Science settles some decades-old debates about the best way to swim

As we go into the final two days of Olympic swimming — the men's open water 10k is today –- scientists are already telling swimmers how to improve their stroke for the next Olympic Games. Two different studies are reconsidering the biomechanics of swimmers' pulls, a hotly debated topic among coaches and athletes.

Top image: Jim Bahn/Flickr

The Duke study (abstract here) is the more surprising of the two — taking on the longstanding consensus about finger positioning. Keeping fingers touching so they form a "spoon" rather than a "fork" is a skill swimmers learn at their first swim lesson. Obsessive watchers of the Olympics may even have noticed that some swimmers spread their fingers in the air, closing them before they enter the water. This can help prevent wrist and finger cramps during races.

But Professor Adrian Bejan's study shows that keeping fingers a tiny distance apart (1/5 to 2/5 their diameter) can actually increase a swimmer's force. Rather than allowing water to slip between the fingers, this spacing uses the water's natural adhesion to give swimmers "webbed" hands. However, it's unclear if even Olympic caliber athletes will be able to maintain such precision without the help of spacers or gloves. Bejan he may have found one of the many places where the human body's mechanical capabilities outstrip actual human ability.

The Johns Hopkins study, by long time swimming researcher Professor Rajat Mittal, may finally put to rest the greatest debate in swimming since the sport's modern inception (either H. Jamison's addition of side breathing to the front crawl in 1906 or the 1956 addition of butterfly as a separate stroke, depending on your point of view).

The "scull" vs. "deep catch" freestyle pull debate seems to have been settled, on the side of the deep pull. In the scull, the hand enters the water above the head, then pulls diagonally to the opposite shoulder then back toward the hip to exit the water. The hand is never more than a few inches below the body, which was believed to create lift, which is a racing swimmer's best friend. In the deep catch, the hand entrance is farther from the head and uses the whole length of the arm to pull down toward the hip. Swimmers tend to choose one or the other of these pulls based on which they learned or which just feels faster or which event they are swimming. Sprinters tend to use the deep catch pull because it takes less time, while distance indoor swimmers tend to use the scull because it uses less energy. Mittal's study shows that the deep catch pull generates 50% more thrust than the scull pull.

With most elite swimmers performing within hundredths of a second of each other, these studies are bound to make waves (sorry) in the sport.