Strength & Power Training Important

The physical activity guidelines issued in 2008 by the federal government echoed other guidelines by recommending that American adults get at least two and a half hours of “moderate intensity” aerobic exercise a week. Aerobic exercise increases your heart and breathing rates so that more oxygen reaches your muscles. Walking at a fast pace of three to four miles per hour (three is brisk; four can feel downright fast) is often held up as the standard for moderate intensity: inexpensive, no special training or equipment needed, and manageable by many, although some people may need to work up to the full weekly amount. And you can get those two and a half hours in 10-minute allotments.

Be strong

There are indeed other types of exercise we should be doing that may get overlooked in the enthusiasm for an aerobic workout. Exercises to improve and maintain our balance, for example, and those that help keep us flexible.

Many researchers argue that the health benefits of strength training (another name for muscle-building exercise) haven’t been emphasized nearly enough. In fact, for older people, it may be even more important than aerobic exercise, because research has shown that it could prevent falls and disability.

The gradual, age-related decrease in muscle tissue called sarcopenia starts at the depressingly young age of about 30 or so. The average 30-year-old will lose about a quarter of his or her muscle strength by age 70 and half by age 90. Some studies show an even steeper drop-off that accelerates rapidly in our 70s.

Vive la resistance

Strength training goes by several names: resistance training, progressive resistance training, weight training, muscle strengthening. The notion of resistance comes from the fact that your muscles are straining against an opposing force — gravity, for example, if you’re lifting a weight. In the typical program, you do the same weight-lifting exercise eight to 12 times, rest for a minute or two, and then do the exercises again. The number of times you repeat a movement (for example, lifting a weight) is often referred to as “reps” (for repetitions) and the groupings as sets. Muscles have to strain to get stronger, so you are supposed to choose the amount of weight that allows you to do only eight to 12 reps — and the last couple of them should be difficult. Two or three sets of each exercise are usually recommended. As you get stronger, you’re supposed to increase the challenge to your muscles by adding more weight. Because muscle needs time to recover, it’s best to limit yourself to two or three workouts a week.

Power up

Most traditional strength-training programs, and especially those for older people, don’t emphasize the speed at which the exercises should be done. As a result, they increase muscle strength, but not necessarily muscle power, which is a function of both how much force a muscle can produce and the velocity at which it can do it. Muscle power declines even faster than strength as we age. And in several studies, muscle power has been more strongly associated with loss of mobility and falls than strength alone. That makes sense. Muscle power, not just strength, helps with everyday activities like climbing stairs because it allows you to transfer weight from one leg to the other relatively quickly, so you’re less likely to teeter and lose your balance. And think about when you stumble slightly: whether you fall or not depends on how quickly your muscles react and compensate for the loss of balance.

A strength program can be adapted to produce more power simply by doing a component of each exercise at a faster speed. It’s been a challenge, though, designing safe modes of power training for older adults.

Dr. Jonathan F. Bean, an assistant professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School, has conducted a number of studies of a program specifically designed to improve muscle power, especially that of the leg muscles. It involves wearing a weighted vest — adding weight to the torso instead of the arms or legs helps people keep their balance during the exercises — and “task specific” exercises related to day-to-day activities such as getting out of a chair or climbing stairs.

The bottom line

Strength training isn’t a vanity project. It’s now recognized as a crucial part of a well-rounded exercise program that will help offset the natural tendency to lose muscle as we get older. Muscle power — strength plus velocity — may be more important than strength alone, and you should explore safe ways to add some power moves to your muscle-building workout.

-From: “Time to put some muscle into it”, Harvard Medical School , HEALTHbeat: 09/15/2009.

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