Japanese has a one-syllable word for 10,000: man. An early wearable stepcounter had the trade name manpokei, or “10,000-step measuring device” in Japanese. The article above, “Association of Step Volume and Intensity With All-Cause Mortality in Older Women,” theorizes that this is the origin of the idea—and default setting for many step-counting devices—that 10,000 steps a day has some magic to it in fostering health. But in a large study of older women (who had an average age of 72), the decline in bad health events seemed to level out at about 7500 steps.
What is more, when relating steps per day to health, it is hard to tell whether steps are causing health or health causing steps—it is easier to take a long walk when one feels good. When one is interested in the ability of steps to make people healthier, the reverse causality effect of health in making steps easier tends to make deaths go down with more steps more than if it were possible to isolate the effect of steps on health. The authors of this study, “I-Min Lee, Eric J. Shiroma, Masamitsu Kamada, David R. Bassett, Charles E. Matthews and Julie E. Buring” control for obvious indicators of health at the time of the step measurement when looking at the association of steps per day and deaths, but there would be a lot of subtle health problems that wouldn’t be in the data set that could affect how pleasant it seemed to go out for a walk. What that means is that 7500 steps might be a modest overestimate of how many steps per day are needed to get most of the health benefits.
Fortunately, on the question of whether making an effort to walk rather remaining quite sedentary improves health, there are other studies that did interventions that I can write about in a later post. Exercise interventions still have the problem of a potential placebo effect; it is hard to hide from people the fact that they are walking extra. But if one is willing to include the placebo effect, interventions do genuinely show the benefits of exercise.
All the evidence we want isn’t in yet, but my advice would be to make sure to do some amount of walking and other physical activity rather than sitting around all day. It doesn’t have to take much extra time. Taking the stairs a couple of flight instead of the elevator doesn’t really take any longer, and taking the first parking space you see even though it is further away probably doesn’t end up taking much more time either. But those few steps might do some real good.
Overall, what evidence we do have suggests that exercise will make you healthier, happier and smarter. And maybe even a modest amount will have those effects. On “smarter,” I find personally that I can solve hard math problems at the limit of my ability much better while on a walk than I can while sitting at a desk. Once I have cracked the math problem, the details are easier to work out with pen and paper, but cracking the math problem is easier to do when my blood is pumping from the walk.
If anyone had the patent on a pill that had the benefits of exercise, they would be filthy rich. Fortunately for you and me, exercise itself is low cost. It does take time, but most people manage to figure out good ways to multitask while exercising—listening to a podcast, watching TV, listening to music, listening to an audiobook, doing math problems, or just enjoying the view.
Don’t miss my other posts on diet and health:
I. The Basics
II. Sugar as a Slow Poison
III. Anti-Cancer Eating
IV. Eating Tips
V. Calories In/Calories Out
VI. Other Health Issues
VIII. Debates about Particular Foods and about Exercise
Julia Belluz and Javier Zarracina: Why You'll Be Disappointed If You Are Exercising to Lose Weight, Explained with 60+ Studies (my retitling of the article this links to)
IX. Gary Taubes
X. Twitter Discussions
XI. On My Interest in Diet and Health
See the last section of "Five Books That Have Changed My Life" and the podcast "Miles Kimball Explains to Tracy Alloway and Joe Weisenthal Why Losing Weight Is Like Defeating Inflation." If you want to know how I got interested in diet and health and fighting obesity and a little more about my own experience with weight gain and weight loss, see “Diana Kimball: Listening Creates Possibilities” and my post "A Barycentric Autobiography. I defend the ability of economists like me to make a contribution to understanding diet and health in “On the Epistemology of Diet and Health: Miles Refuses to `Stay in His Lane’” and “Crafting Simple, Accurate Messages about Complex Problems.”