The Freestyle Square-Off
With the days ticking down until the start of the U.S. Olympic Swimming Trials, a Johns Hopkins University study may settle a long running swimming debate: Which freestyle stroke—the Aussie-perfected deep-catch scoop or the more graceful S-curve sculling method—propels someone forward the fastest?
Ever since the 1950s when legendary swimming coach James “Doc” Counsilman introduced stroke mechanics to the sport, elite swimmers have argued over which arm motion is more likely to propel an aquatic star toward a medal.
“This is a result that is simple but sweet,” says Rajat Mittal, a mechanical engineering professor in the Johns Hopkins Whiting School of Engineering. “The deep catch stroke is more efficient and effective than the sculling stroke.”
But arriving at the answer was no easy matter.
Mittal, who made a name for himself in swimming circles in 2008 after analyzing the butterfly stroke of Michael Phelps, began his analysis with high-precision laser scans and underwater videos of two elite swimmers.
His team then used animation software and computer simulations to create three-dimensional models of the arm moving through the water. They were able to calculate the lift, drag, and thrust for each style.
The results: Lift force provided most of the thrust in both strokes. But the deep-catch style produced almost 50% more thrust than the sculling style.
The findings were featured in the doctoral thesis of Alfred von Loebbecke, who studied under Mittal. The team will publish their work in 2012 in the Journal of Biomechanical Engineering.