Why do professional cyclists train at altitude?

"I’m a big fan of altitude. So is everyone by the looks of it. An increasing number of riders are moving to Andorra where they can “enjoy” altitude all the time. For me, I live in Girona with my wife and two young kids. I head over to Andorra for stints of higher altitude and have noticed I enjoy big fitness benefits, plus it’s great for losing weight."

The words there of Team BikeExchange’s Lawson Craddock, who we caught up with recently from his US home of Texas.

Craddock’s an altitude convert, like the mooted 60 or 70 professionals who can be found ascending and descending the mountains of Andorra. (I was there recently and within 10 minutes I’d wandered past Dan Martin and his wife Jess before spotting the UAE Team Emirates’ livery of George Bennett.) But why are many riders seemingly spending an increasing amount of time in rarefied air rather than solely training camps?

CUMULATIVE GAINS

Late last year I spent time with Jumbo-Visma’s head of performance Mathieu Heijboer. He explained a scientific theory called ‘hypoxic memory’ that suggests important parameters of endurance, like red blood cell count (important for oxygen carrying and delivery), are cranked up by a constant topping up rather than irregular exposure. It’s a similar idea to why three or four consistent rides a week are better for you than just one long ride.

"This enables riders to acclimatise more quickly to altitude at subsequent camps, allowing a higher quality of training, which means the overall training stimulus is heightened," Heijboer said. "It’s why we’re seeing plenty of athletes using our altitude generators and tents in between training camps for “top ups” of altitude while they’re at home."

There was little in-between time for the Dutch team in 2021 with a seven-week altitude camp in Tignes, France, before the Tour. Primož Roglič is based there and, like Craddock, is deemed a 'responder' – someone whose physiology really taps into the benefits of altitude training, of which there are many.  

Primož Roglič (Image: ASO/Alex Broadway/SWpix)

Studies have shown that training at altitude increases aerobic capacity (VO2max); decreases heart rate, both at rest and during exercise; increases myoglobin, the muscle protein; reduces lactic acid build-up; and facilitates greater production of EPO from the kidneys. We’re all aware of EPO, or erythropoietin, the hormone that stimulates red blood cell production. The synthetic version once populated cyclists’ supplement routines all around the world. Altitude, it seems, is the modern-day needle (though scepticism remains about micro-dosing, of course, but that’s for another time).

These benefits start to present themselves after a minimum 10 days but, as the teams and riders are cottoning on, arguably the longer the better, especially when it comes to shut-eye. "Many riders will sleep at altitude, which is easier to tap into in the United States as places like Colorado and Utah are touching 2,000m," Craddock explains. "You’ll sleep at altitude and then often come down to ride."

LIVE HIGH, TRAIN LOW

This live high, train low scenario is common. Why? It’s all down to partial pressure. At sea level, air contains 21% oxygen. It’s the same at 2,000m, 3,000m… but the difference is, as you climb, the air becomes less compressed, thinner and harder to breathe. Because there’s less oxygen the further you climb, the lower your power output. It’s why altitude’s a double-edged sword: while blood markers improve in terms of reticulocyte production (young red blood cells) and haemoglobin levels (the part of the red blood cell that carries oxygen), muscles actually detrain.(Image: Zac Williams/SWpix)

At a recent stint in Andorra, Ineos Grenadiers’ coach Adrian Lopez told me how they’d adopt this template of mixing up training high for cardio gains and low for muscular gains. We also discussed how altitude training isn’t for everyone, especially if you’re a non-responder. As the name suggests, this is where your body simply doesn’t tap into the potential reservoir of physiological gains and can actually lead to detraining. 

This lack of altitude response might be why two of the three riders studied in a recent scientific paper went high, while one stayed low. In ‘How do world-class top-five Giro d’Italia finishers train’ the research team, led by Gabriele Gallo, enjoyed rare access to the training programmes and power data of three world-class riders in the build-up to the first Grand Tour of the season. The data was collected between 2015 and 2018, and at some point in that period each rider enjoyed at least one top-five Giro finish. It’s a physiologist’s nirvana with standouts…

• The riders’ VO2max scores were 81, 82 and 80ml/min/kg, respectively. 
• Maximum 20-minute power output came in at 6.6, 6.6 and 6.4 watts per kg, respectively.
• Surprisingly perhaps training came in at ‘just’ 19.7, 16.2 and 14.7 hours per week, albeit much of this was during the race-preparation period where volume’s generally lower.

As mentioned, only two of the three riders trained at altitude. The two that did spent a collective 92 days seeking rarefied air; in fact, they went very high in search of it – around 2,800m – and over the 1,800-2,200m suggested. The authors qualified that they were ‘altitude natives’ so potentially from South America. In that 2015 to 2018 period, Miguel Lopez, Richard Carapaz, Nairo Quintana and Esteban Chavez all finished top five. It matters not, really, who it was or who it wasn’t. What matters more is the repercussions of being an altitude native.

INDIVIDUALISATION OF ALTITUDE

Like all things altitude, a physiological win’s potentially accompanied by a negative by-product. The win? A recent study in the National Library of Medicine showed that altitude natives perform better than altitude immigrants. The by-product? If you’re raised in the 3,000m-plus altitudes of South America or Eritrea, there are few gains to be had at the lower altitudes of mainland Europe; in fact, there’s a case for focusing on training harder at lower levels as training at around 2,000m will do little for their haematocrit levels but is high enough that they won’t be able to generate maximum power output. It’s arguably why these two studied riders went higher than the norm and the third refrained altogether. 

Like the increased use of 3D scanners for mapping skin suits and bespoke bike-fitting, altitude training is very much an individual thing, which affects the timing of maximising altitude-stimulated adaptations when back down at sea level. Before last year’s Tour de France, Roglič only came down from altitude four days before the race start in Brest. That’s relatively late with many riders having a week or more between landing back at sea level and racing; in fact, elite athletes have been known to peak between one day and four weeks after returning from altitude. "But we know from past experience that Roglič adapts quickly," Heijboer said.

Lawson Craddock (Image: SWpix)

Craddock’s a swift adapter, too. "Before the Giro, we had a team camp in Andorra," he says. "You come down and it takes a couple days to become settled, but then you do feel stronger on the bike. What normally feels like 220 watts is 240 or 250 and you’re just cruising. You also recover much faster, so you might do a maximal effort and it normally would take you 10 or 15 minutes to recover between the next interval. After altitude it takes five or seven minutes."

Despite the empirical world that modern cycling inhabits, there’s still very much a randomness to a rider’s adaptation – what works one year might not the next – but one area that there’s clear coach and rider consensus on is supplementation. 

"You must ensure your iron status is optimal," says professor of exercise metabolism Asker Jeukendrup, who  works with Jumbo-Visma. "But you must ensure this is  before you hit altitude, otherwise you shouldn’t be going as you’ll do more damage than good. Ideally you’d have a blood test and then supplement weeks before as iron absorption is really poor."

Riders should also keep abreast of their carbohydrate intake – namely consume more. "Whether it’s altitude, heat or the cold, any stress on the body will increase carbohydrate metabolism and slow down fat metabolism," says Jeukendrup. "It’s something to keep an eye on." As is your heart rate and heart rate variability as these will skew under the immediate stress of altitude before easing when adapted. 

The application of altitude training’s evolving in the search for faster riding and faster recovery. But one thing the sports scientists and coaches will struggle to dial down is the resilience needed to train at altitude like a Grand Tour winner. We conclude our deep-dive into this legitimate high with Sir Bradley’s reflections in his autobiography 'My Time' of what’s required to mount that sea-level podium in Paris.

"We’d done 4,000m of climbing and had one more 25-minute effort to go… We were at 1,500m altitude and were going to 2,200m. We’d ride one minute at 550 watts, basically prologue power, which you can sustain for a few minutes, then four minutes at threshold torque – 50rpm at threshold, maybe 400-440 watts depending on altitude, which is bloody hard to do because riding in the big ring, say 53 x 16 gear, at threshold on a climb, is like going up a steep hill in your car with your foot to the floor in fourth."

Wiggins and crew did this set five times. Who said it was a sport for strong (wo)men…