Judging from my e-mail, isometric exercise is making a comeback, particularly with seniors, and readers want to know if it's effective and what's the best approach.
In isometrics, the muscles contract and muscular tension increases, but there is no movement.
Isometrics as a form of exercise has been around a long time. Those of you at midlife or older will recall Charles Atlas ads in magazines, depicting a bully kicking sand in the face of a skinny guy. The skinny guy purchases the Charles Atlas exercise plan, grows big muscles, then chases the bully away.
In the Charles Atlas "Dynamic Tension" system, there is no equipment involved — one muscle opposes another as a way of providing resistance.
For example, bend your right arm to 90 degrees with your elbow fixed at your side, palm upright. Place your left palm on top of your right palm. Now, attempt to bring your right palm up to your chin while resisting with your left palm.
You will feel increased tension in your right biceps muscle as it tries to overcome the resistance applied by the triceps muscle of the left arm as it presses downward.
There is increased tension in these muscles, but there is no movement. Does the Atlas system produce results? Let's take a look.
What research tells us
In the 1950s, exercise physiologists investigated the effects of isometrics. Theoretically, isometrics should be the ideal way to boost muscle size and strength.
That's because to make a muscle bigger and stronger you must overload it (make it work harder). When the muscle is overloaded, it will call into play progressively more muscle fibers (cells) to assist. The more fibers you involve, the stronger the contraction.
For example, if I lift a 10-pound dumbbell, I recruit X number of fibers. If I lift a 20-pound dumbbell, I recruit twice as many fibers to help me overcome the increased resistance.
If, however, I contract my muscles against an immovable object (palm against palm, or trying to push against a fixed railing), I won't be able to overcome the resistance, and therefore I should continually recruit more muscle fibers. I will use more muscle fibers in an isometric contraction, in other words, than I will lifting a heavy weight.
Researchers discovered that, despite this theoretical advantage, isometrics proved to be disappointing in two ways.
First, strength increased, but only at the point of application. In the example of the palm-versus-palm exercise, strength would increase only at the 90-degree angle and not throughout the full range of motion of the biceps muscle (from a straight elbow to a fully flexed elbow). Thus, doing isometrics faithfully would have limited impact when trying to push or pull a heavy weight.
Second, isometrics do not stimulate much growth in the size of the muscle. Thus, the Atlas ad, showing the transformation of the skinny guy to a muscular marvel, was overblown, if not downright bogus.
Real-world application
Even though I prefer the use of light dumbbells, isometrics can prevent muscle loss with aging and can promote a modest increase in strength.
Here's a simple program: Using the palm-versus-palm position described, exercise the right arm, then the left. This will challenge and stimulate the biceps and triceps.
Next, for the shoulders and chest muscles, with arms extended in front, palms facing, push palm against palm. Flex the muscles vigorously, but don't hold your breath and don't overdo it. You can use this approach for muscles all over the body.
Just a few minutes each day of isometric contractions can help, especially when combined with a program of walking and stair climbing to keep the legs strong.
Bryant Stamford is an exercise physiologist and director of the Health Promotion and Wellness Center at the University of Louisville. If you have questions about sports injuries, health, exercise or fitness, write to Body Shop, Gannett News Service, care of The Courier-Journal, 525 W. Broadway, P.O. Box 740031, Louisville, Ky. 40201-7431, or e-mail bryant@louisville.edu.