The Impact of 6-Month Land versus Water Walking on Cerebrovascular Function in the Aging Brain.

Introduction: To examine the hypothesis that exercise training induces adaptation in cerebrovascular function, we recruited 63 older adults (62 ± 7 yr, 46 females) to undertake 24 wk of either land walking or water walking, or participate in a nonexercise control group. This is the first multi-interventional study to perform a comprehensive assessment of cerebrovascular function in response to longer term (6-month) training interventions, including water-based exercise, in older healthy individuals.

Methods: Intracranial blood flow velocities (middle cerebral artery (MCAv) and posterior cerebral artery) were assessed at rest and in response to neurovascular coupling, hypercapnic reactivity, and cerebral autoregulation.

Results: We observed no change in resting MCAv in response to either training intervention (pre vs post, mean (95% confidence interval), land walking: 65 (59-70) to 63 (57-68) cm·s-1, P = 0.33; water walking: 63 (58-69) to 61 (55-67) cm·s-1, P = 0.92) compared with controls and no change in neurovascular coupling (land walking: P = 0.18, water walking: P = 0.17). There was a significant but modest improvement in autoregulatory normalized gain after the intervention in the water-walking compared with the land-walking group (P = 0.03). Hypercapnic MCAv reactivity was not different based on exercise group (land: P = 087, water: P = 0.83); however, when data were pooled from the exercise groups, increases in fitness were correlated with decreases in hypercapnic reactivity (r2 = 0.25, P = 0.003).

Conclusions: Although exercise was not associated with systematic changes across multiple domains of cerebrovascular function, our data indicate that exercise may induce modest changes in autoregulation and CO2 reactivity. These findings should encourage further studies of the longer-term implications of exercise training on cerebrovascular health.