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Heart Rate Monitors For Triathletes: Data at the Ironman


Heart Rate Monitors For Triathletes: Data at the Ironman

This past summer, triathlete and coach Jen Rulon told us the story of how she accomplished her life-long goal–to qualify for the Ironman World Championship in Kona, Hawaii. She described the countless hours of hard work she put in, and the instrumental role WHOOP played in her training.

On October 14, Jen’s dream became a reality. She completed the Ironman (2.4 miles swimming, 112 biking and 26.2 running) in 12 hours, 20 minutes and 49 seconds. “At first I was a bit disappointed with my time,” she said. “I was hoping for 11:30 and was 50 minutes off that pace. But then I thought ‘Wait a minute, I just finished the Ironman World Championship. I can’t be disappointed.’”

It was only eight weeks earlier that Jen had punched her ticket to Kona, qualifying for the World Championship on August 20, at Ironman Mont-Tremblant in Quebec, Canada. With less that two months to prepare her body for another 140.6 mile race, Jen knew she’d have to stray from her usual training plan:

“The first week after qualifying I did pretty much nothing. The second week I gradually started to get back into things, but my priority was really just about getting to Hawaii healthy and uninjured. To turn around that quickly was really tough on my 45-year-old body. Physically, I was already at the level that I needed to be at.”

Jen did several long swims prior to Kona, noting “you can recover from them quickly and they’re not too hard on the body.” However, she cut way back on her running, the most strenuous of the three triathlon events. “I also didn’t do any strength training prior to Kona, which felt weird,” Jen said.

In an effort to familiarize herself with the course, Jen downloaded a program to simulate riding a portion of the exact Kona route on a stationary bike. “It’s funny though, I should’ve figured out a way to include the elements,” she added. “Maybe a giant gym fan and a heat lamp to reflect the weather conditions on the mountain.”

Over the three months prior to her qualifying race in August, Jen averaged a daily Strain of 16.7. However, during the limited time she had to get ready for Kona, Jen cut her training load down to an average Day Strain of 13.5. Pictured below are her Day Strains from mid-April through October 13, the day before the World Championship. You can see a clear drop off in workload following her qualifying Ironman on August 20:

Jen flew to Hawaii from her home in San Antonio, TX on Tuesday, October 10, four days before the race. The half-day of travel and five-hour time change undoubtedly took their toll on her body. “I also did a lot of stuff when I got there,” she said. “It was a constant go, go, go. Prior to Mont-Tremblant, I was a lot better at staying off my feet than I was in Hawaii. But I mean, it was Hawaii and I was at the Super Bowl of triathlons. Looking back, I probably should’ve rested more in the few days before.”

Despite relatively low Strains leading up to the race, Jen’s Recoveries stayed in the yellow:

On the morning of Saturday, October 14, the Ironman World Championship began for Jen when she entered the water at 7:20 am. “I was very nervous, at one point just before I wanted to throw up,” she said. As she started her swim, Jen’s heart rate rose to 170 beats per minute, its highest point of the entire day (see the full graph of her HR data below). After a few minutes, it leveled off around 135 bpm. “Once I got over the nerves, the swim was magical,” Jen recalled. “There was a moment when a school of spinner dolphins passed by and I stopped for a second to take it all in.”

Jen finished her swim and got on the bike at 8:49 am. Her heart rate spiked once again, this time hitting 169. She credited an adrenaline rush from moving on to the second stage of the race. A short time later, it steadied in the 140 range.

“There was a difficult stretch about 45 miles in where we had to go up a volcano into the wind,” Jen said (you can see a sustained bump in her heart rate roughly one-third to one-half of the way through her ride). “But, coming back I was going downhill with the wind behind me and pedaling was optional. Unfortunately, for the rest of the race my nutrition was off. When I grabbed my bottles at the midway point they were warm, so I had to go with the on-course nutrition instead. It was fine, but I didn’t consume quite enough calories heading into my run.”

Her run began just after 3 pm, and Jen’s heart rate spiked for a third time. It then hovered around 150 for the remainder of the race. “I felt great for the first half marathon, but then I slowed down,” she explained. “The heat and insufficient calorie intake started to get to me. I’d been in the sun all day with no cloud cover.”

Jen’s early mile splits were in the 8-9 minute range, but over the second half of the run they stretched out to closer to 11. “When I got to the last mile, I picked it up again and started pushing it,” she said (you can see one final spike in her heart rate above). “As I came down the stretch on Ali’i Drive, I started bawling.”

For the 12 hours and 21 minutes Jen was on the course, her heart rate never dipped below 116. Her Day Strain registered a 20.7, and it took two full days for her Recovery to begin bouncing back (17% on Sunday, 16% Monday, then finally 57% Tuesday).

What did it feel like to complete the Ironman World Championship?

“It’s so hard to describe,” Jen said. “Very surreal, it was almost an out of body experience. I was so emotional, it was something I’d been dreaming of doing since 1989. Hearing the voice of Ironman legend Mike Riley say ‘Jennifer Rulon. You. Are. An. Ironman.’ was overwhelming. I’d heard those words 12 other times, but this time, at this Ironman… It makes me tear up just thinking about it.”

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