“Take your marks.” The swimmers bend down on their blocks, ready. The buzzer sounds. Eight of the best male freestyle swimmers in the United States dive into the pool. In a little under 2 minutes the200-meter Olympic swimming trial semifinal is over, and two swimmers are headed to the 2012 London Olympics.
Those swimmers are Michael Phelps and Ryan Lochte, two men with arguably the best freestyle form in the world. But why did Lochte beat out Phelps in this particular heat? New research being published in the Journal of Biomechanical Engineering may not answer that question, but it does lend a bit of scientific credence to their strokes. The short version: It’s all in the arms.
Rajat Mittal is a mechanical engineer at Johns Hopkins University and lead researcher on a project to study the fastest swimming technique. Mittal says swimmers used two different kinds of arm strokes when training for and competing in freestyle events.
One, deep catch, is about as simple as swimming gets. When your arm enters the water, you try to pull it straight back exerting as much force as possible. It’s a difficult stroke to master. Even the highest-level athletes need to change up their strokes on long-distance swims because of the sheer strength it takes to propel through the water with a straight arm.
The other stroke, sculling, became popular in the 1960s when a prominent coach encouraged his athletes to move their arms like propellers underwater. Instead of trying to move yourself through the water using only your shoulders, the sculling stroke allows a swimmer’s elbows to jut out slightly, making it easier for the hands to wave through the water like a propeller creating less resistance.
Mittal’s research focused on one seemingly simple question: Scientifically, which stroke should propel swimmers the fastest? The team started with video; USA Swimming provided Mittal and his team with underwater tapes of world-class swimmers using both the deep catch and sculling strokes while swimming laps. Mittal also modeled the arms of a few swimmers to use in computer animations of the strokes, a time-consuming process.
“It took thousands of hours for each of the simulations,” Mittal says. “We had a computer cranking away for 25 or 30 days for just one result. We were trying to do comparative analysis, and analysis takes even more time and effort than the simulations.”
After months of effort, Mittal and his team got their results. From a purely scientific perspective, deep catch is a far more efficient stroke. Sculling is about 20 percent less efficient than deep catch—a big number when the difference between first and last place is sometimes less than a second. The thrust created by deep catch is unmatched, Mittal says. “I think the results are somewhat controversial, but the notion that the deep catch is more effective might not be news to coaches.”
Mittal’s speculation seems to be spot on. Marshall Goldman, a swim coach for the Weymouth Club Waves swim team outside of Boston, who’s rooting for some of his swimmers during Olympic trials this week, says these results only confirm what many coaches have known for years.
“From a swim coach’s perspective, this study is an obvious thing,” Goldman says. “For them to compare what they did in the 1960s to what we know about swimming these days is dumb. There have been so many different variations.”
Today, most coaches want their swimmers to strive for a deeper catch on every stroke. Coaches teach three different ways of swimming freestyle: shoulder driven, core driven and hip driven. Most athletes use a combination of all three, but it depends on the event. A shoulder driven deep catch stroke can’t be sustained for longer than a few hundred meters, but a hip driven hybrid of deep catch and sculling allows the swimmer to save his or her strength and finish an endurance race strong. What the research doesn’t take into account, Goldman says, is that the strain put on a swimmer’s shoulders by deep catch could be career shortening.
Many coaches take those concerns into account when training younger swimmers. Jim Rumbaugh, the head coach at Pilot Aquatic Club in Knoxville, Tenn., says that age plays a major role in the strokes he teaches his athletes. “It’s different when you start talking about [swimmers younger than 15],” Rumbaugh says. “We typically have all of those kids using the ‘S’ pattern [sculling] stroke. It’s easier on the joints, maintains balance, and saves the shoulders.”
Mittal concedes that there’s a lot more research to be done. Because this kind of computer imaging takes so long, they were only able to model and analyze the movements of one computer-simulated arm. “There are so many aspects of what makes a swimmer a swimmer that we couldn’t model them all,” Mittal says.
Ultimately, Mittal hopes that maybe these results will insert a little science into the way a coach picks a training method. “[This research] is not just about which one [stroke] is better than the other, but it tries to explain why one is better than the other. We used to use a coach’s intuition over data, and now this will change. We have the data now.”