What pros think about racing and training with glucose monitors: Safer, faster ... more like Zwift

This is part three of a series diving into the pioneering continuous glucose monitoring technology that could change the game for pro racers and weekend warriors alike. 

• Part one: How continuous glucose monitoring could change the game
• Part two: Inside the push to bring glucose monitors into the pro peloton

Continuous glucose monitors (CGM) are the next big thing set to shake up the data-driven world of pro cycling.

Companies like Supersapiens and Levels are pushing the CGM technology long used by diabetics into high-level endurance sport. The innovative trackers allow individuals to monitor fueling levels in real-time, meaning riders can time mid-race gels to the minute and dial in their diets to a level never seen before.

CGM is now widely used through the pro peloton, with Jumbo-Visma, Canyon-SRAM, and Ineos Grenadiers among the early adopters. WorldTour riders without a CGM device are now in the minority.

VeloNews spoke to three riders with extensive experience of CGM to hear their takes on the technology’s potential to inform racing, training and beyond.

For racing: safer, faster – less fun?

Continuous glucose monitors are currently banned from competition by the UCI, an outlier in a numbers-focused peloton already able and allowed to track heart rates, power outputs and course maps mid-race.

So would riders being able to see their glucose scores shift pro racing in the way race radios and power meters did decades before? For some, it could be a game-changer.

“When you’re in a race, you’re using so much energy just from concentrating on everything going on that having that information [about glucose] in front of you is so valuable,” former-Canyon-SRAM rider Hannah Barnes told VeloNews.

“You don’t always have the time or energy to think about what you’re eating. Fueling properly can mean the difference between winning or not.”

Riders with a full tank should, in theory, be more explosive and more exciting to watch.

Chris Froome’s historic Giro d’Italia stage win over the Finestre in 2018 was powered by a pioneering carbohydrate strategy, while Mathieu van der Poel lost his legs at the 2019 road worlds in a cross-eyed energy crash.

More significantly, well-fueled riders are safer riders.

Supersapiens boss Phil Southerland told VeloNews of how he has long been arguing for the use of GGM in competition to help reduce crashes. Ineos Grenadiers rookie Magnus Sheffield said he had felt both more lucid and more effective after tweaking his mid-training nutrition with the trackers, and would welcome their use in racing.

But some wouldn’t welcome another layer of data into the instinctual world of racing. Being told what and when to eat represents another nail in the coffin of full-gas, old-school competition.

“As a rider you have to use your skills, and I feel like fueling is also a skill. So [CGM] takes away one of the skills. Eventually, we’ll get to a point where we just race on trainers and it’s Zwift racing without the gamification,” Toms Skujiņš said on a recent call.

“As an athlete you have to get everything dialed yourself. It is your responsibility to make sure that you’re in the right position at an important point in a race or whatever, and it’s the same with fueling.”

Trek-Segafredo rider Skujiņš is one of many voices pushing back against the use of glucose trackers in the pursuit of back-to-basics, full-bore racing.

“Knowing your glucose during a race would help you not under fuel, but it takes out one variable that make races exciting,” he said. “But then I’d also be fine without power meters, I’d be fine without radios. I’d be happy having it all a little bit more unpredictable.”

For training, recovery, body composition, and more

The use of CGM in racing is something that sure splits opinions, and likely always will. But Skujiņš, Barnes and Sheffield all praised how glucose data helped them dial in their day-to-day nutrition.

All three explained to VeloNews how they’d been able to perfect their pre-training meals so as to manage their glucose flows and optimize their workouts. Skujiņš had gotten as granular as possible to identify that eating a protein and fat-rich dish before something more carb-laden gave him better control of his blood sugars.

Skujiņš, 30, also said that he’d been able to identify which gel and drink mixes worked better for him on the bike.

“Some products are slower to react than others and give a quicker release,” he said. “But I think that varies for every individual, so it was nice to see what the reactions are for me personally. It’s definitely something that I will find useful later.”

The potential for CGM to help every athlete find personalized nutrition solutions is huge. Information on a packet can’t be relied on, and everyone’s gut works in different ways.

Chris Froome used Supersapiens to help him hit race weight. GCM has enabled some Canyon-SRAM riders to manage body composition through the rollercoastering demands of the menstrual cycle, while some have used the data to speed the bounceback from jetlag.

Sheffield and Barnes both found that sleep – and therefore recovery – could be improved with a dive into the data.

“A lot of us [Canyon-SRAM riders] were waking up in the night, and we’d realize that we had a crash during our sleep and our body would wake ourselves up to get the glucose hit,” Barnes said.

“There was one rider that would wake up at like 5 am every morning. So before she went to sleep she’d have a banana or something so she wouldn’t get a hunger bonk in her sleep.”

In the ‘real world:’ Cost, education, and keeping it old-school

Like the early days of power meters, CGM don’t come cheap. A season’s worth of the tech is a significant financial outlay, and it’s still waiting on approval for sale in the USA.

For many riders on teams without a relevant sponsorship, it’s a luxury rather than a necessity.

A second hurdle is understanding and application. Without a specialist to hand-hold through the early stages of CGM usage, the numbers could be just numbers without meaning, something Southerland and Supersapiens are trying to remedy through improved education.

Barnes will transfer from Supersapiens-partnered Canyon-SRAM to Uno-X in 2022. She said she’s unlikely to continue with CGM next year.

“There’s more to fueling than just following a number. It takes a long time to train your body to adapt to absorbing 90 grams of carbs an hour or whatever,” Barnes said. “So it’s not as easy as just being able to look at a monitor and say, ‘oh, I need to eat now because I’m having a glucose crash.’”

Skujiņš was also skeptical.

“The skill behind fueling is the same kind of the same argument with power meters,” he said. “That’s why I feel like kids should not have power meters because they still are learning. I feel like it’s important to learn how to feed and understand your energy.”

Race radios, power meters — now add CGM to the growing list of points up for debate in the pro peloton.