[dcgm]

AeT is often benchmarked at the first ventilatory threshold, which we sometimes characterize as the point where you can no longer breathe exclusively through your nose or comfortably carry on a conversation. Some other sources (I don’t want to play “let’s you and him argue”, but I’m thinking specifically of Gordo Byrn’s stuff) talk about the first faintly perceptible deepening of the breath, which seems a little truer to the graphs of respiratory volume vs pace that one sees in the literature. The thing is, at least for me, these points don’t necessarily coincide and seem to shift pretty dramatically from day to day, especially when I’m not training consistently, and they all seem quite a bit slower than the fastest pace at which I experience no more than 5% HR drift over an hour. For context, here are some numbers for mostly-flat outdoor running:

First faintly-perceptible deepening: 10:30-12:00/mi, HR 120-150 (both HR level and intra-run dynamics seem super variable depending on weather), super easy, volume limited by impact

Comfortably carry on a conversation: 10:00-11:00/mi, HR <= 150 or so, pretty easy

Nasal breathing: 9:30/mi, HR <=155-160ish, kinda easy

HR drift: 8:45-9:00/mi, HR <= 165ish (this one might be as variable day-to-day as the breathing metrics, come to think of it, I just wouldn’t know because I don’t test it as often), steady and sustainable but not easy, I will get pretty tired if I do this for an hour every day

~30min time trial (included as a sanity check): 6:50-7:00/mi, average HR 180-190, pretty damn hard

So a pretty wide range of paces for AeT depending on the criterion I use. I don’t expect someone to bust out the perfect “just do this” answer that makes me stop thinking about it, but I do wonder what to make of it all. Thoughts?

[Scott Johnston]

You bring up some very good points.  As you point out; there is no simple answer.

For good measure you could toss in the intensity at which blood lactate has its first appreciable rise (or rises by 1mMol/L according to some sources).

There is even a newer method of defining this point using HRV.  I’m not familiar with this but as I recall: By noting when HRV decreases by, I think 25% this corresponds closely to the gas exchange test for VT1.

The physiology definition of VT1 (first ventilatory threshold which many would call the aerobic threshold) is the intensity at which the rate of ventilation (volume of air inhaled and exhaled in a minute) increases fasted than than the rate oxygen is extracted by your muscles (VO2).   Up to that intensity these two markers increase in lock step. Beyond that the ventilation increases faster than the O2 extraction.  This point is hard to find without a gas exchange yes in a lab. Ventilatory markers of conversation and nose breathing only roughly correspond to it and vary quite a bit from person to person.

Your observation that nose breathing and conversational breathing paces vary a good deal from day to day is consistent with what I have said for years. It depends on your recovery status and your training modality.

I can’t say much more definitively except that we have seen pretty good agreement between the gas exchange test and the HR drift test. Beter than the perceived ventilation markers of nose breathing and conversational pace.

Scott

 

 

[dcgm]

the rate of ventilation (volume of air inhaled and exhaled in a minute) increases fasted than than the rate oxygen is extracted by your muscles (VO2).

I think this was a misunderstanding on my part–I didn’t quite realize that VT looks at relative rate rather than absolute rate (and even some reasonably erudite sources aren’t very clear on this point.). Thanks.

[Author]

Posts