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Old 07-13-2008, 07:27 PM   #11
George Mounce
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Re: physiology of energy pathways and implications

Sorry to see you go Steven. Good luck.

I really don't think any of us need to understand at all how the energy systems work, but we know they do.

Its kind of like flying, no pilot really cares how a compressor fan moves air into an ignition chamber for a jet engine, as long as it works.

The fact is that at a cert it was quoted "CrossFit will only get you in the top 20%". It has never been stated that CrossFit will make you the best at something. I have no idea where people get this idea. But lately people have felt the need to defend a fact the creators of CrossFit have stated as far as I have been doing it - I knew this wouldn't make me the greatest at everything. The fact is, I like bowling, and CrossFit isn't going to make me a better bowler. But I do know that I scored a 100 for 19 year olds on the USAF PFT - at the age of 30. I like when young kids wonder how they got their *** beat by a 30-year-old.

For Mil/LEO/first responders the fact is you never know what you will deal with. In specific sports you do. I highly agree that people who want to specialize (which is the basis of your argument) should specialize their training for what they are doing. As for general fitness CrossFit is a fine way to accomplish that, and those whose jobs are primarily venturing into the unknown its a great program.
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Old 07-14-2008, 09:43 AM   #12
Christin Street
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Re: physiology of energy pathways and implications

You are a wealth of knowledge, Steven, but I stopped listening to you because of your condescending, all-knowing tone. I'm just being perfectly honest with you. Without being asked, you assumed the role of Moderator countless times. Good luck to you and thanks for the help.
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Old 07-14-2008, 09:51 AM   #13
Phillip Garrison
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Re: physiology of energy pathways and implications

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Originally Posted by George Mounce View Post
Sorry to see you go Steven. Good luck.

I really don't think any of us need to understand at all how the energy systems work, but we know they do.

Its kind of like flying, no pilot really cares how a compressor fan moves air into an ignition chamber for a jet engine, as long as it works.

The fact is that at a cert it was quoted "CrossFit will only get you in the top 20%". It has never been stated that CrossFit will make you the best at something. I have no idea where people get this idea. But lately people have felt the need to defend a fact the creators of CrossFit have stated as far as I have been doing it - I knew this wouldn't make me the greatest at everything. The fact is, I like bowling, and CrossFit isn't going to make me a better bowler. But I do know that I scored a 100 for 19 year olds on the USAF PFT - at the age of 30. I like when young kids wonder how they got their *** beat by a 30-year-old.

For Mil/LEO/first responders the fact is you never know what you will deal with. In specific sports you do. I highly agree that people who want to specialize (which is the basis of your argument) should specialize their training for what they are doing. As for general fitness CrossFit is a fine way to accomplish that, and those whose jobs are primarily venturing into the unknown its a great program.
I disagree, on not needing to know. Having such knowledge gives you more power and effectiveness as an athlete. Knowing how they work, and why, and how to best minipulate them can allow to tweak your workouts to maximize your goals, and develop long term plans and strategies.
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Old 07-14-2008, 10:35 AM   #14
Elliot Fuller
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Re: physiology of energy pathways and implications

Quote:
Originally Posted by Christin Street View Post
You are a wealth of knowledge, Steven, but I stopped listening to you because of your condescending, all-knowing tone. I'm just being perfectly honest with you. Without being asked, you assumed the role of Moderator countless times. Good luck to you and thanks for the help.
To his credit, these are open boards where people ask open questions. This is the only time I've seen Steven "preach" without being asked, and after over a year here, it's one of the most interesting reads I've come across. Also to his credit, he is a somewhat community-made authority on many subjects that have been covered; not because he wants to be, but because he has the knowledge to be.

Call that being a Moderator if you like, but as far as I'm concerned, he's just very well informed. Correcting someone on his/her logic or post is not Moderating, provided that he's actually correct; and 90% of the time he is -- 10% margin of error

If you shut out everyone with a "condescending tone," odds are you wouldn't have nearly the amount of general knowledge that you do. While Coach G. and the affiliates, and the trainers, get paid to answer the same questions over and over and over and over again, the folks in the know on these boards (like Steven) do it for free, and without much thanks. So... I dunno. Your choice to tune it out, I guess... more knowledge for the rest of us

Edit: George, I gotta disagree with you on that one, too *gasp* I'm not a pilot, so obviously what I say has a lot less credibility, and I say it mostly for argument's sake. But when the "machine" is not a plane, but your own body, I think the knowledge of its inner workings are even more important. Yes, it's ok to not know how the lymphatic system works -- as long as it works. But what if something goes wrong or you spring a leak? It's important to recognize the symptoms of failure, the symptoms of progress, and the potential underlying causes of those symptoms in order to better understand what can be done to either avoid or obtain those results.

We can't always turn to the CrossFit injuries boards looking for answers (as much as I'd like to, heh) when something isn't working the way it should be.

As far as flying planes goes, you may be right in that respect. But as far as CrossFit and performance and the human body go, in my eyes it's a little different.
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Old 07-14-2008, 07:43 PM   #15
Steven Low
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Re: physiology of energy pathways and implications

Unfortunately, I realized today that I forgot to mention pretty much anything about lactic acid threshold training. I will rectify this (and this will be my last post.. I think, heh).

All links in next 2 posts WFS

-------------------------------------------------------

This post was originally posted somewhere else, but after I saw it and was earlier discussing with Brandon earlier today about it I decided to write a response detailing what is actually occurring. (This will be crossposting from PMenu forum -- sorry mods -- but I don't feel right posting a straight up link.


Quote:
From the P&B.....may be a bucnh of scientifical BS but what I'm hearing from folks I know still involved in the silliness that is bike racing thsi stuff pans out..in....you know... like in the real world and stuff.

........ the current thinking is that lactate per se isn't actually the cause of muscular fatigue. It is a fuel and actually may buffer changes in muscular acidosis and prevent fatigue (this is probably why high intensity warmup that actually generate some lactate seem to improve performance in the actual event, the lactate ends up buffering changes in acid levels).

However, Billat's thing is getting mired in a lot of semantic crap in my opinion. The old idea of the lactate or anaerobic thresholds (as originally defined) are likely garbage. However, this doesn't negate the existence of a threshold speed or intensity above which fatigue occurs very very rapidly. That it occurs is more important practially than what you call it or what is causing it.

The simple fact is that a runner may be able to maintain (and these values are pulled out of my butt)

10mph for essentially forever
10.5 mph for an hour but it works the hell out of them
11 mph and they fatigue in a few minutes

again, values are for example only.

clearly there is a criticial threshold point above which fatigue occurs rapidly. from a practical standpoint, that's essentially what the old ideas of LT/AT/OBLA/etc. were describing.

you can graph velocity versus time to exhaustion and see that kind of pattern. below some level, the athlete can go until they get bored or run out of muscle glycogen, around some point they are working very hard but can maintain speed for extended periods (cyclists will test 20' although an hour maximum time trial isa better indicator), above that point and fatigue hits like a hammer after a few minutes.

It's actually looking like H+ production (rather than lactate per se) is the cause of this. It's also turning out (going to ccrow's point) that the aerobic engine is a much bigger determinant of this than previously thought. Mitochondria buffer acid levels and the bigger the aerobic engine, the less acid is produced.

A common trend in a lot of endurance sports is going back to volumes of low intensity aerobic work with just a bit of higher intensity stuff thrown on to top off the system (the system adapts quickly but stops adapting equally quickly, some of hte interval studies in cyclists show that 6 workouts across 3 weeks pretty uch maximizes the benefits)).

An example, there's a paper describing the training of the german track cycling team in the 1km (or was it 4k). An event last 4 minutes which most would argue is highly anaerobic. Most of their training was easy aerobic with some stage racing and a bit of specific track training thrown in at the end.

As I recall, a typical rowing race is roughly 6 minutes and even there they are going back to volumes of low intensity work to build the aerobic engine.

There's also an old idea (Maglioscho's book gets into this) that too much high intensity training can actually degrade the aerobic engine which *might* be what the US Rowing team was experiencing: if their caoches emphasized too much work around or at LT (or high intensity intervals) and lose aerobic engine size, that could actually be detrimental.

Translation of my long-winded crap: it may be better over extended periods of training to build this engine (again going to ccrow's comment) with lower intensity aerobic work. This can be topped off with higher intensity stuff as needed.

Maybe the boxer and martial artists who did extended road work weren't so wrong after all.
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Old 07-14-2008, 07:44 PM   #16
Steven Low
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Re: physiology of energy pathways and implications

And this is my response (sorry mods I keep hitting word limit):

--------------------------------------

Muscular acidosis is due to the hydrolysis of ATP to ATP and other substrates being used for energy in the muscles.

Basically what happens is this:
ATP + H2O → ADP(hydrated) + Pi(hydrated) + H+(hydrated) ΔG˚ = -30.54 kJ/mol (−7.3 kcal/mol)


Lactic acid is directly through the following equation (FYI pyruvate is the end result of glycolysis):
Pyruvate + NADH <-> Lac + NAD+

The reason why this doesn't actually produce a H+ ion is because pyruvate itself is already a carboxylic acid Ch3-CO-COOH which is deprotonated already at body pH. Therefore, it's already pyruvic acid (pyr- + H+ + NADH <-> Lac- + H+ + NAD+) where the H+ cancel on each side of the equation. This stoichiometric mistake was why people THOUGHT lactic acid was the cause of acidosis; however, as you can see this is not true.

Lac has a pKa of ~3.85 which means that at equilibrium in the body some of the lac will be pronated but most will have no H on the carboxylic acid. However, as the pH drops, a greater proportion of the carboxylic acid becomes pronated thus effectively buffering acidosis as described above.

----------------------------------------------


Alright, here's the fun part which I was actually just discussing today with someone regarding the "lactic acid threshold." What is actually happening here is a couple of things.

Basically, what happens when intensity becomes high enough (thereby increasing demand in energy) is that the body needs to produce energy. The oxidative pathway becomes bottlenecked at pyruvate/acetyl-CoA because it cannot handle the load of NADH that is being produced. Thus, NADH accumulates.

The reason why NADH accumulating is bad is because glycolysis uses the non-hydrogenated carrying form of NADH (namely NAD+) to produce NADH. Thus, lactic acid is produced for the body to change the extra NADH back to NAD+ so that glycolysis can keep running.

Here's the brilliant illustration I thought up today. Think of the oxidative pathway as a pipe. This actual "pipe" consists of the citric acid cycle (or TCA/kreb's cycle whatever you want to call it) which consists of 10 steps, transport of electron carrying coenzymes such in the form of NADH and FADH2 (from glycolysis and CAC) from the cytoplasm into the mitochondria along with ADP, dumping of electrons into the proteins of the mitochondria wall (the electron transport chain) whereby these proteins pump H+ across the membrane to create a H+ gradient. This gradient is then harnessed by ATP synthase to produce ATP. NAD+ and ATP must be shipped out of the mitochondria into the muscles. This takes some time obviously to get "running."

Note: this also why people with large aerobic engines are also buffered well against acidosis because their mitochondria pumping H+ across the membrane provides a greater buffering effect.

In any case, glycolysis is a simple pathway which consists of about 10 steps all of which occur in the cytoplasm. This occurs very quickly because ADP is readily available because the myosin-actin is close by and need very little transport activity.


Thus, let's take into account the scenario from the original/cross post:
Quote:
10mph for essentially forever
10.5 mph for an hour but it works the hell out of them
11 mph and they fatigue in a few minutes
10 MPH:
At 10 mph the effect of what is happening is that the glycolysis funnel (we'll just call it a funnel) dumps NADH and pyruvate into the oxidative "pipe." It can handle the capacity. Thus, it can basically run forever without getting overloaded.

10.5 MPH:
What happens at 10.5 MPH when it is slightly overloaded is that there is some spill over out of the glycolytic "funnel" that the oxidative "pipe" cannot handle the total volume. Thus, what occurs is that the pyruvate is converted to lactic acid to use up the NADH converting it back to NAD+. This allows the glycolytic cycle to continue to provide energy to the muscles because there is a limited amount NAD/NADH in the body. However, since there is "little" spill over, the body can handle the pace and keep continuing.

11 MPH:
Now we arrive at 11 MPH. What is occurring here is that there is a large spill over out of the glycolytic pipe as glycolysis consumes a lot of the muscles glycogen stores very quickly. Since there is a large spill over, the body can only convert some of the pyruvate to lac to generate NAD+. Thus, it can only keep producing a limited amount of energy as the lac keep accumulating. Eventually you will reach a point where there is too much ADP (and hence pH drops enough) that glyolysis + oxidative pathway cannot keep up to reproduce ATP. This leads to muscular failure.

Here's a nice picture I made in paint to illustrate the above (click to enlarge):
http://img235.imageshack.us/img235/9...holdei6.th.png

In any case, what is also interesting is the adaptations that occur because of the former scenarios.

10 MPH:
With the 10 MPH that is sustainable, it clearly strongly work the oxidative "pipe" at max capacity for a long time. This produces a strong response on the oxidative pathway increasing mitochondria, type I fibers, and other aerobic changes which is why you NEED to do long distance work to build up a sufficient aerobic base if you ever plan on competing in elite long distance racing.

10.5 MPH:
What happens here is that since there is an overflow of the glycolytic funnel, the glycolytic pathway is stressed as the glycolyticenzymes need to keep up with the rate as NAD+ is resynthesized quickly. The oxidative pathway is stressed because it is working at full capacity, but the duration is shorter than the former. What you end up with is some increases in anaerobic and aerobic qualities in the muscles.

11 MPH:
This is the interesting concept because it shows clear "pushing" against the "lactate" threshold. So basically since there is a large overflow from the glycolytic funnel we get an extremely strong stress on the glycolytic energy pathway. This induces strong anaerobic changes in the muscles. However, since the duration is extremely short, the oxidative pathway receives little to moderate stress resulting in only poor-decent gains in aerobic fitness UNLESS this is continually pressed through for a while. For example, a HIIT session that continues after you get gassed or a metcon that keeps going a couple minutes longer after max intensity drops will help produce aerobic changes.

This is why HIIT/tabata/metcon all have the tendency to produce anywhere from mediocre to strong aerobic changes as well as strong anaerobic changes in energy pathway metabolism.

Basically, for longer duration rowers/runners/etc. this is COUNTERPRODUCTIVE because they do not need improvements in the anaerobic engines which will induce changes that will counteract their aerobic engines. This is easily observable and agrees with the OP & anecdotal evidence.


I think that's about it. Hope you learned something. Enjoy.

Steve
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Old 07-14-2008, 08:07 PM   #17
George Mounce
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Re: physiology of energy pathways and implications

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Originally Posted by Phillip Garrisonq View Post
I disagree, on not needing to know. Having such knowledge gives you more power and effectiveness as an athlete. Knowing how they work, and why, and how to best minipulate them can allow to tweak your workouts to maximize your goals, and develop long term plans and strategies.
I'm interested at how you would tweak energy pathways to improve my bowling score. My goal is a 250 average by October.

My guess is the best plan is beer and bowling.

You can PM me the answer, as I'm leaving this thread. I have to agree with Christin - there is a difference between providing helpful information (see just about any of Gant Grimes posts and experiments) and just throwing stuff out there. The basic principles of the energy systems are just about anyone would need to get into, not a graduate level discussion of their application, because for the vast majority here it means absolutely nothing.

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Old 07-15-2008, 12:05 AM   #18
Steven Quadros
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Re: physiology of energy pathways and implications

Great information, certainly worthy of multiple read throughs.

Thank you Steven, I suppose I'll see you over at P menu, where your material seems to go over better.
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Old 07-15-2008, 06:23 AM   #19
Tirzah Harper
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Re: physiology of energy pathways and implications

Wow. I need to read this on a rest day sometime and figure out how exactly that breaks down to real life.
See you on the PM forums.
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Old 07-15-2008, 06:30 AM   #20
Brandon Oto
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Re: physiology of energy pathways and implications

It took me a while to sort out this stuff in my head, so here's my basic understanding in a somewhat simplified form. Read this then reread Steven's stuff, it may make more sense.

THIS IS JUST MY UNDERSTANDING, IT IS PROBABLY WRONG IN SOME WAYS. Science types, please check work.


For those who skipped bio, just remember that ATP is the fuel source for your muscles.

1. The first result of work output is that you use ATP in the muscles. This only lasts a few seconds. It is recharged by the phosphocreatine process, which is a closed loop that looks like this: Pcr + ADP <--> Cr + ATP. In other words, you have Pcr (phosphocreatine) floating around, which is a short-term energy store; when you use up available ATP, Pcr immediately combines with ADP (basically the used-up ATP) to produce more ATP and replace it. The byproduct of this is Cr (creatine), which can then combine with the ATP again to get you back where you started. It's a closed system with only energy going in and out.

Note: yes, when you take creatine, the idea is to increase the amount of fuel that's stored in this way as Pcr.

2. After this, glycolysis becomes the dominant energy source. The fuel path here is glucose->glycogen->glycolysis->ATP. Glucose is sugar, glycogen is the form it's stored as in your muscles, glycolysis eats up glycogen to make ATP. Glycolysis is a more complicated process, but the relevant portion of the reaction is: glycogen + NAD+ -> pyruvate + NADH + ATP.

Note: glycolysis (and PCR, to the extent that it does anything) is a very INEFFICIENT process. That is, for each unit of input (glucose), it produces very little ATP. However, as long as it lasts, it has a high max output, and can be "ramped up" very fast.

3. Finally, we have the aerobic process, which has various names. This one's MUCH more complicated but again the relevant bits are: pyruvate, NADH, and other stuff (oxygen, fat, even protein, etc.) becomes NAD+, other stuff (carbon dioxide, etc.), and of course ATP.

Note: You'll notice that some of the outputs of glycolysis are inputs for oxidative (pyruvate and NADH) and some of the outputs of oxidative are inputs for glycolysis (NAD+).

4. So during intense exercise, it can happen that oxidative is basically "not going fast enough," in the sense that it's not turning NADH into NAD+ fast enough. Since glycolysis needs NAD+ to work, this creates a bottleneck, where glycolysis has to "wait" for its NAD+ from oxidative. This is no good.

5. This situation is solved by a supplementary process. Since we need to turn some of this NADH into NAD+, we can do it by combining NADH with pyruvate, and producing NAD+ and something new called lactic acid. So we're basically solving our NADH --> NAD+ throughput problem by producing some lactic acid as a side effect, and glycolysis continues apace.

Note: what happens to all this lactic acid? When the body starts to deplete its glycogen reserves (which glycolysis needs, and oxidative needs its stuff from glycolysis, so this is bad for everyone), one of the ways that oxidative keeps up the output is by reversing the reaction in #5. That is, lactic acid production was done this way: pyruvate + NADH <--> lactic acid + NAD+. Since this is a reversible reaction, we can now run it the other way, and turn lactic acid and NAD+ (glycolysis fuels) into pyruvate and NADH (oxidative fuels) and therefore keep running oxidative a while longer.

6. Okay, where does this process fall apart? From what I can tell, it's due to two things:

First, you can only produce lactic acid so quickly, so if intensity rises enough, then it outstrips our "lactic acid solution"; we'll come back to the original problem of not enough NAD+ for glycolysis, and once again we simply aren't producing enough ATP.

Second, the process of actually using ATP in the muscles turns it into ADP and a free-floating hydrogen ion (H+). This is normally fine because they get recombined during glycolysis, but since we're now expending ATP faster than we generate it, we're gathering a bunch of ADP and H+ milling around. Lots of H+ means we're getting increasingly acidotic (PH is dropping), and this causes more problems for the above processes. I'm not quite clear on what these problems are, but either way the basic issue is obvious -- we're not turning ADP and H+ back into ATP fast enough.

Note: this rate-based failure (working harder than you're making energy) should not be confused with running out of fuel. After enough work, you'll simply exhaust the available glycogen faster than it can be replenished, at which point the oxidative system becomes dominant simply because glycolytic can't do much anymore. (Oxidative can keep working because it can use other fuels, such as fat, aside from the pyruvate output from glycolysis.)

Also note: ALL of these systems are ALWAYS working -- why? Well, because you weren't created two seconds ago, so it's not like the "clock" just started, followed by Pcr, followed by glycolysis, etc. So they're all running concurrently. However, it is true that they don't all respond at the same speed; the reason we order them like this is because the later stages have higher "latency," or take longer to increase output. If we suddenly start sprinting, oxidative may take thirty seconds, a minute, whatever before it's increased its output commensurately. Combine this with the fact that its maximum output per unit of time is less than the anaerobics, plus the fact that the latter can be exhausted (PCR or glycogen run out), and you understand why we call them "short term" and "high power."

I'm more confused on the adaptations point, so I'm going to hold off on summarizing that until I can confirm it.
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