SPORTS: Fingers Key to Speed in the Water

by Karin Zeitvogel

Watch a video of Michael Phelps swimming, and you'll notice that his fingers are slightly spread as he slices through the water.

Phelps swims with forked hands, and a U.S. researcher is urging all swimmers to do the same if they want to go faster.

Swimming with fingers apart can result in a whopping 53% increase in total force says Duke University engineering professor Adrian Bejan. 

In a study published in the June issue of the Journal of Theoretical Biology, Bejan and coauthor Sylvie Lorente of the University of Toulouse in France said that spreading the fingers the right distance apart creates an invisible web between them, which boosts the force of the stroke and increases speed in the water.  The right distance is roughly half the diameter of each finger.

“The finger moves through the water and a sheath of water essentially moves with it, creating a finger that looks thicker than it really is. Think of it like honey stuck to a spoon,” he told Water Citizen in a phone interview.

“A faster swimmer is one who creates a bigger wave above the water.  You need force to lift yourself above the water, and you get that by having greater downward force from your hands,” Bejan concluded.  Phelps spreads his fingers instinctively.

Of course, this is just one of Phelps’s secrets. His hands are said to be the size of dinner plates even without invisible finger webbing.  He is also tall (6'4"), has a two-meter arm span, a long torso, and comparatively short legs.  All these attributes help him move through the water faster than most people.

Bejan based his swimming finger principle on a law he devised in 1996, which says that anything that moves - be it rivers, trucks on highways, swimmers, or runners - does so with morphing configurations that help movement become easier and easier. 

The researcher was inundated with calls and e-mails in the run-up to the London Olympics asking him to predict who would climb to the highest step of the podium at the Games.  He replied that taller people would have the advantage, as would swimmers who spread their fingers in the water, but he was unable to say more.  Now he wonders if human ingenuity will come to the rescue and the next swimming aid will be tiny wedges that fit between a swimmer's fingers to hold them just the right distance apart. 

The results of the fingers study show that adjusting body configuration just a little can bring a “significant  change in force,” Bejan said, wondering if the next swimming aid will be tiny wedges that sit between swimmers’ fingers to hold them just the right distance apart, to help the swimmer go faster.