10,000 steps is a marketing number, not a biological threshold

A large meta-analysis combining 15 international cohorts found that among adults 60 and older, mortality risk fell progressively as daily steps increased but the curve largely flattened around 6,000–8,000 steps per day.

For adults younger than 60, the plateau occurred somewhat higher, around 8,000–10,000.

That does not mean:

7,999 = beneficial
8,001 = useless

Dose-response curves don't work that way.

It means something more reassuring:

You do not have to achieve an arbitrary five-digit number before walking “counts.”

Moving someone from 3,000 → 5,000 steps may be far more meaningful than moving an already active person from 10,000 → 12,000.

That is a useful clinical framing because attainable progress beats a magical target.