Impact of Aging and Life‐long Exercise on Cerebral Vasomotor Reactivity

Abstract

This study investigated the impact of aging and life-long aerobic exercise training on cerebral vasomotor reactivity to changes in end-tidal CO2. We used transcranial Doppler to measure cerebral blood flow velocity (CBFV) in response to hypocapnia and hypercapnia induced by hyperventilation and CO2 rebreathing method. Eleven sedentary healthy young (SY, 27 ± 5 yr, 5 women), 10 sedentary seniors (SS, 72 ± 4 yr, 3 women) and 10 Masters Athletes (MA, 72 ± 6 yr, 1 woman) participated in this study. Compared with SY, resting CBFV was reduced and cerebrovascular resistance was increased in both SS and MA (P < 0.05). The relative changes in CBFV (%) in response to hypercapnia were greater in SS and MA than in SY (79 ± 21, 96 ± 23 vs. 56 ± 11 %, P < 0.01), but the absolute increases in CBFV were similar among 3 groups ( 39 ± 19, 41 ± 17 vs. 35 ± 8 cm/s, P > 0.2). During hypocapnia, both relative and absolute decreases in CBFV were less in SS and MA than in SY (P < 0.05). These decreases also were less in MA than in SS (P < 0.05). The cerebral vasomotor reactivity, in the sedentary and physically active elderly, was preserved or enhanced to hypercapnia, but reduced to hypocapnia. It suggests that there are probably defense mechanisms against chronic cerebrovascular constriction in the elderly which improve cerebral perfusion efficiently in hypercapnia and keep the brain of hypoperfusion in hypocapnia. This study was supported by R01HL102457-01.