Women get more cardiovascular benefit from physical exercise than men

There is a gender gap that runs through every department of medicine. From the most basic research—for decades, only male animal models have been used in preclinical trials, for example—to diagnosis and treatment. The field of cardiology, one of the disciplines where this inequality in care between men and women has been most studied, is paradigmatic : in heart attacks, for example, women tend to be diagnosed later, their symptoms are less easily identified or are more trivialized; and when treating them, doctors are also more conservative and perform fewer invasive procedures.

All of these identified deficiencies are being addressed, but the edges of the deep gender gap have yet to be fully understood. New research , published this Monday in the journal Nature Cardiovascular Research , has delved into these inequalities in the field of prevention and has discovered that physical exercise recommendations also overlook gender differences: according to this study, women can obtain greater cardiovascular benefits from physical activity than men. That is, they achieve significant cardiovascular protection with lower doses of physical exercise than men need to achieve the same benefits.

Let's be clear: physical exercise is beneficial for everyone. And it's one of the most effective preventive measures for cardiovascular health: it reduces the risk of coronary heart disease by up to 20% and the risk of dying from this group of conditions by 28%. But the benefits are not uniform for both sexes.

In this study, a group of Chinese researchers analyzed activity data from wearable devices (such as smart bracelets) on more than 85,000 people in the UK Biobank to examine gender differences in the association between physical activity and cardiovascular health. They used health authority guidelines as a starting point, which recommend about 150 minutes of moderate to vigorous physical activity per week— moderate could be brisk walking, vacuuming, or cycling; and vigorous could be running, swimming, or playing tennis—for both sexes.

In a cohort of 80,200 individuals without coronary heart disease, the study found that women who met the health guidelines (those 150 minutes per week) had a 22% lower risk of coronary heart disease, while the reduction in men was 17%.

Along the same lines, subsequent analyses showed that if this physical activity amounted to 250 minutes of weekly exercise, women achieved a 30% reduction. However, men would need 530 minutes to achieve this cardiovascular benefit.

The authors also found that, in a cohort of about 5,000 people with coronary heart disease, women who exercised had a three-fold greater reduction in mortality risk than men.

The estrogen hypothesis

Regarding the mechanisms that explain this disparity, the researchers admit that they are unclear, but they speculate on several hypotheses. For example, that circulating estrogen levels are much higher in women and this hormone "may promote body fat loss during physical activity," says Jiajin Chen, a researcher at the Institute of Cardiovascular Diseases at Xiamen University (China) and author of the study. "A randomized controlled trial has also shown that estrogen supplementation can increase lipid oxidation in men during exercise, which is known to improve clinical outcomes in coronary heart disease," he explains in an email response.

Another mechanism that may be involved, the authors suspect, is the gender disparity in the morphological composition of skeletal muscle: the fibers are different, and so is muscle metabolism. “These differences may contribute to the observed greater sensitivity to physical activity and greater clinical benefit in women,” they contend in the article. Although Chen admits that “more biological experiments are needed to explore the mechanisms underlying sex differences in the cardiovascular benefits of exercise.”

The authors do, however, consider that their findings justify "the need for gender-specific management in the prevention of coronary heart disease." This is especially true given that women are more physically inactive and less likely to achieve risk factor control goals.

For José María Guerra, a member of the Arrhythmia Unit of the Cardiology Department at Sant Pau Hospital in Barcelona, ​​this research, in which he did not participate, is "very interesting" and the data are "very good." "It's very interesting because we're starting with a female population that's less used to exercising, less motivated, and has more sedentary habits, and you're setting exercise guidelines for men. If you ask them to do less, because you know you'll get the same benefit, you'll be more likely to get them to do it," the cardiologist reflects.

Regarding the causes, the doctor admits that he missed the hypothesis put forward by the study, which stated that "exposure to the disease is also different." "Cardiovascular disease in women begins to develop after age 50, after menopause; but in men, on the other hand, it probably begins earlier, after age 20. There's a longer exposure period, and they don't discuss that. It's true that the disease progresses more quickly in women, but perhaps they also have a greater capacity to regress or be molded."

Encourage women to play sports

In the article, the researchers warn that these identified gaps "could result in worse clinical outcomes in women." They emphasize a key message: "Compared to men, women obtain equivalent health benefits with only half the exercise time. The findings could have the potential to encourage women to engage in physical activity."

Guerra agrees: “When making recommendations, you have to consider who you're recommending to. We still have a long way to go, and this study proves it. But these differences between men and women must be taken into account when treating or preventing.”

This research has limitations, such as the fact that the cohort, from the UK Biobank, tends to have a very homogeneous demographic profile: middle class and white. In an accompanying commentary , Emily S. Lau of Massachusetts General Hospital (USA) raises the need to address how these findings translate to diverse cohorts, "especially because socioeconomically disadvantaged and minority populations experience the lowest levels of physical activity and the worst cardiovascular outcomes," she reflects.

However, Lau notes: “This study provides further evidence that a one-size-fits-all solution does not fit all and challenges us to move from conversation to action.” A gender-sensitive approach to care, with research that pays attention to sexual and gender differences, has contributed to a 30% reduction in cardiovascular deaths in women, according to experts.