anEconomist wrote:
i have my phd in finance, if i get in argument with someone about finance and they clearly don't know what they are talking about i can just cite them the relevant studies and tell them where I am getting my information and where they might find it
Exactly! Phoenix has his b.s. Ph.D. and wants to argue, but cannot provide any documentation to support his claims. Thanks for the backup, anEconomist.
spaniel wrote:
TRY to learn something before acting like you know something and arguing with someone like Phoenix who actually knows what he's talking about. Lactate cannot be metabolized without oxygen, so if you're low on oxygen under heavy exercise you are not using it for a fuel source. It is only after oxygen levels increase with decreased/ceased activity that lactate will be recycled as fuel.
Rising wrote:
Was this addressed to me? I was not arguing with Phoenix whatsoever. I was ASKING him.
Yes, of course he addressed it to you (despite his backtracking now). For proof: 1) he quoted YOU in the post, and 2) the 'reply to' has your name.
Be a man, spaniel, and admit when you're wrong.
Phoenix wrote:
wellnow wrote:After that, all energy systems are Aerobic, including the use of Lactate as a muscle fuel.
Whatever you may have read or heard to the contrary is wrong, and just plain bad science.
wellnow, you are plain wrong and plainly unfamiliar with basic metabolic biochemistry.
The end product of glycolysis is lactate. Mitochondria can directly metabolize lactate or its precursor for energy via the TCA cycle. For mitochondria to utilize lactate directly, mitochondrial lactate dehydrogenase (MLDH) converts imported lactate into pyruvate first.
Production of lactate can indeed outpace the ability of mitochondria uptake and metabolize lactate hence the accumulation of blood lactate with intense exercise. Under these conditions active glycolysis is still producing ATP and therefore energy. Because this energy production does not acutely require oxygen it is aptly termed anaerobic.
I am not sure what your background is. Please describe and I would be happy to write at a level suitable to your background.
Also, if you wish to refute my argument, please provide a detailed description of the biochemical model you support and describe how that model refutes what I have written. You should also cite the sources to back up your model.
Phoenix
Hi Phoenix, thanks for posting.
You might have guessed by now that there are 2 wellnows on this thread. I started this thread, and I don't have a PHD or an MS.
However, I am aware of the research done by Brookes et al and Robergs et al in metabolic biochemisty.
I am therefore very much aware that glycolysis does not require oxygen. However, since Lactate is oxidized, the term "Going Anaerobic" should not be applied.
On another thread, you stated that the term anaerobic respiration is a paradoxical misnomer, since respiration implies oxidation.
Don't you think that it's about time this confusion was cleared up? I certainly do.
wtf?
spaniel wrote:
Lactate cannot be metabolized without oxygen, so if you're low on oxygen under heavy exercise you are not using it for a fuel source. It is only after oxygen levels increase with decreased/ceased activity that lactate will be recycled as fuel.
midwaste wrote:
you actually sounded like you knew what you were talking about until this paragraph.
spaniel wrote:
Really? Then point out what part of that paragraph is wrong.
I think I can off further debate on this little sidebar. I suspect that when you said "so if you're low on oxygen under heavy exercise you are not using it for fuel", he probably thought that the word "it" was referring to "oxygen", and not to "lactate" as I think you intended. This is a reasonable reading since "oxygen" is mentioned closest to "it". THAT assertion would have been wrong, would it not?
Or are you just upset because I called out a dimwit who understands nothing of metabolic biochemistry but starts a thread trying to act like an expert?
While I understand you are referring to "wellnow" here, I freely admit that I also am quite the dimwit but always willing to learn.
Funny thread.
Now let's run!
One other question Phoenix. On another thread you also stated that Cytosolic lactate concentrations exceed pyruvate by ten times. Brooks has stated that cytosolic lactate exceeds pyruvate by an order of magnitude. Others have stated that lactate is the prefered fuel during exertion.
Given these statements, how can references to aerobic and anaerobic exercise and the proportions of the contributions of each be considered to be realistic, and not just complete guesses on the part of the researchers?
spaniel wrote:
Rising wrote:Yes. That's "adenosine triphosphate" or something close to that, right? (Unlike you guys, I am a complete amateur at this). And as I understand it, ATP is the immediate energy source.
So roughly speaking (very roughly), as I understand it
glycogen + oxygen --> ATP and lactate
Then lactate + oxygen --> more ATP
And the reason that these processes start up in earnest at faster paces is that far fewer oxygen molecules are required to make the same amount of ATP.
About right?
No, completely wrong.
Glycogen --> glucose --> lactate and ATP (anaerobic)
or
Glycogen --> glucose --> lactate and ATP --> pyruvate + oxygen --> CO2 and lots more ATP (aerobic)
Both pathways are always functioning to some extent, so it is false to say you are aerobic or anaerobic exclusively. However one pathway or the other can predominate. Anaerobic respiration can only continue to a certain point before fatigue occurs.....the percentage you are operating over the threshhold where you are no longer clearing lactate dictates how long this will be. Not that lactate necessarily is directly causing the fatigue, but its level is correlated with the onset of fatigue.
TRY to learn something before acting like you know something and arguing with someone like Phoenix who actually knows what he's talking about. Lactate cannot be metabolized without oxygen, so if you're low on oxygen under heavy exercise you are not using it for a fuel source. It is only after oxygen levels increase with decreased/ceased activity that lactate will be recycled as fuel.
spaniel, there is no anaerobic respiration from lactate. I made this point on another thread, and it generated a rather interesting argument. That is to say people were arguing with Phoenix on the point. Phoenix agreed with me.
I would like him to share his views on this subject some more.
You say that lactate cannot be used as fuel if you are low on oxygen, but actually, there is never a shortage of oxygen in the muscles to prevent lactate oxidation.
wellnow wrote:
You say that lactate cannot be used as fuel if you are low on oxygen, but actually, there is never a shortage of oxygen in the muscles to prevent lactate oxidation.
Actually this can happen when you go anaerobic.
The argument that your muscles are never short of oxygen is flawed to the core. Refer where you are getting this information. They usually measure vascular oxygen levels....these are not a surrogate for cytoplasmic concentrations. Delivery from the vascular system to the mitochondria is a significant process.
To look at it from a purely observational standpoint, why would you need to breath harder if you're never depleting your oxygen levels? And why do lactate levels increase with high exertion? By your theory there should never be an increase as there's always plenty of oxygen around to obviate the need for increased ATP production from glycolysis.
And I never said there was anaerobic respiration FROM lactate, but that lactate is the result of this process. Seriously, get a basic biochemistry book and read it.
Show me any evidence that there is ever a lack of oxygen in muscles in high intensity exercise?
It has been argued for more than twenty years that lack of oxygen is not the reason for lactate production, Brook's lactate shuttle hypothesis 1984.
Why do we breathe harder, why do lactate levels increase with high exertion?
Because core temperature is rising during high exertion and we need to recruit more muscle fibers to maintain the pace. As the workrate increases, Pyruvate entry into the mitochondria cannot supply all the fuel fast enough to meet the energy demand, and Lactate production and its oxidation increases.
As for Anerobic respiration, this term cannot be applied to lactate prodution, since lactate cannot be respired anaerobically, it can only be produced anaerobically.
As for reading basic chemisty books, that is not usually a reliable source of information, since the text nearly always contains many flaws.
spaniel wrote:
To look at it from a purely observational standpoint, why would you need to breath harder if you're never depleting your oxygen levels?
An increase in breathing rate has more to do with CO2/H2O exhalation than O2 inhalation in response to increased anaerobic metabolism.
[quote]spaniel wrote:
To look at it from a purely observational standpoint, why would you need to breath harder if you're never depleting your oxygen levels? And why do lactate levels increase with high exertion? By your theory there should never be an increase as there's always plenty of oxygen around to obviate the need for increased ATP production from glycolysis.
./quote]
funny that you would criticize someone for using a flawed argument, and then use one yourself.
Thanks Ray, I think I know who the imposter is. Of course I didn't say Phoenix had a bullshit Ph.D
I don't agree with everything Phoenix says, but the imposter just wants to stir up trouble.
Well, good thing you got back to us...um... 20 MONTHS after the fact to clear that one up. Did you hear that Obama was elected president?
wellnow wrote:
The only true sources of energy for muscle contraction which can be described as Anaerobic, are the stored Phosphates which last approximately six seconds at the start of an effort. After that, all energy systems are Aerobic, including the use of Lactate as a muscle fuel.
Whatever you may have read or heard to the contrary is wrong, and just plain bad science.
It's about time this confusion was rectified, so that people involved in all sports can be given better training advice.
I think you need to be Rectified.
I have addressed the issues much better in this thread:
http://www.letsrun.com/forum/flat_read.php?thread=2289921&page=19