In the spirit of what Karky said, - i.e looking for a short simple answer - perhaps I could re-submit a question I'd made earlier which gets back to the original issue raised in this thread. Namely, the issue that if you start training at a relatively high % MHR, your body will use muscle tissue as a fuel source. Many of us consider this to be a " myth " - under normal circumstances.

So, I think in the context of this particular case / post " the myth " has to to do more with someone who is going to the gym to do a simple cardio session on the treadmill - not a marathon. And to me at least , that would be about 30 +/- minutes and more than likely no more than 1 hour on the treadmill IMO.

So to me, the question is, for the average gym rat who trains and eats / fuels properly.......

If an average gym rat runs on a treadmill at around 80-85% MHR for 30 or 60 minutes, how much ( i.e what % ) of the total energy ( calories ) needed to complete that run - if any - would you estimate stems from an actual breakdown of " muscle tissue " ?

illiniphase4, matt182 - thoughts ?

lol you know all those huge pro football players

i imagine they spend all week above 80% heart rate ... and do they look without muscle

Professional athletes of all walks of life actually follow a periodized program supplemented by extreme nutrition plans that include specific protein supplements to counteract any protein catabolism that occurs during improvement conditioning stages of periodization.

Not a myth, even for the average gym rat. The protein energy system is used at all levels of exertion, and like the fat and carb energy systems, fuels come from within the cells, as well being delivered by the blood stream. The most accessible proteins are found in within the muscle tissues themselves. Granted I'm not saying that the general exercising populace is going to see any sort of protein/muscle catabolism on the level of marathon training and running, but there is some level of protein catabolism (from both muscle fibers and free amino acids) even while not at heart rates in excess of 80-85% of HRmax. However, once an individual breaches that heart rate range, the body must rely more heavily on protein catabolism for energy, resulting in great muscle tissue catabolism (again, though, not at the level of a marathoner).

This is one of the reasons that the ACSM, NSCA, NASM, etc. all recommend 85% of MHR to be the max heart rate for improving aerobic fitness (along with greater risk of injury due to fatigue and bone joint impact).

Most of my college texts are back in storage, but I will continue to look and see if I can find some specific information about the breakdown of fuel usage at higher exercise intensity levels.

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So every cardio exercise we do, regardless of the intensity - in essence - burns some existing muscle mass to fuel exercise.

In other words, all cardio exercise cannibalizes muscle tissue for fuel to one extent or another - is that correct ?

Are you saying that although we have amino acids in our blood we could convert for use as energy, it is much easier ....these amino acids are more " accessible " .....to use amino acids that are taken from muscle tissue ?

So due to easier " access ' your body is more inclined to take amino acids from muscle tissue to fuel cardio than to take amino acids from your blood - have I got that right ?

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Again, so you're saying all cardio, regardless of the intensity will - to varying degrees - always use up muscle tissue to help fuel cardio.

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btw - How much more ?

I get that people may use small amount of amino acids for fuel while exercising with cardio under what we might consider normal circumstances. I get that.

The issue to me is, does tissue have to provide the amino acids for energy when amino acids are floating around in your blood readily available for use in producing energy to fuel cardio. You say muscle tissue has to be part of the equation in fueling cardio.

So, you're saying that.....

1. if an average gym rat runs at 80-85% of HR max for 20 or 30 minutes, in your opinion, is it a 100% certainty that some muscle tissue will be broken for to help fuel the run ?

2. if an average gym rat runs at 80-85% of HR max for 20 or 30 minutes, in your opinion, is it NOT possible that only amino acids found in your blood are sufficient enough to fuel the run so that amino acids from muscle tissue can be spared ?

...have I got that right ?

I've read everything... EVERYTHING, you hear??? And now I'm dizzy and my heart is racing... I will never read again or I'll turn skinny like before....

Ok heres my opinion.

The body has evolved to provide energy in the most effecient, cheapest way it can. By cheapest i mean not having a larger conseqence. Protein would result in loss of muscle and other specific proteins compared to fat and carbs which wouldnt effect anything other than reducing the overall quantity of it.

In an exercise physiology book i happen to have - you might as well? If you flick around to the subject of RQ, (which is a very accurate modality to determine what is being burned), we've already mentioned that .7 would be pure fat and 1 would be pure carbs. So it covers the whole realm of possibilities (even going beyond, which has a simple explanation).

Well ill get to the point. In the textbook it has all the calculations for what each score would burn, they DO NOT mention any protein, as the heading gives you the hing "NONPROTEIN RQ'S".

Why? because the body doesnt use precious protein when other - much more effecient and quicker mechanisms are available, which are ACTUALLY designed for energy. unlike protein.

To sum up, you can go jog at 85% as your specified and have no worry about breaking down your muscle.

Yes, it's true muscle proteins "can be" broken down and used for energy during aerobic exercise. But don't worry, you are constantly breaking down and re-building muscle tissue anyway. This process is sometimes called "protein turnover." Your body is constantly alternating back and forth between anabolic (building) and catabolic (breaking down) cycles. That's just a normal part of life. Your goal is simply to tip the scales slightly in favor of increasing the anabolic side and reducing the catabolic side just enough so you stay on the anabolic side and you gain or at least maintain muscle. If cardio is done, just make some appropriate adjustments. I dont know if the "average person" even needs to worry about such things in the first place.

Its seems I have this type of action down. I do extensive cardio (most would interpret during leaning down), and for two weeks my weight of 162 has maintained, but my body fat has dropped (professionally determined, and exactly what I am after). And, I can do as much as 3 cardio sessions in one day (called "Plate Weight Cardio"):Proper keen eye on diet and weight training will stave off any ill effects of cardio (if any exists in the first place--particular to the person).

Cardio rocks when working with it correctly. Nuff, said


Best regards,


Chillen

do you personally know every professional athlete in the world?
besides how does this have to do with above %80 heart rate

Are you saying the " this process " of mechanisms associated with "protein turnover " provide " energy during aerobic exercise " in the same way that mechanisms associated with gluconeogenesis ( i.e creating glucose from non-carb sources like amino acids etc. ) do ?

Are you suggesting that " protein turnover " is synonymous with gluconeogenesis ?

Like what ' adjustments ' exactly ?


Is this " extensive cardio " the same protocol of doing cardio 3X a day that you said you do ( below ) ...or something else ?


Why the heck would you have to do cardio " 3 cardio sessions "...is this to optimize fat loss ?

What is the physiological rationale for doing cardio 3X a day any way ...i.e instead of once a day as in a hard HIIT session ?

Doesn't doing cardio 3X a day seem like a bit of overkill ?

And what is " "Plate Weight Cardio" exactly ? Never heard of it.

Yes, I know every athlete in the whole wide world.

It didn't have anything to do with 80% heart rate and protein catabolism, but you had made the comment about professional athletes, knowing that they work out at high intensity levels, and still manage to put on muscle mass. However, most strength and conditioning programs built for athletes on any scale are based on a periodized program that actually limits intensity level during the competition portion of the training programs.

And you assume this to be a result that protein catabolism is the culprit?

The above quote I personally select to answer, since its you responding: I know me and my response to cardio when my diet is within certain criteria, and with weight training encircling it. I simply elect to do so, and the results of maintaining weight and a reduction in body fat simply speaks for its self. I have been through this before, and isnt nothing new. Another reason: I set my own standards, no one else does . When I am done, I will be at about 161 pounds (or about 6 pounds heavier than before--approximately), and about 6 to 7% BF.I would say somethig is rocken on! Not suggesting others do as much, but bare in mind I do it for other reasons. Within the confines of the COL it does explain the other reasons (just have to look, Im not going to retype it). I will be posting pics (several of them for proof for those interested) in a short period of time.


Happy New Year!

Chillen

Only a minor consideration. Within a periodized training program designed for a seasonal sport, conditioning tapers off as the competitive period begins and is replaced with a moderate intensity "maintenance" phase primarily designed for preventing injury and maintaining energy levels for competition.

or/and to have your body supercompensate.