Can a simple sign make people more active? According to a study from New York City, it can. Signs in buildings suggesting that people take the stairs instead of the elevator immediately boosted stair use from 9 to 35%.

People think that they're immune to the messages in signs. Studies have shown that this isn't true. One published last year found that signs placed near soap dispensers greatly increased how often doctors washed their hands. But as that study revealed, the signs have to be worded right. Word them wrong and they don't work.

New York City now gives out similar signs to any manager of a public or private building who requests them, free of charge. So far, over 26,000 have been distributed.

The New York City signs say "Burn Calories, Not Electricity." And they seem to be doing the trick. Stair use remains up, nine months after the signs were first posted.

People are less active today than they were in the past. Much of the bending, stretching and moving that used to be a part of everyday life has been replaced by sitting. And too much sitting is bad for your health and may even shorten your lifespan. One way to fight back is to climb the stairs instead of taking the elevator. Do it often enough and it burns as many calories as jogging. But not enough people do. Maybe they just need a gentle reminder, like the one in a sign.

Signs were posted in a three-story health clinic, an eight-story affordable housing building and a ten-story academic building. Stair and elevator trips in these buildings were then recorded, for nine months at the health clinic and housing site and briefly at the academic building.

Nine months after the signs were posted, stair use was still up: total stair use was up 43% at the housing site and stair climbing alone was up by over 20% at the health clinic.

Instead of removing the signs at the study's end, they were left in place, where they remain today. New York City now gives out similar signs to any manager of a public or private building who requests them, free of charge. So far, over 26,000 have been distributed.

If you'd like to get more exercise in your life, all signs point to the stairs as the easiest way to do so.

The study appears in the American Journal of Preventive Medicine.