Some guide metric for endurance is aerobic decoupling and endurance training advice is to keep it low respectively train it to be low by keeping power in check as soon as too much decoupling occurs.
But couldn’t you interpret aerobic decoupling also as some form of larger muscle involvement/requirement (which led to higher oxygen demand which led to higher HR) and therefore something to be desired (instead of avoided) in order to train larger motor units to be more aerobic for better endurance.
So that’s one metric with 2 contradicting training prescriptions. Or am I making Number 2 up?
@empiricalcycling could be a nice question for your podcast. Any opinion?
I don’t know about #2. That would definitely be more in Kolie’s area of expertise.
In general, I don’t look at decoupling in ride. I use it as a metric to help me determine how my athletes are progressing in terms of endurance, and as one input to push longer durations for developing athletes (i.e. riders who’ve never done much work beyond 2 or 3 hours). With the concept of minimum effective dose in mind, I don’t just leap in and throw 4-6 hour prescriptions at newer/lower category/developing riders because those rides can cause quite a bit of fatigue, so generally I will progress duration for those guys starting at 3 hours and moving out. How fast I move that out… well, EF and decoupling are inputs to that.
Otherwise, if you have a goal duration for your longest rides in mind (e.g. you’re training for an Ironman and you want to progress your longest rides to 5:30 or so), you can use decoupling as a metric to determine when you’ve developed adequate endurance and can move on to a more build focused training block, then touch on those long rides every couple of weeks to maintain endurance.
Generally speaking, when I see really high decoupling (like 15-20%), I pull the string to ask my athletes how the ride felt, how they fueled it, how hot it was, etc. I want to know if the duration really stressed them or if something else is going on.
Some of the highest decoupling I’ve seen my athletes have are when they are brand new to pacing long rides and I give them a HR cap to keep things under control. (This is kind of what you’re talking about with #1) That’s where they would see their power drop off quite a bit late in the ride to maintain below 75% max HR. That’s not an approach I stick with for very long with most people, and it’s only really something I use to ensure people don’t go blow themselves up and get the idea of riding easy for longer durations. But as mentioned, I never track decoupling in-ride and adjust the ride because of it… there are a lot of factors as to why it might be high at any given time.
Good question. Not sure I have a good answer other than ‘yes, and’
Kolie probably has a better mechanistic answer, but my handwavy coaching answer is yes, progressive motor unit recruitment would contribute to cardiac drift, but I don’t think cardiac drift is a good proxy for motor unit recruitment in the real-world. Other factors (blood volume changes, glycogen depletion, central fatigue, inter-muscular recruitment changes rather than intra-, etc.) I think have larger effects.
My current approach is to keep low intensity training targets low enough that the athlete doesn’t need to decrease power over time during prolonged training to accommodate either for a large cardiac drift or (more importantly, IMO) RPE drift, given their available training time and ability to recover between sessions.
If an athlete is prioritising training consistency, then IMO managing fatigue from a single training ride to allow the next session to be at an equally high quality is the top priority. Cardiac & RPE drift don’t need to be zero, but the athlete needs to understand how the prolonged fatigue from today’s ride will affect their training (and the rest of their life) tomorrow, next week, and next month.
One of the daily outcome goals I discuss with coaches & athletes is to get home from a training ride and not feel like they need to raid the fridge and melt into the couch for the rest of the day… that means managing fuelling, hydration, and fatigue (central and peripheral) appropriately during the ride, starting from minute 00. But I mostly consult with working athletes where melting into the couch for the afternoon isn’t an option.
I really like @kurt.braeckel’s answer using cardiac drift descriptively for monitoring, and focusing on individualised progression of duration. see:
Good questions and I’ve definitely noticed the seemingly opposing suggestions. Not much I can add here, Kurt and Jem answered well since they’re no slouches in this department. But I’ll try anyway.
I think generally speaking we can do a fair job of controlling for other things that cause HR drift and use it as an approximate marker in the long term in some types of workouts, but I agree on what’s implied that the day to day variability is too noisy to really use it to keep power in check. I personally like cardiac drift caused by larger motor unit recruitment, as I think we really do want to expose those motor units to sustained energetic demand. The metric is also subject to the efficiency of larger motor units too, and fiber type distribution among other things, and the O2 demand once we get into those fibers.
Practically, when I have people ride to RPE the power stays the same or increases a bit, regardless of decoupling. This works for me since it seems to me, all other factors equal, LT1 varies with fatigue and I can’t predict it day to day and RPE guided consistent power and increased decoupling doesn’t seem to add any undue fatigue, which would be the signal I watch for to determine if something’s unduly hard or adding too much internal strain.