Text by Bruce Cohn, Globe staff graphic/Joan McLaughlin

Lie on your stomach with your legs shoulder - distance apart extended long and turned out. Do this on a mat or towel and rest your forehead on your hands.

Raise one leg off the ground and notice if the back of your thigh or your butt contracts first. It may take two or three times to see what you feel.

Your butt muscle (gluteus maximus) is supposed to be the first muscle to contract, followed by the hamstring in the back of your thigh. However, because the hamstring tends to be tight and shortened from excessive sitting, it will take over.

To correct this, try lifting the leg again but before you do, think of squeezing your butt and the muscle in the front of your thigh (quadriceps). You will notice immediately how much lighter your leg feels. And you will feel less strain in your lower back because you are firing your butt muscle first.

Do this movement for 10-12 repetitions alternating from side to side. Do it slowly and think of lengthening your leg more so than lifting it higher. Doing this exercise regularly can change faulty firing patterns and, after time, you should notice your butt muscle firing automatically in anticipation of lifting your leg.