Mary, an American sports psychologist. Saunders gave this sport an interesting name, called "Mud Surfing". This method sounds easy to do, but after trying it, you will find that it is much more difficult to complete this exercise than the usual fitness method, because the resistance of human body in water is 12- 15 times that in air. So when doing this exercise, try to walk fast in the water, so that your body can consume more calories. Take a woman who weighs about 125 kg as an example. When doing this exercise, her body can consume 17 kilocalories per minute, and the effect is that she spends 5. After walking at a speed of 5 miles at the same time, the body consumes twice as many calories as before.