Preventing sports injuries:
part two

Warming up, cooling down and stretching

By DR. MORT MALKIN

Among the many sports myths that float around sports and exercise circles, warming up, cooling down and stretching seem to be in permanent orbit. The reasons given for these rituals vary from the prevention of injury to improving performance. But the reasons don’t always square with the physiology. Let’s look at the why, when and how based on what is happening within the tissues and organs.

The purpose of the warm up is to physically warm the muscle fibers so they will move freely when they go through cycles of contraction and release during the exercise. The three ways to warm muscle tissue are: 1) raising the temperature of the body’s immediate environment (hot tub, anyone?), 2) massage (two or more therapists may be needed to warm all the muscles in a reasonably short time), and 3) increasing blood flow through the muscles by causing them to contract rhythmically. The third is easily achieved by a few minutes of the same exercise you will do in the workout, of course at a slower pace. Calisthenics to warm up is not as muscle specific. Stretching before the workout does not produce warmth.

If stretching is not necessary for warming up, do you need to stretch at all? The answer is found in another question: When? After the workout is complete and the working muscles have contracted a few thousand times, the level of lactic acid and other metabolites is elevated, and the muscles are highly sensitized. The books on stretching list enough stretches to keep you busy for hours—the body contains many muscles. For any specific exercise/sport it is the power producing muscles that need stretching. For example, distance running uses the calf muscles and quadriceps for stride production and the lower back muscles for posture support while the legs pound out the miles. To stretch a particular muscle (or group), position yourself so the muscle is lengthened and hold it at length for 30 seconds or more.

The calf muscles are stretched by placing one foot forward with your toe close to a wall (or tree or pole) and the other 24 inches back with the heel on the ground. Then bend the forward knee so the body moves forward while the back heel remains on the ground. In 30 seconds the calf muscles of the back leg will be adequately stretched and you can switch. (Incidentally, for folks who suffer cramping of the calf muscles during sleep, nocturnal claudication, this stretch will serve as a preventive intervention.) Quadriceps stretches require the leg to be held in a maximally bent position. Sprinters must add hamstring and groin (flexors) stretches to the regimen. Whatever the sport, just figure out which muscle groups work the hardest and hold them at length for 30 seconds.

After the end of the workout and before stretching, it is important to cool down. Just reverse the warming up process. Continue the exercise but at less intensity. The purpose is two-fold: 1) to maintain blood flow through the working muscles and thereby wash out some of the lactic acid that has built up and 2) to have the muscle groups act as a supplemental pump to help return blood from the legs to the heart until heart rate slows down. Blood levels of lactic acid will decline to minimal levels after a few hours, but the cellular concentrations of lactate take longer to return to normal, sometimes 24 hours or more. At the same time it takes at least 48 hours to replenish the muscle glycogen, which forms the principal energy supply of the power producing muscles. After a hard workout, only light activity is advised until two days later.

Part three of this series of articles will discuss the importance of form and technique in preventing injury. Watch this space.

[Dr. Mort Malkin is an Attending Surgeon Emeritus at Brooklyn Hospital Center and is the author of three books on sports and exercise, most recently “Aerobic Walking-The Weight Loss Exercise.”]