Amerika

Science gets clobbered by fads like the rest of humanity. Our history seems to be one of manias, fads, panics, lotteries, and gold rushes. Consequently when some research gets sponsored to give a nice easy answer, everyone falls over themselves doing that and they miss the larger picture.

In this case, it turns out that the ten thousand step fad was a bit wrong, and you need fewer steps to reduce your chance of mortality:

Based on our meta-analyses, compared with 2000 steps per day, 7000 steps per day was associated with a 47% lower risk of all-cause mortality (HR 0·53 [95% CI 0·46–0·60]; I2=36·3; 14 studies), a 25% lower risk of cardiovascular disease incidence (HR 0·75 [0·67–0·85]; I2=38·3%; six studies), a 47% lower risk of cardiovascular disease mortality (HR 0·53 [0·37–0·77]; I2=78·2%; three studies), a non-significant 6% lower risk of cancer incidence (HR 0·94 [0·87–1·01]; I2=73·7%; two studies), a 37% lower risk of cancer mortality (HR 0·63 [0·55–0·72]; I2=64·5%; three studies), a 14% lower risk of type 2 diabetes (HR 0·86 [0·74–0·99]; I2=48·5%; four studies), a 38% lower risk of dementia (HR 0·62 [0·53–0·73]; I2=0%; two studies), a 22% lower risk of depressive symptoms (HR 0·78 [0·73–0·83]; I2=36·2%; three studies), and a 28% lower risk of falls (HR 0·72 [0·65–0·81]; I2=47·5%; four studies).

But ten thousand is a nice round number and more importantly, it gives people an activity that they can talk about, so it took off like a meme despite being an overzealous interpretation of the old wisdom that those who sit around too much tend to kick off early.

In fact, the ten thousand number was invented to sell a product back in the 1960s:

So where did that magic 10,000 number come from? A pedometer company called Yamasa wanted to cash in on 1964 Tokyo Olympics fever. It launched a device called Manpo-kei — literally “10,000 steps meter.” The Japanese character for 10,000 resembles a walking person, while 10,000 itself is a memorable round number. It was a clever marketing choice that stuck. At that time, there was no robust evidence for whether a target of 10,000 steps made sense. Early research suggested that jumping from a typical 3,000 to 5,000 daily steps to 10,000 would burn roughly 300 to 400 extra calories a day. So the target wasn’t completely random — just accidentally reasonable.

Now another followup points out that maybe the number is less important than the speed at which people move, echoing earlier research:

Fast walking as little as 15 minutes a day was associated a nearly 20% reduction in total mortality (HR: 0.81, 95% CI: 0.75-0.87), while only a 4% reduction in mortality (HR: 0.96, 95% CI: 0.91-1.00) was found in association with more than three hours of daily slow walking.

Interestingly, faster walking speed correlates to both longevity and higher education:

First, we examined walking speed of about 11,700 English individuals, and identified differences in aging trajectories by sex and other characteristics (e.g. education, occupation, regional wealth). Interestingly, higher educated and non-manual workers outperformed their counterparts for both men and women. Moreover, we transformed the differences between subpopulations into single years of age to demonstrate the magnitude of those gaps, which appear particularly high at early older ages.

This paper expands research on aging and physical performance. In conclusion, higher education provides an advantage in walking of up to 15 years for men and 10 years for women.

This builds on decades of previous research showing that higher IQ correlates to longevity up through the middle seventies:

The results show a positive relationship between intelligence and survival (HR•: 0.79; 95% CI: 0.81–0.76). This association is significantly moderated by the years of follow-up, the effect size being smaller the more years elapse between the intelligence assessment and the recording of the outcome. Intelligence is a protective factor to reach middle-high age, but from then on survival depends less and less on intelligence and more on other factors.

For a long happy life, be intelligent and walk fast for at least seven thousand steps a day, which is probably a couple miles. If you want to die young, keep eating cheeseburgers, being stupid, drinking sodas, and sitting on that sofa. Maybe they can bury you on it and save coffin costs.

Tags: hbd, health, IQ, longevity, walking