Data science and physics give Olympic swimmers the edge

What do American Olympic swimmers Kate Douglass, Gretchen Walsh and Paige Madden, French gold-medalist Leon Marchand, and Australian Olympian Kyle Chambers have in common? In their training, these five leading swimmers and numerous others have employed (and, in the case of Douglass, personally helped develop) advanced data science and physics techniques to fine-tune their athletic performance.

Many of these top swimmers, who have traditionally relied on their “feel” in the water, now employ accelerometers strapped to their bodies, measuring movements in 3-D up to 512 times per second, thus capturing a “hydrodynamic profile” of their body and swimming technique:

1. American swimmer Kate Douglass (2024 Paris gold medal winner for 200m breaststroke) has published a paper in The Mathematical Intelligencer (see also this Scientific American article) outlining some of the techniques she has helped develop.
2. Australian swimmer Kyle Chalmers employs a tracking device known as “Swim BETTER.”
3. French swimming sensation Leon Marchand, a four-time Olympian (and quadruple 2024 Paris gold medalist), has participated in a government-funded research program, which involves learning his “hydrodynamic profile.”
4. Olympian Paige Madden (2024 Paris silver medal) recalls using plastic wrap to affix a sensor to her back. “It gives us a mental edge knowing that we have access to this information that you can’t see with the naked eye.”

Many of these techniques have been developed under the direction of University of Virginia mathematician Ken Ono, who in mathematical circles is well-known for published research on the Riemann hypothesis and the Rogers–Ramanujan identities. Among other things, Ono was a consultant for the movie “The Man Who Knew Infinity,” about legendary Indian mathematician Srinivasa Ramanujan.

Ono’s approach is to measure and analyze, in great detail, the forces involved as a swimmer performs. For example, after an in-depth analysis of Kate Douglass’s technique, Ono and Douglass concluded that her head position in her underwater breastroke pullout was not optimal. When compared her technique with that of Lilly King, a breaststroke specialist, they concluded that the forward bend of her head was most likely creating extra drag. Mathematical modeling suggested that with this adjustment, Douglass (currently the American-record holder in the 200 breaststroke), could save as much as 0.15 seconds per pullout.

Ono’s interest in swimming stems from a mathematics conference in Norway about 10 years ago, where he learned that mathematicians from the Norwegian School of Sport Sciences had been working with Olympic cross-country skiers, using accelerometers to record their movement patterns. When Ono returned to Virginia, he used some accelerometers that had been designed to track sharks to analyze the swim technique of Andrew Wilson, a math student who was also a competitive swimmer. Wilson later won a gold medal as part of the U.S. medley relay swim team at the Tokyo Olympics.

Ono has now tested approximately 100 top U.S. swimmers, although he works most closely with a group at the University of Virginia. Thomas Heilman, who is youngest American male swimmer since Michael Phelps to qualify for the Olympics, is one of his group. As Ono explains,

“Swimming is the perfect application of mathematics and physics. … We were never designed to swim in water. So to swim quickly in water is a really unique and complicated combination of athletic prowess and attention to detail in terms of physics and mechanics. That’s why I like it.”

Other groups around the world are now employing similar techniques. In France, a research team led by Ricardo Peterson Silveira has analyzed the performance of French swimming sensation Leon Marchand. One test measured the drag while he was pulled through the water in a streamlined position. According to Silveira, Marchand registered the lowest value for this passive drag of any swimmer that Silveira and his team have ever tested — evidently Marchand’s body is custom-designed to be a top swimmer. After some effort with the team, Marchand was able to improve his technique. And clearly these efforts worked: Marchand won four 2024 Paris Olympic gold medals, and set four Olympic records in the process.

For additional details, see this New York Times article, from which some of the above was gleaned, as well as this Atlantic article, this Nature article and this Scientific American article. The Scientific American article, which is co-authored by Kate Douglass, Ken Ono and others, includes some detailed quantitative analysis.