Everesting at Altitude: Does it matter?

On June 20, 2020, EF Education pro Lachlan Morton set a new Everest Challenge Record a time of 7 hours, 29 minutes and 57 seconds, https://everesting.cc/ less than a week after his first attempt was nullified due to incorrect altitude data; tip: if you need precise altitude data, do not rely on your bike computer. Both attempts, however, we set at an altitude ~7500 ft, begging the question, what are the pro’s and con’s of such an attempt. Therefore, as a follow-up to my previous article on altitude training and racing, I dive into Morton’s numbers for this challenge to discuss the potential impacts altitude had on his attempt, and whether everyone should do future attempts at altitude.

Morton’s Climb of Choice

In his second attempt, Morton used the backside of Rist Canyon outside Fort Collins, CO. The 1.05 mile long segment had an average grade of 11%. The segment started at 2240 m and ended at 2440 m. The temperature was ~45d F, and the barometric pressure can be estimated to be 580 mmHg at the start and dropping to about 565 mmHg at the top; the relevance of this data will be covered in a moment.

Morton’s Physiological Estimates

While I do not have Morton’s personal physiological test data, based on his attempt, his racing level, and some known values of World Tour riders, we can derive a good estimate to use. We also know that he rode each ascent at just over 5 w/kg early on, but sliding steadily downward to about 4.5 w/kg in the last 15 ascents. So here’s my composite based on known and estimates:

Height: 1.80 m Weight: 62.1 kg

Estimated Performance values:

VO2 Max: 80-83 ml/kg/min PPO5-min: 7 W/kg

1-hr FTP: 5.5 – 5.7 W/kg % VO2 Max: ~80%

Ascent power as % PPO5-min : 61-77%

Ascent power as a % of FTP: 75-97%

As an aid, I’ve displayed each ascent relative to his FTP (5.5 or 5.7 w/kg, BLUE and GREEN), as well as his peak 5-min power (PPO 5-min in RED). I’ve also estimated his oxygen consumption for each ascent (YELLOW dots). Here we can see a couple things. One, each ascent is sub-maximal, and his power declines steadily over time. Now much ado has been made regarding the altitude both he and Keegan Swenson’s attempts; ~2300 m here, and 1800 m for Swenson). For the sake of argument, those two altitudes are comparable, and neither would likely have had a significant negative impact on performance; if we must, we could say Swenson had more power up, but more resistance down (see below).

Data on altitude training and competition are fairly extensive, but mainly focus on maximal endurance efforts (up to 3 hrs) up to VO2 Max. Recall from my previous article, an unacclimatized athlete can expect about a 15% drop in VO2 Max and 10% in FTP power at ~2300 m. But what about acclimatized?

How acclimatization works

During early altitude exposure the body responds by increasing breathing rate (air transport in), cardiac output, and blood flow to the muscles. All of this let’s you maintain submax performance, but not maximal work. But after acclimatization, red blood cells increase, allowing for increased oxygen carrying in the blood, perhaps almost to sea level values at moderate altitude. Thus, cardiac output declines some due to the thicker blood, but more oxygen gets to the muscles at submax intensity. However, you’re still stuck at max exercise. Additionally, many other changes occur that may further improve altitude performance. (Fulco et al. 1998)

We know that Lachlan lives in Boulder, CO (1600 m) and that he recently set a new record on the Kokopelli Trail weeks earlier (1500 – 2400 m), so its safe to assume he is fully acclimatized. Therefore, we can assume that the altitude of Rist Canyon would have minimal impact on his sub-FTP performance on the way up, but what about on the way down?

The advantage of altitude for Everesting attempts

It is well known that for short sprint events, and even the hour record, the reduced air density improves aerodynamics, if you have the physiology and are acclimatized. (Fulco et al. 1998) However, I was skeptical that the reduced air density would be an advantage to the overall attempt considering the limited amount of time going downhill (~1 min in the latest attempt). Nonetheless, I reached out to Robert Chung, best known for his aero expertise and “Chung Method” for aero testing. However, as Professor Chung noted, he spent roughly 47-min of his 7 1/2 -hr attempt, which already had me questioning my skepticism. Chung went on to break it down as follows:

Both Morton and Swenson both made attempts of similar altitude – close enough to probably not matter between these attempts. So at 2000+ m air density was ~20% less than at sea level. Lachlan broke the old record by 10-min, or 600-sec. Over 47 laps, that’s about 12-sec per lap (~575-sec), or roughly 2%. Therefore, based on the available data, it is likely that Morton could not have broken the record at seat level.

A major point of discussion soon after Morton’s now defunct first attempt was not only the physiologic impact of altitude on the way up. The potential aerodynamic gains on the way down, however, are a real consideration. In that discussion, which included Phil Gaimon, who would like to retake the record, was whether to the next attempt be at sea level or altitude. I believe, based on the available data we have, fully acclimatized elite level athletes should be minimally impacted, therefore, were Gaimon to try his attempt, it would likely need to be at altitude. It’s unclear if Gaimon, who lives at sea level, could acclimatize sufficiently to offset the altitude.

Conclusions and Thoughts for Future Attempts

Based on the available data, the major conclusions one can draw from this analysis are:

  1. Among acclimatized elite cyclists, moderate altitude (1500 – 2300 m) would have little, if any impact on sub-threshold climbing reps. However, it’s unclear the impact on unacclimatized athletes.
  2. Altitude likely offers a significant advantage on the descents to such an extent that similar athletes would likely need to make attempts at altitude. However, a higher caliber rider, like Chris Froome or Egan Bernal, likely have the climbing power (w/kg) to offset this advantage.
  3. The average Joe/Jane should probably would not benefit from an altitude Everest attempt, especially if they’re unacclimatized.

After completing this analysis, I am more intrigued by the optimization between climbing and descending times. While these ascents are well below what we consider high-intensity intervals, I believe there is an optimal balance between work and rest, as well as slope, air density (i.e., aero) and the time descending. What those numbers are, however, would require a bit more work than I have available at this time. However, if anyone knows Phil, you might recommend he consider this…or to keep things simple, just use the same segment as Morton.

Special thanks to Robert Chung for his help with the aero analysis, as well as Jessica Kutz, PhD, and Tom Swensen, PhD for their insight and feedback on this article.

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