These are brilliant questions (sorry for the circle-jerk), and conveniently moves us away from HR training 101!onemanpeloton wrote: ↑Mon May 20, 2019 10:20 amI love this topic and I think it's great to challenge the "norms". I'm sure we can all agree or disagree whilst still being respectful.
My question is, if HR is such a reliable measure of what the body is doing, then why would efforts be adjusted dependent on caffeine, sleep, stress etc? Surely 65% of HR is exactly that, and the stress on the heart is exactly that, regardless of what other factors come in to play. And if you then argue that this isn't the case, how do you know if you're stressed or if the weather's having an effect and how much do you adjust your training for this?
Also, if there are a certain number of coaches that can take you to extremely high levels with power based training, then this suggests that all of your concerns regarding power based training should be aimed at coaches (which I know you've already done to some extent) and not at the nature of the training itself. Otherwise how could these power based coaches get such good results given that you say they have no basis in science, and only in experience?
The adjusting of efforts depending on caffeine/sleep/stress etc. is indeed an interesting topic. First, let's preface by stating that elite athletes are very careful about their diet and have very standardized sleep/workout/eating schedules so they are far less affected by environmental factors. However, obviously this is not the case for recreational or semi-serious athletes.
So, let's say it is 10 minutes before a ride, you are geared to go and your heart rate is 60bpm. But then you eat a burger (hypo). Your heart rate increase to 65bpm. What does this mean? Well, your heart is pumping more blood to your stomach and digestive organs - not exactly what we have in mind when we talk about aerobic exercise. What does this mean when you exercise? Well, your heart is still pumping blood to your stomach (but a bit less so), so your heart rate will be elevated relative to your actual effort and will in fact hinder your ability to effectively exercise within your Zone (although the range within each Zone somehwat minimizes this downside).
What about caffeine? Well now that's a bag of worms. Certainly it increases your heart rate, but it also increases the amount of fat released into your bloodstream as an energy source, along with certain neurological effects which delay fatigue and increases power.
Sleep? Well that's another bag of worms. Not only does a lack of sleep decrease your rate of muscular recovery and adaptation, it typically leads to an elevated heart rate. But oftentimes this means that your muscles haven't recovered sufficiently to be able to sustain effort levels up to the prescribed level of effort required for that particular day, or it means that you'll blow past your prescribed Zone, risking a vicious cycle of overtraining and not enough recovery.
Before I go further, all these issues have an equal impact on FTP based training. Afterall, FTP is meant to act as a surrogate for lactate threshold (i.e., the "do not cross line"). Essentially FTP is the power meter equivalent of LTHR (lactate threshold heart rate), and both really depend on your heart. But this leads to another very controversial question - do these "artificial" increases to your heart rate (diet, sleep, stress, etc.) accelerate, or decelerate the onset of lactate accumulation (i.e., lactate threshold?). The research seems to suggest, these environmental factors do not in fact accelerate the onset of lactate accumulation at lower intensities. In other words, it appears to be OK to be a few BPMs higher if you are doing say a Zone 1 - low Zone 3 level of effort. HOWEVER, the research seems to suggest that at higher intensities, these environmental factors DO accelerate the onset of lactate accumulation. Highly controversial, but hugely important to people chugging caffeine pills before an event right?
Can someone please create a thread of the effect of caffeine on training? 
So what's the takeaway from this? Well I asked a lot of questions, without really giving you answers. The problem is, ultimately it depends on what you ate, how much, how much sleep you got, how much sleep you got the day before. And there is no formula that can quantify or compensate for these events.
Which is precisely why any good coach will tell you to have a routine before exercise - to eat well at the right time, to avoid heavy foods before exercise and try to get sleep. And this is also why people say a poor diet or sleeping habits can completely derail your training.
There is some light at the end of the tunnel however. Few if any elite endurance athletes do their base miles with a heart rate monitor on. After a period of time of training with a heart rate monitor, you become very good at guessing your current effort level, at least within the confines of the rather generous lower aerobic effort zones (Zone 1, 2, lower 3). So you can make slight adjustments to your effort level on the fly, depending on how hard you feel your heart beating. Where the elites continue to use heart rate monitors are during hard sustained efforts, such as longer intervals or tempo rides. This is because it is crucial that you absolutely avoid crossing your lactate threshold, because once you do, your muscles quickly accumulate lactate acid which will essentially "freeze" your muscles from being able to produce the efforts required to complete the workout.
We can have this discussion for days, so I'll leave this here for now.
As to your last point, yeah I guess I should have been clearer that I should have directed my rant at the coaches who have spread this particular brand of misguided FTP-based training (i.e., completely dismissing heart rate based training as some antiquated, inferior form of training). Power is a brilliant way of measuring progress, but it is a very indirect way of communicating information as to how you are currently feeling. "I'm only pushing 150 watts today so I must be pretty tired, yeah I can feel my heart pounding OK let's ease it up..." <--- this is no good! Rather, "Man I'm only pushing 150 watts but my heart rate is 180bpm I'd better slow it down until my heart rate comes down to 130bpm" <--- smart training!
P.S. Since we're talking about diet, don't ever ever drink and exercise! It is extremely hazardous and damaging to your health!!!!
. Ask me again how I did come September. 
But binge drinking is obviously bad for your health, and drinking even a single drink the night before can affect you the next day. But then so is eating delicious food, so I won't judge. Something generally on alcohol consumption and exercise:
