Long time lurker. Rarely post, but help me troubleshoot unusual data…
What could be the causes of negative decoupling? I will consistently see -3 to -10 decoupling, through a variety of training routines: hour long rides with intervals… four hour long rides with intervals, even recovery rides.
Power is coming from power tap chainrings, polar v800, and Lemond revolution trainer.
All indoor training. Same temperature. Small fan from warm up to end. When I’m doing Long intervals at 4+ w/kg (20 minutes) I might get -9 for the interval.
I’ve done some sessions by doing a warm up first, then ending the session and opening a new one to hit the main sets. I’m trying to rule out warm-up noise.
I still get negative decoupling. Should I be looking at other sources of noise?
I have the same issue and my coach and I believe it just takes a long time for my body to warm up. This can create some problem when it comes to racing crits(multiple cats in a day) as it’s a challenge for me to warm-up enough while still keeping my reserves topped off.
Negative decoupling in “hour long rides with intervals” and “recovery rides” doesn’t mean much IMHO. If you are doing a 4 hour ride around .70-.80 IF (intervals or not and I am assuming Ironman effort intervals) and getting negative decoupling something is wrong with your equipment, either your PM or HRM. Another problem could be that your FTP is way too low. Just to review how decoupling is calculated you can refer to this link. The formula is halfway down the page.
I also just noted that you were looking at decoupling as a metric for a 20 minute interval. Any increase in the % would indicate a higher EF and an improvement, however I don’t believe the main goal of the decoupling metric is to evaluate shorter efforts. The link also explains that however it may be TL:DR for you.
Decoupling is useful when analyzing steady endurance rides/runs (Zone 2 or whatever you are used to calling those). It is not a relevant metric for interval workouts.
Fair enough. But does that mean I should only look at this for Long steady State rides? For instance, if I have a four hour ride and do 30’ w/u then 6x20 at HIM power with 5’ recoveries, then 60’ at IM effort. Say I ‘lap’ each of these intervals. Am I off to think there is a value in looking at the decoupling over the whole workout? And, am I off to think there is value in looking at the decoupling for each lap? My HIM power is about 80% of ftp…so still aerobic, right?
That is, is decoupling really only useful if I were to go 4 hrs steady IM effort? I am not new to training with power, but I haven’t used training peaks for a while now, and I haven’t used this metric before. I want to believe I am either getting more efficient or more aerobically fit (or both). But im guessing something is off when I keep seeing negative numbers here. In theory I should see my hr drift upward. Right?
When I’m doing Long intervals at 4+ w/kg (20 minutes) I might get -9 for the interval.
Are you doing them at fairly constant power, or is your power increasing during the interval? There is an issue with Pw:HR in that it doesn’t account for the HR you’d have if just pedalling at 0W.
For example, I have a delta of about 2W/bpm. So if I were riding at e.g. 240W 140bpm, then increased my power to 280W, I’d expect my HR to increase to 160bpm. But the ratio would have changed from 240/140=1.71 to 280/160=1.75, giving negative Pw:HR if I were to make that change 10 mins into a 20 min effort, even though in reality the two represent exactly the same relationship between power and HR for me.
Haha. I was hoping you’d help me. And I appreciate your sometimes blunt honesty on this forum. So I know you know what decoupling is, and I’m sure your question is meant to help me think about whether I know what I’m asking…
So I’m a nutshell I’m not super clear on this. It is a new metric for me. But I think it goes like this—-in general hr and power are coupled when they maintain a relationship such that when one goes up or down so does the other at the same ratio. I put out more power, my hr should also rise, I reduce power and he falls. If the ratio remains constant, then hr and power are coupled. Decoupling happens when hr rises or falls out of step with power. I put out more power but my hr drops…or I put out less power and my hr rises.
I understand that this involves math that compares the ratio of hr to power at the first half of a given duration with the last half of the duration.
It matters to me insofar as it may be an indication of aerobic fitness or efficiency. I’m trying to figure out what the numbers might mean…
Right. Yes, I do keep it constant for the laps. It’s great that you’ve got things figured out to watts/bpm level. How do you interpret the pw:hr numbers for yourself? What does this tell you and how is it useful for training?
I don’t pay any attention to Pw:HR. My main performance indicator is my HR for a given sub-maximal power, as this is very strongly correlated with my power for a 25 mile TT, so I look at my training bringing that HR down as a measure of how well it’s working.
All indoor training. Same temperature. Small fan from warm up to end. When I’m doing Long intervals at 4+ w/kg (20 minutes) I might get -9 for the interval.
?
If you are really interested in this detail you might also want to verify the humidity throughout the ride as that could have an effect. Something like turning on the a/c could remove humidity from the air as you ride, although I would suspect your body is adding just as much, if not more humidity to the space you are cycling in
Thomas—humidity would impact the pm right…maybe make it drift such that “250 watts†would both feel easier and require less work (lower hr) simply because it’s not the same 250 watts due to a decrease in humidity?
Power/heart rate is a surrogate for O2 pulse, or the product of stroke volume and arteriovenous O2 difference. As such, changes in power/heart rate (under the same conditions) would be indicative of changes in cardiovascular fitness. Performance, however, is more closely related to muscular metabolic fitness, so power/heart rate isn’t as useful as you might at first think.
That covers changes in power/heart rate across workouts, i.e., over days/weeks/months/years. Changes in power/heart rate within a workout would be indicative of cardiac drift. The latter can have many causes (e.g., hyperthermia, cardiac fatigue), but is diminished by endurance exercise training. Notably, however, there is no evidence or sound basis for relying on the magnitude of cardiac drift for determining when your “base” is sufficient. Furthermore, since the purpose of training is to improve performance, which is determined primarily by metabolic, not cardiovascular, fitness, attempting to minimize cardiac drift, per se, is focussing on the wrong thing.
Andrew—
Ok. I think I understand that. There’s no good reason to try to figure out what’s wrong with numbers that aren’t very useful to begin with.
Thomas—humidity would impact the pm right…maybe make it drift such that “250 watts†would both feel easier and require less work (lower hr) simply because it’s not the same 250 watts due to a decrease in humidity?
I wasn’t even thinking in terms of the PM, I was thinking in terms of the body’s ability to dissipate heat. Dissipating heat is half of the game, so if the humidity is lower because then you hr should come down for the same effort as it spends less resources to cool the body