Woman running outdoors

Exercise: How Much Is Enough?

There is plenty of evidence that exercise is good for us. We know the importance of eating a healthy diet and getting the recommended 150 minutes of relatively intense activity each week. 

But can you do too much exercise?

Some people believe that the fitter they are, the healthier they are. The truth is that it’s not as simple as many think.

Exercise and Heart Health

A recent study from the Netherlands looked at about 150,000 individuals over 7 years and the impact of their exercise regimes. The participants were divided into 3 groups – those with no previous history of heart disease, those with one or more cardiovascular risk factors and those who had already suffered a cardiovascular event such as a heart attack. 

  • In the healthy group and those with at least one risk factor, the study found that there was a certain plateau above which there were few if any benefits from exercising more. 
  • For the group that had suffered from a cardiovascular event, it seemed that the more exercise they could do, the better it was for their health. 

It seems that exercise does not affect us all equally. Of course, we know this already. Running five miles a day doesn’t necessarily mean you will live for longer. Winston Churchill was, for much of his life, obese, drank whiskey by the bottle and smoked cigars. He died at the age of 91. Whereas there are countless examples of people who were extremely active and maintained healthy lifestyles who have died as a result of cardiovascular-related issues at a surprisingly young age.

How Much Exercise Is Enough?

Man running outside

Long-term studies provide us with the best evidence when it comes to the effect of exercise on health. These are few and far between but there have been some interesting results. 

A study running over 25 years looked at more than 3,000 participants, dividing them according to the hours of exercise they put in each week. 

Most of these people were between 18 and 30 when the study started. When they were older, the study tested them for their coronary calcium score. This measures the amount of calcium that has been deposited on the walls of arteries. A low score means that an individual has a very low risk of a heart attack in the future.

Strangely, the group that exercised the most each week (more than 7.5 hours) showed a bigger increase in artery calcification than groups that exercised less. In addition, when white males were separated from other ethnic groups, the coronary calcium score was even higher. 

The group that benefited the most were those who exercised between 3 and 5 hours each week. 

Another study with 80,000 participants compared aerobic activities such as running or cycling with anaerobic ones such as weight lifting. These were also compared to inactive individuals who took little or no exercise. 

The first result isn’t too surprising – it found that those who lived sedentary lives were more likely to develop health problems over the years than those who participated in either aerobic or anaerobic exercise. 

There was, however, a difference between the weight trainers and the cyclists or runners. The study found that anaerobic activity reduced cancer risk by about 31% while aerobic activity reduced cardiovascular risk by a more modest 21%. 

This isn’t that surprising because we know that cardio activities such as running improve blood flow and heart health. 

What is happening with weight training is less obvious. It could be that improving muscle strength and circulation in specific areas, helps to redirect valuable blood flow away from precancerous cells. This is just a theory but what is clear is that resistance training may well reduce your cancer risk significantly. 

Other studies have also shown that regular and excessive exercise doesn’t necessarily equate to better health. One looked at very athletic individuals with an average age of 55 and found that more than half of them had coronary artery calcification. 

Of course, it could be that many people who exercise more than most of us also think that they can eat what they like. A poor diet could contribute to them developing cardiovascular risk factors however physically fit they are. Indeed, one study involving marathon runners found that they often had a similar psychological relationship with food as those suffering from anorexia.

The Right Balance

What most of the evidence seems to show, at least for the majority of us, is that there is a sweet spot for the right amount of exercise. This lies between 3 and 5 hours a week. Ideally, this should be split into two-thirds aerobic or cardio such as brisk walking, running or cycling and one-third weight or resistance training.

The content above is based on the information featured in the article linked below. 

The author of the article is Dr Ross Walker, one of Australia’s most esteemed cardiologists and a member of the Miskawaan Medical Advisory board.

https://switzer.com.au/the-experts/dr-ross-walker/exercise-how-much-is-enough/