Math Helps U.S. Olympians Trim Swim Times

August 12, 2008

Milliseconds can make the difference between triumph and defeat at the Olympics. So, Timothy Wei of the Rensselaer Polytechnic Institute developed flow measurement techniques to help U.S. swimmers shave seconds off their lap times, perhaps enough to capture medals and set world records in Beijing this August.

Wei and his coworkers took flow measurements of swimmers and obtained more detailed information than ever before about how swimmers interact with water. "These techniques have contributed to some very significant improvements in the lap times of Olympic swimmers," Wei said.

The key, Wei said, is understanding how water moves. Wei's flow diagnostic technology involved modifying and combining force measurement tools developed for aerospace research with a video-based flow measurement technique known as Digital Particle Image Velocimetry. The system incorporates sophisticated mathematics with stop-motion video technology that identifies key vortices, pinpoints water movements, and computes how much force a swimmer exerts.

"You have to know the flow," Wei said. "To see how a swimmer's motion affects the flow, you need to know how much force the swimmer is producing, and how that force impacts the water."

After conducting tests late last year, U.S. Olympic coaches and swimmers incorporated what they learned into their training regimes. "This project moved the swimming world beyond the observational into scientific fact," said Sean Hutchison, a coach for USA Swimming. "The knowledge gained gave me the foundation for which every technical stroke change in preparation for the Beijing Olympics was based."

Wei predicted that the U.S. team would make a strong showing in swimming at the Olympics in Beijing. And he's already thinking of ways to make his technology more effective when training swimmers for the 2012 London Olympics. "It's been a wonderful, unique experience," Wei said. "It's everyone's dream to make a difference, and I'm excited to keep helping the team."

A research video showing the water flow around 2008 Olympian Megan Jendrick doing the breast stroke can be seen at http://www.rpi.edu/news/video/wei/videos.html.

Source: Rensselaer Polytechnic Institute, Aug. 8, 2008.