AeT and AnT too close together?
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Hey, Coaches.
My latest AeT and AnT tests have me a little confused. This week, I did a 30-minute uphill AnT test. According to TrainingPeaks, I averaged an 8.8% grade and had an average HR of 172. A few weeks ago, I did a HR drift test on a 1/4 mile track and got an average HR of 168 with a Pa:HR of 3.87%. I feel like, based on my training history, the AeT seems too high and too close to my AnT.
Is there something that I might be doing wrong here? Is it possible the AeT is too high? Or that I underestimated my AnT?
For a little bit of context, I am currently running about 6-7 hours a week and in the past have typically averaged 3-4 hours per week with a max of about 6 hours per week, almost all in Z1-Z2. In addition, this week it got really hot and humid where I am and I’ve been used to milder weather. I also have had some rough sleep and stress this week so my performance may have suffered a bit on the AnT test for all those factors. Perhaps this test was an underestimate of my AnT by a few bpm.
My previous AnT tests were in Aug 2020 I did a 30 minute test (on the same course as this week) and got an AnT of 174. Six months later, I did a 45-min test with an 11.4% grade and got an AnT of 174.
My previous AeT tests were in Aug 2020 where I got a Pa:HR of 5% at a HR of 165, so I retested at 160 and got a Pa:HR of 2.96%. I tested again 6 months later in Jan 2021 and had a Pa:HR of 3.95% at 165.
Based on all of that, should I use 168 as the top of Zone 2 and 174 as the top of Zone 3? These seem very close, so I’m concerned I might be doing something wrong!
Thank you,
AndrewAndrew: Thanks for writing in with your question. This is very unusual to see AeT and AnT so close together. I normally see, in the very aerobiacally fit, a spread of 5-8%.
From your consistent historical data, I would say you have done a good job on the tests with only one possible point: Have all your AnT tests been uphill at the same grade? This could matter because running uphill requires more muscular endurance. So, local muscular fatigue in the legs could potentially limit your HR on the uphills. The steeper the hill, the more the ME and local muscular fatigue effect. A 9% grade may produce this effect depending on your specific leg ME. I hope this makes sense.
It is entirely possible to have thresholds this close together for a person will a very well-developed aerobic base. A good test of whether you’ve nailed these zones is: Can you train daily at AeT (165-168) and recover well within 24 hours? Or would it be too fatiguing to train your normal volume at that intensity? With AeT and AnT only 3-4% different, I would expect that training in Z2 would not be possible long-term without risking overtraining. Z2 is just too dang hard, too close to your maximum sustainable effort to be sustained day after day after day.
I hope this helps.
Hey, Scott.
Thanks for the response.
I have done the AnT test twice on the exact same course, which has a grade of 8.8% and got 174 and then 172. I have done a 3rd test on a course with an 11.4% grade and got a similar number: 174. But your line of thinking has me wondering if I may be limiting the AnT test by muscular endurance. While I do plenty of general strength training, I haven’t done much of any ME work and I haven’t been doing hill sprints or Z3 workouts recently. There were times during this test that I had to walk–not because of my breathing–but because of fatigue in my legs.
To the second part, when I did my most recent AeT test back in March, I initially tried to run all of my runs at the top of Z2 in that 165-168 range. I quickly found that I was getting beat up by that and ended up inserting a rest week and repeating the previous training week. After that, I decided to relax my pace and allow myself to complete my runs around the bottom of Z2 or even in Z1 (in the 136-159 range) and haven’t had any issues since.
If I understand what you’re saying, if I could run at 165-168 day-in and day-out then 172 is probably not my AnT because if my AnT was 172 then 168 would be far to fatiguing.
Putting all of this together, I am wondering if I would benefit from some ME work or Z3 intervals to gain enough muscular endurance to get a more accurate (and probably higher) AnT result. And in the meantime, keep the rest of my runs at least 5% below that 168 AeT threshold so stay below about 159.
Andrew:
I think you answered your own question. If you were forced to walk during the AnT test not because of your breathing but because of local leg muscle fatigue, then ME is the limitation for your AnT. You will benefit from adding ME training to your plan. Either Z3 longer hill reps, weighted uphill hikes or the gym ME program will all help this.
Scott
Thought I’d follow up in case it is helpful for anyone who finds this.
I spent the last ~3-4 weeks of training doing weekly hill sprint and uphill ME intervals running on a 30-40% grade. Today, I re-did my lactate threshold test and was really pleased with the results. I was able to maintain a running pace on a ~9% grade for the full test and didn’t feel like I was slowed down by heavy legs. I ended up with an average HR of 180 bpm for the duration of the test (up from 172 four weeks ago). with an AnT of 180 and a AeT of 168, I feel like that’s a much more reasonable spread of ~7%.
Thanks, Scott!
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