Dynamic Cerebral Autoregulation during Repeated Handgrip Exercise: Comparisons with Spontaneous Rest and Sit-Stand Maneuvers

Induced arterial pressure oscillation may improve the assessment of dynamic cerebral autoregulation (dCA) based on transfer function analysis (TFA). This study investigated dCA during repeated handgrip exercise (RHE) and compared it to spontaneous rest and sit-stand maneuvers (SSMs) which are often used for dCA assessment. After a 5-minute rest, 20 healthy young adults (10 women) underwent 5 minutes of RHE and SSMs at 0.05 Hz and 0.10 Hz in random order. Power spectral densities (PSDs) and TFA gain, phase, and coherence of mean arterial pressure (MAP) and blood velocity in the middle cerebral artery (MCAv mean ) were compared in very low (VLF: 0.02-0.07 Hz) and low (LF: 0.07-0.20 Hz) frequencies. End-tidal CO 2 (EtCO 2 ) was recorded throughout the study. Compared with rest, RHE increased PSDs of MAP and MCAv mean in VLF (444% and 273% respectively) and LF (1571% and 1765% respectively), with significant elevations in TFA coherence (VLF: 131%, LF: 128%), while SSMs exhibited the highest PSD and coherence values (all P < 0.05). TFA gains and phases were similar between RHE and rest, but VLF gain was higher while VLF and LF phases were lower during SSMs than RHE (all P < 0.05). EtCO 2 was higher during SSMs than rest and RHE (both P < 0.05), with the individual changes positively correlated with VLF gain changes (R 2 = 0.289, P < 0.001). These results suggest that RHE significantly increases arterial pressure oscillation and TFA coherence and may improve the dCA assessment in individuals not capable of performing repeated postural changes.