Physical activity before age 40 helps prevent hypertension during menopause

According to a Brazilian researcher, specialists estimate that up to 80% of women will develop hypertension during the change of life.

By Karina Toledo, Caxambu

Agência FAPESP – Cardiology specialists estimate that 80% of women will develop hypertension during menopause. To prevent this condition, regular physical exercise should be included in women’s daily routines by around age 40, well before the last menstrual cycle occurs.

Universidade Estadual Paulista (Unesp) researcher Angelina Zanesco coordinates a study focused on uncovering the biological mechanisms responsible for the increase in arterial pressure in women in this age range.

Zanesco presented the first results of the FAPESP-funded study during the 28th Annual Meeting of the Federation of Experimental Biology Societies (FeSBE) held from August 21 to 24 in Caxambu, Minas Gerais.

“Many women only worry about physical activity after age 50, when their bellies begin to grow. But our results showed that, to prevent the development of hypertension, intervention must begin before metabolic and hormonal changes occur,” stated Zanesco.

To reach this conclusion, Unesp Rio Claro’s Cardiovascular Physiology and Physical Activity Laboratory team evaluated a group of pre- menopausal women and a group of post-menopausal women to understand the functioning of the renin-angiotensin system (RAS), a set of peptides, enzymes and receptors involved in controlling arterial pressure.

“The renin-angiotensin system is responsible for elevating arterial pressure, mainly through the constriction of blood vessels, and this has physiological significance. In the event of an accident, such as a hemorrhage or generalized infection, this system prevents the arterial pressure from dropping too much and the individual from fainting. But when the mechanism is activated unnecessarily, it ends up leading to hypertension,” explained Zanesco.

The researchers collected blood samples from 42 women over age 40 who had not yet entered menopause and from another 32 who had not menstruated in at least 12 months.

“To be certain that the volunteer was in fact in menopause, we measured the levels of luteinizing hormone (LH) and follicle-stimulating hormone, which are markers of ovarian failure,” explained Zanesco.

Next, the plasma levels of angiotensin-converting enzyme and several peptides, such as angiotensin II and angiotensin 1-7, were measured in the two groups of women. The results showed that, in general, the renin-angiotensin system was 80% more active in post-menopausal women than in perimenopausal women.

“When we compared only pre- and post-menopausal normotensive women, we did not observe a major difference. However, when we compared hypertensive women, the increase in renin-angiotensin system activity reached 150%. These data show that, if a women waits until menopause to change her lifestyle, it could be too late, and this system will be already be activated, potentially causing a pathological condition,” commented Zanesco.

Benefits

Since the mid-1990s, several studies have shown the benefits of aerobic exercise in controlling arterial pressure. The effect has also been proven in an experiment conducted with 40 women – 29 normotensive and 21 hypertensive – at Unesp’s Cardiovascular Physiology and Physical Activity Laboratory.

After two months of regular exercise on treadmills, which included three 40-minute sessions per week at a moderate pace, there was an approximately a three-centimeter reduction in abdominal fat. Furthermore, the arterial pressure of the normotensive women dropped by four millimeters of mercury and that of the hypertensive women dropped by seven millimeters of mercury.

“This would be the equivalent of a drop in pressure of 13.2 to 12.5, which is a significant reduction for a short period and sufficient to reduce the risk of myocardial infarction and stroke,” affirmed Zanesco.

At present, the researchers are attempting to discover the biological mechanism by which physical activity helps to regulate blood pressure. Their first idea, which has not been confirmed, is that the regulation is related to a reduction in the levels of cortisol and testosterone.

“We know that cortisol, the stress hormone, is produced and released by visceral adipose tissue. We thought that reducing belly fat would reduce the level of cortisol, but that is not what we observed,” commented Zanesco.

The plasma testosterone levels – which have been correlated to the increase in arterial pressure during menopause in prior studies – were also unaltered after a period of physical training.

“We are now going to initiate a new round of experiments and measure other biomarkers, such as nitric oxide and cyclical GMP (guanosine monophosphate), which are vasodilating agents,” she explained.

Another hypothesis to be investigated is that physical activity stimulates the release of antioxidant enzymes, such as superoxide dismutase (SOD) and catalase (CAT), which will promote a reduction in oxidative stress and help to reduce arterial pressure.

Lastly, Zanesco will carry out inflammatory tests – such as measuring C-reactive proteins produced by the liver and interleukins produced by visceral adipose – which could be the origin of the problem.

“If we manage to understand the mechanisms of hypertension in this age range, we can find ways to more effectively prevent the problem. In addition to improving the population’s health, this will greatly reduce health system expenditures,” said Zanesco.

According to data from the Brazilian Cardiology Society (SBC), hypertension is responsible for 40% of strokes and 25% of terminal kidney failure.

According to the Brazilian Guidelines on Cardiovascular Disease Prevention in Menopausal Women and the Influence of Hormone Replacement Therapy, published by the SBC and the Brazilian Menopause Association (Sobrac), more men aged 55 and under have hypertension than women in this age range.

However, from 55 to 74, the percentage of women with hypertension is slightly higher than that of men. Above 75, the percentage of women with hypertension is significantly higher. The specialists who developed these guidelines estimate that roughly 80% of women will eventually develop hypertension.

According to the Ministry of Health’s 2011 Vigitel (Chronic Disease Risk and Prevention Factors Survey conducted by phone), arterial hypertension affects 22.7% of the Brazilian adult population, and the prevalence of the disease increases with age. Hypertension is diagnosed in 5.4% of people aged 18 to 24. By age 55, the proportion is tenfold higher, affecting more than half the population (50.5%) studied. At age 65, hypertension affects 59.7% of the Brazilian population. Unlike the data from the SBC and Sobrac guidelines, Vigitel indicates that there is a higher incidence of hypertension in women of all ages than in men.