pushing AeT up from below – how big a difference is too much?

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  • #59419

    So we improve AeT by pushing it up from below. If my AeT is 130 and I accumulate a lot of Z2 hours at just below that HR, say at 125, I will build aerobic capacity. If I accumulate a lot of Z1 hours, say at 110, I still build aerobic capacity, but at a slower rate, right?

    Three questions: can I assume that
    (a) capacity building rate increases as HR gets closer to AeT,
    (b) work done below Z1 does not contribute to raising AeT,
    (c) as long as I am recovering properly, capacity increases most rapidly
    if I am doing Z1 and Z2 workouts near the top of each zone?


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    Edgar Carby on #59423

    Can we add a (D) to Bill’s list?

    Similar question, possibly a dumb question, but I’m asking it anyway – I understand that AeT is a HR BPM number. As we get fitter and our AeT increases, does that mean our AeT HR BPM goes up or goes down? Does it mean we get faster at the same AeT HR BPM, ie, more power, higher work rate, etc for the same BPM value?

    I think it’s obvious that fewer BPM means your heart is working at an easier rate and so you can go longer, but when we talk about raising our AeT, that sounds like raising the BPM, which seems counter to the whole lower BPM = easier.

    Nate Emerson on #59431

    Bill: Doing all Zone 2 might be too hard for some individuals, while doing all Zone 1 might not provide enough stimulus. Putting total sub-AeT training volume in that context, doing everything at the top of these two zones may be too hard for some individuals, affecting their capacity to recovery. If our recovery isn’t optimal, we aren’t optimizing our training.
    You can train at the top of the zones it if it’s working over a longer period. If it feels too hard and you aren’t recovering, titrate your intensity (do more in the middle of the zones) so you can recover adequately.

    Your assumptions are probably all correct, but the relative importance of each of those factors would be hard to figure out for an individual. I don’t necessarily encourage people to be right at the top of the zone. It’s far more important to train consistently and frequently, so that you have a generally high training volume. What might be most established in the literature is that a high chronic training volume below AeT has the biggest effect on aerobic adaptation. Starting workouts with lower glycogen levels is suggested to be the best way to promote mitochondrial biogenesis and other major factors in improving aerobic fitness. Doing this with too much dietary manipulation (e.g. keto/fasting) would likely preclude good recovery and higher training volumes, although this is probably very individualized. It seems more logical to set up conditions to get more training volume and have appropriate recovery. We have a lot of discussion in the general forum about this.

    Edgar: Raising AeT can mean raising the AeT HR and/or AeT pace. AeT HR can go up, but we don’t want to see that trend occur at the same workload. We’re not concerned about AeT HR as a singular metric. As long as AeT Pace is higher, it’s implied there’s an improvement in fitness. That can occur with or without AeT HR increases. If an athlete has improved their training strategies to specifically target aerobic fitness, and trains consistently for several months, we’ll likely see that they no longer have cardiovascular drift at the previously measured intensity. This could be due to improvements in muscular strength, efficiency, fat adaptation, etc, but the resultant outcome is that cardiac stroke volume doesn’t decrease at the previous workload so HR doesn’t need to increase to compensate.
    It’s not uncommon for us to see individuals who have little change in AeT HR, but with good training we’ll see that they are doing their aerobic threshold tests at a steeper grade and/or faster pace.

    With targeted training, you’re likely to increase your AeT HR and/or AeT pace, but as a mountaineer, what’s really important is being faster at your AeT.

    Edgar Carby on #59432


    What got me thinking of raising my AeT HR is the 10% aerobic deficiency syndrome. I’m at 140 and 165 which is about 17% so I’m aerobically deficient.

    So, if I understand it correctly, I need to raise my AeT HR to bring it to 10% or better of my AnT HR to get out of the ADS and the way to do that is with many hours of AeT.

    Or am I trying to raise my AeT pace (~9min/mile) to be within 10% of my AnT pace (~7:15min/mile) also with many hours of AeT?

    Or is it pretty much the same thing, just stick to AeT and don’t worry about it? Then retest in 90 days and see where I am?

    bill on #59437

    Nathan – thanks for the detailed response. Here’s my TL;DL version:

    – With the principles of progression and modulation underpinning the training plan, working closer to AeT builds capacity faster as long as you are recovering between sessions and injury-free.

    – If you aren’t brutally honest about your state of recovery, you are going to train too hard.

    – We can see two improvements as we build aerobic capacity: the gap between AeT and LT will get smaller and the pace at any given HR below AeT will improve. That’s why the drift test has to be done either with pace information (outdoors) or at steady pace and incline (indoors).

    Sorry for all the questions. I was trained as an engineer… understanding process and variables gives me confidence in the system I am using and I really want to avoid making more of the zillion training mistakes I’ve made over the years.


    MarkPostle on #59445

    Edgar- A few additional thoughts here. Firstly I find for some of my athletes getting to within 10% difference from AeT to AnT just isn’t realistic do to restraints in time, recovery capacity and/or genetics. The take home message in my mind is to try and minimize the difference but realize not everyone will get to 10% (its good to have goals ;)) Secondly my experience is poorly trained athletes can move the needle a fair bit on their actual AeT HR and their zones change a bit with proper training, once folks are moderately well trained the pace at that heart rate is where most of needle moving occurs. Some of this initial improvement is certainly improvement in aerobic metabolism but I think a lot is also just also getting strong enough that they move in a way to get accurate HR data. When folks train by HR on the same course locally they will often come to us and say they improved their time by a certain amount whilst maintaining the same avg HR and perceived effort.

    Edgar Carby on #59452

    Thanks Mark. I was thinking I belonged on the island of misfit toys with my tragic case of ADS.

    Looking a little harder at my data, since August 1, I’ve only spent ~59 hours in Z1 or Z2 out of ~99 hours of activity. That 99 hours includes a 50k trail race effort as well as the misery of running in Mississippi in August, but I am beginning to think I am pushing a little too hard too often.

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