When people reach a certain age — we shall refrain from going into the depressing particulars — they need to start paying more attention to keeping the lower back in shape.

You ignore your back at your peril. Then one day you make an innocent but awkward move: picking up a box, moving a chair, toweling yourself dry, reaching down to scratch the dog’s ears.

Bingo, you throw out your back. And after a couple of weeks where a strained whatchamacallit becomes the center of your universe, you heal enough to tell yourself: "Well, I never want to go through that again."

That’s where the preventive medicine of a proper exercise routine comes in, one that targets the muscles of the lower back and the core muscles of the abdomen, which provide a crucial supporting role.

We asked longtime Denver fitness trainer Donna Miller to put together a few basic lower-back exercises that can be used by beginners and advanced athletes alike.

"There are lots of different ways to skin a cat in keeping your back healthy, but these are good basic exercises," Miller says. "You don’t need a gym to do these exercises. You can do them at home."

Some of the exercises require a fitness ball or 8-pound kettlebell weight, available at most sporting-goods stores and gyms.

Miller advises doing the exercises in slow, controlled movements, with strict attention to form — mainly keeping the back straight. The goal is to make the overall session last about 30 minutes.

Try to do each exercise for three sets of 10 repetitions each, although beginners might be able to do only five or so reps at the outset.

"People who are really looking to improve their back strength should do these routines four times a week," Miller says.