Bike riding and swimming are both forms of aerobic exercise that, over time, can improve your overall health and fitness. In comparison to jogging or running, cycling and swimming offer relatively low-impact forms of exercise. Each form of exercise has different effects on your body and may affect your motivation differently. Consult your doctor before starting any new exercise regimen.
The number of calories burned in an hour of biking or swimming will depend on a number of factors including the intensity of the exercise and your current weight. A person weighing 150 lbs. would burn approximately 410 calories per hour of leisurely swimming, but 682 calories in an hour of vigorous lap-swimming. Bicycling at a pace between 14 and 15.9 mph burns 682 calories per hour for a 150-lb. person, rising to 1,091 calories at 20 mph.
In general, you will burn more calories the more you weigh. An hour of swimming at a leisurely pace will burn only 245 calories if you weigh 90 lbs., but 791 if you weigh 290 lbs. Riding a stationary bike at a moderate intensity level burns 286 calories for a 90-lb. person but 923 calories for a 290-lb. person. However, the increased calorie burn with a heavier weight should be considered in relation to the slowing effect of excess weight. The more overweight a person is, the less likely he is to keep up a vigorous swimming pace or intense bicycle workout for a full hour.
Biking is usually more tiring the faster you go, on rough surfaces and on hilly terrain. The intensity of a swimming workout varies with your speed and the type of stroke you use. According to an interview with professional swimmer Sharon Davies, reported in the British newspaper "The Daily Mail," an average adult will burn 360 calories per hour swimming breaststroke. Front crawl burns an average of 600 calories per hour, and butterfly stroke burns 900 calories per hour for the same average adult.
The physical actions, benefits and disadvantages of biking and swimming are different. Cycling primarily uses the muscles in your legs, whereas swimming uses most major muscle groups and tones your whole body. Swimming is also a form of non weight-bearing exercise, which can be both an advantage and a disadvantage over cycling. If you have problems with your joints or skeleton, swimming provides a form of exercise in which your weight is supported by the water, reducing joint strain. However, non weight-bearing exercise does not have the bone-strengthening effects of sports such as running or cycling.