TY - JOUR
T1 - CO2 supplementation dissociates cerebral oxygenation and middle cerebral artery blood velocity during maximal cycling
AU - Hansen, Rasmus K.
AU - Nielsen, Peter S.
AU - Schelske, Markus W.
AU - Secher, Niels H.
AU - Volianitis, Stefanos
N1 - doi: 10.1111/sms.13582
PY - 2020/3/1
Y1 - 2020/3/1
N2 - This study evaluated whether the reduction of prefrontal cortex oxygenation (ScO 2) during maximal exercise depends on the hyperventilation-induced hypocapnic attenuation of middle cerebral artery blood velocity (MCA V mean). Twelve endurance-trained males (age: 25 ± 3 years, height: 183 ± 8 cm, weight: 75 ± 9 kg; mean ± SD) performed in three separate laboratory visits, a maximal oxygen uptake (VO 2max) test, an isocapnic (end-tidal CO 2 tension (PetCO 2) clamped at 40 ± 1 mmHg), and an ambient air controlled-pace constant load high-intensity ergometer cycling to exhaustion, while MCA V mean (transcranial Doppler ultrasound) and ScO 2 (near-infrared spectroscopy) were determined. Duration of exercise (12 min 25 s ± 1 min 18 s) was matched by performing the isocapnic trial first. Pulmonary VO 2 was 90 ± 6% versus 93 ± 5% of the maximal value (P =.012) and PetCO 2 40 ± 1 versus 34 ± 4 mmHg (P <.05) during the isocapnic and control trials, respectively. During the isocapnic trial MCA V mean increased by 16 ± 13% until clamping was applied and continued to increase (by 14 ± 28%; P =.017) until the end of exercise, while there was no significant change during the control trial (P =.071). In contrast, ScO 2 decreased similarly in both trials (−3.2 ± 5.1% and −4.1 ± 9.6%; P <.001, isocapnic and control, respectively) at exhaustion. The reduction in prefrontal cortex oxygenation during maximal exercise does not depend solely on lowered cerebral blood flow as indicated by middle cerebral blood velocity.
AB - This study evaluated whether the reduction of prefrontal cortex oxygenation (ScO 2) during maximal exercise depends on the hyperventilation-induced hypocapnic attenuation of middle cerebral artery blood velocity (MCA V mean). Twelve endurance-trained males (age: 25 ± 3 years, height: 183 ± 8 cm, weight: 75 ± 9 kg; mean ± SD) performed in three separate laboratory visits, a maximal oxygen uptake (VO 2max) test, an isocapnic (end-tidal CO 2 tension (PetCO 2) clamped at 40 ± 1 mmHg), and an ambient air controlled-pace constant load high-intensity ergometer cycling to exhaustion, while MCA V mean (transcranial Doppler ultrasound) and ScO 2 (near-infrared spectroscopy) were determined. Duration of exercise (12 min 25 s ± 1 min 18 s) was matched by performing the isocapnic trial first. Pulmonary VO 2 was 90 ± 6% versus 93 ± 5% of the maximal value (P =.012) and PetCO 2 40 ± 1 versus 34 ± 4 mmHg (P <.05) during the isocapnic and control trials, respectively. During the isocapnic trial MCA V mean increased by 16 ± 13% until clamping was applied and continued to increase (by 14 ± 28%; P =.017) until the end of exercise, while there was no significant change during the control trial (P =.071). In contrast, ScO 2 decreased similarly in both trials (−3.2 ± 5.1% and −4.1 ± 9.6%; P <.001, isocapnic and control, respectively) at exhaustion. The reduction in prefrontal cortex oxygenation during maximal exercise does not depend solely on lowered cerebral blood flow as indicated by middle cerebral blood velocity.
KW - cerebral oxygenation
KW - controlled-pace exercise
KW - end-tidal PCO
KW - middle cerebral artery blood velocity
UR - http://www.scopus.com/inward/record.url?scp=85075440301&partnerID=8YFLogxK
U2 - 10.1111/sms.13582
DO - 10.1111/sms.13582
M3 - Journal article
SN - 0905-7188
VL - 30
SP - 399
EP - 407
JO - Scandinavian Journal of Medicine & Science in Sports
JF - Scandinavian Journal of Medicine & Science in Sports
IS - 3
ER -