Swimming is an almost ideal way to stay in shape. If you don't already swim, it's not too late to start. And if you don't like to swim, there's a wide range of other workouts you can do in water.
Swim your heart out
If you're looking for exercise that improves heart and lung capacity, but is gentle on your joints, swimming is a top choice. Like other aerobic exercise such as running, it can improve cardiovascular fitness as well as cholesterol levels, provided you swim at a brisk pace.
Aim to swim laps for 20 to 40 minutes at a pace that keeps your heart rate up. Start slowly; initially you may need to rest between laps. Over time, work out longer, preferably using different strokes and speeds. Because swimming places less demand on the heart than running and other sports, your heart rate won't go up as high. That means your target heart rate—if you know it—will be lower by 10 to 20 beats per minute.
Blood sugar and blood pressure control
Several studies have found that swimming can improve various measures of blood sugar control, such as insulin sensitivity. This is true even though swimmers tend to weigh more and have more body fat than, say, runners or cyclists. Swimming is beneficial in this regard not only because it can provide an aerobic workout, but also because the resistance provided by the water builds muscle, which helps with blood sugar control.
Some other research has shown that swimming and water exercise programs can help people lower blood pressure.
Studies on the effects of swimming on weight have produced inconsistent results. While swimming burns a lot of calories (about 600 an hour, on average, depending on the stroke and intensity), recreational swimmers tend to lose less weight than would be expected from other aerobic activities, such as running, cycling or brisk walking. That may be because cold water dissipates much more heat from the body than air at the same temperature does. There's some evidence that this leads to increased appetite in the hours after swimming.
You'll burn the most calories doing the butterfly stroke or a fast crawl. Next come the breaststroke and backstroke, then the sidestroke. It's good to do a few different strokes for a well-balanced workout.
Even if swimming doesn't help you lose weight, it can help reduce body fat and waist circumference, while toning all major muscles (arms, shoulders, hips, legs). Swimming is also a good way for runners and cyclists to cross-train, since it uses different muscles.
Arthritis and back pain relief
Studies have generally given swimming and water workouts a thumbs up for people with arthritis or other musculoskeletal problems, especially if they are very overweight. Exercising in warm water, in particular, can relieve joint stiffness and pain and increase flexibility. It's easier to move around in water, and water brings relief by reducing the load on knees and other joints.
Many types of gentle exercise are good for back pain, but water workouts are among the best. A 2009 Turkish study found that aquatic exercise helped relieve chronic back pain better than a land-based program. Also in 2009, a Belgian review article in Clinical Rehabilitation found sufficient evidence to conclude that aquatic exercise is a safe and effective way to relieve chronic low-back pain. And a 2006 Swedish study found that water exercise reduced the incidence of back pain in pregnant women. Working out in water reduces the stress on the spine, promotes muscle relaxation and improves joint flexibility.
The downside is that swimming and water workouts are not weight-bearing exercise and thus, unlike running and strength training, do little to strengthen your bones.