How to Climb Well on a Bicycle at High Altitudes

By Coach Fred Matheny

In the past, I’ve coached at Carpenter-Phinney Bike Camps, run by Olympic road race champion Connie Carpenter and her husband, Davis Phinney, the 2-time Tour de France stage winner. Their U.S. camps were based in Frisco, west of Denver, nestled in a high mountain valley.

All rides started at 9,000 feet (2,743 m) above sea level and went up from there to summits such as Vail Pass (10,600 ft.; 3,231 m) and Loveland Pass (12,000 ft.; 3,658 m). That was intimidating for flatlanders who would come to these camps. They wondered if they’d be able to ride at such oxygen-starved heights — or even walk up the stairs.

The higher you climb, the less barometric pressure, so less oxygen can be absorbed by the blood. The percent of oxygen in the air doesn’t change, but the air’s density does. As a result, there’s less oxygen to breathe. At the top of Vail Pass there’s one-third less oxygen available in a given volume of air than at sea level. No wonder climbing Colorado’s passes is so demanding.

Because your blood can absorb less oxygen, your VO2 max (the amount of oxygen that your muscles can absorb and use) is also negatively affected. At 5,000 feet above sea level, your VO2 max will decrease about 5%. If you do the Mount Evans Hill Climb that ascends to a bit over 14,000 feet, your oxygen uptake will drop 25% compared to sea level.

Some lucky cyclists don’t seem to be affected negatively by altitude. I’ve ridden with guys from Indiana who immediately felt right at home and couldn’t tell they were 2 miles higher than their usual training roads through the cornfields. Others were badly afflicted with “Chicago lungs” and panted while lubing their chains. In general, though, riding at altitude isn’t as demanding as imagined. Even for those who have trouble initially, the body usually acclimates quickly.

If your plans include some high country cycling, following a few tips can help you learn how to breathe easier.

Arrive early (or late).  Experts used to suggest arriving at altitude 3 weeks before an event. This is usually impractical, and research indicates it isn’t necessary. Instead, some racers arrive at high-altitude venues the night before one-day events, ride, and head back to sea level. The thinking is that they can trick their bodies into working hard before they realize how thinly the oxygen molecules are dispersed in the mountain air. You just have to hope that your body is gullible and easily tricked.

If you have time, a stay at altitude might be beneficial because your body, reacting to the elevation, creates more red blood cells to carry greater quantities of oxygen to working muscles when you return to sea level. That’s why high-altitude camps and “altitude tents” are popular. But some studies have shown minimal positive results from long stays at altitude and, in fact, endurance performance could worsen.

Hydrate.  You’ll lose a lot of fluid through perspiration at high elevations and not realize it. Sweat doesn’t gather on your skin but evaporates immediately due to the low humidity. So you’re in danger of dehydrating quickly. At Colorado cycling camps we encourage riders to keep a water bottle with them at all times off the bike. Have a bottle next to your bed at night and take a sip when you wake up. If you’re not urinating at least twice a night, you’re not drinking enough.

Use sunscreen.  Exposure to the sun at high altitude can result in severe burns, even on skin that has been tanned at lower elevations. So slather on the sunscreen and wear protective clothing (a long-sleeve jersey, leg warmers) if you show signs of sunburn.

I have lived at 6,000 feet and trained at higher elevations for more than 30 years. Even though I use sunscreen and wear a billed hat while hiking, I’ve developed actinic keratoses (pre-cancerous skin roughness) from the exposure. My dermatologist routinely burns off these small irritations with liquid nitrogen. It isn’t fun.

Ride easily the first few days.  You can ride into a high altitude event if you gradually increase the intensity of your efforts. Don’t ride hard the first couple of days. Give yourbody time to adjust to the elevation.

Don’t go anaerobic.  Many riders who come to the mountains feel pretty good as long as they keep their efforts reasonable. In fact, they feel so good that they’re tempted to hammer some climbs. That’s when they discover that high elevation gives new meaning to the term “going anaerobic.” Once they start gasping and panting, it’s often over for the rest of the ride — they won’t feel comfortable again no matter how slowly they ride. Going hard at elevation really takes it out of you. So learn to ride safely below the red line.

Sleep high, train low.  In the best of all worlds, you’d be able to sleep at high altitude (9,000 feet or more) and train at fairly low elevations (sea level would be best). Why? You can generate more power at sea level and thus get a greater training stimulus. But by sleeping high, your body is forced to create more oxygen-carrying red blood cells that improve your performance.

Of course, there aren’t many places in the world where you can comfortably commute from a sea-level training venue to a high-altitude bedroom unless you have a helicopter. Hence the popularity of altitude-simulating hyperbaric chambers (so-called “altitude tents”) that allow low-altitude riders to sleep at artificially high elevation. Their use raises 2 issues. First, there’s some question whether they work well enough to improve performance. Second, their use might be considered unethical because they artificially increase red blood cells by a means that not every athlete can afford.