This has long been a point of debate between a few of us;
Does caloric burn increase as you increase power (w) output. In a static environment it seems that it does based on the math that’s been described above.
But what isn’t accounted for is the human body adapting and becoming more efficient over time to do the same amount of work.
**You make a fat guy who sits on the couch hold 400w for an hour he’s going to burn a LOT of calories. You get a guy who rides national level TT to the same amount of work, I don’t know if he’s going to have the same caloric burn. **
In the latter case he has become more efficient over time at doing the same amount of work, and therefore should have a lower caloric burn. So does the human body adapt to work over a period of time, and does that result in a lower caloric burn for the same amount of work done in a previous period?
Not a very good analogy since most “fat guys on the couch” could not hold 400 watts for more than 60 sec at the most, unless they just happen to be ex-cyclists who gained a bunch of weight:)
haha you guys get too caught up in literal comments and chase the rabbit down the hole.
it was an analogy plain and simple, meant to take something to a bookend point as a test.
haha you guys get too caught up in literal comments and chase the rabbit down the hole.
it was an analogy plain and simple, meant to take something to a bookend point as a test.
It was specifically a tweet by a Willet (can never keep Kraig/Kirk straight, sorry) that got me looking at that.
The “at best CTL is redundant, at worst misleading”
In my n=2 case it looked more like at worst it is redundant, and best it is enlightening. It happened to be the redundant case that I found first, so I was like OH MAYBE WILLET IS RIGHT!
For someone of normal height that is 30mph territory.
Ya, I started to qualify it by saying “or unless he’s really naturally gifted” but OTOH I did say “most” so I was covering that possibility. JOOC, assuming decent aero-ness, what type of time for the 40K TT would 400 watts for an hour give you, something like 27-28 mph or so???
Well, in that case, I’d say that “most fat untrained guys on the couch” could not even reach, even for 2 seconds, a speed of 30 mph on a flat road with no tailwind; at best they might hit 30 mph for 0.1 sec as their top speed in an all-out sprint before slowing down and stopping gasping for breath:)
For example, in a study we’re conducting right now of heart failure patients (so low absolute power and VO2 data, combined with little-to-no cycling experience) gross efficiency as determined using a ParvoMedics cart and Lode cycle ergometer has still been reproducible to w/in +/- 0.3% in an absolute sense and +/- 2% in a relative sense. That’s about as good as it gets, and means that we’d need to study <6 subjects/group to detect a difference of the magnitude reported by Hopker et al. (i.e., 1.4% absolute) with an alpha of 0.05 and a 1-beta of 0.90.
Thanks for that info! I don’t see you getting much better reproducibility, especially when humans are involved.
Yeah, I wasn’t so much thinking that it was the measurement method as much slow components not achieving any form of steady-state with the ramp protocols. Ten minutes versus three is decidedly different. With breath-by-breath (and resolution you’re getting), you might be able to see the exponential/log response in VO2/VCO2 coming from each step response in intensity. Would wonder if the time constant/magnitude of that step response might tell you something, or may overconstrain the data.
I’ll fully admit that I’m outside of my knowledge depth, so please correct me if I’m wrong. I’m an electrical engineer, so the signals part of the deal makes sense, but my understanding of the underlying processes is far from robust.
I wasn’t so much thinking that it was the measurement method as much slow components not achieving any form of steady-state with the ramp protocols. Ten minutes versus three is decidedly different.
True, that could be part of it. That is, steady-state VO2 could be lower in highly-trained cyclists, but their VO2 kinetics would also be faster, such that during shorter stages the net-net is no difference from the untrained state. During longer stages, however, the difference in economy/efficiency would emerge.
(We’re using 6 min stages since VO2 kinetics are slowed in heart failure.)
With breath-by-breath (and resolution you’re getting)
Just an FYI: The ParvoMedics cart uses a mixing chamber, so while it calculates respiratory gas exchange for every breath, it isn’t a true breath-by-breath system (which would require sampling FeO2 and FeCO2 at the mouth). That is probably precisely why we’re getting really “clean” data, i.e., true breath-by-breath systems are notoriously problematic.
Thanks again! Lots of condensed info there to digest.
Totally makes sense “mechanical averaging” on the ParvoMedics cart. I knew that breath-by-breath systems were noisy, but assumed (knowing well the true meaning of that word) everyone was doing heavy filtering in-post. (Kalman?) I’m probably wrong about the filtering being done.
when you consider we are about 25% efficient at cycling, ie the 400w you produce at ftp(cuz we are on slowtwitch) requires the body to expand ~1600w to produce that 400w to the pedal. more or less
Or when like when I expend maybe 250W on average swimming in a 83F pool, I turn slightly red trying to get blood to the surface of my skin to cool the 750W of heat I’m releasing. Meanwhile the old hippos doing aquacise are expending maybe…being generous here… 50W, and have 150W of excess heat… all of which they need just ot keep warm.
I love it when they try and tell me that I’m just working harder and get a better workout being hot… you know because sweat rate indicates quality of work performed…always.
What? A guy averaging 400W for an hour did twice as much work as a guy who did 200W for an hour. Work done in kJ is close enough to the number of Calories burned. How did you get 7.5 times?
