I don’t know how many people live at or often ride at “high” elevation/altitude (say… over 10,000 feet), but wondering how Xert “calibrates” those efforts in terms of XSS score and recommended future workouts. In general, achievable heart rate and power (including FTP) will be lower with increasing altitude. So, a workout of similar effort/stress/percentage of available power will log a lower power number if done at altitude than it would at sea-level or an intermediate elevation. Does Xert take this into account when calculating XSS score or when recommending future required workouts or efforts (and in the fatigue score)?
Reading others threads I believe that’s on Xert’s team whish list but not implemented yet.
I think that’s quite a challenge.
Numbers are relative. If you always training at the same altitude I don’t see that there is much need for that kind of detail. Using the power meter analogy, as long you do your training with the same PM the results are consistent.
The problem will be for people that are lucky to have access to such variation in altitude that frequently that it matters to them.
Such as pretty much everyone in Colorado, parts of California, southern France, Northern Spain, Switzerland, Austria, Northern Italy, so not a small number of potential users, at least in terms of those who have access to significantly higher elevations than their homes. For myself (fairly typical avid cyclist in Colorado), in the summer, it’s a rare week that I don’t ride up to at least 3-4000’ higher elevation than our home and usual training altitude and several times a year to over 10,000’. The issue is those efforts a altitude put significant stress on the body yet the recorded data (HR and power) will indicate a fairly easy ride if that same HR and power expended at low altitude. This could really throw off the calculated stress and workout recommendations.
Wouldn’t the the effect of lower O2 at elevation be reflected in your heart rate?
That’s actually the issue. I assume things like the XSS score for rides is based on where one normally rides - in my case 5,000’ +/-. But if I do a ride that ranges between 8,000’ - 10,000’ my max power available is less because max HR is lower. So a power of 250 watts might be 90% of max. available at altitude but Xert would think I was only doing 70% of max since most previous data was gathered at lower elevation.
I echo my fellow Colorado neighbor
If you do search of the forum you’ll see it’s come up before, is something complex to do (altitude varies within a ride) and seems to be down the list of things to do… some compared it to the effects of heat or riding indoors which also give a lower signature typically
There was one practical suggestion to manually change your signature down at altitude, but unfortunately not a lot on how much to adjust it by (as it depends… and altitude varies within a ride as mentioned above)
The relationship between FTP and altitude is detailed in this linkCycling at altitude
Aerobic power at a given altitude as a percentage y of what is normally available at sea level, where x = elevation above sea level in km:
for acclimatized athletes (several weeks at altitude): y = -1.12×2 – 1.90x + 99.9 (R2 = 0.973)
non-acclimatized athletes (1-7 days at altitude): y = 0.178×3 – 1.43×2 – 4.07x + 100 (R2 = 0.974)
(Proposed Solution) So you can calculate your XSS (at altitude) for the ride by calculating your discounted FTP with the equations above and enter this new ftp (lower ftp) into your activity using “advanced MPA”. This will calculate a new XSS as well as tell you if you had a break through “at altitude“. Take a screen shot of the results but DO NOT SAVE or it will screw up your fitness signature. If you save you can always fix it later but that is more steps. But now you know your adjusted strain and breakthrough at Altitude. Adjust freshness bar as needed to reflect extra strain and slower recovery at altitude.
Let me know if you think I am out to lunch on this 
Useful and interesting, but it would be nice if Xert could do this automatically since it’s just a matter of simple calculation. The altitude of the ride is available in the .fit file.
My thought… statistical population averages are rarely applicable to individuals. Most people will be outside what is probably a formula that is only true if you are one of the few people who are “average” in how altitude affects your biology. One of the things that makes Xert so good is how the three parts of the fitness signature are unique to each person and how it can be used to determine your performance in different contexts. Throwing a non-unique value into the mix would water down the value of the fitness signature. Just my 2 cents! I didn’t read the article linked to (reading for later).
Agreed, my method is a bit of hack to get a truer XSS. The method could be personalized for those with the math skills to collect and plot the data. For me, above 10500 ft I ride at approx. 50% of my lowland capacity. I use high altitude rides as training opportunities and measure improvement on low land rides (post altitude) when I return home and have fully recovered.
An interesting problem to be sure. This, and heat, and hydration and fueling status, and no doubt other variables.
Hydration and fueling levels don’t have objective, accessible data as do heat and elevation. It’s just math and computers are good at that. ;^) Worst case, use time-averaged elevation and temp for adjustment calculations. Plus this isn’t some free app we’re paying a non-trivial amount of money to track our training and prepare for events. The guidance it provides should be as accurate as possible/reasonable.