Should you keep your fingers closed or relax your hand while swimming to allow them to separate a bit? Many non-TI instructors and coaches say—and most swimmers seem to believe—that you achieve the best grip with fingers closed because that makes the hand more paddle-like.
In contrast, TI has long taught swimmers to avoid swimming with a stiffened hand and TI coaches watch carefully for closed fingers, even on recovery, as I demonstrate here.
So who is right, TI or the traditionalists?
According to this article in the journal Science, a study presented last month at the 69th Annual Meeting of the American Society of Fluid Dynamics suggested that freestyle swimmers are most efficient when they swim with fingers slightly apart, as this swimmer shows. (She also forms a beautiful line from right hand to right toes.)
Physicists using 3D-printed plastic hand and arm models in a wind tunnel found that the model with its fingers spread 10° created the most drag because the slight opening between the fingers still obstructed air flow.
Though the subject under study was swimming, they performed this experiment in a wind tunnel rather than a pool to avoid the influence of surface waves. Because fluid dynamics follows the same principles as aero dynamics, they’d have reached the same conclusion in water.
The researchers calculated that a 10-degree finger spread could boost a swimmer’s speed by 2.5% compared with swimming with fingers pressed together. That translates into several tenths of a second over a 50-meter freestyle race, an enormous margin considering that the 2016 Summer Olympics 50-meter women’s freestyle race was won by 0.02.
A triathlete who completes 1500 meters in open water in 40 minutes could swim a minute faster, simply by relaxing the hand.
But the benefits of a relaxed hand can be even greater. Our primary reason for teaching a relaxed hand is that a common hydrodynamic effect of stiffening the hand and closing the fingers is that it leads to scooping the hand upward as you extend forward. This drops the legs, significantly increasing drag.
In contrast, when you relax your hand, it can cause the hand to naturally arc downward, lifting the legs and reducing drag, leading to far greater increases in speed.
I’ve been convinced for a long time that a relaxed hand can make you a significantly faster swimmer by improving balance and reducing drag. At the same time I was also fairly certain that it also makes the stroke more propulsive.
I arrived at this conclusion by performing a simple experiment: Just put the hand in water (at the pool or in a deep sink) and move it back and forth. First with fingers together, then allowing them to separate naturally (i.e. don’t splay them; just don’t squeeze together). Compare the resistance you feel with closed and separated fingers.
But it’s nice to have our ideas bolstered by physicists.
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