Sex Differences Exist in Popliteal, but not Brachial Artery Flow-Mediated Dilation in Physically Active Young Adults

Abstract

Conflicting reports regarding sex differences in flow-mediated dilation (FMD) may be due to not considering smaller arterial diameters in females, between-group differences in aerobic fitness and/or habitual physical activity (PA) and sedentary behaviours. It was hypothesized that males would exhibit greater brachial (BA-FMD) and popliteal artery FMD (POP-FMD) when scaled for baseline diameter. FMD, aerobic fitness, objectively measured PA and sedentary time (ST), were measured in 13 males (23±3 years) and 13 females (24±2 years). Both groups had similar moderate-vigorous PA (p=0.25) and ST (p=0.08) but males had greater aerobic fitness (p<0.001). Females engaged in more light PA (p=0.03), which was positively correlated to POP-FMD in the pooled sample (r=0.43, p=0.04). When allometrically scaled, BA-FMD was similar between sexes (p=0.75) but POP-FMD was still greater in females (p=0.03). Covarying for light PA did not influence the sex difference in POP-FMD (p=0.008). Sex differences existed in lower-, but not upper-limb FMD.