How many calories you burn while swimming depends on your stroke, effort, speed, distance, duration, gender, weight and skill. Because most people swim a mix of strokes at various intensities, computing your exact calorie count is difficult.
For example, a 150 pound athlete burns about 272 calories by swimming 1500 yards in 30 minutes; swimming butterfly for 30 minutes burns 38 percent more calories, breaststroke burns 25 percent more and backstroke 12 percent less. Compare that with a 120 pound athlete who burns only 218 calories swimming the same 1500 yard workout (60 lengths in a 25 yard pool).
Generally, the faster an athlete swims, the more calories he burns in an hour. For example, if the 150 pound swimmer above swims one more length per minute, he burns 102 more calories in the same 30 minute period, but it works out to nearly half a calorie LESS per length. This anomaly occurs because he swims more efficiently.
The table below lists the approximate calories burned per hour for a person weighing 150 pounds:
Swimming moderate effort 272 calories
Swimming ocean, river, lake 408 calories
Swimming none-lap, leisure 408 calories
Swimming laps, moderate to light effort 476 calories
Swimming backstroke 476 calories
Swimming crawl/freestyle, 50 yards per minute 544 calories
Swimming sidestroke 544 calories
Swimming synchronized 544 calories
Swimming fast, vigorous effort 680 calories
Swimming breaststroke 680 calories
Swimming butterfly 748 calories
Swimming crawl/freestyle, vigorous effort, fast 748 calories
Your weight affects the number of calories burned, with heavier people expending more than lighter ones when doing the same exercise. For example, a 100 pound person burns 1/3 fewer calories, so multiply the above numbers by 0.7; a 200-pound person burns 1/3 more so multiply by 1.3.
Because most people are unable to do butterfly continuously, crawl or freestyle is the most effective swim stroke, burning between 540 and 750 calories per hour.
Inexplicably, elite swimmers have an average of 5% more body fat than their equivalent running counterparts, despite burning the same and sometimes even more calories with their high intensity interval training which the steadier pace of distance running lacks.
Interestingly too, women, regardless of their skill level and weight, typically use fewer calories per mile than men because of their higher body fat percentage. They naturally stay afloat without having to burn calories doing so.
Swimming nonstop for half an hour is realistic for a beginner but strive for an hour. Vary your strokes. For example, warm up by doing 4 lengths freestyle, 4 lengths breast stroke, then get your heart rate up by swimming 4-6 lengths freestyle at a faster pace. When you feel tired or out of breath, switch to breast stroke or back stroke or even use the kicker board, and when you catch your breath, go back to freestyle.
If you can, incorporate butterfly. Flip turns too; they ensure a continuous workout without you needing to pause between lengths.
If swimming appeals to you but you are not strong enough to swim for an hour, consider using flippers together with the kicker board which you hold out in front of you. Because your head is above water the entire time, breathing is not an issue; while your legs and butt get a fabulous workout.
Despite being surrounded by water, you sweat when you swim. Be sure to stave off dehydration by drinking water before and after your session, even if you do not feel thirsty.
Swimming is an excellent aerobic workout, using a large number of muscle groups and burning as many calories per hour as running or cycling at the same intensity. It increases your heart rate for the full duration, you breathe harder and work your entire body.
Swimming strengthens your heart muscles thereby improving the delivery of oxygen to all parts of your body, it improves your physique, flexibility, stamina and balance. If you do other exercise, swimming serves as a great cross-trainer, lengthening and strengthening your muscles.
Mentally it relaxes you and frees you of tension; socially you can enjoy it with friends and family to develop a spirit of competitive camaraderie.
Swimming poses no strain on connective tissue or joints, so is safe for the overweight, elderly, people with lower back and leg problems, and those whose joints cannot handle high-impact sports. Because water supports the body, swimming is recommended as a rehabilitation exercise.
Ideal for pregnant women, swimming strengthens both abdominal and back muscles, enabling them to better carry their extra weight. High blood pressure, joint stiffness and discomfort commonly associated with pregnancy can all be eased by exercising gently in water, although you may want to consult with your doctor beforehand.
Whether you splash around burning 400 calories an hour, or expend 748 calories per hour perfecting your butterfly stroke for hard-core competition, any swimming burns calories. In fact which ever sport you enjoy is the one which will burn the most calories for you in the long run.