Central command and the increase in middle cerebral artery blood flow velocity during static arm exercise in women

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.