Midway through swimming a lightning lap at Greason Pool, the Olympian was passed by a member of the Bowdoin Women's Swim Team speeding one lane over.
"We were towing someone else next to him and he couldn't see the string," chuckles Burnham, "so it looked like he was being passed by a relative novice."
What Crocker couldn't see was a filament of 50-lb. fishing line hooked by a simple harness to the swimmer's torso underwater. At the other end, the line was attached to a small motor and drum housed at pool's edge. With a command from Burnham's laptop computer, the line retracted, pulling the swimmer past Crocker at a whopping three meters-per-second.
"Most of the swimmers scream the first time they are hooked up on it," says Burnham of his towing rig. "It's such a feeling of fun going world-record speeds or faster." swimmers
Burnham's apparatus for "assisted" swimming isn't merely an aquatic joyride. It is the latest in a series of biomechanical innovations in swimming that Burnham and his independent research partner Mark Glauth are pioneering at Bowdoin — assisted by volunteers from the swim team, Bowdoin professors, and even some staff members.
They are advancements that could revolutionize the ways swimmers of all abilities measure and improve their performance. And at this point at least, Burnham and Glauth are lengths ahead of the competition.
Tethered swimming has long been a part of resistance training for swimmers, explains Burnham, who joined Bowdoin in 2000 as only the third swimming and diving coach in the College's history. Harness
Most commonly, swimmers have worked it in reverse: building strength and endurance by swimming against stretch chords attached to various pulleys — some suspended over the pool, others underwater.
In recent years, however, some training programs — including the U.S. Olympic Swim Team — have experimented with towed swimming as a means of creating a "downhill" training course for swimmers.
In speed-training sports, explains Burnham, "the body needs to learn quickness more than force. You put the athlete into a situation where things are happening fast, where you're living on that edge and just have to use your instincts. Your brain will react and you quickly learn as you go.
"That's easy in skiing, where you can always find a steeper mountain, but in swimming there is no downhill. You have to propel as well as reduce resistance. Gravity won't take you to the wall." Making a Splash
Biology major Megan McLean ’07 admits she was skeptical when Burnham first suggested she strap on a belt and try towing. After all, she already had several College records and NCAA All-American Honors under her own belt .
“It was really weird at first,” says McLean, who has since performed hundreds of towed laps. “You feel a big difference in the way the water flows around you.”
It is that very difference that has helped McLean shave six seconds off her 200-freestyle and swim her best year ever, she says.
“When you go at high speeds,” she explains, “any small imperfections in your stroke you notice more. You’ll feel more resistance in the water. For me, the head position was a huge thing I was able to change. Also, tucking my hips in, which helps with the rotation of the stroke. Numerous repeats with towing made it a habit for me to change some things.”
A lifelong competitive swimmer, McLean says Burnham is “the best coach I’ve ever had. He has a technique-based program that if you engage yourself in, can really help you improve – whether you’re doing towing or not.”
While the idea behind Burnham's towing system is simple — motor, pulley, line — its automated mechanics and finely calibrated software are highly refined. They let him vary the force and speed of the towline almost infinitely. "We can program it to go five or 10 percent faster, so they can feel what the next step feels like," says Burnham, "or experience something really fast."
But there is another element that elevates Burnham's apparatus from mere towing machine to high-performance measuring instrument. He is actually collecting data from the swimmer as she makes her way down the lane.
Based on minute calculations of tension on the towline, Burnham's computer is recording vast amounts of data about the swimmer's position in the lane — her distance from wall to wall. That lets him extrapolate average speeds between thousands of positions, or benchmarks, in any given lap. The computer also calculates force by measuring how hard the machine has to "work" to pull her through the water, based on her body mass.
These combined measures show up on his laptop computer in wave patterns, much like an audio editing screen. The information is gathered from the swimmer every few milliseconds and is being relayed at half the speed of light.
Burnham has lots of recorded data on Bowdoin swimmers — both on and off the teams (some Bowdoin staff and faculty members have volunteered for trials) — which he can use to evaluate individual progress or analyze differences between swimmers.
"Look at this," Burnham says, comparing the recorded output on two swim lengths just completed by Megan McLean '07 during a lunchtime swim. She holds five individual school records for butterfly and freestyle and earned NCAA All-American Honors in 2005. She also has participated in hundreds of training runs since Burnham installed the equipment in April 2006.
"This one length shows her freestyle strokes. The peaks are moments of high velocity, or speed," he says, leaning in for a closer inspection. "Hmmm. It's funny what's happening. There is more variation in the beginning, then the wave tightens up as she goes. As I analyze it you can see there is a higher velocity average in here, toward the middle of her lap."
McLean bobs at the edge of the pool like seal, awaiting Burnham's feedback. At pool's edge Mclean has participated in hundreds of training runs since Burnham installed the equipment in April 2006.
"This is good, real good," he says, wandering over. "Just remember to keep the long neck, right? And the abdominals should be tight. You tend to arch a little bit. Think more about cutting through the water. Okay, go."
She blips underwater and emerges in an all-out butterfly stroke. A small wake fans out behind her as she passes swimmers in the next lane; they seem almost geriatric by comparison.
"There are theories about what makes swimmers go faster, but there is so little measurement in this sport," says Burnham. "Without this machine, you'd be looking at her stroke and could time a length or two at a time, that's it. You wouldn't really know what went into those laps.
"Now we can really analyze her strokes and her streamlining — that moment when she comes from underwater to the surface. She races in about a week, so we're just getting ready for that."
In a way, the sport itself urges Burnham to approach his coaching like a physicist (in fact, he says, he has consulted Bowdoin physics professors Dale Syphers and Mark Battle in developing his equipment). Because his athletes operate in water, he must take into consideration basic principles of fluid dynamics — whether doing traditional coaching or developing his biomechanical aids.
It's hardly an exact science he says, because people are not exact.
"If you were building a destroyer at BIW, you'd have a good idea how much fuel it would take to send the ship through either calm or rough water at varying knots," he says. "They've tested it and can calculate it fairly well because the hull of the ship doesn't change.
"But humans are not that simple," he adds. "We move, we bend, we twist. The body is squishy. And beyond that even, every swimmer is different. They have a different size, shape, they have different mechanics. What we're trying to do is measure very directly what's going on with a particular body going through the water."
Burnham hopes his Bowdoin swimmers will take the project to the next level by incorporating their particular results it into their academic work at the College. Women swimmers “I thought the men would latch onto this, but the women have been more interested," notes Burnham, poolside with team members (l to r) Suzanne Plant '07, Mclean, and Jessica Horstkotte '08. "That's okay. Some don’t enjoy the pool investigator process, some do.”
"In the end, we want these to be student-driven projects," says Burnham. "We hope to have kids on the team who could take their data files and start to analyze them in math and statistics classes. Then they can they can intentionally improve their swimming because they can measure this or that aspect of their strokes underwater. They will have some tools to really learn things."
Satisfied with the basic operation of the tether, Burnham and his research partner are looking ahead to the next step. This spring, Glauth will come to Bowdoin to help Burnham install underwater cameras in Greason Pool that will be time-synched to the tether.
With the addition of video, the swimmer's speed changes can be analyzed as they occur in real time with each stroke, allowing Burnham to isolate aspects of body position and stroke that affect velocity.
As they design the camera software further, he says, "You'll be able to define different objects underwater — a swimmer's head, their hips, their arm. You can go back to the swimmer and say, 'This is graph of your speed when you swim, this is where your hips drop; work on solving that puzzle and you should see an increase of speed.' You'll also be able to capture the speed of a few swimmers at once, for comparison."
The depth of information available through the cameras may ultimately make the linear measurements of the tether look insignificant, acknowledges Burnham.
"The cameras could actually make the towing machine look crude," he says, offering some final pointers to McLean gleaned from good, old-fashioned eyeballing. "But there may always be a benefit to pulling a swimmer through the water a little faster, giving them a boost to let them know what it's like.
"All of these devices only enhance coaching," he adds. "This is just another tool to work with. The sky's the limit in terms of what you can devise to help other people improve. You can work just as inventively on the mental aspect, or the physical, or physics and physiology, motivation. There really is so much to it that's interesting. You can go in any direction as a coach."