Beginner: I want to Run not Walk RE: AeT base training frustration :) | Uphill Athlete

Beginner: I want to Run not Walk RE: AeT base training frustration :)

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  • #34228


    The title is slightly in jest, but I am indeed having quite a bit of frustration and want to understand more why I am observing strange (to me) effects while training.

    Quick Background: I am switching modes to mountain running for a big adventure in 2020. For the past year I have only been a casual trail runner as slight cross training for my focus which has been ultra mountain bike racing. I have been ultra bike training and racing for the past 6 years.

    To support this, I have been following a custom training plan created by Alison Naney. I am on week 6 of 8 weeks of base AeT training. I am fully committed to the concept to the patience phase of building my base AeT and running slow to not get above threshold and subsequently walking to force my heart rate down within the aerobic zone.

    However….. It has been really frustrating and seemingly random that on some morning AeT run workouts which last 1h, I end up having to walk many many times to keep the heart rate in check. Whereas, other days, I have no problem keeping the heart rate where it needs to be.

    It seems that about 1 in 3 runs this happens: About 20-30min in, my heart rate will quickly spike up about 10 beats/min higher than threshold. My alarm goes off and I try to “run” as slowly as possible, and that always results in a walk. After about 10-15 sec of walking my heart rate is lower than threshold and then I start to run again. Within a few seconds I am back up to 10 beats higher. It spikes. I then have to walk again. I may do this 10 to 15 times in a 1h session. My perceived effort is very low when my heart rate spikes, in fact, I am usually cooling off or getting cold when this slow and would prefer to run than walk. It’s like all of a sudden my heart rate just wants to jump above threshold and I have to beat it down by walking to prevent it occurring.

    The thing is I don’t know how to prevent this. I don’t know what prompts it to happen on some runs but not others. It feels so frustrating when it happens that I am usually cursing out loud that I have to stop and walk. I think the main frustration is that I feel like I should be training myself to prevent this but I don’t know how. Since it seems to be consistently random over these 6 weeks, it feels like I am not progressing in that way. (I do feel improvement in my fatigue while running for long duration though).

    Is this a normal issue that will dissipate as I build a better base?
    Do I get the most benefit out of the training by strictly forcing myself to drop back below threshold every time my heart rate spikes?

    One other tangent question about running in the aerobic and anaerobic zones. If say I am running along at AeT and then all of a sudden I start running in an intentional way to get my heart rate up into the anaerobic zone, does the aerobic process of generating energy switch off? ie do I ultimately switch over to the anaerobic mechanism only, or do both mechanisms work at the same time? In other words, am I throwing away aerobic power and relying only on anaerobic power (which is time limited) when I cross that threshold?

    I would love your thoughts and help. Thanks!


Posted In: Mountain Running

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    Anonymous on #34232

    Hi Scott! I hope others will chime in too, but I wanted to give my two cents as well. Congrats on the good work you’ve been putting in so far. My first thought is that it’s probably time to test your AeT again. Since you switched sports, you already had a really good aerobic base, but not the movement efficiency with running that you did with biking. After all the running you’ve been doing, you’ve no doubt become more efficient with running, and your aerobic threshold could be higher now. My other thought is that it’s totally normal! My own personal experience is that I’ve been running ultras for over 15 years now and there are still times that I have to hike to keep my heart rate low, especially if I’ve been running several days in a row and have fatigue in my legs. I’d be curious to know if you feel good the following day, ie. can run more at AeT. I’ve found both with my own training and many athletes I coach that the day that’s hard to keep under AeT helps you keep the effort easy enough to be a recovery workout and the following day feels great. Hopefully we can chat soon to put together the next phase, based on how everything’s been going for you. I hope this helps!

    TerryLui on #34233

    Hey Scott,
    A few thoughts come to mind:
    1) Without knowing much of your background, my guess would be that you have ADS and have developed a running efficiency in the higher HR zones. Hence why your heart wants to jump to where it is most comfortable at/trained at.

    2) The inconsistency of HR jumping up sometimes vs other times may be a factor of any number of things. We are human and some days are “good” and others “bad”. Ex. Recovery, life/work stress, rest, diet, etc. Your comment of improving endurance for long runs is encouraging. If you’re willing, you may try tracking your sleep, food/water intake, etc. This builds a historic database you can look back on to tease out any correlations over time and experience.

    3) I experienced a similar thing when I first started with UA, spent SOOOO much time walking it was boring. But…such is developing an aerobic base.

    4) My understanding of the energy pathways for AeT vs AnT is that the body switches fuel sources from fat primary (AeT) to carb primary (AnT). At the crossover stage/transition period b/w AeT & AnT, a bit of both is used and it’s not just an on/off switch. Not sure if I would call it throwing away aerobic/anaerobic “power” but your body drawing on a more limited reserve of carbs and becoming depleted is more imminent than staying within AeT and drawing on a near limitless reserve of fats.

    BTW, I’m assuming Alison created the custom plan for you as a 1 time thing? It may be worth booking a phone call w/ her/Scott to check in on the above?

    sidener2002 on #34239


    Thanks for your thoughts! If I had to describe how things have been progressing so far, I would definitely use your phrase of “becoming more efficient running”. I definitely feel like that has happened some. I think I will use one of next week’s workouts as a new AeT test and see what happens.

    As far as fatigue effects go, there may be an aspect to that as well. Since my big runs are on the weekend and my day off is Monday, I do get the impression that the Tuesday run is typically easier to keep my heart rate where I want it.

    I am definitely looking forward to planning the next steps with you and debriefing what I have and have not learned 🙂 Part of this 8 weeks of training was to help me lock-in my decision about my objective for July. At this point I am convinced that it’s a go! Although, doubts still creep in from time to time, but that is natural.


    Thanks for your response as well, I really appreciate your perspective. In my years of ultra MTB racing, I have indeed found that I end up doing most of my work in high heart rate zones. In fact, historically, I have completed races where the Garmin claimed I spent a not-possible percentage of my time in the red zone even though I had what I thought was a good understanding of my zones from testing. Also, that history is part of what is bringing me to the UA method. I want my metabolic power to get as high as possible without going into that anaerobic zone. I have historically had to rely upon constant, difficult to sustain, carb fueling to get me through 5 – 7 days of continuous racing. I really want to reduce that requirement and logistical nightmare of carrying enough fuel. I think I was at the point of diminishing returns without really focusing on spending most of my time in the fat burning mode.

    Your answer about the two modes being exclusive at either end of the range makes sense to me. In essence what I was contemplating is this (made up problem for example):

    I want to perform at fastest possible speed for 3 days:
    a) use aerobic up to 250 Watts infinite time, carry only maintenance fuel, train to increase aerobic power to go faster.
    b) push into high power 300+ Watts anaerobic zone early, really fast, limited time, digging hole, requires huge caloric consumption along the way and still digs a hole. Speed profile drops off with time to a lower level than (a).

    The hope I had was that the aerobic power base was additive in that if I increase my aerobic capability, then I would need to add less anaerobic process to make up the desired total power. Problem is, if I go anaerobic and switch over to that mode, it sounds like having a higher aerobic threshold output power doesn’t help or add to the equation because my body has effectively turned off that mechanism.


    Anonymous on #34245

    One more thing that I’ll add is that this is by far the most common thing I hear from athletes. I know it’s frustrating but it’s also really satisfying when you get to the point where you can run for hours at a time, feel good, and even better than that, wake up the next day and be able to do it again because it’s not stressing your body too much. The only way to be able to do that, is to be at the low heart rate. Scott Semple wrote a great article about this topic here:

    anthony.orkiolla on #34316

    Great post, i think most athletes struggle with this because its difficult to understand that “fitness” is truly only measurable to a single sport as far as sports specificity. It doesnt matter how fit you were in whatever sport. Another thing people discount is the complexity and specificity of movement. For instance, i went through a similar change from road running to mountain running. Now i can do mountain runs all day with little or no calories and not be destroyed the next day, however, my road running efficiency has become abysmal in the sense that now my z3 pace on the road is 1 minute to 1:30 slower per mile. In other words, you cant be good at everything all the time, and developing efficiency in a certain style of running takes time and often at the cost of efficiency in other sports or modalities. People think that they can just go out and “run” but running is a skill, like weightlifting, climbing etc. Skills take time to develop and refine. Most people can move their legs at a pace faster that walking-but i would argue that not many people who consider themselves runners actually have developed the efficiency and skill of movement to actually be called “runners.” Many people take years to refine their technique, so it is not surprising that after biking a lot at a high level you do not have refined running technique and therefore do not have the efficiency within the skill to maintain steady cardiac output (amongst the other variables such as nutrition, training stress, sleep etc).

    Anonymous on #34377

    Sorry to be late to this thread. Definitely some great info for Scott to chew on. I concur with all that has been mentioned above. However………

    Here is a really simple possibility: You may just need to wash your HR monitor chest strap. When the strap becomes dirty/salty this will completely throw off the conductivity. I have seen this for many years with many athletes and all brands of monitors. Just rinse it in the shower or use some hand soap and hang it up to dry.


    sidener2002 on #34416

    Anthony and Scott,

    Thanks so much for your thoughts as well!

    Yeah, switching modes is really a big learning and training experience. I think that a lot of my mental attitude, dealing with adversity, strategy, going around the clock and race mentality will carry over well, just not the physical efficiency that I have developed.

    I am encouraged to see how much I have improved in reducing the perceived effort and subsequent fatigue from running over just the last 6weeks. I hope that continues.

    I had thought of heart rate sensor issues. I’ve had those troubles before with the straps. I’m now using a Garmin watch with the built in wrist led sensor. It seems to be behaving, ie if I walk my heart rate does drop as expected.

    Ok, here is a another beginner question with respect to AeT and multi-day running/hiking with big vertical gain and loss. I’m wanting to get my head around this and it may be too simplistic of a question, but here goes:

    Say I want to run/hike 100 miles non stop where the average elevation gain and loss is roughly 1000 feet per mile. In a perfect world, Should I strive to do that at or below AeT? Right now, that feels impossible. If I add serious vert. I don’t know how I would ever keep my heart rate low enough.



    Anonymous on #34419

    You need a chest strap! That’s no doubt affecting the results, as the wrist monitors aren’t as accurate. And to your last question, you definitely want to stay at or under AeT for your goal. If you look at what the records are for it, much of it is hiking pace, even for the user-fit, fastest people out there, so you’re still getting a lot of specific training even when hiking.

    sidener2002 on #34428

    Hi Alison, I do have a heart rate strap, so I will switch over to that and see if things stabilize better. Also, thanks for answering the question about training myself to perform at AeT or below for the duration of the event. It is exciting and reinforcing to hear that. That is what I really want to be able to do, I’m just still getting my head around everything.


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