Exercise is good for your overall health and especially for your heart. Guidelines recommend that we should do 150 minutes of moderate to vigorous activity per week. But does it matter when you do this exercise? Should you spread it out over the week or will it lose some of the benefit if you cram it into the weekend?
A new study analyzing data from the UK Biobank has attempted to answer this question. About 90,000 healthy middle-aged people wore wristbands (accelerometers) that tracked their activity. It recorded their activity level over a week with a particular focus on moderate to vigorous activity (more on that later).
The researchers found that in the six years following the accelerometer assessment, people who regularly engaged in moderate to vigorous activity had fewer strokes, heart attacks, heart failure and atrial fibrillation (an irregular heart rhythm) compared to sedentary people.
The novel finding of this study was that there was no difference in results in people who did more than half of their activity over the weekend compared to those who spread it out over the week. No matter when it was done, moderate to vigorous physical activity was associated with improved heart health.
In the study, the authors called people who did more than 150 minutes of moderate-to-vigorous activity a week “weekend warriors.” This gives the impression of lycra-clad cyclists riding up mountains or muddy middle-aged men playing grueling 90 minutes of football.
More than 37,000 people in the study fit the definition of the “weekend warrior,” so why aren’t the roads filled with cyclists and the parks full of football players? It certainly seems to contradict the epidemic of obesity and sedentary lifestyles that we hear so much about.
Weekend warriors? Real?
It may seem like semantics, but the definition of the “weekend warrior” is important. In this study, the threshold used for moderate to vigorous exercise was three “mets” (metabolic equivalent of task). The mets scale is used to measure physical activity. For example, washing dishes is 2.5 meters, vacuuming 3.3 meters and walking at 5 km/h is 3.5 meters. To put this in context, cycling at 24 km/h on the flat is 10 metres.
The three mets threshold is rather unambitious and seems like something many people would reach in their daily lives without a concerted effort to practice. So when we think of the people in this study, instead of being called “weekend warriors,” they should have been called “Saturday strollers” or “Sunday stretchers.”
The other point of this study is that these people were not sports people or athletes, but rather normal middle-aged people doing their normal activities, some of which included exercise and others normal activities measured on an accelerometer.
This context is important when thinking about how we can use these results to inform our patients. I wouldn’t want anyone to think that two and a half hours of vacuuming or walking on the weekend is enough to prevent heart disease. It is the bare minimum of exercise. To see real benefits, you have to work up a sweat.
The relationship between exercise and heart health is simple: the more you exercise, the greater the improvement in your health. This study did show that doing some physical activity is better for your heart than being sedentary, which is an important message for the many people who can’t do 150 minutes of moderate activity per week.
Knowing these limitations of this study, we should avoid the interpretation that it is okay to be sedentary from Monday to Friday and then compensate by walking for an hour or so on Saturday and Sunday.
The findings of this study do not support this interpretation. If 150 minutes without sweating is all you can handle, then it doesn’t matter when you do it. But if you can handle something more strenuous, then you really have to put in the effort to do it.
The findings of this study don’t apply to more intense exercise, and if the opportunity arises to cycle to work on Tuesday or go swimming on Thursday, take it. Your heart will thank you.
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