With 2018 stretching out before us, shining with promise, many of us have made resolutions to be more active.
As a researcher of exercise and health, I spend most of my waking time figuring out ways to help people become more active. I also apply that research on myself by regularly going swimming, for a bike ride or walking around my neighbourhood.
My work addresses the main reasons people give for not exercising: That there's "not enough time," or there's a lack of facilities or "it's just easier to sit and watch TV."
Recent media coverage of new research studies has added to this list of excuses, through headlines such as: "Excessive exercise may harm the heart."
Is this really the case? Could exercise be bad for your heart? Is there such a thing as too much exercise?
Well, unless you're participating in ultramarathons and running 160 kilometres, it's unlikely you're going to overdo it.
Exercise is good for us, and always has been.
Does exercise cause heart disease?
During 2017, three studies came out suggesting that exercise may actually cause heart disease, as older athletes had more atherosclerotic plaques (a build-up of fat in your artery that can lead to a blockage) than people who didn't exercise.
These athletes weren't ultramarathoners either. On average they exercised 45 to 60 minutes per day —an amount that many people are already doing, and only three times more than the World Health Organization's physical activity guidelines (150 minutes of moderate activity per week).
So are these studies conclusive that you can do too much exercise? No.
All three studies measured the amount of plaque using something called "coronary artery calcification." Coronary artery calcification is a marker of how much plaque a person has in their heart. The greater the coronary artery calcification, the more likely that person has a plaque, and the greater the size of that plaque.
It's important to note that none of these studies looked at actual heart events like heart attack or death. While coronary artery calcification is a marker of heart disease, it does not automatically mean someone with a high amount will have a heart attack.
A different type of plaque
The studies were also observational, meaning that they were not designed to see if exercise causes plaques. They only compared plaques in those who exercise with those who do not. They were also small studies in terms of the number of participants (between 250 and 3,000) compared to the studies that have shown the benefits of exercise (in the 10,000s and more).
In one of the studies, the association between exercise and higher coronary artery calcification was only present in white men, but not in the white women, black men and black women who were also studied. The authors acknowledged that this could be a fluke finding. This is very likely, because why else would exercise be bad for white men but no other groups?
Lastly, and perhaps most important, is that the type of plaque in the athletes was different from that in the non-exercisers.
In the athletes the plaques tended to be of the more stable type which are less likely to lead to a heart attack compared to the plaques in the physically inactive people. So it is believed that the coronary artery calcification seen in athletes is actually protective.
Reduce your risk of depression and cancers
We've known for centuries that exercise is good for us, ever since the Greek doctor Hippocrates (c. 460 – c. 370 BC) said that, "walking is the best medicine."
More recently, countless studies have shown that exercise is associated with reduced risk in conditions such as depression, some cancers, heart disease, stroke and premature death.
In our recent study of more than 130,000 people from 17 countries, we saw no upper limit at which the benefits of exercise stopped.
In fact, the reduction in risk for heart disease and premature death occurred at amounts of activity 17 times that of the guidelines (effectively walking for eight hours per day). This has been confirmed in a subsequent research study in people at even higher levels.
Increase your lifespan
Even in people with heart disease, exercise is beneficial. Studies more than 25 years ago showed that exercise programs reduced risk of premature death (by any cause) by 20 per cent to 25 per cent.
So today, participating in exercise is part of standard guidelines for treating people with heart disease whether in Canada, the United States or Europe.
The overwhelming evidence suggests that regular activity and exercise is beneficial for preventing heart and other diseases, as well as increasing lifespan. It is also one of the cheapest things you can do to improve your health.
We should recognize that a key problem in our society is that people don't do enough exercise, not that they do too much.
So if you're looking to begin an exercise program in 2018, you can do so knowing that it is really is one of the best things you can do for yourself.
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