Neilson has been using WHOOP for years. When the same thing had happened in the past, he had often gotten sick.

And his partner Frances had been feeling a little bit off the day before. She decided to go get a COVID test. As a precaution, Neilson decided to go get one too. It came back positive. Neilson had COVID-19. Three days later, the headaches started. Neilson lost his sense of taste and smell and started coughing. He was short of breath. Thankfully, his case of COVID was relatively mild. Within a week, he was on the mend. But he might have put himself further behind had he gone out and trained hard that first morning or during the days before he started to feel ill.

That is the power of WHOOP. It can listen to your body in ways that you can’t, so that you can make more informed decisions about your health, lifestyle, and training. That is not to say that you don’t need to listen to your body, too.

“Using WHOOP takes some intuition as an athlete,” Neilson says. “In stage races, my recovery scores might be pretty low, but you just have to keep pushing and can still have great days. For the most part, I use WHOOP to track trends.”

One big trend that Neilson has noticed during his years of using WHOOP is the importance of sleep. One bad night might not make a decisive difference to his performance, but a few in a row certainly will. That’s especially important during a three-week race like the Tour de France.

“Basically, what I have learned is that during a race, especially in a grand tour, the most important thing is just getting the maximum amount of time asleep possible,” Neilson says. “The more time you are sleeping, the more time you are giving your body to heal itself.”

Examining long-term trends in his WHOOP data has also encouraged Neilson to change his eating patterns. In the past, he would often eat light meals during the day and have a big dinner at night, but he noticed that those habits hindered his recovery. He has found that it is much better for him to eat more right before and right after his training.

“If I have a light dinner, my values are actually a bit better in the morning,” he says. “So, I have started to eat heavier breakfasts and lunches, and at dinner, I don’t overdo it. There are normal meals, and then there are endurance-athlete meals. Breakfast and lunch are my endurance-athlete meals, and then dinner is my meal to be a normal person. That has actually helped my values, because my body is not working so much through the night to digest this massive amount of food that I have just given it.”

Each morning, Neilson will check his resting heart-rate, heart-rate variability, and respiratory rate. Blips in his heart-rate data can often be explained by circumstances.

“I can adapt on the fly if any metrics are really out of whack,” he says, “but a lot of times a single day can have a pretty big swing—maybe you wake up at a different time or you just didn’t sleep well one night. Most of the time, if it is just one day that it is off, you can just keep pushing and not really think too much of it, but if you have a week of really high resting heart rate and really low heart-rate variability, then it tends to point to a sign of a deep fatigue going on.”

That’s when Neilson would back off on his training.

A spike in his respiratory rate usually signals that his body is fighting something off though, as he experienced with COVID. His rate of breathing was elevated for about a week, while his body contended with the virus. His resting heart rate was about 10 beats higher than normal too, while his heart-rate variability remained depressed. As those numbers returned towards their expected values, Neilson regained the confidence he needed to resume light training, even though he had a lingering cough for another week and a half.

“I had to still go through the process of getting a heart-check done, and getting a blood test, but once all of that stuff came back clear, I knew that every now and then I would cough, but it wasn’t like it was really embedded in my lungs anymore,” he says.

Before long, Neilson was back to full health and focused on the training block he used to prepare for the Tour de France and his win at the Clásica de San Sebastián.

On the bike, he could focus on the performance metrics that he gets from his Power2max powermeter, but he has learned that he needs to combine that information with biometric data from his WHOOP to make smarter decisions and optimise his health and his performance.

That is an ongoing process.

When Neilson got sick after Stage 3 of Paris-Nice last week, he turned again to his real-time health insights from WHOOP. That night, he slept poorly, his respiratory rate went up, and he started coughing. When he checked in the morning, his resting heart rate was up and his heart-rate variability was down. He took a COVID test, which came back negative.

Stage four was a 13.4-km time trial, which would not put too much strain on his body. After consulting with the team doctor, he decided to ride it, but go easy, to buy time and see if his condition might improve. It got worse. The evening after the TT, Neilson started hacking and developed a fever. In the morning, his temperature was over 38°C. His respiratory rate was 18 breaths per minute when 15 breaths per minute is his normal. Neilson and the team doctors agreed he had to go home. His recovery score was just three percent.

Back in Nice, he has since watched his WHOOP numbers return to normal.

“I’ve seen a steady improvement from that second day when I had the fever,” he says. “By Sunday, I was feeling pretty good again. All of my WHOOP numbers were excellent, but I still took the day off to make sure that I would back that up with another good day. On Monday, I woke up with another great improvement on WHOOP, and my energy felt pretty good. I got out on the bike and felt good too, so hopefully I am on the upward swing.”

He will ease into training. After his experience with COVID last year, he knows it's best to be patient and continue to monitor his health.

“I know my heart is ready for some strain again,” he says. “From here on, I am free to continue riding, but it is not like I am going to go out tomorrow and do five hours with a bunch of intervals or anything like that. It has got to be a steady progression again.”

Neilson's WHOOP will tell him when he is ready to make another big push to get ready for the Tour de France.

You can head to join.whoop.com/EF1PCT for their exclusive membership and join the EF Pro Cycling team by entering the invite code COMM-EF1PCT upon becoming WHOOP members.