Swimming burns lots of calories, anywhere from 500-650 per hour depending on how efficiently you swim (you burn more flopping around than swimming cleanly!) and how buoyant you are (the more body fat you have, the more you float and the fewer calories it takes to swim). Very early and original research on swimming and calorie expenditure showed that swimming, regardless of the stroke, burned about 89% of the calories burned during running and 97% of the calories burned during cycling for the same time period. Stated another way, swimming burns about 11% fewer calories than running but only 3% fewer calories than biking. One important caveat about this data is that calorie expenditure is dependent on the intensity of exercise, and so it's entirely possible to burn more calories swimming than running in the same period of time as long as you swim hard enough, and particularly so if compared to running at light intensity.
At a gym you get a tour, an induction, a programme; at a pool you simply get told where the changing rooms are. But bad stroke technique can be counterproductive and even dangerous.
There's a woman I see regularly at the pool where I swim. She completes one length of breaststroke at best to my three, an expression on her uplifted face suggestive of the pool being filled with sewage or something equally terrible. It's plain that she is enduring rather than enjoying her swim, and I can't help thinking that part of the reason is her lack of proficiency: after all, mastery enhances the pleasure to be had from executing any skill.
I often feel sorely tempted to say something. If only she'd stop kicking her legs and stroking with her arms simultaneously, she'd stop cancelling one action out with the other. “Legs then arms,” I silently will her.
Of course, she's …
One of the most important muscles in your body is the heart. Swimming is an aerobic exercise and provides life-giving exercise to the heart. It gives the ability to pump more efficiently which in turn leads to improved blood flow. Aerobic exercises have also been proven to combat the body’s inflammatory responses that lead to heart disease. It is advised that you exercise at least thirty minutes a day and you can use swimming. If you only swim for thirty minutes per day your coronary heart disease is cut by almost 40%. Blood pressure, according to the Annals of Internal Medicine, is also improved by swimming aerobically. Swim away high blood pressure, live longer, and avoid coronary heart diseases.