Rereading some of Scott J’s posts, it seems clear to me that a 3-hour TTE test at a steady pace would provide a good approximation of AeT.
. . . consider the marathon. This event is competed at an individual’s aerobic threshold or just a tiny amount above that. So, minimal involvement of the anaerobic system. This is true for someone running a 2:05 race or a 4:05 race. That 2:05 marathoner can sustain a pace of 4:45/mile for 26 miles relying 95% on his aerobic system for energy.
The trick is to know what pace to begin the test with so that exhaustion is reached within 3-4 hours.
@todd.struble I think that Scott J. has always been clear that nothing is written in stone. The HR drift does not require *exactly* 30-minute laps and you don’t need *exactly* 5% drift to determine AeT. Our bodies are not machines and a phenomenon as complex as AeT–which is the product of processes occurring at many different levels and in many different locations–cannot, in reality, be totally understood with a single number. It’s a ballpark.
The whole reason I would like an actual test of my long-term TTE is that my Gas Exchange Test was clearly wrong. My RER 0.85 crossover point was 164-167 bpm. There is no way I can hold that HR for very long. That test was done in June this year when I was 63 years old. (When I was 62 years old I did a HRmax test with a chest strap monitor and reached an actual HR of 178 bpm on an elliptical machine.) I don’t think the gas exchange tests work the same for low-carb high-fat (LCHF) athletes. If you look at the FASTER study, which Steve and Scott cite in TFTUA, their elite LCHF athletes did a 3-hour bout at 64% VO2max at RER of 0.73-0.74. The balanced diet elite athletes had RERs of 0.86 at rest. I could not find their exercise RERs in the journal article.
I eat LCHF, so it makes sense that my AeT would occur at a lower intensity than my 0.85 RER. (I don’t eat LCHF for performance reasons but, rather, for other health reasons.)
Since my Gas Exchange Test did not give me a solid basis for deciding my AeT, I then did a few HR drift tests. On October 9, I had an average HR of 152, followed by 156. But, realistically, I can’t imagine going higher. I can’t even imagine going 3 hours starting at 152. When the HR drift test ended I was happy to be done and I would have been very unhappy if I would have had to repeat it the next day. These sentiments suggest to me that I was going higher than my AeT.
So, I am very tempted to spend a long Saturday in the gym starting at, I don’t know, 142. I’ll bring a bottle of water, perhaps, and see how long I can continue, taking breaks for a minute or so every hour to restart the machine.
I am thinking that a lot of the limitations that could be present in indirect tests (gas exchange, lactate, HR drift) could be eliminated by a direct TTE test. Of course the TTE test has its own limitations, being both inconvenient and disruptive. But it also might give the best approximation of AeT.
And from my understanding of everything written by Steve and Scott J., nothing is more central to effective UA programming than an accurate value for AeT. It really is the key to the UA paradigm. (I welcome all criticism of any and all of my ideas. You would be helping me improve my understanding of this.)
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