Power will go up, cadence does not matter. Ignore Garmin most of that stuff is crap. Sorry to be so blunt but it’s the truth.
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Not a Garmin fan ? What do you use to gauge progress?
Performance metrics…
Power/HR is a nice one for Z2 progress. More power for the same HR means your cardiovascular system has improved capacity-wise.
If you can hold the power for longer before HR drifts upwards, you have improved endurance-wise.
Track those metrics over longer periods and plot them to see the gradual change.
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I’m a Garmin fan when it comes to hardware but I totaly agree with Alex that their software platform and all the ‘made-up’ metrics are more or less crap to help them sell more…
The Aerobic Training Effect is a metric that should give you an idea of how much impact the training had on your actual Aerobic fitness. If you keep the duration equal, the effect will go down because your fitness has already improved and you need more duration to get the same or higher effect.
All these ‘specials’ are alternatives to metrics and performance markers that already existed from other studies and are well described. Garmin (just like other manufacturers) throws one of those known metrics in a pot and do some miracle stuff with it to anounce it like a new wonderfull tool to help you get better. Each and every one claims they have the best algorithms. But when you start searching for proof or studies, nothing can be found. It’s the usual marketing stuff.
Trust the well described and known metrics and algorithms and you will go a long way. You don’t need all that voodoo stuff. But that’s off course not going to make you buy anything new…
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I am a Garmin fan. As Claude says these particular metrics are just bad. I have their expensive watch. I like it. If you do this zone 2 training, average power going up is the important metric.
Ok longer day than expected.
I’ll move this forward in a smaller way than I thought I’d have time for.
First the disclaimer, when I talk about this stuff, I’ll often say, “Humans have adapted” if I slip, I’ll say evolved. I’ve worked with enough people that, eventually, someone gets offended. So let it be said I don’t care if you are a creationist or an evolutionist or something else I’ve never heard of, and the debate doesn’t interest me; either your faith says you were created to function metabolically like you do or nature selection removed all your other options. In the end, it doesn’t matter for this conversation. If I suggest you read primal endurance and you read it don’t get offended by the evolution statements in the opening chapters go focus on the findings and let that stuff roll off of you it doesn’t matter, and you don’t have to agree with those parts. What matters is this stuff works, and it works for the majority of average people statistically, we are all average the few that are not; don’t need this stuff they can go make millions and hire coaches to do it differently. Ok, now, with that out of the way.
The Zone 2 stuff works because your metabolism is built to survive famine, starvation, and the shortage of food. When you put food into your body and nutrients into your blood, your body is going to release insulin, and insulin has 1 function; store energy as fat. That’s the simple reason calorie counting logs are the surefire way to lose weight. It is just not always the type of weight you are after.
Ok so point #1 that we need to memorize to guide our training. The Brain runs on Glucose as it main energy substrate. Memorize that.
Your Brain needs a continuous supply of glucose in your blood. Without a substrate for energy to feed the brain, you are in serious trouble. Fortunately, the brain can also run on Ketones such as β-hydroxybutyrate (βHB) and acetoacetate (AcAc), as occurs with fasting, prolonged starvation, or chronic feeding of a high fat/low carbohydrate diet (ketogenic diet).
So Let’s play with the Glucose info for a bit. You have glucose in your blood, in your muscles, and in that gel pack in your pocket. When you exercise, you start to burn the glucose in your blood, and, eventually, what’s stored in your muscles. How much is in your blood depends on when you last ingested the source and whether or not insulin has started to convert it to fat.
" At exercise onset, blood [glucose] transiently rises before beginning to decline after ∼30 min, causing a subsequent decline in blood [insulin] and rise in blood glucagon. This leads to many downstream effects, including an increase in glucose output from the liver to maintain adequate glucose in the blood to fuel both the muscles and the brain." Blood Glucose Regulation during Prolonged, Submaximal, Continuous Exercise: A Guide for Clinicians - PMC
This is on average, and it’s why your first 30 minutes of endurance exercise hurt more than you think it should. While unproven, the prevailing thought is that during this 30-minute mark the “The Central Governor Theory” kicks in more and more aggressively. The idea is that your brain is going WTF are you doing? You consuming all my fuel, and you get the I should quit soon feeling. If you pound a sugar gel, the feeling passes. However, if you press on without the gel; then the Brain tells the liver to get to work and make fuel., So what’s a liver to do but follow instructions? The liver can take two paths; it can break down Protein into glucose or it can break done fat into Ketones for fuel. The liver’s going to choose what’s in your blood first and kick into action. If there’s a ton of protein present, then it’s going that route first; because fat is precious because you might look like Smeagol if you lose your precious…
This is the problem with taking onboard protein before or during an endurance ride if you are trying to burn off fat; you are encouraging your body to continue to run on glucose, and you can’t get the weight loss or the fat adaption you really want. It gets worse once you consume all the protein to make glucose; there isn’t anything left for muscle synthesis after the workout; and the liver, as it switches to fat burning will continue to pull protein from other sources to make some glucose; your brain is stubborn about it Glucose preference it’s not going to tell the liver to stop once that seal is broken on protein conversion. Ok it will stop but the pivot takes about 20 minutes in the average person depending how which study we look at. UNLESS you are going hard; in that case you are going to deplete your muscle glycogen and then your going to start eating into muscle itself to some degree until you take on simple sugars or you bonk and the The Central Governor Theory ends your day. If you think you have bonked you probably haven’t; you more likely had a TCGT shutdown, a true bonk requires defeating the TCGT, and it looks like Julie Moss in 1982 https://youtu.be/nVKqFAPdjIA very few people have the will to get this bad. So don’t miss use bonk if you can avoid it.
Ok so what happens if you don’t put protein or sugar in. Welll that’s the good stuff. After 30 minutes the brain will say liver get to it I’m afraid this fool is killing me. If fat is prevalent in the blood and sugar and protein are not; The liver is going straight to ketone production; and it will deplete free fat in the blood first; follow by instructing the muscles to start breaking down the surrounding fat. This is the part that requires adaptation. IF the body you are piloting is a carb munching machine; your muscle really don’t want to do this because they are lazy.
At this point there are two types of people those that practice Keto or Perodic randomized fasting (PRF) ; or carb addicts that are doing proper endurance work. If you are Keto or PRF then you body is going to kick in to fat mod high gear; and at minute 35 you start to feel darn good. The reason you need to stay in Zone 2 is you don’t want your body to start questing for Glucuse because sorry your fat burning is really only useful for zone 2 efforts. This is why the strict MAF philosophy of don’t go over the limit. So Keto and PRF people your happy.
Meanwhile, Our Carb critters not so much; if you live by carbs, then you have to teach your body to do this new thing. That means you are NOT going to see great results for 4 weeks. You will see steadily improving results, but you might feel pretty crappy during those 4 weeks, and you need to stick with it. It’s best if you can just go hard-core endurance for the 4 weeks and take your lumps. Ask anyone that’s gone Keto or PRF at first; the headaches and the flu feeling will make you question your life choice; but as the fog clears, you feel great, and your brain will seem lively because you’ll begin to “idle” on fat even if you aren’t eating it as your primary food source, this is because your brain gets most of the glucose for itself and it’s a happy mental monster. If I’m coaching a carb addict, they kick, scream and call me names for these for weeks. They tell me it’s not working, it’s stupid, and that they are getting slower. And then it starts to work; and they complain less; and eventually they learn to say “yes coach” or they get mad and kick me to the curb.
Ok, so how do I tie this hot mess together into simple things you can use and remember?
- Endurance rides are Zone 2
- You need to train your body to use fat for the fuel in Zone 2
- You have plenty of fat you won’t run out
- Any exercise effort will start with Glucose
- On average you need 30 minutes to deplete glucose
- Your brain doesn’t want you to deplete glucose and it’s going to try and stop you
- Sugar and Protein before endurance ride bad, they block fat adations. Fat meanwhile is just fine before a ride. Have the spoon full of almond butter.
- Easy to access protein will put the body in to cannibalization mode
- Pushing hard after 30 minutes without fueling will flip back out of fat burning and has negative effects. Going hard has to be fueled you can’t escape that if you want to get stronger. The point of these rides and this part of training is not to go hard
- You can get gains from minute 35 onwards, but you start to hit the upper limits at 3 hours
- Fasted endurance rides are best; no food prior for 3 hours prior; and just drink water with electrolytes while riding sets you up for success.
- Caffine has ZERO impact to athletic output unless you go super extreme so don’t worry about that drug just consume however you normally do. Coming in low on caffeine compared to normal is actually a negative.
- You have to put in the 4 weeks to really see the light.
- A proper Endurance base phase will only demand about 6-8 hours of your time a week so take that time crunch philosophy and chuck it in the garbage; that’s just quick fix nonsense.
Now for everyone going BUT BUT BUT …Chilll. This is just the endurance part of training; it’s the foundation part. It’s important because most people have athletic skills built on a foundation of quicksand. This endurance stuff is bedrock. If you want a tall house you need a solid foundation and nobody is saying you will do this forever, but if you neglected it you are going to have to do it longer than you like; just not a a long as you fear.
Sorry but it’s way too late to do a grammar proof read; I’ll do that tomorrow and clean this up to fix any readability issues.
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Power/HR Metrics - intervals.icu has got this - really enjoying the Z2 and HR Ergmode on Trainerday (and all the Z2 discussions)
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I think you need to write a book 
I will buy it.
One thing I know Maffetone claimed was that if you do this very gradual warm up and stay under your aerobic limit is that you will stay in more of a predominately fat burning state from the beginning, and once you are out of this fat burning state, it’s harder to get back in it. He said higher intensity scares your body into “oh crap” I need some quick energy, but without this it will happily go on burning fat just like you were before you started your training assuming you are in a fasted state. His opinion may have changed since his original books but it’s contrary to what you are saying so it seems something interesting to understand further.
What you are saying also goes against what my personal experience was and many in the forums have observed which is more consistent short sessions seems to have a greater aerobic benefit then less frequent longer sessions (that said, I know Coach Andrea, top world tour coach and friend/partner, feels the weekly long ride is critical but he has not been a zone 2 hr guy but starting to come around).
These “tests” were not scientific but just a perceived observation. For example after doing 100 days in a row of 20-30 minutes a day and saw huge aerobic progress and that was after already following years of fairly string low HR running.
I need to check that out. I like Intervals and like David a lot and in general don’t want to add a lot of metrics to our platform or compete with him at all but this is one I have always wanted to do, I will have to check out his implementation of this. Glad you are liking “HR ERG,” you just made me realize that is what I need to call this
Running versus; Biking. We’re more steady state and he is basically saying the same thing his “oh crap” was insightful as heck and long long before the Govenor Theory studies where done. Runners can walk and get back into Zone 1 and then work back up into Zone 2. That’s just hard to do on an erg trainer. Meanwhile, we are using his numbers outside of his intention to control and prevent protein cannibalization that’s not to prevalent in runners because they get sloshy bellies and the gingerbread man will come to visit if they ingest protein before a workout.
You were probably adapted. What you just said is very consistent with phase 2 when we switch to polarized training; that hard 1 hour, slow 1hr, hard 1hour slow 1hr, slow 1.5 hours, slow 2.5 hours repeat. Once you complete 1-4 x 4 week blocks to get adapted then you get great results from short sessions; if your not adapted first then it take like 8-10 weeks to see the gains. so base building timelines are compressed by a steady diet of longer endurance rides. It’s also very useful to convince people that there is aerobic critical power, and anerobic critical power.
So it’s not contrary, it’s multipurpose coaching so that the work outs teach the athlete. Your experience tracks with the science and the practice; it’s just in isolation as you suggest it takes a special stubbornness to get the benefit.
So yep coaches are manipulative bastards. or the at last the good ones are.
Good point, yes you said once fat adapted (which I definitely was) then I can stay in fat burning much more easily so 20 minutes a day is will produce results.
Yes, and for sure running is different than biking but and I see your point regarding this study
But putting Maffetone’s fat adapted runners on one side and T2 out of shape individuals at the other end, the rest of us fall in the middle some where and Maffetone’s claim that we stay in fat burning from the beginning of our training might occur very quickly in this transition process for the average cyclist. Right? I also should re-read Maffetone to make sure I am not missing some critical details in his suggestions
Although, to your point again, it’s obviously highly individual and depends on too many variables, so playing it safe we could argue it’s safer to follow your evidence based science in the beginning to focus on that plus side of 30 minutes at least until we see obvious signs of fat adaption.
I would like to understand more about what you mean about this aerobic critical power and anaerobic critical power. I understand CP and W’ fairly well but not what you are saying
I also don’t remember reading anything regarding governor theories related to very low intensity and how this could relate to fat burning at such low intensities. Any more insight there would be interesting as well. You made a claim a bonk is not a bonk but does that even matter? Most of us are not trying to win the TDF so a bonk is going to seriously slow us down even if it is possible to over power it.
@Alex Can we bundle these posts by @Ratz in a separate category, pinned post or something alike?
There is so much good information that explains what happens in the body during AeT work and I would like to have it in one easy to find place.
The better we get at explaining why the LIT is so important, the more people we can convince to give it at least a try.
I assume the thread is talking about Peter Attia’s
As Attia talks about in this Q&A
the zone 2 he’s talking about is defined physiologically as highest power while keeping lactate below 2 milli-mol. It’s also zone 2 out of 5.
The Coggan cycling zones that say TrainerDay and others might use is a 7 zone system. So without a lactate meter we’re just using a proxy such as heart rate, HRV, DFA-1A, or power to approximate the zone 2 Attia is talking about.
Bonk reference. When we take a Carb power athletic and change their mind and the do a carb free 150 minute low intensity ride; the suffering so so bad at first we get the “omg I bonked, this will never work” then we have to explain to them they didn’t bonk , they will live, and that long low and slow can be as hard/painful as a short high intensity work. They just never see it coming that it might actually feel worse if done correctly
The Governor Theory is rooted in Brian Self defense and preservation, there are many ways to trigger the Glycogen depletion warnings. High and Low intensity. The High intensity stuff got all the attention because when the lights go out the power plummets for all to see; The low intensity stuff got less press because it’s all psychosomatic (psst just stop, no really you don’t want to do this any more, psst if you stop you’ll feel better, psst if you don’t stop I’m going to make you legs hurt like hell…)
No doubt. I agree 100%. A gold mine. 
let’s think of the best way to organize this.
The Maffetone 180 formula does it for me. Last winter I committed to zone 2 training with great results (and not yet with the fantastic new feature 
) So I had to change the power on a regular base. It is correct that when you improve it gets harder. The first couple of days (weeks?), there are days where you really have to adjust it down to stay within the “limits”. My project for the next winter is to experiment with lactate devices… Now that Trainerday has this functionality, that must really be something !
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Critical Aerobic Power “CAPa”; the power you can normally put out at the top of Zone 2 and not experience cardiac drift. Aka is’t the max you can sustain and stay in Zone 2
Critical Anaerobic Power “CAPn” = FTP as measured using a 20minute test - CAPa AFTER an aerobic clearing.
Time to Exhaustion then is drive by how long you can operate with your CAPn stacked on top of your CAPa all out effort. Aka true FTP which is still best measure during a TT event. I recommend people do a Team Time Trial in Zwift; you want to know your FTP do one of those events 45-1 hour long. The desire to not disappoint the group will tell you what you really can do in 1 hour. It’s worth learning how to do those if you can’t really do a TT outdoors. Solo run self done just isn’t the same as the competitive people are watching space.
I’de like to subscribe to your newsletter @Ratz.
I do have a question: What are your thoughts about fueling after a zone 2 workout? (carbs, protein, fats).
For background, I just started (mountain) biking this year, mostly for fun, and I go out every Friday morning, often with friends (but also enjoy solo). I’m the least fit, heaviest, oldest, and slowest of the crew I hang out with, so I get dropped (well, I drop myself) regularly. This is ultimately my motivation and goal, to get fitter and keep up. So I started using an indoor training and putting together a plan (I also do a Tuesday VO2 max session for two intense sessions a week).
I’m very steady at 195lbs with no effort including increased/decreased load, so it’s very clearly my “set point”). I do certainly have more lean mass now than at the beginning of the hear (just based on body shape/blubber). My plan was not to focus on weight loss as I wanted to get a good baseline of my fitness and power so that when I do “cut” I know what I could come back to. Don’t laugh, but after months of cycling and then getting my first garmin (and power meter) my VO2 max was 34 and my FTP was 139 (March 2023).
A few of my goals before focusing on fat loss was to get to 40 VO2 max (I just got there), do Brushy Creek’s Peddler’s Pass under 20 minutes (which I also recently got), and 200w FTP (again, not focusing on watts/kg yet). I’m currently at 162w and still seeing good progress.
So I’m getting closer to wanting to focus on weight loss (fat loss), but I’ve put it off because honestly all of the confusing and conflicting advice, so would like to start with making small changes.
Today I just tried a 1 hour indoor zone 2 based on info in this post (125-135bpm) and it was the first time I didn’t have carbs, although out of habit I had to have something so I had some tea w/ coconut power (MCT). I was really surprised at how well I handled it and it felt great (I stopped under 90 minutes due to saddle soreness). Probably because I had the MCT so there was a smooth transition at “35 minutes”.
But when I was done, I wasn’t sure if I should refuel with carbs (I had some white rice) since that seems like common advice to do within 20 minutes. Or would it be better to be more focused on protein, or both? fats?
I’m able to structure my mornings pretty well from both an exercise and nutrition perspective and the rest of the day/eve/night is chaos, so I like the idea of starting with / getting very specific with nutrient timing around my morning exercising where I have more control.