The faster you move through the water, the more resistance you'll encounter.
Why is the water a wall?
Keep in mind that water is nearly 1,000 times denser than air. If you put your arm out a car window at just 30 mph or ride a bike at 20 mph you immediately understand the relationship of speed and drag.
In a medium as dense as water, it takes very little speed to create a whole lot of drag. When anything tries to move through water, water pushes back. The faster you move or the harder you try to move, the harder it resists.
How does this affect your swimming? In running, even if you're very average, about 90 percent of the energy you expend is converted into forward motion. In cycling, your efficiency is increased by gearing. World-class swimmers, if they have strokes that are as efficient as possible, convert only about 9 percent of their energy into forward motion.
Much of the other 91 percent is spent moving water out of the way. And these are swimmers who can easily do 25 yards of freestyle in fewer than 10 strokes!
Recreational swimmers may be converting as little as 2 to 3 percent of their energy into forward motion. Is it apparent that you should spend much of your practice time learning to be more slippery?
Simple Strategies for Avoiding Drag
Aleksandr Popov, the world's fastest human, is one of those fortunate swimmers who reach that nearly unattainable standard of 9 percent mechanical efficiency. Still, he spends hours each week swimming slowly and easily, simply tuning in to where he feels resistance on his body's surfaces and trying to feel less.
The simplest and best strategy is to regularly do just what Popov does: Heighten your sensitivity to drag, using all available senses.
First, use sense of touch. Push off the wall in an intentionally poor position arms wide, head high. You'll really feel drag. Then push off in the most streamlined position you can manage. Compare the feeling of drag on your various body surfaces. Then pay closer attention to the resistance you feel, and do everything you can to feel less of it.
Second, use your sense of hearing. How noisy is your stroke? Do you splash, plop and plunk? The less of your mechanical energy that is converted into sound energy, the more you convert into forward motion. Silent swimming is one of the best ways to tune in to how you're flowing through the water.
Finally, use your eyes. Goggles make it easy to spot bubbles in your stroke. Total Immersion coach Don Walsh thinks more about eliminating bubbles from his stroke than anything else. That helped him complete the 28.5-mile Manhattan Island Marathon Swim in 14,000 fewer strokes (calculated by multiplying his strokes per minute by nine hours) than his peers. If you slip through the water rather than battle it, there will be far fewer bubbles and much less turbulence in your wake.
Swimmers have a choice to make each time they arrive at the pool. They can spend their time training hard and long to increase their propulsive force and aerobic capacity, or they can train with perhaps less physical effort but with great focus on minimizing drag.
A single trip to the aquarium—one filled with either fish or humans—provides dramatic proof that the path of least resistance is the smarter choice.