Improved Cerebral Vasomotor Reactivity After Exercise Training in Hemiparetic Stroke Survivors

Abstract

Background and Purpose-Animal studies provide strong evidence that aerobic exercise training positively influences cerebral blood flow, but no human studies support the use of exercise for improving cerebral hemodynamics. This randomized study in stroke survivors assessed the effects of treadmill aerobic exercise training (TM) on cerebral blood flow parameters compared to a control intervention of nonaerobic stretching. Methods-Thirty-eight participants (19 in TM group and 19 in control group) with remote stroke (Ͼ6 months) and mild to moderate gait deficits completed middle cerebral artery blood flow velocity measurements by transcranial Doppler ultrasonography before and after a 6-month intervention period. Middle cerebral artery blood flow velocity was assessed bilaterally during normocapnia and hypercapnia (6% CO 2 ). Cerebral vasomotor reactivity (cVMR) was calculated as percent change in middle cerebral artery blood flow velocity from normocapnia to hypercapnia (cVMR percent) and as an index correcting percent change for absolute increase in end tidal CO 2 (cVMR index). Results-The TM group had significantly larger improvements than did controls for both ipsilesional and contralesional cVMR index (PՅ0.05) and contralesional cVMR percent (PՅ0.01). Statin users in the TM group (nϭ10) had higher baseline cVMR and lower training-induced cVMR change, indicating that cVMR change among those not using statins (nϭ9) primarily accounted for the between-group effects. There was a 19% increase in VO 2 peak for the TM group compared to a 4% decrease in the control group (PϽ0.01), and peak fitness change correlated with cVMR change (rϭ0.55; PϽ0.05). Conclusions-Our data provide the first evidence to our knowledge of exercise-induced cVMR improvements in stroke survivors, implying a protective mechanism against recurrent stroke and other brain-related disorders. Statin use appears to regulate cVMR and the cVMR training response. (Stroke.

Cerebral Vasomotor Reactivity during Hypo- and Hypercapnia in Sedentary Elderly and Masters Athletes

“…30 In contrast, a recent study of stroke survivors reported that cerebral CO2 reactivity was improved after 6 months of aerobic training, although resting CBFV did not change. 11 In the present study, we found minimal effects of life-long aerobic exercise training on age-related differences in CVMR. Masters athletes only demonstrated a smaller hypocapnic CVMR when compared with the sedentary elderly.…”

“…12 Accordingly, the purpose of this study was to determine the impact of life-long aerobic exercise training on age-related changes in CVMR. Based on previous studies, 10,11 we hypothesized that cerebral CO2 reactivity to both hypo-and hypercapnia would be reduced in the sedentary elderly compared with young adults. Furthermore, we hypothesized that age-related reduction in cerebral CO2 reactivity would be attenuated in Masters athletes.…”

Cerebral blood flow and cerebrovascular reactivity at rest and during sub-maximal exercise: Effect of age and 12-week exercise training

“…Furthermore, 6 months of aerobic exercise training can even increase brain volume in previously sedentary older individuals (Colcombe et al 2006), so a corresponding increase in CBF would seem plausible. Yet Ivey et al (2011) found no increase in CBF following 6 months of aerobic-based exercise training in chronic hemiparetic stroke patients. In summary, cross-sectional data indicate that fitness training may increase CBF, consistent with the demonstrated improvements in neuronal mass and metabolism, but it remains to be shown whether CBF is actually increased with training or whether this occurs in both young and older healthy individuals.…”

“…This is only the second known study to report on the effect of fitness on cerebrovascular reactivity in humans. Ivey et al (2011) demonstrated a~30 % elevation in cerebrovascular reactivity to 6 % CO 2 in stroke survivors following 6 months of exercise training. Interestingly, the elevation in fitness across the training intervention was positively correlated with the change in cerebrovascular reactivity, indicating that the increased aerobic capacity is at least, in part, responsible for the improved cerebrovascular reactivity.…”

“…Ivey et al (2011) demonstrated an elevation in cerebrovascular reactivity to CO 2 following 6 months of exercise training in stroke survivors. Whether similar improvements can be observed in healthy young and older individuals following a lesser amount of exercise training is unknown.…”