Author(s): KLEIN, T., MANN, V., FELDHEGE, F., BRUHN, S., Institution: UNIVERSITY OF ROSTOCK, Country: GERMANY, Abstract-ID: 1546

INTRODUCTION:
Physical exercise is a critical stimulus for cerebrovascular health, with acute increases in cerebral blood flow, measured as middle cerebral artery velocity (MCAv) serving as a primary driver for cerebrovascular adaptation. Previous research indicates that MCAv responses may be exercise-modality dependent, peaking at maximal intensity during rowing but at moderate intensity during cycling exercise, but direct comparisons are missing. Evidence suggests potential sex-related differences in MCAv responses during acute exercise. This study compared MCAv responses to rowing and cycling in young males and females during high-intensity all-out exercises.
METHODS:
Eighteen healthy adults (11 males: 23±5 years; 7 females: 23±3 years; P=.77) completed two 3-minute all-out exercise bouts on a rowing and cycling ergometer in a randomized order, separated by at least 72 hours. Females were tested during the early follicular phase of their menstrual cycle, to minimize hormonal variability. MCAv, end-tidal partial pressure of carbon dioxide (PETCO2), and mean arterial blood pressure (MAP) were recorded continuously. The primary outcome was defined as the change from baseline to the mean value of the final 30 seconds of exercise. Data were analyzed using a repeated measures ANOVA with factors of EXERCISE (Rowing vs. Cycling) and SEX (Males vs. Females).
RESULTS:
At baseline, MCAv (EXERCISE: P=.15; SEX: P=.14), PETCO2 (EXERCISE: P=.89; SEX: P=.97) and MAP (EXERCISE: P=.84; SEX: P=.22) were similar between groups. During exercise, the change from baseline in MCAv was significantly greater during rowing compared to cycling (P<.01, ηp2=.60), and females showed a higher increase compared to males (P=.02, ηp2=.31). PETCO2 increased to a greater extent during rowing than cycling (P<.01, ηp2=.78), with no significant sex differences (P=.82). MAP responses were similar between exercise modalities (P=.20) and between sexes (P=.34).
CONCLUSION:
Young adults showed significantly higher MCAv responses during rowing compared to cycling at high-intensity exercise, with females exhibiting a more pronounced increase in MCAv than males. Although the higher PETCO2 observed during rowing (a difference of ~3mmHg on average compared to cycling) contributed to larger increase in MCAv, this difference does not fully account for the magnitude of the MCAv response. The sex-specific difference, where females showed higher increases in MCAv despite similar PETCO2 and MAP responses, suggests that cerebrovascular regulation during high-intensity exercise is sex-dependent. These findings are critical when prescribing exercise modalities to optimize cerebrovascular health.