4%), respectively. V̇O2max was augmented (P < 0.05) by 10 ± 7% after the training period and decreased (P < 0.05) by 8 ± 7% with phlebotomy. Concomitantly, Q̇max was increased (P < 0.05) from 18.9 ± 2.1 to 20.4 ± 2.3 l/min (9 ± 6%) as a consequence of the training intervention, and after normalization of BV by phlebotomy Q̇max returned to pretraining values (18.1 ± 2.5 l/min; 12 ± 5% reversal). Thus the exercise training-induced increase in BV is the main mechanism increasing Q̇max after 6 wk of endurance training in previously untrained subjects.
AB - With this study we tested the hypothesis that 6 wk of endurance training increases maximal cardiac output (Q̇max) relatively more by elevating blood volume (BV) than by inducing structural and functional changes within the heart. Nine healthy but untrained volunteers (V̇O2max 47 ± 5 ml·min-1·kg-1) underwent supervised training (60 min; 4 times weekly at 65% V̇O2max for 6 wk), and Q̇max was determined by inert gas rebreathing during cycle ergometer exercise before and after the training period. After the training period, blood volume (determined in duplicates by CO rebreathing) was reestablished to pretraining values by phlebotomy and Q̇max was quantified again. Resting echography revealed no structural heart adaptations as a consequence of the training intervention. After the training period, plasma volume (PV), red blood cell volume (RBCV), and BV increased (P < 0.05) by 147 ± 168 (5 ± 5%), 235 ± 64 (10 ± 3%), and 382 ± 204 ml (7 ± 4%), respectively. V̇O2max was augmented (P < 0.05) by 10 ± 7% after the training period and decreased (P < 0.05) by 8 ± 7% with phlebotomy. Concomitantly, Q̇max was increased (P < 0.05) from 18.9 ± 2.1 to 20.4 ± 2.3 l/min (9 ± 6%) as a consequence of the training intervention, and after normalization of BV by phlebotomy Q̇max returned to pretraining values (18.1 ± 2.5 l/min; 12 ± 5% reversal). Thus the exercise training-induced increase in BV is the main mechanism increasing Q̇max after 6 wk of endurance training in previously untrained subjects.
U2 - 10.1152/ajpregu.00028.2014
DO - 10.1152/ajpregu.00028.2014
M3 - Journal article
C2 - 24622974
SN - 0363-6119
VL - 306
SP - R752-R760
JO - American Journal of Physiology: Regulatory, Integrative and Comparative Physiology
JF - American Journal of Physiology: Regulatory, Integrative and Comparative Physiology
IS - 10
ER -