Backstage, in dressing rooms, and at the edge of movie sets, performers are trilling and flapping, running through scales, scrunching their faces, bending and reaching. They are focused, concentrating on the routine that readies them to deliver with control and power.

While singers and actors are likely to have perfected a series of exercises that prepare them for a performance, many public speakers and presenters do not. But they should: warming up, even an hour or so before a presentation, reduces tension and strengthens the muscles used in speaking, both of which lessen vocal strain and the likelihood of injury to the voice.

Another happy by-product? A fuller, more resonant voice.

GET PHYSICAL

To get your blood moving and reduce nervousness, march in place or do arm circles for a couple of minutes. Then stretch slowly and deliberately—a few shoulder rolls and some neck rolls to the front and to the back. Turn your neck to the side and stretch, followed with a deeper stretch by pointing your chin toward your shoulder. Lift one arm and reach up, lengthening your ribs; follow with the other arm. While one arm stretches up, the other stretches down.

Shake out your hands. Massage your face. Yawn. Tense your face and then relax it. Smile. You're ready to breathe.

JUST BREATHE

Many of us tend to take breaths by expanding the chest and pulling the stomach in. But that's not enough air to fuel physical exertion. Breathing from the belly supplies better airflow to your body.

So as part of your vocal warm-up, stand with your feet almost shoulder-width apart, your weight forward, more on the balls of the feet than the heels, your hands at your sides. As you inhale, your belly should expand—your chest and shoulders shouldn't move. Place one hand over your belly button. Slowly inhale one long breath through your mouth while silently counting to four. Your stomach should expand, pushing your hand forward. Hold that breath and count to four again. Then exhale the breath through your mouth to a count of four. As you exhale, release your shoulders, relax your neck, unclench your teeth. That's a good breath.

MAKE SOUNDS

Now connect your breath and voice by inhaling. As you exhale, voice a very gentle and sustained "Haaa" sound until you run out of air. Try it several times and then add a shoulder bounce. With your hands relaxed by your sides, lift your shoulders, take a breath and then exhale a "Haaa" while dropping your shoulders.

By reducing tension in your vocal cords, this exercise helps you prepare your voice to speak.

Another good one is trilling. Trill your lips by placing them together loosely and releasing air to make the sound of a motorboat or horse. To loosen your tongue—in a good way—place it behind your upper teeth and trill an "R" sound as you exhale, sounding very much like a purring kitten. Or tiger.

Warm up your lips and loosen the jaw by saying the letters "X-Q." Run through a few phrases such as "minimal animal, minimal animal" and "red leather, yellow leather" for increased vocal agility. Or repeat tongue twisters such as "Mommy made me eat my M&M's" or "Sally sells sea shells by the sea shore."

After such a series of exercises, your voice will be in performance mode. And so will you.