Picture: 123RF/Brian Jackson
Picture: 123RF/Brian Jackson

All doctors worth their medicinal salts prescribe exercise as an essential part of healthy lifestyle habits for all their patients. But do they really know who benefits most from exercise? Just as importantly, do they know how much exercise is too much?

A vast body of evidence shows that staying physically active helps people live better, longer. Exercise improves symptoms of a wide range of chronic conditions, from arthritic conditions and asthma to type 2 diabetes, hypertension (high blood pressure) and cardiovascular disease (CVD — heart disease and stroke).

Until now, though, no studies have looked specifically at which groups of patients are most likely to benefit most. A new, large, cohort study suggests that it is CVD patients.

The study is published in the European Heart Journal and was presented at the recent European Society of Cardiology Congress in Paris. Many of the researchers are South Korean, from Seoul National University. They say that their findings can be applied globally because the role of physical activity in CVD is common to all populations.

They compared the effects of exercise on the risk of death in a cohort of healthy participants and a cohort of participants with pre-existing CVD. Data show that individuals with cardiovascular disease benefit more from exercise than healthy individuals. The data also show that the more that heart patients exercise, the better.

The right type and amount of exercise will almost always improve cardiovascular reserve and function [but] over-exercising can be harmful for both cardiac and non-cardiac patients
Dr Riaz Motara

Johannesburg cardiologist Dr Riaz Motara says that study confirms what we have always known. “As a species, we are designed to move,” Motara says. “The right type and amount of exercise will almost always improve cardiovascular reserve and function.”

However, while more can be better for heart patients, like all the good things in life, too much can be bad. Exercise is no exception.

“Overexercising can be harmful for both cardiac and noncardiac patients,” Motara says.  

Overdoing it causes what he calls “sympathetic overdrive”,  medical speak for too much adrenaline and not enough counterbalancing dehydroepiandrosterone (DHEA) and cortisol.

This causes what doctors call the “fight or flight” response reflex that can lead to worsening of cardiac function and an increase in blood pressure (hypertension).

That’s backed up by long-term US research in 2017 suggesting that the more — and more vigorously — that some men exercise, the greater their risk of premature death from heart disease. The study published in the journal Mayo Clinic Proceedings showed that the risk applied more to white than black men.

The research team, from the University of Illinois at Chicago and Kaiser Permanente, looked at the physical activity trajectories of 3,175 black and white participants in the 25-year study assessing physical activity and the presence of coronary artery calcium (CAC).

The presence and amount of CAC is “a significant warning sign to doctors that a patient may be at risk for developing heart disease and a signal to consider early preventive care”, the researchers noted.

They expected to see an association between higher levels of physical activity over time and lower CAC levels. Instead, they found the opposite: participants who exercised the most were 27% more likely than those who exercised the least to develop CAC by middle age. And when they stratified the findings by race and gender, they found that white men were by far at highest risk (86%).

Motara advises moderate-frequency exercise — and low-intensity exercise, such as walking, yoga, tai chi and Pilates, as much better than high-intensity aerobic exercise.

He also promotes exercise as just one element of a heart-healthy prescription. He advises his patients to follow a plant-based diet, meditate, and find “love and connection in their lives”.

Scottish GP Dr Malcolm Kendrick endorses Motara’s sentiment on love and social connection. Kendrick has made a special study of heart disease over decades in his practice. He is author of The Great Cholesterol Con: What Really Causes Heart Disease and How Best to Avoid It (John Blake Publishing 2008).

At heart, he believes that one the biggest threats to cardiovascular health is excess stress.

Of course, it’s a global phenomenon that 21st-century living and working are sources of stress. And if it really were a case of cause and effect, we’d all be dying like flies from CVD if stress were the most common cause.

Kendrick writes extensively on the effects of too much stress in general, and in particular, repeated activation of the fight-or-flight reflex. He says that it can eventually lead to a breakdown, burnout or dysfunction of the HPA axis and the unconscious nervous system, usually called the autonomic nervous system.

The HPA axis is a medical term for the hypothalamic-pituitary-adrenal axis that doctors use to represent the interaction between the hypothalamus, pituitary glands and adrenal glands.

Kendrick is not alone in believing that the HPA axis plays an important role in the stress response, and that keeping that axis in healthy balance is key to warding off heart disease.

His prescription for healthy hearts is a simple one, encapsulated in his own philosophical approach: “Enjoy life, enjoy friends and family, do a bit of exercise and don’t worry too much.”