Chasing Sub-7: Lars Bottelier Talks Open Water Swim Pacing for Kristian Blummenfelt's Ironman Record
It’s been just over a year since Kristian Blummenfelt shattered his record-breaking goal of completing an Ironman in under seven hours.
With the support of a team of professional race pacers, including pro open water swimmer Lars Bottelier—who just surpassed the milestone of swimming one million meters with his FORM goggles—Blummenfelt was able to cross the finish line in an unprecedented 6 hours, 44 minutes, and 25 seconds.
And to celebrate the anniversary of this incredible achievement, we spoke with Lars about the experience of being on Kristian’s team and what was involved with helping an incredible athlete to swim even faster in open water.
FORM: How would you describe the experience of working with Kristian Blummenfelt to achieve his Sub-7?
Lars Bottelier: It was quite a journey! We both had busy schedules, so it was hard to find time to train together. We tried once in England, once again in Holland, and we even tried to catch up two weeks before the race.
In the end, we didn’t have much time. We ended up having only one week to prepare for the race.
Once we started training, the pacing wasn’t the hard part. The challenge was figuring out how to work together in the water in the most effective way.
During training, Kristian’s team is next-level with research and preparation. They calculate everything to the tiniest detail and felt really confident that he could finish in under seven hours. So, everyone was going crazy before the race. The atmosphere was awesome.
How did you approach the process of helping Kristian—who’s already a pro triathlete—to become even faster in the water?
Along with Jan Hercog, who was also helping Kristian with his pacing, we did some open water swimming sessions together in a lake using our FORM goggles to help us measure our pace. Our goal was to figure out what the fastest swim formation would be and to decide whether it was better to have one pacer or two.
In order to figure this out, we tried different formations for certain intervals.
For example, we tested out having one pacer in front of Kristian and one behind him, and we’d try to swim the same speed and measure how fast we were on that interval. We also tried having Kristian right on our hips.
We tried literally anything you can think of.
Kristian’s typical open water swim pace is around one minute and 15 seconds per 100 meters. But, during our training sessions, we already had a feeling that we could swim 1:13/100m at the minimum—and maybe even as fast as 1:12/100m or 1:11/100m.
In the end, we realized that Kristian was fastest when he was swimming at our feet—about 2 or 3 seconds per 100 meters faster than normal. He’s a great swimmer, but he benefited a lot from the drag.
And being right at our feet allowed him to communicate with us about whether we were going too fast or too slow.
We had a system where Kristian was able to squeeze my left foot if I needed to go faster, and he’d squeeze my right foot if he needed me to swim slower.
In the end, Kristian was allowed to have 10 pacers for his Sub-7 attempt. So, he ended up going with eight cyclists, one runner, and myself as the one swim pacer—it was more efficient to just have one person in the water with him, and the cycling leg is where you’re able to make up the most time in the race.
How was the experience of being in the water with Kristian on race day?
It was an amazing day during the race.
On the day itself, we had a few different means of tracking our open water swim pace.
First, we had our FORM Goggles connected with our Garmin watches that helped us stay on pace as we were swimming without having to break our stride or look up from the water.
We also had a supporter on a boat with three different flags: red indicated we were slow, green was good, and blue was right on our target pace.
The race itself was actually more challenging than expected. In the beginning, it was all good, but as we kept going, our FORM goggles told us we were slower than our target open water swim pace, and at every buoy, we’d get a sign that we needed to speed up.
We were aiming for 1:13/100m but we wound up swimming closer to 1:16 or 1:18/100m.
It turned out every athlete in the race was moving slowly and it all had to do with a stream that was coming into the lake, and the current from the stream was slowing everyone down.
Kristian ended up being about five minutes off of our expected time.
But, in the end, we still did a great job. If you watch the Sub-7 attempt, you can tell we were really working together as one. Some of the other athletes went with two pacers and it just wasn’t working very well.
Our tactic was straightforward: work as a team in the water, find a good balance between speed and drag, and make sure Kristian was able to get out of the water as quickly as possible.
It’s amazing what he achieved—not only did he meet his goal, he finished in well under seven hours.
It was really nice to be part of Kristian’s team. In the end, Kristian had to deliver the race. But everyone involved really made sure we were part of the team. It was an honor to take part in that and to help a great athlete to become a little bit faster and reach his ultimate goal.
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