Lifting the Curtain On Ironman’s Top Cyclist: Part 3

We’ve fawned over Wurf’s numbers on the bike. Now let’s look at this data from the sport that really challenges him: swimming.

There’s no denying it: Cam Wurf is a superstar on the bike. Just look at his times at his recent races—or read the last two installments of this series, where we focused on his bike mechanics and his metabolic cycling numbers.

But Wurf was a pro cyclist before turning to the dark side, er, becoming a triathlete. The other two sports, he’s had to pick up on the fly. And that means they can be more of a struggle.

“My swimming in races is spectacularly inconsistent. I can swim front pack, and I can be last of pack; it’s really quite impressive how much my swim times can fluctuate,” he says, laughing. So for Wurf and Sebastian Weber—co-founder of INSCYD, a software platform that allows coaches to get granular with their athlete’s numbers—bringing data on what he was doing right, and wrong, while swimming just seemed like a smart move.

To calculate aerodynamics in the water, Weber put Wurf into a flume (one of those never-ending pools that spits water at you as you swim in place) and had him freestyle at a variety of intensities. The second an interval was over, they’d slap a V02 max mask over his face, then calculate exactly how hard he was working during the interval by watching his recovery. “It is called reverse extrapolation and is highly published in peer reviewed scientific papers,” Weber explains.

Using the swim/slap/breathe/calculate technique, Weber tested Wurf’s efficiency—from an aerobic standpoint—at a variety of different speeds. They also tested how Wurf’s outfit choices changed his overall aerodynamics (or, uh, aquadynamics). Here’s how his results broke down—and how you can similarly evaluate your own efficiency in the water.

Test One: Energy Demand Versus Speed
The point of this test was to evaluate at what speed Wurf’s body was most efficient. Like the tests we talked about in the last story, this allows Weber and Wurf to work out a pace and a nutrition plan for race day—something to simply stick to and not stray from. Wurf says the numbers he saw were illuminating, and not in a good way. “I guess the interesting thing was to see exactly at what speed I start to work really hard in the swim. Unfortunately for me, it’s way below the pace I’ve been racing at. I’ve got a serious amount of work to do in the water before Hawaii,” he says. Basically, Wurf can swim pretty darn quickly—he’d put all of us non-pros to shame. But he’s burning a lot of energy doing it.

The great thing about a flume is that an outside tester can manipulate its speed, so you know exactly how fast the athlete is going during the test. Still, you don’t need one to test your own efficiency. A pool and a timer and a good coach will work wonders, says Santa Monica, California-based Gerry Rodrigues, coach for Tower 26 and host of the Be Race Ready Podcast. In fact, his favorite way to evaluate swim efficiency is to use video analysis. Just by watching an athlete’s form—both at a variety of paces and as he or she fatigues—Rodrigues, and any good coach really, can help athletes figure out ways to become more efficient. In fact, this is something Weber did with Wurf too. And the result? “It indicated I’m more than capable of swimming a lot faster than I have been so that’s encouraging,” Wurf says.

Test Two: Gauging the Speed of Swimwear
There are lots of products out there that promise free speed, but Weber and Wurf were dubious. So they did a round of testing using the different outfits Wurf could wear on race day in Kona. “I’ve honestly always been a little skeptical about the claims swimskins make,” Weber says. First they put Wurf in a wetsuit. By far, it sped him up. No surprise there.

But things got more interesting when they tested him in his speedo versus his bike and run kit, versus a special swimskin. “The swimskin was actually more efficient,” Weber says, enough to make the extra changing time in T1 worth it. The next best option was his speedo, with his bike and run kit coming in a distant third.

“There was discussion about what he was going to wear, but that’s been settled now,” Weber says.

You can do your own version of this testing in a pool by swimming a time trial and keeping track of the time for each outfit choice. Don’t do the trials all in one day—you’ll wear yourself out and it will skew the results. Or, you can just take Wurf’s results and assume they apply to you too—because they probably do—and maybe even more so. “The advantage of wearing a wetsuit is massive, especially for the 1:20 to 1:40 Ironman swimmer,” says Rodrigues.

The Takeaway
In a few short weeks, Wurf will hit the Pacific Ocean for a day of fun with triathlon’s fastest long-course racers on the Big Island. He says he hasn’t made major tweaks to his swimming form or bike fit just based off these tests, but he’s has gained something else: Confidence. “Most of this testing simply confirmed that we had the correct strategy,” he says. For example, some folks have suggested that Wurf slow his bike split to save his legs for the run. “The reality is I’m not a good runner and my riding speed is actually relative to the riding effort of my rivals,” he says. So it’s not that he’s blowing himself up, it’s simply that he’s that much stronger.

Finally, these tests have let him fine-tune every last aspect of race day, from what he’ll wear to exactly how much he’ll eat. “I’m extremely excited to get to Kona. This data has certainly filled in some key blank spaces we had in our strategy,” he says. What is that strategy? “Go hard from the gun,” he says.