Oral contraceptives, or birth control pills, are used by women to prevent pregnancy, manage acne, relieve menstrual cramps, and reduce the risk of ovarian cysts. Although some types are known to increase resting blood pressure, the effect of these pills on blood pressure during strenuous exercise remains unclear.

Chennai: Oral contraceptives do not increase the blood pressure response in women during heavy muscle exercise (such as cycling or running), according to a study conducted Monday by researchers at Indian Institute of Technology (IIT) Madras.

Women take oral contraceptives or birth control pills to prevent pregnancy and reduce acne, menstrual cramps and the risk of ovarian cysts.

Although some oral contraceptives are known to increase resting blood pressure, the blood pressure response to exercise during strenuous exercise is not yet well understood.

Additionally, research is ambiguous about whether hormonal fluctuations during the menstrual cycle influence blood pressure.

Researchers, including from the University of Minnesota, in the United States, found that both oral contraceptive Use and general fluctuations in endogenous ovarian hormones (such as estrogen) in young women (aged 20 to 25 years) did not influence blood pressure.

The results were similar with lower body exercise and activation of skeletal muscle sensory neurons – known to contribute to exaggerated blood pressure responses in people with cardiovascular disease.

“The results of this study have broad application and are important because they shed light on the influence of oral contraceptives on the blood pressure response to exercise in women,” said Dr. Ninitha AJ, assistant professor at department of biotechnology at IIT Madras.

Exercise can significantly increase blood pressure due to increased activity of sympathetic nerve (fight or flight) sensory neurons in skeletal muscles, known as the “exercise pressor reflex” (EPR).

The RPE causes increased blood flow from the heart to the skeletal muscle to meet the needs of the muscle. It is known that the RPE is higher in men than in premenopausal women and is also exaggerated in people with cardiovascular disease.

Estrogens are cardioprotective, reducing sympathetic activity and increasing blood flow to skeletal muscle via nitric oxide bioavailability.

Thus, the researchers expected that during the ovulation phase of their menstrual cycle, when estradiol peaks, women would have the lowest RPE compared to women in the early follicular phase (where the estradiol is lowest) and with the use of oral contraceptives, which also results in low serum estradiol levels.

However, researchers demonstrated that regardless of the phase of the menstrual cycle or the use of oral contraceptives, the RPE was similar in women.

This suggests that oral contraceptives do not increase the blood pressure response in women any more than in those who do not use oral contraceptives, revealed the results, published in the renowned peer-reviewed journal American Journal of Physiology -Regulatory, Integrative and Comparative Physiology.

“The next step in this work is to determine whether RPE is a contributing factor to cardiovascular risk in postmenopausal women,” said Dr. Manda Keller Ross, assistant professor at the University of Minnesota.