Joint flexibility and muscle stretchability are important to reduce the risk of injury during strength training.

Most people are aware that strength training is necessary for improving muscular fitness and that endurance exercise is essential for enhancing cardiovascular fitness. However, fewer people find time to stretch, which helps with joint flexibility and movement.

Why is stretching a low priority? For one thing, people may not appreciate the importance of joint flexibility. However, mobility becomes a higher priority as we age; older adults are more inclined to stretch.

Another incorrect perception is that stretching is less useful than strength training and endurance exercise because it requires little energy and burns relatively few calories. But joint flexibility and muscle stretchability are essential for enhancing performance and reducing injury risk.

There are many forms of stretching.

Static stretching is slowly moving the joint into a muscle-stretched position, then holding the maximum stretch for 10 to 30 seconds. Static stretching is best performed during the cool-down.

Ballistic stretching requires fast and bouncing movements such as windmill-type alternating toe touches. Unfortunately, ballistic stretching invokes an automatic neuromuscular response known as the stretch reflex. Basically, when a muscle is elongated rapidly, it triggers an immediate contraction response to prevent possible tissue damage. It may cause tissue damage if performed too abruptly.

My preferred stretching technique is known as dynamic stretching. It involves controlled joint movements performed relatively slowly.

An example of dynamic stretching is gradually expanding arm circles to increase shoulder joint flexibility. You begin with very small arm circles and gradually progress to larger arm circles that place greater stretch on the shoulder muscles. Arm circles become progressively larger, but at the same slow and controlled speed.

Unlike static stretches, dynamic stretches may be performed during your warm-up period, as well as during your cool-down period. Because of the slower and smoother movements, dynamic stretches do not activate the counter-productive stretch reflex as do ballistic stretches.

I recommend that you perform a few dynamic stretches as part of your warm-up routine and a few static stretches as part of your cool-down routine.

Wayne L. Westcott is senior fitness executive for the South Shore YMCA in Quincy, Mass., and adjunct professor of exercise science at Quincy College. He is author of 22 books on strength training and physical fitness, including his latest release, "Get Stronger, Feel Younger" by Rodale Press.