When swimming, the water in front of you is pushed forward to create high pressure, and the water behind you creates a low pressure that drags you down.
The shape resistance is the square of the speed, that is to say, if the speed is 1 times faster, the resistance will increase by 4 times, because the size and shape of the body determine the strength of the shape resistance, the best way to reduce the shape resistance when swimming is to fake the body go through a very small circle in the water, if your body is perfectly streamlined, any movement made by your hands, feet or head will increase the shape resistance.
When swimming breaststroke and butterfly, the shape of the body in a streamlined shape under the water surface has the least resistance. Therefore, when swimming breaststroke, the body should maintain the above posture for two-thirds of the time for each stroke of the water; When swimming butterfly, you should also maintain the above position between strokes
water wave resistance
The resistance of the water wave will consume a lot of the swimmer's strength. The faster you swim, the bigger the waves, and all your energy is used to stir up the waves instead of pushing forward.As mentioned earlier, if the speed is doubled, the shape resistance will increase by 4 times;The water wave resistance is more powerful, the speed is doubled, and the shape resistance is increased by the third power；That is, the speed is 1 times faster, and the water wave resistance is 8 times larger.
One of the reasons fish (and the human body when it's streamlined in the water) move so fast is that they can't afford water waves, so wave resistance is negligible,This is why swimmers try their best to move up to 15 meters in the water when they turn around and kick off the edge of the pool.
Short swimmers are more advantageous in breaststroke and butterfly because both positions have a considerable amount of time to advance in the water, on the other hand, tall swimmers almost dominate freestyle and backstroke because of their height and body length.
The two most important ways to reduce water wave resistance :
(1) Lengthen the body line every time you stroke the water, The body line in the waterline has less water wave resistance relative to the width.
(2) The strokes should be smooth, elongated, and slow strokes will not easily cause splashes or waves, and the resistance will be small.
Surface resistance is the resistance caused by friction between water and skin, no action skills can change this natural law, but if you wear the right swimsuit, take off the loose big swimming trunks and put on the close-fitting small swimming trunks, the difference is immediately visible.
Since 2000 AD, swimmers have been very concerned about swimwear, they will wear high-tech swimsuits made of special materials to reduce surface pressure.