Enhanced cerebro-cardiovascular responses before starting voluntary exercise in young men with higher peak aerobic capacity

We recently reported that countdown (CD) before voluntary exercise induced cerebral activation and pressor responses, resulting in muscle vasodilation ( J Appl Physiol 128: 1196-1206, 2020). We examined whether responses were enhanced as peak aerobic capacity (⩒O 2peak ) increased. We studied 27 young men with ⩒O 2peak from 25.2 to 61.4 ml·kg −1 ·min −1 . We evaluated CD responses before initiating voluntary cycling at 50% of ⩒O 2peak for 1 min in a semi-recumbent position while measuring middle cerebral artery blood flow velocity (V MCA ; Doppler ultrasonography), heart rate, mean arterial pressure (MAP; finger photoplethysmography), oxygen consumption rate (⩒O 2 ), cardiac output (Q˙ c ; Modelflow), total peripheral resistance (MAP/Q˙ c ) and oxygen saturation in thigh muscle (near-infrared spectrometry). All subjects performed 8 trials, intermitted by ≥5-min rest, and were either given a 30-sec countdown (CD+) or immediately signaled to begin exercise (CD−), with the order randomized and counterbalanced. We classified subjects with both V MCA and MAP increases by CD as “responders” (Resp, n=11) and those with either V MCA or MAP increase, or an increase of neither, as “minimal responders” (MinResp, n=16). We found cerebro-cardiovascular and ⩒O 2 responses to CD before starting exercise were all significantly greater in Resp than MinResp (all, P<0.017), and cerebro-cardiovascular responses were significantly correlated with individual ⩒O 2peak in data pooled from both groups (all, P<0.034). The increase in ⩒O 2 by CD in Resp continued for a few seconds after starting exercise. Thus, cerebro-cardiovascular responses to CD before starting voluntary exercise were enhanced as individual ⩒O 2peak increased in young men, which might accelerate ⩒O 2 response at starting exercise.