Author(s): DELPECH, N., DOUMENC, C., LAFFETAS, P., ENEA, C., Institution: UNIVERSITE DE POITIERS , Country: FRANCE, Abstract-ID: 2442

INTRODUCTION:
Heart rate variability (HRV) and baroreflex sensitivity (BRS) are indexes of cardiac autonomic modulation, which are influenced by a number of factors including gender, physical activity and ageing [1, 2]. In women, HRV and BRS also appears to be affected by hormonal variations specific to womens lives (menstrual cycle, hormonal contraception or menopause) [3, 4]. On the other hand, physical activity is known to have a beneficial effect on cardiac autonomic regulation. The aim of this study was to investigate the effect of hormonal status on these indexes and to determine whether regular physical activity can modify this effect.
METHODS:
A total of 29 young women were divided into two groups, according to their hormonal status: oral contraceptives (CO+, n=17) or natural menstrual cycle (CO-, n=12). The Global Physical Activity Questionnaire was used to assess moderate-to-vigorous physical activity (MVPA) and sedentary time. Non-invasive measures of beat-to-beat arterial pressure and heart rate (Finapres) were used to assess baroreflex sensitivity and heart rate variability. The mean values of systolic blood pressure (SBP), diastolic blood pressure (DBP), HRV parameters (LF, HF, LF/HF, SDNN, RMSSD and RR) and BRS of the two groups were compared using Students unpaired t-test. A Pearson correlation matrix was used to test for an association between the amount of weekly MVPA and SBP and DBP in women.
RESULTS:
SBP and DBP were significantly higher in CO+ than in CO- women (CO+: 121.8 ± 9.9 and CO-: 109.3 ± 9.8 mmHg, p<0.05; d=1.2; CO+: 73.2 ± 9.5 and CO-: 64 ± 9.5 mmHg, p<0.05; d=1). However, neither BRS nor HRV differed between CO+ and CO- (BRS CO+: 19.8 ± 9.7 and CO- 22.7 ± 8.7 mmHg/ms p>0.05; d=-0.3). MVPA did not correlate with better cardiovascular regulation or lower blood pressure in either group.
CONCLUSION:
Despite higher SBP and DBP in oral contraceptive users than natural menstruating women, our results suggest that neither hormonal status nor MVPA levels influence cardiac autonomic regulation in young healthy women. Further studies are needed to determine whether older women are affected by these both factors.

REFERENCES:
[1] Zhou et al., (2023). Cardiovagal baroreflex sensitivity, blood pressure and blood pressure variability - the Maastricht study. Journal of hypertension, 41(2), 254–261.
[2] Barnes et al., (2012). Association of cardiac baroreflex sensitivity with blood pressure transients: influence of sex and menopausal status. Frontiers in physiology, 3, 187.
[3] McKinley et al., (2009). The impact of menstrual cycle phase on cardiac autonomic regulation. Psychophysiology, 46(4), 904–911.
[4] Mascone et al., (2023). Naturally menstruating women exhibit lower cardiovagal baroreflex sensitivity than oral contraceptive users during the lower hormone phase. Experimental physiology, 108(12), 1481–1489.