Aerobic Exercise Training Reduces Cerebrovascular Impedance in Older Adults: A One-Year Randomized Controlled Trial.

Older adults have higher cerebrovascular impedance than young individuals which may contribute to chronic brain hypoperfusion. Besides, middle-aged athletes exhibit lower cerebrovascular impedance than their sedentary peers. We examined whether aerobic exercise training (AET) reduces cerebrovascular impedance in sedentary older adults. We conducted a proof-of-concept trial that randomized 73 older adults to one year of AET (n=36) or stretching and toning (SAT, n=37) interventions. Cerebrovascular impedance was estimated from simultaneous recordings of carotid artery pressure (CAP) via applanation tonometry and cerebral blood flow velocity (CBFV) in the middle cerebral artery via transcranial Doppler using transfer function analysis. Fifty-six participants completed one-year interventions, and forty-one of those completed cerebrovascular impedance measurements. AET group showed a significant increase in VO2peak after the intervention (estimated marginal mean [95% confidence interval]; from 22.8 [21.6 to 24.1] to 24.9 [23.6 to 26.2] ml·kg-1·cm-1, P<0.001), but not SAT (from 21.7 [20.5 to 22.9] to 22.3 [21.1 to 23.7] ml·kg-1·cm-1, P=0.114). Coherence between changes in CBFV and CAP was > 0.90 in the frequency range of 0.78-3.12 Hz. The averaged cerebrovascular impedance modulus (Z) in this frequency range decreased after one-year AET (from 1.05 [0.96 to 1.14] to 0.95 [0.92 to 1.06] mmHg·sec·cm-1, P=0.023), but not SAT (from 0.96 [0.87 to 1.04] to 1.01 [0.92 to 1.10] mmHg·sec·cm-1, P=0.138). Reductions in Z were correlated positively with reductions in carotid pulse pressure (r=0.628, P=0.004) and inversely with mean CBFV (r=-0.563, P=0.012) in the AET group. One-year AET reduces cerebrovascular impedance in older adults, which may benefit brain perfusion.