If you want to beat Michael Phelps in a race, you should probably just give up. Or, you can try to figure out what the best freestyle stroke is. Turns out, there are two different kinds of freestyle strokes, the “deep catch” and the “scull.” Scientific American explains the difference:
In the deep catch approach, a swimmer puts his or her arm straight forward, then down as deep as possible into the water, and pushes that arm back as hard as possible, keeping the palms perpendicular to the direction the swimmer wants to move. In sculling, swimmers reach out but then bend their elbow, keeping it high in the water as their lower arm bends back past their body in an S-shaped pattern.
So, which is better? How will you beat Michael Phelps? Well, the answer is complicated, apparently. But don’t worry, science is on the case. Researchers at Johns Hopkins University have taken high-resolution videos of the two strokes, and compared their efficiency. After analyzing the results, they’ve decided that the deep catch is better than the scull. Here’s a video explaining why:
But, the story doesn’t end there. Others, like former Olympian Gary Hall Sr, say that drag is by far the most important part of speed. “The speed we can generate is directly proportionate to the power that we generate, but it’s inversely proportionate to the frontal drag that we create during our swimming,” he says in this video.
In the pool, it seems like swimmers pick whichever stroke works best for them and the distance they swim. Michael Phelps uses the sculling method, but he experimented with the deep catch for a few races. A lot of sprint swimmers use deep catch, while longer distance swimmers use the scull method. In the end, Phelps went back to sculling, unhappy with how the deep catch method felt, and perhaps more unhappy with his times using it. He’d still beat you, though, no matter which stroke you’re using.
More at Smithsonian.com: