Aching knees?

Try these low-impact exercises

Do you avoid exercise because your knees ache from arthritis, excess weight or just getting older? You may be able to exercise without pain if you avoid high-impact movement. Check with your doctor. Light exercise may even help reduce your pain while improving your fitness level.

Below are some low-impact ways you can move more. Start slowly to make sure you're not overexerting yourself. If you have arthritis, aim to get 30 minutes of physical activity every other day. It's OK, though, if you can only manage 10 minutes to start. Be sure to check with your doctor before you begin a new workout routine.

At the gym

Many fitness centers offer options for those who want to avoid weight-bearing exercise. School gyms, religious centers, hospitals or your place of employment may offer similar equipment for a lower membership fee -- or sometimes for free.

Do water aerobics

Many gyms have indoor pools. If you like being in the water, but don't have the stamina for swimming laps, take a water aerobics or water fitness class instead. Work at your own pace. If you prefer to work out on your own, try walking across the shallow end of the pool or doing leg lifts in deeper water while holding on to the side. You can even "bicycle" your legs in the water to work your hip and thigh muscles.

Take a yoga or tai chi class

Both types of exercise can be easy on the knees and other joints. Tai chi helps with flexibility and range of motion. Basic yoga involves poses that stretch your body without straining it. If you prefer, buy a DVD to practice the moves at home.

Try the elliptical machine or recumbent bike

First make sure it is OK with your doctor. Both of these pieces of equipment give you a good cardio workout without putting as much strain on your knees.

Use upper-body ergometers or rowing machines

Ergometers are like stationary bikes, but you use your arms instead of your legs to move the pedals. Rowing machines also work your upper body. Although you do push off and bend your legs with each repetition, your arms pull your weight.

At home

These gentle stretches and seated exercises can be done in the comfort of your living room. They can help strengthen the muscles that support your knees and may even give you some relief if your joints are stiff or sore.

Seated leg extensions

• Sit in a sturdy, firm chair.
• Slowly extend one leg straight out in front of you, keeping your thigh on the chair.
• Hold for a few seconds, and then slowly lower to the starting position.
• Repeat with the other leg.

Floor leg lifts

• Lie on a mat on the floor with one knee bent, foot flat on the floor and the other leg straight.
• Bend your straight leg at the knee and bring it toward your chest.
• Push your foot up in the air to straighten the leg and then slowly lower it to the ground. Repeat with the other leg.

Seated hamstring stretch

• Sit in a chair with one leg extended in front of you, slightly to the side.
• Slowly lean forward and reach toward the extended foot with both hands.
• Hold the stretch for a few seconds.
• Repeat on the other side.

If your knees start to hurt after any activity, stop and check with your doctor before trying it again. For more help with exercises suitable for bad knees and other joint problems, your doctor may refer you to a physical therapist.