Author(s): YU, T.A.1, WANG, C.W.2, CHEN, L.Y.1, WANG, C.K.3, FANG, S.H.2, WANG, S.C.1, HE, C.S.1, Institution: NATIONAL CHUNG CHENG UNIVERSITY, Country: TAIWAN, Abstract-ID: 654

INTRODUCTION:
High-Intensity Interval Exercise (HIIE) has been proven to have positive effects on improving cardiovascular function (1). However, disparities in arterial stiffness improvement may exist among premenopausal women in different menstrual phases (2). Therefore, this study aimed to investigate the acute effects of HIIE on cardiovascular function in healthy young women during different menstrual phases, aiming to clarify the benefits on cardiovascular function.
METHODS:
Thirteen female college students with regular exercise habits were recruited, and their menstrual cycle status was determined through a menstrual cycle questionnaire. One week before formal HIIE, the participants peak heart rate (HRpeak) was measured. Subsequently, one HIIE session was conducted during both the follicular and luteal phases of the same menstrual cycle. Each session comprised 10 sets of 1-minute exercise at 90% HRpeak intensity with 1-minute rest intervals. Blood pressure and finger-toe pulse wave velocity (ftPWV) were measured at Rest, immediately post-exercise (T0), and at 15 (T15), 30 (T30), 45 (T45), and 60 (T60) minutes post-exercise. Repeated-measures two-factor analysis of variance was employed for statistical analysis.
RESULTS:
ftPWV at Rest, T0, T15, and T30 was significantly lower in the luteal phase group compared to the follicular phase group (p < 0.05). Systolic blood pressure (SBP) at Rest was significantly lower in the luteal phase group (p < 0.05), while the follicular phase group showed a significant decrease in SBP at T30, T45, and T60 compared to Rest (p < 0.05). Diastolic blood pressure (DBP) at Rest, T30, T45, and T60 was significantly lower in the luteal phase group (p < 0.05). The area under the curve (AUC) of ftPWV, AUC SBP, and AUC DBP during Rest-T0 was significantly lower in the luteal phase group (p < 0.05).
CONCLUSION:
The acute effects of HIIE vary among different population groups. In healthy young women, cardiovascular stability is observed in the luteal phase following HIIE, potentially associated with elevated estrogen levels, suggesting a lower cardiovascular risk. Conversely, despite poorer vascular function, the follicular phase exhibits a significant decrease in SBP post-exercise, indicating a more pronounced vascular response, and implying a higher cardiovascular risk during HIIE in the follicular phase. Future exercise programs should consider the influence of different menstrual phases on vascular function to select appropriate exercise timing.