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Purpose: Aging is associated with impaired cerebral blood flow (CBF) and increased risk of cerebrovascular disease. Acute increases in CBF during exercise may initiate improvements in cerebrovascular health, but the CBF response is diminished during continuous exercise in older adults. The effect of interval exercise for promoting increases in CBF in young and old adults is unknown.

Methods: We compared middle cerebral artery blood velocity (MCAv), end-tidal CO2 (PETCO2) and blood pressure (mean arterial pressure [MAP]) during intensity- and work-matched bouts of continuous (10-min 60%Wmax, followed by 10-min rest) and interval cycling (10 x 1-min 60%Wmax, separated by 1-min rest) in 11 young (25 /- 3 yr) and 10 old (69 /- 3 yr) men.

Results: Middle cerebral artery velocity was higher during continuous compared with interval exercise in the young (P < 0.001), but not in the old. This trend was also seen for changes in PETCO2. Although absolute MAP was higher in the old, the relative rise (%[INCREMENT]) in MAP was similar between age groups and was greater during continuous exercise than interval. When we assessed the total accumulated change in MCAv (area under curve: exercise recovery), it was higher with interval compared with continuous exercise in both groups (P = 0.018).

Conclusion: These findings suggest that interval exercise may be an effective alternative for promoting acute increases in CBF velocity, particularly in those older adults who may have difficulty sustaining continuous exercise.

(C) 2019 American College of Sports Medicine