Q. Long ago, I was told that isometric exercises, like weight lifting, shouldn't be done by anyone with a heart condition. Is that still the prevailing wisdom?

A. Isometric exercises are those in which a muscle tenses but doesn't contract. Clasping your hands together and pushing or lifting free weights are examples of isometric exercises. Physicians once discouraged people with heart disease from doing predominantly isometric exercises, like weight lifting and other resistance exercises, in part because they can lead to temporary but dramatic increases in blood pressure. Lifting weights is also thought of as an anaerobic exercise, one in which the body's demand for oxygen exceeds supply. The fear was that the combination of increased blood pressure and oxygen depletion might trigger a cardiovascular event like a heart attack.

The American Heart Association says that resistance exercise should initially be done in a rhythmical manner at a slow to moderate controlled speed. It offers these tips:

Perform strength training through a full range of motion. Involve the major muscle groups of the upper and lower extremities by doing exercises such as chest press, shoulder press, triceps extension, biceps curl, pull-down (upper back), lower-back extension, abdominal crunch/curl-up, quadriceps extension or leg press, leg curls (hamstrings), and calf raise.

Start out with weights that are heavy enough so you can do 8-12 repetitions per set. If you are older, more frail, or have heart disease, start with lighter weights that let you do 10-15 repetitions.

Limit yourself to a single set of exercises twice a week.

Avoid holding your breath and straining by exhaling during the contraction or exertion phase of the lift and inhaling during the relaxation phase.

Alternate between upper- and lower-body exercises so you don't overtax muscle groups.

In reality, though, resistance exercises are combinations of aerobic (activities that improve the body's ability to use oxygen) and anaerobic exercise. For most people, lifting weights for 30 minutes in multiple cycles with intervals of rest has a substantial aerobic component. Equally important, we now have solid data showing that moderate strength training is safe, even in most people with heart disease. It has multiple health benefits, including improved sensitivity to insulin, increased muscle mass, and better bone density.

In 2007, a scientific statement from the American Heart Association recommended resistance exercise for both preventing heart disease and treating it (Circulation, July 31, 2007). It isn't for everyone, of course. People with uncontrolled heart failure should steer clear of strength training, along with those with uncontrolled rhythm problems, severe and symptomatic aortic stenosis, or uncontrolled high blood pressure. But for most people with heart disease, strength training is an excellent complement to aerobic exercise if done in moderation and with gradual increases in resistance. -- Richard Lee, M.D., Associate Editor, Harvard Heart Letter,

(c) 2010 Harvard Health Watch