Influence of sex on microvascular and macrovascular responses to prolonged sitting

Increased daily sitting time is associated with greater cardiovascular risk, and, on average, women are more sedentary than men. Recent reports have demonstrated that prolonged sitting reduces lower leg microvascular (reactive hyperemia) and macrovascular [flow-mediated dilation (FMD)] vasodilator function. However, these studies have predominately included men, and the effects of sitting in young women are largely unexplored. This becomes important given known sex differences in vascular function. Thus, herein, we assessed popliteal artery reactive hyperemia and FMD before and after a 3-h sitting period in healthy young women (n = 12) and men (n = 8). In addition, resting popliteal artery hemodynamics (duplex Doppler ultrasound) and calf circumference were measured before, during, and after sitting. Resting popliteal artery shear rate was reduced to a similar extent in both groups during the sitting period (women: –48.5 ± 8.4 s–1 and men: –52.9 ± 12.3 s–1, P = 0.45). This was accompanied by comparable increases in calf circumference in men and women (P = 0.37). After the sitting period, popliteal artery FMD was significantly reduced in men (PreSit: 5.5 ± 0.9% and PostSit: 1.6 ± 0.4%, P < 0.001) but not women (PreSit: 4.4 ± 0.6% and PostSit: 3.6 ± 0.6%, P = 0.29). In contrast, both groups demonstrated similar reductions in hyperemic blood flow area under the curve (women: –28,860 ± 5,742 arbitra...

Source: AJP: Heart and Circulatory Physiology - April 1, 2017 Category: Cardiology Authors: Vranish, J. R., Young, B. E., Kaur, J., Patik, J. C., Padilla, J., Fadel, P. J. Tags: RAPID REPORT Source Type: research