How Many Steps for Optimal Health? 🏃
Hey guys, welcome to the Easter weekend edition of the humanOS newsletter!
This week, I thought we’d take a dive into some of the research on walking, and how different “doses” of steps influence all-cause mortality.
Walking is probably the least sexy physical activity intervention, which makes it easy for adrenaline junkies (like me) to overlook it. But research suggests that it is surprisingly powerful, especially in proportion to the amount of effort it requires. When people increase their daily steps, even in fairly modest amounts, they experience better sleep quality, they snack less on hyperpalatable food, they have better blood sugar control, they show mood improvements, and so on. All of these tiny effects, cumulatively, appear to lead to a longer life in observational studies. But how many steps should we shoot for? This question doesn’t really have a straightforward answer, and it is likely to vary between individuals, but the literature does provide some clues as to useful targets.
🔸 More is better: There are incremental risk reductions in all-cause mortality for every increase of a thousand steps.
🔸 Reductions in risk of dying seem to level off somewhere between 8000-12000 steps, though getting as many as 15000 steps or more may offer metabolic benefits.
🔸 The biggest impact on health outcomes seems to be at the lower thresholds, like going from being sedentary to getting a moderate amount of steps. In other words, increasing from 2000 steps up to 4000 steps has a bigger “payoff” than increasing from 7000 to 8000.
🔸 Walking faster seems to be associated with improved longevity compared to moving slowly, although this is probably less important than the total amount.
To get more details, scroll on down 👀
This Week's Research Highlights
Researchers at Harvard had 16741 older women wear activity monitors for one week to capture their habitual physical activity patterns, and then followed them for an average of more than four years. Subjects in the lowest quartile of number of steps (an average of around 2700) were at the highest risk of dying over the study period. Compared to this quartile, women who walked on average 4400 steps per day were at 41% reduced risk of mortality. Risk of death continued to decrease up to the highest quartile, who were around 58% less likely to die over the study period, leveling off at 7500 steps per day.
Researchers analyzed pooled data from 11 population-based surveys in England and Scotland, which included a total of 50225 participants. The subjects had provided information about their walking pace, and surveys were linked to mortality records. The researchers found that those who walked at a moderate or a brisk pace had a 20% and 24% lower risk of all-cause mortality, respectively, compared to those who walked slowly, and this association remained after adjusting for total leisure time physical activity.
Researchers followed a cohort of 2110 middle-aged adults for around 11 years. During the study, subjects wore trackers to count their steps, and they were divided into groups based on daily step volume: low (<7000 steps/day), moderate (7000-9999 steps/day), and high (≥10 000 steps/day). The researchers found that those who got at least 7000 steps per day had a 50%-70% lower risk of mortality over the study period, compared to those who got less than 7000, and risk reduction leveled off at around 10,000 steps daily.
Researchers affiliated with the CDC and NCI’s Division of Cancer Epidemiology and Genetics analyzed data from a representative sample of 4840 participants who had worn activity trackers for up to a week, and then were followed for almost a decade thereafter. Compared to individuals who got less than 4000 steps per day, subjects who took 8000 steps per day were at 51% lower risk of dying over the study period. Taking 12000 steps per day, meanwhile, was associated with a 65% lower risk of all-cause mortality.
Random Trivia & Weird News
🚶 The goal of 10,000 steps a day actually originates from an old marketing campaign to sell pedometers.
10,000 steps per day is a typical default goal for wearable devices, and as you can see from the studies discussed above, it’s certainly not a bad target. But oddly enough, that number didn’t emerge from epidemiological research - it actually was a marketing tool.
Back in 1965, a Japanese clockmaking company released a pedometer called a manpo-kei (万歩計; “10000 steps meter”), and that number has stuck ever since.
(Kind of speculating here but it could have been chosen because 万, the kanji for 10000, sort of looks like a person walking? 🤔)
Podcasts We Loved This Week
- Danny Lennon & Alan Flanagan: Is a vegan diet really best for diabetes? Via Sigma Nutrition Radio.
- Benjamin Thompson & Nick Petrić Howe: Why do naked mole rats live as long as giraffes? Via Nature Podcast.
Products We Are Enjoying
One of the studies cited above showed that walking faster was linked to somewhat greater reductions in mortality, compared to walking slowly. Which I suppose makes sense. But it's worth noting that research has shown that some of the improvements in cardiovascular and metabolic risk factors associated with walking may be tied to energy expenditure, rather than the intensity per se.
For example, one study comparing runners and walkers found that either walking or running produced similar risk reductions as long as the same amount of energy was expended during the activity. Of course, you can boost energy burn by walking faster, but if you are unable or unwilling to do that, another way is by adding resistance.
This vest is very lightweight and unobtrusive (and cheap!), which is why it appealed to me.
But there are all different sizes and weights out there if you need something more formidable - there are some adjustable vests that can accommodate more than a hundred pounds!
humanOS Catalog Feature of the Week
Sedentary behavior is clearly deleterious to your cardiovascular health, which is one reason why we recommend integrating movement breaks into your day. But emerging research also suggests that physical activity, including just standing and walking, may influence aspects of your cognitive performance. This is due, in part, to changes in blood flow to the brain, as well as through a long-term rise in levels of growth factors in the brain. Pretty cool!
In this course, we review:
🧠 Effects of exercise on the mind
💡 How physical activity within the day can improve your thinking
🏋️ Strategies to integrate more movement into your day
Thanks for reading, and have a happy Easter 🐣