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  #11  
Unread 05-24-2011, 08:04 PM
Zé Apelido Zé Apelido is offline
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whoops yes I did, excuse the tangent!
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  #12  
Unread 12-26-2011, 10:00 AM
FutureisNow FutureisNow is offline
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Default Silly question?

This has been bugging me ...

Why wouldn't the energy required to return the body to its original state be equal to the energy released during the exercise?

For example, if you discharge a battery, you will need to recharge it with as much energy as was spent, in terms of watts at least.

Or say you wind up a rubberband airplane. The energy spent winding it is released when it unwound. Then it would require that amount of energy to rewind so it's ready to fly again.

So if exercise burned 400 calories, why wouldn't it require 400 calories of energy for the body to reset to its previous state?

By this, EPOC (or whatever else it may be called), would be 100% of the energy spent, which I admit sounds fishy but where is the flaw in this logic?

Not looking for a dieting short-cut, just curious about the creative accounting...

Thanks!
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  #13  
Unread 12-26-2011, 02:21 PM
CleanSnatch CleanSnatch is offline
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Part of the energy expenditure is like using currency or a debit card, the other part is via a loan such as a credit credit.

Eg: if you want to spend $100 on a gift and only have 40 in cash and borrow the other 60 (via say an unsecured loan such as a credit card) then your "EPOC" is only $60. You need to pay back your creditor (your lactate system) to the tune of $60 to return yourself to zero debt. The 40 dollars damage to your wallet is like the fats and glycogen you utilize.

So your EPOC does not have to equal the total caloric expenditure. I know my explanation is mostly hand waving, but correct from an analogy standpoint.
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  #14  
Unread 12-26-2011, 07:10 PM
FutureisNow FutureisNow is offline
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Quote:
Originally Posted by CleanSnatch View Post
Part of the energy expenditure is like using currency or a debit card, the other part is via a loan such as a credit credit.

Eg: if you want to spend $100 on a gift and only have 40 in cash and borrow the other 60 (via say an unsecured loan such as a credit card) then your "EPOC" is only $60. You need to pay back your creditor (your lactate system) to the tune of $60 to return yourself to zero debt. The 40 dollars damage to your wallet is like the fats and glycogen you utilize.

So your EPOC does not have to equal the total caloric expenditure. I know my explanation is mostly hand waving, but correct from an analogy standpoint.
That makes sense if you're not going to replenish your fuel stores. Assuming you are eating at maintenance, including the exercise calories,
then those fat/glycogen stores will be replenished, at a cost. One thing I've found out, actually I knew but didn't connect, was that
the ATP energy spent will be replenished through aerobic processes, even if it was released anaerobically, so there are efficencies during recovery.

Also, the idea of O2 debt for anaerobic processes has been under scrutiny lately. I can't claim to understand it fully, it seems that Dr. Chris Scott has been leading the charge. I found this interview at http://www.builtlean.com/2011/06/29/...her-scott-phd/. He also has a textbook out on the subject: http://www.amazon.com/Primer-Exercis.../dp/B002FB6XIU.

Last edited by FutureisNow : 12-26-2011 at 07:14 PM.
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  #15  
Unread 12-26-2011, 07:50 PM
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lylemcd lylemcd is offline
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The oxygen debt was the very old explanation for EPOC, but there is more going on than that.
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  #16  
Unread 12-27-2011, 10:49 AM
CleanSnatch CleanSnatch is offline
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Quote:
Originally Posted by lylemcd View Post
The oxygen debt was the very old explanation for EPOC, but there is more going on than that.
Oxygen debt is a dated concept but makes for a good analogy vis a vis my credit card/debit card example. I was not trying to provide a lecture on physiology.

If you want to restore your body to the identical point you were energetically (simple energy balance i.e. book keeping) before your bout of exercise you will also need to replenish your glycogen and fat stores that were used. However, thanks to entropy you will find restoring yourself back at least from a energetic perspective requires more calories than you spent in exercise.

Another good analogy comes from global warming (if it exists, since I don't want to turn this into a "does global warming exist or not" thread). Global temperatures cannot be lowered by creating a iceberg in a giant refrigerator then dropping the iceberg in the warm equatorial waters. The energy (heat) absorbed by the melting iceberg will be less than the heat created by the refrigerator that turned water into the iceberg in the first place.

So you will always expend more calories to get back all the glycogen/fat/amino acids you burnt to restore yourself from an energy balance due to the inefficiency in all heat engines (the human body included). EPOC is good because from a thermodynamic perspective it is more energy inefficient than simply burning fat using low intensity steady state cardio.

Last edited by CleanSnatch : 12-27-2011 at 11:04 AM.
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  #17  
Unread 12-27-2011, 11:08 AM
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lylemcd lylemcd is offline
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I was simply making a statement of fact, nothing more and nothing less. And I wasn't responding to you in the first place.
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  #18  
Unread 12-27-2011, 11:24 AM
CleanSnatch CleanSnatch is offline
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OK, did not mean to cause offense.
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  #19  
Unread 12-27-2011, 01:33 PM
FutureisNow FutureisNow is offline
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Quote:
Originally Posted by CleanSnatch View Post
Oxygen debt is a dated concept but makes for a good analogy vis a vis my credit card/debit card example. I was not trying to provide a lecture on physiology.

If you want to restore your body to the identical point you were energetically (simple energy balance i.e. book keeping) before your bout of exercise you will also need to replenish your glycogen and fat stores that were used. However, thanks to entropy you will find restoring yourself back at least from a energetic perspective requires more calories than you spent in exercise.

Another good analogy comes from global warming (if it exists, since I don't want to turn this into a "does global warming exist or not" thread). Global temperatures cannot be lowered by creating a iceberg in a giant refrigerator then dropping the iceberg in the warm equatorial waters. The energy (heat) absorbed by the melting iceberg will be less than the heat created by the refrigerator that turned water into the iceberg in the first place.

So you will always expend more calories to get back all the glycogen/fat/amino acids you burnt to restore yourself from an energy balance due to the inefficiency in all heat engines (the human body included). EPOC is good because from a thermodynamic perspective it is more energy inefficient than simply burning fat using low intensity steady state cardio.
Anyway, the oxygen debt analogy makes sense in regards to some of the post-exercise recovery processes. And the debit in terms of fat/glycogen does as well.

I think some of the thermodynamic calculations depend on there being a closed or open system. What you say is true in a closed system. However the body is an open system. But generally I agree you need to pretty much eat back (an estimate) what you work off (an estimate) to maintain stasis (another estimate). It's all an approximation.

What that Dr is finding is that the recovery burn from single sets of certain strength training exercises exceeds that of the expenditure. The expenditure isn't that great. But the recovery exceeds 100% of that apparently, according to his measurements. Interesting ... though not sure if his subjects were at maintenance calories or stayed in deficit either.
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  #20  
Unread 12-28-2011, 04:07 PM
CleanSnatch CleanSnatch is offline
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You are confusing things.

1st law holds for all systems, open or closed. It is only a simple accounting of energy.

Energy created - Energy destroyed + Energy influx - Energy efflux + Work done on the system - Work done by the system = Energy stored

It does not account for entropy, irreversibilities and friction within the system. Heat produced by exothermic biochemical reactions is an expression of entropy.

So if you expended 400 calories then to get back those 400 you will need more. How much more depends on the lossyness of the human system. Since no one has developed equations of state for every biochemical reaction in the body quantifying it cannot be done directly. Only empirically. If you eat 200 kcals a day and dont gain or lose weight then thats your maintenance requirement. Base your diet on that.

All this is moot since you will never completely restore yourself to the pre exercise state. Adaptations caused by exercise will mean you can never go back in time.

If you want to lose weight be in a deficit. Gain weight then be in a surplus. Want nutrient partitioning, decide on the kinds of exercise you need to do, plus the macros you eat. You don't need to know the intricaces of enthalpy, entropy and latent heats etc to get ripped.

Last edited by CleanSnatch : 12-28-2011 at 04:10 PM.
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