I tend to view skeptically science reporting that leans heavily on simplistic concepts and flashy titles. However, “skeptical” does not mean “dismissive.” Mainstream reporting may focus on click-bait terms but that doesn’t necessarily mean anything about the underlying science.
I have seen lots of recent headlines about the benefits of being a “weekend warrior” and decided to look at the primary research. The net benefits of getting most of your physical activity over the weekend, rather than spread throughout the week, are not intuitive. Being relatively inactive for 5 days a week may have its own negative health impacts. Also, trying to compensate for lack of time with increased intensity can have its risks. But at the same time, a “week” is an artificial construct, not a biological concept, and so perhaps averaging physical activity over this timeframe may be just fine.
Let’s look at the recent study prompting those headlines – Associations of “Weekend Warrior” Physical Activity With Incident Disease and Cardiometabolic Health. First I note that the “weekend warrior” meme comes from the researchers and is not an invention of the media. This does not mean it’s automatically a good thing – often researchers or press offices will use techniques to increase the visibility of their research and the media happily comply. But in this case I think it’s a benign shorthand for people who get most of their exercise on the weekend.
The study looks at “89,573 participants (62±8 years of age; 56% women) of the UK Biobank prospective cohort study who wore an accelerometer for 1 week between June 2013 and December 2015.” So this is a retrospective correlational study (even though the data comes from a prospective cohort study). It is not controlled or blinded. The advantage of these kinds of studies is that you can look at large numbers of subjects. The downside is that it is difficult to account for every possible confounding factor.
One apparent weakness is that subjects only had to wear an accelerometer (like a FitBit) for one week. We cannot assume this one week is representative of their long term activity.
They broke the subjects into three groups – 150 minutes per week but with 50% or more concentrated in two days on the weekend, and >150 minutes but spread out more evenly throughout the week. When compared to the inactive group, the weekend warrior group and the regular exercise group both showed a significant decrease in risk for >200 conditions assessed. The associations were strongest for cardiovascular disease. When compared directly to each other, there was no difference between weekend warriors and regular exercisers. There was also no difference when compared to those who got >230 minutes of exercise per week.
It’s important that when making public health recommendations that we don’t make the perfect the enemy of the good enough. The notion of “regular exercise” may seem intimidating to many people, either because of their busy schedule, or because they have physical limitations. Often the concept of “exercise” is paired with imagery of people in their 20’s engaging in vigorous exercise. So it’s important to get the message
