Endurance: Exploring the Limits and Potential

Researching the limits of an athlete's performance and a scientist's capacity to measure it.
By redbull.com

Red Bull Project Endurance was a five-day-long athlete-science program that put together -- in one science lab -- 11 scientists from around the world and six world-class athletes, including endurance mountain biker Rebecca Rusch, ultra-runners Karl Metlzer and Dakota Jones, tri-athlete Kirsten Sweetland, cyclocross competitor Tim Johnson, and off-road motocross racer Kendall Norman.

The scientists, working closely with each athlete, were tasked to answer the following questions about the science of endurance and the limitations of an athlete:

  • How much further can endurance go?
  • Can recovery be improved or sped up?
  • What limits endurance, both physiologically and mentally?
  • How can we make these athletes perform at the next level?

Watch the clip above to see the scientists and athletes in action.

Team Science

The Red Bull High Performance Mobile Lab was set inside one of the hottest places in the world, Death Valley -- the perfect place to test the athlete physically and mentally. The team was led by professor of sports medicine at Pepperdine University Holden MacRae, who also serves as Red Bull’s chief physiologist, along with physiologist Lesli Shooter and high performance manager Per Lundstam.

With wrappers from gauze pads, alcohol swabs and electrodes littering the floor, the lab felt like a combination of a graduate physiology lab, a NASCAR pit stop, and the first-aid tent at a 10K race.

“A good thing,” said Tim Johnson. “In the field is where the athlete can really learn. You’re not going to get a university lab to look like this.”

Behind the Gear

Athletes wore Myonwear shorts, impregnated with sensors that measure minute changes in electrical activity in muscles, recording the firing of hams, quads, glutes. They wore Dexcom glucose meters, which slip a wire the diameter of a human hair into a fatty spot and transmit blood glucose information full time. They wore FirstBeat sensors when they slept, which captured information about heart rate and movement, creating a nightly sleep quality record.

When they saddled up to ride, scientists swarmed them, taping on electrodes measuring their hearts and brains, sticking tubes in their mouths to quantify their breath and even capturing their sweat to study electrolyte levels.

“The future of training is to stop cookbook recipes of generalized regimens," said Frank Bour, whose PhysioFlow impedance cardiography device generates electrical signals that create an electrical representation of heart function, again giving athletes a level of data that yields performance insights still on the frontier of sports science. Because one source of cardiac data is never enough, they wore Equivital monitors that they simply pulled on over their heads like jerseys.

And they wore NIRS -- Near InfraRed Spectrometry -- devices, which measure tissue blood saturation with sonar. The device issues signals, which reflect back differently according to whether hemoglobin in blood and tissue is oxygenated or not, giving scientists a real-time measure of what’s happening in an athlete’s muscles rather than taking a lactate measure and deducing muscle status from that. “NIRS is the reporter in the arena at the hockey game,” said scientist Juerg Feldmann. “Lactate is the report from yesterday.” As Bour described it, “It’s like a mission to Mars. Only the lab is not quiet.”

Science fiction wasn’t the half of it. During testing physiologists took blood samples and shouted commands, encouraging athletes to work through VO2 max tests or delivering data points to scientists peering at nearby computers.

The athletes bunked together in group houses, starting each morning with blood data, downloads of their sleep equipment, and self-reports on how they felt; each day ended with group meals and discussions of the day’s tests, with scientists explaining what they were measuring and athletes describing how it felt and asking for clarification.

“I am my toughest competitor,” said Rebecca Rusch, eyeing a skin of wires and tubes waiting to be strapped, taped, and inserted. “The question is, does this help you defeat that competitor?” The Mobile Lab work enabled the scientists to stand side-by-side, watching monitors of athletes’ performance and looking for the connections that will fuel future research.

They could see muscle recruitment increase on the EMG screen and look across the corridor to the screen showing NIRS data and see the blood flow changes that might be causing the extra effort. “It’s good to see what you need to work on,” said triathlete Kirsten Sweetland. “It will be great to get the numbers.”

Testing the Mind

One of Lundstam’s main interests during the camp was testing the role of the mind in controlling performance. “The Day of Deception” began with a time trial climb in which Lundstam did not tell the athletes the length of the ride or allow them to use their usual bike sensors, requiring only that they try to perform at levels determined during the previous days’ testing. The machines gathered their usual data, and MacRae asked each athlete when they finished the ride -- it turned out to be 6.1 miles and 2,000 vertical feet -- for self reports on separate physical and mental effort scales.

It’s like a mission to Mars. Only the lab is not quiet.

But that was only deception number one. When the athletes arrived back at the Mobile Lab, they were informed that after an hour’s rest they would have to do the test again. “I am issuing a disclaimer,” said ultra runner Karl Meltzer. “I’m not doing this a third time.”

“The main intention is to create discussion among the scientists, like we’re doing here,” said Lundstam. “It’s education for everybody. It’s a conference but it’s a practical conference. So if we can create stimulation for discussion, good. And if the athlete can learn something of use for him, that’s a good framework. Or maybe the camp was even simpler. “How often,” asked Frank Bour, “do you get a chance to play like this?”

The research and the work continues, and not all the questions can be fully answered today -- but a project like this is a step forward in researching the limits of an athlete's performance.

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