I had a gas exchange test done at elevation 5,200′. They reported AeT=142 and AnT = 152, HR_MAX=171 and VO2_max=40. I felt like I was suffocating though. Exhalation was impeded by the mask.

The next day I went home and climbed a hill from 7,900′ to 8,900′. My HR averaged 162 for the 30 minutes that hill climb took so I think the 162 at elevation ~8,500′ is a better estimate than the 152 at 5,200′ the gas exchange at 5,200′ gave. I think that must have been substantially low as the 2,600′ elevation drop should have given me an even higher AnT than the 162 I got going from 7900-8900′. I sort of trust their 142 for AeT and the 40 for VO2_max. I did trust the HR_Max until yesterday when I noticed the May 19 number. I’ve never used HR_max but it did seem to put a ceiling on things that now seems to have been raised a bit. I’ve also not used VO2_max. Even so, it was satisfying that from October to April it increased from 30 to 40 according to my Polar watch (with the 40 confirmed by the gas exchange).

AnT is around 162 not 172 so it is 91% of the 177 HR_max.

I’m not totally sure what my main concern is. I’m kind of a waffler. After PPA I’ll do something else. I finished a 50K 11th in my age group and would like to do the next one faster. At 64 I’m not going to break any speed records. I hope to finish the PPA and hopefully not in last place for my age group. I might climb a largish mountain some day if I can find one that appeals that doesn’t have crowds. Something like Amne Machen: big enough to be interesting, seldom climbed, no crowds.

The literature suggests that the HR_max, AeT, and AnT heart rates decrease with elevation but that HR_resting increases. This is what I would expect intuitively as well. Resting heart rate rises because your heart has to pump faster to provide oxygen to itself. HR_max, AnT and AeT are related to one’s ability to perform work and that drops with elevation. I’ve seen people get confused about that and think that because HR_resting increases everything else increases too.

Given the elevation dependence of the thresholds, the question becomes what is the elevation dependence of the ADS diagnosis? I think that AeT has a greater dependence on elevation than AnT which means that people can go in and out of ADS simply by changing elevation unless one changes the definition of ADS to include the effect of elevation.

The definition Scott and Steve use for ADS diagnosis in my language is:

AnT-AeT < eps AnT means NO ADS

with eps = 0.1.
[eps is short for epsilon which I take to be a smallish (compared to 1) non-negative number.]

If AnT-AeT > eps AnT means ADS

One could include elevation effects by placing elevation dependence in epsilon. Maybe epsilon should increase a few percent for each 2,500 meters or something like that. For example if the change in epsilon was 2.5% per 2,500 meters then at sea level eps=0.1 and at 8,000′ eps = 0.125 etc. . That might sort of work, but variability of individuals response to elevation might mean a simple alteration of the definition like that might not be useful unless the altered definition deals explicitly with the variability. Perhaps the ADS diagnosis should only be made at sea level ?

I put some tables in this that were munged by formatting. I am trying to correct that.

As fast as you can for as long as you can? Isn’t the protocol for the AnT test: go as fast as you think you can go for 30 minutes? My AnT field tests tend to have plateaus. The last one I did began with a 14 minute plateau with HR=161, then a 5 minute plateau with HR=162 then a 7 minute plateau with HR=167. (The missing 4 minutes were between the plateaus.) The overall HR average was 162. I conclude that 162 is a good lower bound for my AnT HR at that elevation and that 167 is likely a good upper bound. I used 162 in my training.

The drift test has some fairly serious issues independent of altitude. I personally don’t think it is trustworthy.

Issue 1 is rounding error. This is minor and can be easily fixed.

For whatever reason Training Peaks, Polar, and Suunto all report heart rate averages to the nearest beat per minute. They shouldn’t do that. They seem to think they are suppressing something they call “false precision” which doesn’t actually mean anything. They should report the average heart rate to four or five significant figures. The reason is that if you’re doing a drift test you’re going to take a difference and the difference you get has a two bpm spread because of rounding. That two beat spread in the difference can affect the conclusion. Here’s an example of what I am talking about. I like to think in terms of the actual number of heart beats as I am fairly certain those devices report it.
TABLE 1
Number of heart beats true reported
first 30 minutes HR (bpm). HR(bpm)
4215 140.5 141
or
4214 140.46. 140
second 30 minutes
4425 147.5 148
or
4424 147.46. 147

In table 1 the true HR is the number of heart beats over 30 minutes divided by 30 minutes. The reported HR is the integer HR average after rounding. The calculated difference between the rates that rounded is between 6 and 8 beats per minute.

TABLE 2
beats in 1st interval beats in 2nd interval reported % difference true % difference
4214 4424 (147-140)/140=5.0% 4.98%
4214 4425 (148-140)/140=5.7% 4.98%
4215 4424 (147-141)/141=4.25% 4.95%
4215 4425 (148-141)/141=4.96% 4.96%

The true per cent difference is, to good approximation, 5% in all 4 cases, as it should be. The reported per cent differences run from well below 5% to well above whereas the true percent difference is very close to 5% in all cases. Talk about false precision!

This is easily remedied though. All they have to do is report the average heart rate correctly without rounding. Seems like a big deal to me because if you see a drift of 5.7% you’re likely to think you were too fast and if you see a drift of 4.25% you’re likely to think you were too slow. You might get by saying if the drift is between
4% and 6% then your starting heart rate is an adequate estimate of your heart rate at AeT. But then there’s Issue 2.

ISSUE 2 this one is more serious and why the procedure is not trustworthy.

The drift rate drifts. Say you stay on the treadmill for say 100 minutes. Take the heart rate time series that began at T=20 minutes and ends at T=80 minutes and compute the two 30 minute heart rate averages. Then assume your warmup ended at T=25 minutes and take the two 30 minute averages beginning then. In that 5 minutes my drift dropped from 5% to 3.5%. Which one should I use and why? The choice is arbitrary and is going to have a significant impact on my training.

All the treadmills that I’ve been able to use had time limits of 100 minutes which also causes problems if you want to look at how much your drift drifts. What I do is warm up for 25 minutes then shut the treadmill off and restart it as quickly as I can and warmup for another 5-10 minutes until I’m back at the same work load and my HR has stabilized again. Then I can do 3 30 minute intervals to see how much the drift changes over 90 minutes. The drift between the final two 30 minute intervals tended to drop to near zero with the work loads I’ve used. The first 30 minute drift was usually substantially higher than the second.

Below is some data from one of my drift test attempts.

# r(t) is defined as the 30 minute average heart rate from t to t+30 minutes
# dr is defined as r(t+30)-r(t)
#

t(min) r(bpm) dr(bpm) dr/r(%)
20 138 7 5
25 141 5 3.5
30 141 5 3.5
33 142 6 4.2
35 143
50 145
55 146
60 147
63 148