Impairments In Lower Limb Microvascular Function Associated With Cycle Phases In Young Healthy Women

PURPOSE: Differences in women’s hormone concentrations throughout the menstrual cycle affects vascular responsiveness. Previous investigations have shown that these changes can be modulated by regular use of oral contraceptives. However, most of these studies only assessed changes in vascular function at the upper limb conduit artery level. This study investigated whether vascular function at the lower limb microvasculature of healthy young women might be affected by the phase of the menstrual cycle.

METHODS: 14 young (25 ± 5 years of age) physically active women participated in the study. The participants were assigned to two groups of seven participants each according to oral contraceptive use: non-contraceptive group (women who did not use any contraceptive within the last two years prior to the intervention - NCP) and oral contraceptive group (seven women who used oral contraceptive regularly for at least two years prior to the intervention – OCP). The participants underwent two lower limb vascular occlusion tests (5 min of baseline, 5 min of occlusion, and 8 min following cuff release) in two different phases of the menstrual cycle (follicular and luteal phase). Microvascular responsiveness was

assessed by the percent of change of the NIRS-derived muscle oxygen saturation (StO2) reperfusion slope (%/sec) of the tibialis anterior muscle.

RESULTS: There was no difference in the reperfusion slope of the NCP group between the follicular (1.18 ± 0.5 %/sec) and luteal (1.01 ± 0.3 %/sec) phases. The reperfusion slope of the OCP group was significantly steeper in the follicular (0.85 ± 0.2 %/sec) compared to the luteal phase (0.63 ± 0.2 %/sec).

CONCLUSION: Use of oral contraceptive is associated with reduced microvascular function in the luteal phase in young physically active women.