Individual data from a representative subject during maximal voluntary apnoea.

BH: breath-hold; MAP: mean arterial pressure; CBFV: cerebral blood flow-velocity; : phase angle between the MAP and CBFV time series; PhSI: phase synchronisation index. N.B.: values for and PhSI were obtained from the low-frequency region of the MAP–CBFV relationship (i.e., 0.01–0.15 Hz), where dynamic cerebral autoregulation is considered most active.