February is the month things go south in our exercise routines. The excitement of New Year’s resolutions fades and the dark and cold keep us in bed, rather than on the treadmill.
This is a shame, because regular exercise is really beneficial. It can control high blood pressure, improve mental health and reduce falls among older adults. A review of 187 randomized controlled trials covering nearly 30,000 people found exercise lowered mortality risk by 13 percent.
Given the fact that people struggle to stick with exercise, the crucial question is: How can we design fitness programs that maximize long-term adherence?
Unfortunately, a lot of research and media coverage is focused instead on asking what the best type of exercise or the optimal amount is. Is walking better than tennis? Is running better than swimming? Is it really important to do 80 percent of your workout at 60-70 percent of your max heart rate (known as Zone 2)? These questions serve an engaged population and promise that with a bit more knowledge, you can maximize your health. The trouble is, they are basically impossible to answer well, and most of the answers we get are misleading and wrong.
...
Because of these challenges, most of the evidence on the so-called best exercise comes from what are known as observational studies. Instead of randomizing people to different programs, these studies ask people about the exercise they already do and compare their health outcomes to those of people who do more or less exercise, or who do different types of exercise. The trouble is that such studies almost always confuse correlation and causation.
...
The limits of our knowledge are a tough pill to swallow (especially since it’s not just exercise; the research on nutrition is equally shaky). It can be frustrating to know there are some questions we’ll never answer. I also think it can be freeing, an invitation to let go of optimization and focus on what we do know. In the case of exercise, we can say with confidence that it’s good to regularly do something that raises your heart rate.
People also want to know how much exercise to do; this is also very hard to know. The randomized studies showing benefits of exercise typically aim for 2.5 hours per week. After that, we are mostly relying on lower-quality observational studies. Those show that the benefits of exercise tend to flatten around seven to 10 hours a week.
What we do know is that people are more likely to stick with an exercise program that is tailored to their preferences and lifestyle. When doctors are advising patients about exercise, they should be as open as possible to the variety of ways people might want to get moving. Research should focus on which approaches are best to lead to long-term, sustained exercise habits — ideally, research with randomized trials. The type of flawed observational research discussed above gets in the way of both of these priorities — it takes research time from studying what matters, and it creates misleading and constraining advice. It doesn’t really matter which exercise people do — they just need to do it past February.