Getting out of a chair, climbing stairs, reacting to a fall -- these everyday actions take more than strength or cardiovascular fitness. They require power as well.
But this distinction can be lost on many people. Professional athletes know the importance of developing power, as do researchers studying the elderly. Average gym-goers may not.
Power is the ability to exert great force in a short period of time and results in being able to move quickly and explosively, says Mark Verstegen, founder of Athletes' Performance in Tempe, Ariz. His facility specializes in training competitive athletes, teaching them, among other things, to accelerate and change direction quickly. That ability is developed by lifting weights rapidly and helps athletes move more explosively during games and other competitions.
In short, it's weight training at high speeds.
"Think of strength as dial-up Internet; it serves a great purpose but is slower to boot up when you need it most," he says. "Power is your high-speed broadband connection, ready to be used instantly on demand."
A significant degree of power is the efficiency with which your nerves communicate and your muscles respond to the need to apply force. When you lift as much weight as you can -- as in traditional strength training -- the muscles respond more slowly.
Scientists at the U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University have shown that strength isn't the best indicator of muscle performance. In a 1992 study published in Clinical Science on the effects of strength training in the elderly, researchers found a 100% increase in strength but only a 28% increase in stair-climbing power among the subjects.
Since then, some researchers have come to understand that there is a velocity component to daily activities. A study published in 2002 in the Journal of the American Geriatrics Society divided 30 women in their 70s into two groups to compare the results of high-velocity strength training with traditional strength training. The study demonstrated that high-velocity training increases leg power in older women with disability more dramatically than strength training.
The most effective way to boost power is to lift weights rapidly. This trains muscles to contract quickly and react appropriately when it is necessary to exert force. But rapidly lifting a free-weight or piece of iron attached to a machine can cause inconsistent resistance and jerking, increasing the risk of injury to joints.
