I have painful knees. Is swimming a good exercise option for me?

DEAR DOCTOR K:

I’m overweight, and I want to exercise. But I have painful knees that make it difficult to walk. Is swimming a good alternative?

DEAR READER:

In terms of convenience, it’s hard to beat brisk walking as a form of exercise. You don’t need any special equipment or venue, and you can do it in many places. But during the winter, harsh weather can make walking outdoors unpleasant — even treacherous at times. And for some people — such as those with achy knees, sore hips or substantial weight — walking may be uncomfortable.

The good news is that swimming allows you to meet your fitness goals with less stress on your joints and muscles than brisk walking.

Large studies looking at the benefits of physical activity have tended to lump swimming together with other types of exercise. That’s because relatively few people swim on a regular basis. But plenty of evidence points to lower rates of heart disease among people who do regular, moderate- to vigorous-intensity exercise. And swimming laps definitely qualifies.

Recreational swimming will burn about the same calories as brisk walking. One key advantage to swimming is that water makes you buoyant, which takes the stress off your joints. This can be especially helpful for people who are carrying excess weight.

Water also offers resistance as you move through it, which allows you to work out vigorously (if you’re able) with little chance of injury. Swimming laps can also be relaxing and meditative, which may offer some stress relief. Finally, swimming is an activity you can do throughout your life.

If you haven’t been swimming in a while, start slowly. Try swimming just five to 10 minutes while coordinating your breathing, strokes and kicking. Invest in a pair of well-fitting goggles. If doing laps isn’t your thing, try walking or running in water. Another option is water aerobics. These exercises are done in waist-deep or higher water and may use floating devices and weights. Many community centers, YMCAs and other facilities with pools offer water aerobics classes.

One downside to swimming is that, because it’s not weight-bearing, it’s not optimal for keeping your bones strong. If you do decide to take up swimming as your main form of aerobic exercise, you’ll need to supplement it with some weight-bearing exercise. Strength training, walking, dancing, stair climbing or gardening all fit that bill. True, they put stress on the knees. But the exercises will have strengthened support for your knees, and that should reduce any discomfort.

Severe arthritis of my right hip caused me to have a hip replacement. I attributed the arthritis in that hip to the jogging (on hard surfaces) I’d done for decades, so I stopped jogging. If I lived in Southern California (where I was raised) and had a pool, I would have switched to swimming. However, in Boston where I live, only indoor pools have water most of the year, and getting to a pool every day is a hassle. So I use an elliptical cross-trainer. It minimizes the impact on leg joints, though not as much as swimming. A local gym is very likely to have these machines.