WE'RE ALWAYS being told to climb the stairs instead of taking the elevator. It's good for the heart to do all that climbing.

Never ride when you can walk.I have to say I usually follow that advice - after all, you never know when an elevator will stop and strand you inside.

This has actually happened to me.

Luckily, there was a phone inside, and I was only there for about five minutes before being rescued. It was a very long five minutes.

The other thing is that an elevator is a great place to be mugged. Knowing that, I have looked uneasily at a number of potential mug-gers as they have enthusiastically boarded the elevator with me.

I'm especially unnerved by those who race into the elevator just as the doors are closing. That's because I haven't had a chance to size them up yet. Then the door closes and I'm alone with strangers.

So I like to take the stairs, you know, for my heart.

Nine flights, usually. Or 10, if I arrive late.

It's great exercise.

Only thing is - I have noticed something I want to share. I hope you're sitting down because you may never have considered this.

Stairs are dangerous, too.

You have to be careful when you're using them because they are not all built the same.

As you go up or down a staircase you develop a certain cadence, so one stair that is not the same size as the rest can cause problems - enough to send you careening to the bottom on your tush.

I'm very serious now.

Some stairs are in fact shorter than others - and when you hit one like that it is startling.

You can be thrown off cadence. You can trip and fall - or at least pull several muscles - as you save yourself from falling.

Often it is that final stair that is different from the others.

It seems as though the guy who poured the staircase or built it didn't measure exactly - and when he got to the bottom, there wasn't quite enough room. So he made the last stair shorter - causing you to come up short when you hit the bottom.

Or sometimes, the last stair is a bit taller than the others.

In that case, you go down much farther than you intended, and you have a major shock. This can cause a tendon tear if you're not going too fast - or a bashed-in head if you are.

Now I'm not trying to upset anyone.

As long as you approach climbing with caution, you can probably surmount this problem along with the stairs. But if you start thinking this is your exercise for the day, it may be the last exercise you take.

Or at the very least, you may be a victim of shinsplints - that's an injury or inflammation of the tibial and toe extensor muscles or their fascia - and it is caused by repeated traumas from hitting cement or wooden stairs.

Believe me - you don't want shinsplints.

If this alarms you, you could always resort to the elevator.

Providing you have Mace or a water pistol on your person.

Providing you don't mind being alone with strangers.

Providing you don't have a constant need to be engaged in meaningful conversation with people you've never met.

Providing you enjoy craning your neck upward at the numbers for eight floors.

Providing you have a strong stomach that adjusts easily to jerky motions.

Providing you don't mind being confined to small spaces for an extended period of time in the event the elevator is unable to travel to your particular floor.