Central command and the increase in middle cerebral artery blo...

We examined the role of central command in static exercise-induced increase in middle cerebral artery mean blood flow velocity (V(MCA)). Eleven young female subjects performed static elbow flexion for 2 min at 30% maximal voluntary contraction without (control exercise; CONT) and with vibrations to the biceps brachii tendon (EX+VIB) in order to reduce the effort needed to maintain the set contraction intensity. The rating of perceived exertion in exercising muscle (Arm RPE) at the end of EX+VIB was lower than that of CONT (mean +/- s.d.; 4.8 +/- 1.1 for CONT versus 3.5 +/- 1.0 for EX+VIB; P < 0.05). The increases in mean arterial pressure (36 +/- 8 versus 22 +/- 7%; P < 0.05), heart rate (36 +/- 16 versus 21 +/- 7%; P < 0.05) and cardiac output (56 +/- 26 versus 39 +/- 14%; P < 0.05) during EX+VIB were also lower than those during CONT. Similarly, the increase in the V(MCA) during EX+VIB was lower than that during CONT (29 +/- 5 versus 17 +/- 14%; P < 0.05). These results suggest that the influence of central command contributes to cerebral blood flow regulation during static exercise and the decrease in V(MCA) is likely to be caused by attenuated brain activation in the central command network and/or by the reduction in cardiac output.