Linear relationships between things are easy to understand: more of this, leads to more of that. But the world is more nonlinear than we think, and than scientists would like to think.

We have analyzed the pitfalls of the naive linear thinking in a former article

https://braininlabor.com/2020/11/10/non-linear-thinking/

When it comes to being fit and healthy, we’re often reminded to aim to walk 10,000 steps per day. This can be a frustrating target to achieve, especially when we’re busy with work and other commitments. Most of us know by now that 10,000 steps is recommended everywhere as a target to achieve – and yet where did this number actually come from?

The 10,000 steps a day target seems to have come about from a trade name pedometer sold in 1965 by Yamasa Clock in Japan. The device was called “Manpo-kei”, which translates to “10,000 steps meter”. This was a marketing tool for the device and has seemed to have stuck across the world as the daily step target. It’s even included in daily activity targets by popular smartwatches, such as Fitbit.

Research has since investigated the 10,000 steps a day target. The fact that some studies have shown this step target improves heart health, mental health, and even lowers diabetes risk, may, to some extent, explain why we have stuck with this arbitrary number.

A new study (Sheng et al, open access) shows the relationship between steps/day and all-cause mortality. The data boils down to two major points:

  1. Walking is generally amazing for your health.
  2. And you do not have to do a buttload of it.

The data from Sheng et al shows that you do not have to walk even close to 10,000 steps/day for it to be worth your while. The benefits are “non-linear”: you get a lot of benefit up front, a huge reduction in health hazards by the time you’ve hit 5K steps… at least double what you get out of the next 5K.

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Many people can’t walk 10,000 steps per day to begin with, due to disability and illness. But even many of those who can probably should not. Extra benefits are there for the keen walkers who push past 10, 12, 16k steps/day… but at what cost? The risk of long-term health issues declines ever more slowly, but the short-term risk of overuse injuries surges. As most of the relations, the shape is an Inverted U curve, having at some point a plateau (a threshold) and then, suddenly, an inversion.

How much more plantar fasciitis is there in the world because of the 10k step myth? Shin pain? iliotibial band syndrome? Achilles tendinopathy? At some point you start to risk self-sabotage. That point probably comes sooner that you think.