What surprises me a bit is that in the article of Keir et al. you highlight, lactate is described as a byproduct/waste product. They don't even acknowledge (figure 1) that lactate is an important substrate for the Krebs cyclus. According to some it's the essential substrate (Lactate as a fulcrum of metabolism by George A. Brooks (Redox Biology 35, 2020)).
It doesn't make a difference in your analysis here, but I'm interested in your opinion on this.
How do you see the role of lactate in muscle metabolism during exercise?
Hi Marco, fascinating article as always. Two follow-up questions
1). Do you know anything about using DDFA from a heart rate monitor to measure thresholds? I get this data from pretty much every run
2). What are some primary ways to improve economy? I assume just running more is a big one, but is there anything we can do diet-wise or during our daily lives?
2) Indeed running more (think years) should be a big driver of changes, as well as in the short term the specificity of training (e.g. running the pace you are racing). Other effective ways could be strength training and plyometrics (see Zanini et al.).
So interesting as always!!! I wanted to ask you if lactate, which is a measurement much more affordable than indirect calorimetry, can be useful in any way to identify limiters in the physiological profile of an athlete, thanks!
Lactate can be very useful in the context of assessing overall progress (a shift of the curve to the right), or to identify the first threshold (and therefore the boundary between easy and not-so-easy training), which can be informative for training prescription or pacing in races. What lactate cannot tell us is running economy or substrate utilization, for that we need to look at gas exchange (O2/CO2). Hence in this case unfortunately we need a more expensive tool. You can find some more thoughts on Lactate specifically, here: https://marcoaltini.substack.com/p/coachcorner-understanding-lactate
More seriously, I have always been fascinated by energy economy. Especially with uncoupling phenomenom in the ETC in mitochondria. I wish I understood more these things like the role of brown adipose tissue, etc.
I have always wondered if this machinery is part of the ability of some people to stay lean despite eating a ton or to get bigger just watching at a cake at the pastry shop.
A very savvy nephrologist friend of mine has just sent me a nature metabolism paper on FGF21 to drive the uncoupling in adipose tissu mitochondrias, thus "loosing energy" and enhancing energy intake by mouth to maintain weight.
Maybe chilly skinny people have a little bit less of uncoupling... but I stop there I feel like I'm on the edge of doing chinese medicine !!
So I can't wait to see if the rise in protein intake you get through PN will also lower FGF21 and make your ETC more coupled ;)
wow, really great to share these experiences with us Marco, expect a french guy to ask you soon about a low intensity test in April before the Crossing Tuscany Trail Run ;) You will have the n=1 of a guy not periodizing his nutrition but just cleaning it.
I liked the read! However, I find it always worrying when substrate utilisation is interpreted from VO₂max ramp data. During these non–steady-state tests, RER often exceeds 1.0, which can create the illusion that fat oxidation has completely “shut off” (which your graph also suggests) when in reality it hasn’t. Fat and carbohydrate metabolism always coexist; RER >1 mainly reflects buffering of accumulating lactate, not the true absence of fat use.
thanks Bart, I agree of course, in fact I think I’ve explained it at least three times in the blog, plus introduced a protocol to address the issue with long steady steps when it comes to substrate utilization or economy :)
Absolutely and I appreciate that you introduced the longer steady-state protocol later in the piece. My comment was more about the figure. A figure says more than a thousand words and when the graph suggests that 100% of energy is coming from carbohydrates at the end of the ramp...
hi Pedro, if you are only interested in ventilation, it can be a proxy (I’ve seen quite some differences in my data but still, I find it an interesting signal so far). I might write more about it in the future
I’ve been testing the Tymewear for the last month and I’ve found it pretty inconsistently off when running. I’ve tested against a metabolic cart (VO2 Master) as well; I specialize in ventilatory side of exercise. The easiest way to understand that VT1 is getting adapted to easy nose breathing at below HRZ2. Once easy nose turns into power nasal or mouth, you’ve crossed. You can’t hide the bodies response to CO2 which we further assess at rest as well to determine how people are generally handling stress and energy.
Hei Marco,
Interesting read as always, thanks.
What surprises me a bit is that in the article of Keir et al. you highlight, lactate is described as a byproduct/waste product. They don't even acknowledge (figure 1) that lactate is an important substrate for the Krebs cyclus. According to some it's the essential substrate (Lactate as a fulcrum of metabolism by George A. Brooks (Redox Biology 35, 2020)).
It doesn't make a difference in your analysis here, but I'm interested in your opinion on this.
How do you see the role of lactate in muscle metabolism during exercise?
thanks Hans! Agree with you and Brooks, I was probably focusing only on the ventilation side of things when reading the paper!
Hi Marco, fascinating article as always. Two follow-up questions
1). Do you know anything about using DDFA from a heart rate monitor to measure thresholds? I get this data from pretty much every run
2). What are some primary ways to improve economy? I assume just running more is a big one, but is there anything we can do diet-wise or during our daily lives?
thanks Joshua!
1) On DFA, see here: https://marcoaltini.substack.com/p/q-and-a-what-are-your-current-thoughts
2) Indeed running more (think years) should be a big driver of changes, as well as in the short term the specificity of training (e.g. running the pace you are racing). Other effective ways could be strength training and plyometrics (see Zanini et al.).
So interesting as always!!! I wanted to ask you if lactate, which is a measurement much more affordable than indirect calorimetry, can be useful in any way to identify limiters in the physiological profile of an athlete, thanks!
grazie Francesco!
Lactate can be very useful in the context of assessing overall progress (a shift of the curve to the right), or to identify the first threshold (and therefore the boundary between easy and not-so-easy training), which can be informative for training prescription or pacing in races. What lactate cannot tell us is running economy or substrate utilization, for that we need to look at gas exchange (O2/CO2). Hence in this case unfortunately we need a more expensive tool. You can find some more thoughts on Lactate specifically, here: https://marcoaltini.substack.com/p/coachcorner-understanding-lactate
Thank you again!
Grazie mille!
More seriously, I have always been fascinated by energy economy. Especially with uncoupling phenomenom in the ETC in mitochondria. I wish I understood more these things like the role of brown adipose tissue, etc.
I have always wondered if this machinery is part of the ability of some people to stay lean despite eating a ton or to get bigger just watching at a cake at the pastry shop.
A very savvy nephrologist friend of mine has just sent me a nature metabolism paper on FGF21 to drive the uncoupling in adipose tissu mitochondrias, thus "loosing energy" and enhancing energy intake by mouth to maintain weight.
Maybe chilly skinny people have a little bit less of uncoupling... but I stop there I feel like I'm on the edge of doing chinese medicine !!
So I can't wait to see if the rise in protein intake you get through PN will also lower FGF21 and make your ETC more coupled ;)
wow, really great to share these experiences with us Marco, expect a french guy to ask you soon about a low intensity test in April before the Crossing Tuscany Trail Run ;) You will have the n=1 of a guy not periodizing his nutrition but just cleaning it.
anytime my friend!
ottimo ! The big uncertainty is : can I bring you some speciality chocolates from my area or it's gonna break your PN plan ?
haha dark chocolate only!
sadly for you the best are with some very good praliné but I put your answer in a corner of my memory
haha I can make an exception in this case :)
Hi Marco, great article! Do you provide the testing for athletes you don’t coach as well? I would be interested
thanks Martin! I'd love to in the future, something we are working on setting up
I liked the read! However, I find it always worrying when substrate utilisation is interpreted from VO₂max ramp data. During these non–steady-state tests, RER often exceeds 1.0, which can create the illusion that fat oxidation has completely “shut off” (which your graph also suggests) when in reality it hasn’t. Fat and carbohydrate metabolism always coexist; RER >1 mainly reflects buffering of accumulating lactate, not the true absence of fat use.
thanks Bart, I agree of course, in fact I think I’ve explained it at least three times in the blog, plus introduced a protocol to address the issue with long steady steps when it comes to substrate utilization or economy :)
Absolutely and I appreciate that you introduced the longer steady-state protocol later in the piece. My comment was more about the figure. A figure says more than a thousand words and when the graph suggests that 100% of energy is coming from carbohydrates at the end of the ramp...
True! Thank you Bart for the feedback, appreciate it
Any thoughts on the Tymewear HR band, that supposedly has great correlation with a Cosmed K5, maybe a possible review?
hi Pedro, if you are only interested in ventilation, it can be a proxy (I’ve seen quite some differences in my data but still, I find it an interesting signal so far). I might write more about it in the future
I’ve been testing the Tymewear for the last month and I’ve found it pretty inconsistently off when running. I’ve tested against a metabolic cart (VO2 Master) as well; I specialize in ventilatory side of exercise. The easiest way to understand that VT1 is getting adapted to easy nose breathing at below HRZ2. Once easy nose turns into power nasal or mouth, you’ve crossed. You can’t hide the bodies response to CO2 which we further assess at rest as well to determine how people are generally handling stress and energy.
thank you Brian for sharing your experience!