Aquarobics are aerobic exercises performed in water. They have benefits similar to aerobics, but they also have additional advantages. Vigorous body movements create water turbulence which massages the superficial muscles. More importantly, the buoyant effect of water reduces the risk of joint injuries. This makes it a particularly attractive exercise for people who are overweight, or have orthopaedic or back problems. Because body weight is supported, aquarobics does not stimulate bone growth, so it does not protect against the development of osteoporosis. However, it is much better than land-based aerobics for anyone who is already suffering from brittle bones or a bad back. Many land-based athletes train in water when recovering from injuries that would be aggravated by high impact exercises. Recent research has shown that running in water (aqua running) preserves endurance and leg strength, and maintains fitness.

When exercising in water, the heart rate is lower than when exercising at a similar intensity on land. This may be due to water compressing the body and making the blood flow more easily. Whatever the reasons, it seems that the stress on the heart is less in water than on land. Nevertheless, it has been suggested that the average person uses 450 to 700 Calories during an hour of aquarobics, with 77 per cent of the calories coming from fat stores. This helps to reduce fat body mass, while movements performed against the resistance of the water stimulate muscle growth and increase lean body mass.

In 1981, the benefits of aquarobics were recognized in the United States by the President's Council on Physical Fitness and Sports, who recommended an exercise programme for small bodies of water. The programme included standing water drills (e.g. toe touching, side-straddle hopping, and jogging on the spot), pool-side standing drills (e.g. stretching the arms out and pressing the back against the wall), gutter-holding drills (e.g. knee hugs and a variety of flutter kicking), bobbing, and treading water.

Aquarobics is quickly gaining in popularity and manufacturers are responding with a whole range of exercise aids that include aquarobics footwear, buoyancy cuffs and vests, water belts which offer resistance, and peculiar devices called ‘woggles’. These are six-foot long, very flexible, sausage-shaped pieces of foam that provide a buoyant weight to push against, and to act as a support when performing muscle-strengthening exercises. At the end of a workout two woggles are often used together, one under the head and the other under the knees, to give a full support for relaxation while floating.