Effect Of Aquatic-treadmill Training On Cerebrovascular Function In Community-dwelling Stroke Survivors

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Exercise-induced increases in brain blood flow are a key mechanistic pathway for improved brain function through regular exercise. Water-based exercise augments this response and therefore may represent an optimal exercise strategy to target this mediator of improved brain health, particularly for those with impaired cerebrovascular vascular function such as stroke survivors. While aquatic treadmill exercise has been reported to improve gait re-education in stroke rehabilitation, no research has assessed whether cerebrovascular function in stroke survivors is improved following water-based training.

PURPOSE: To examine the effect of a 4-wk aquatic treadmill (ATM) training intervention on cerebrovascular responsiveness in community-dwelling stroke survivors.

METHODS: Six community-dwelling stroke survivors (58 ± 11 yrs), with chronic stroke (>6 months), completed a 4-wk ATM training intervention of 30 min water-based walking, 3 times/wk. Before and following the intervention, resting cerebral blood flow velocity (Transcranial Doppler) of the stroke affected and unaffected cerebral hemispheres was assessed along with cerebrovascular responsiveness, as indexed from the percent change in middle cerebral artery blood velocity (MCAv) to a 4-min hypercapnic stimulus (5% CO2 in air). ANOVA was used to compare pre and post intervention measures.

RESULTS: Pre-training resting MCAv was similar between the affected and unaffected side (mean ± SD: 46 ± 12 vs 46 ± 19 cm/s, respectively; p=0.96), and the 4-wk intervention did not change this relation (p=0.42) nor significantly change the resting MCAv value (post training: 47 ± 11 vs 52 ± 15 cm/s; p=0.29). MCAv-CO2 responsiveness increased by 40% in the affected hemisphere (2.8 ± 1.9 to 4.2 ± 1.8 %MCAv / mm Hg PETCO2) and 65% in the unaffected hemisphere (3.0 ± 1.1 to 4.9 ± 0.9 %MCAv / mm Hg PETCO2) following the 4-wk intervention, although this main effect did not reach statistical significance (p=0.08) nor was there statistical support for a differential increase between hemispheres (interaction effect: p=0.41).

CONCLUSIONS: This pilot study supports ATM training as a feasible option in stroke rehabilitation, and shows promising potential of enhanced cerebrovascular function for stroke survivors in this chronic phase of the rehabilitation pathway.