How much cardio can you do that it will still be effective? I mean like when does it stop burning fat and start burning muscle? Also, If you were to do say 45min, have a break and then come back and do another 45min would you be burning fat both times??

i hope this post makes sence, i wasnt quite sure how to write it...

tree

How much cardio can you do that it will still be effective? I mean like when does it stop burning fat and start burning muscle? Also, If you were to do say 45min, have a break and then come back and do another 45min would you be burning fat both times??

i hope this post makes sence, i wasnt quite sure how to write it...

tree

It is relative to your diet and your condition. If you do endurance work, and have eaten enough, you can burn a lot of calories without burning muscle.

The body doesn't switch from burning fat to burning muscle. What happens is that is starts out burning fat, then as you exercise, it immediately adds glycogen (carbs) to the fuel mix. A little later, it turns up the fat burning. Whether this shuts down the glycogen or not depends on the intensity of the exercise, but for most things we call exercise, the glycogen keeps burning, but at a slower rate.

At this point, (somewhere around 20 minutes in), the stuff you hear about the "fat burning zone" is sort of true for many people. It was not true in the first few minutes before the fat metabolism can get cranked up.

After another while (something like 90 minutes in), then the "fat burning zone" is again wrong - because you may be running out of glycogen. That is where you will experience "bonking" which comes with a bunch of symptoms (like you can't stand up, your pupils dilate, you get dizzy, you might puke....). If you actually bonk hard, then you will signal your body to start throwing some protein on the fire. So that is probably what you are wondering - when to stop before you burn muscle.

You still keep burning fat the whole time though.

Now there are people who have different goals. A guy running in an ultramarathon is going to have to avoid bonking so he can finish the race. Well then what can he do? It turns out that this has been carefully studied. It is enough to for that guy to eat some quickly absorbed carbohydrates from time to time during the exercise - like dextrose gel. It keeps his blood glucose up and avoids the bonk, and the muscle burning.

What it really comes down to is that very large amounts of cardio can be done without burning muscle:

http://www.nytimes.com/books/98/10/25/specials/ali.5.jpg
http://www.writestuffautographs.com/shop/images/products/boxing44.jpg
when you look at how boxers train, it's cardio and more cardio. Why? Because sometimes it meant 15 rounds of this:

http://www.artletics.com/images_db/product/regular/boxing_vp_marciano_charles_pv.jpg

They just have to eat enough Calories to support the activity.

wow! thanks heaps zenpharaohs! that was like the best post i have ever read :D really awesome that you have so much knowlegde

One more question...

say you bike for one hour nonstop, will you burn more calories than biking 2 x 30 mins with a long break? Just wanna know if getting tired will make you burn more than being 'fresh'? thanks....

One more question...

say you bike for one hour nonstop, will you burn more calories than biking 2 x 30 mins with a long break? Just wanna know if getting tired will make you burn more than being 'fresh'? thanks....

IF you do the one hour at the exact same intensity as the two half hours, then you burn the same amount.

But if you get tired during the hour and cannot keep up the same intensity as the two half hours, you can burn considerably less in the hour than the two half hours where you keep the intensity up.

In fact, this is similar to the idea of HIIT (high intensity interval training). It's better to have 30 totally intense one minute intervals separated by rest intervals than 30 minutes of modest intensity. The amount of rest or whether you exercise at low intensity in a rest interval doesn't have that much to do with it. It's the intensity of the hard intervals which matters.

And this effect keeps going pretty much without a theoretical limit. The limit is whether you can do it. There are incredibly brutal HIIT workouts such as 'Tabata' where you have 30 seconds of total intensity and 10 seconds of recovery interval. Those are extremely productive and beneficial workouts. But not many people can actually do them. Even Olympic caliber athetes have a real problem doing seven or eight Tabata intervals. People in really good shape can do five or six honest ones. This is the fact behind those claims of "a complete workout in under four minutes". If you do six Tabata intervals, it takes three minutes and fifty seconds. And it is a very good conditioning workout indeed. You do not need a $14,000 machine either - you can do it with any exercise for which you can attain the high intensity. Heavy barbell snatches would do just fine and for that you could get a used set of barbell and plates for under $100.

Most people these days want to take advantage of the convenience and efficacy of HIIT. You should get it into your exercise plan. But it is not something to start out with, and it shouldn't be your only workout if you want the healthiest body you can train. There should be some amount of low intensity steady state (LISS) which is a bit better at recruiting mitochondria to the muscles than HIIT is. LISS is also good for getting your joints happy, where most forms of HIIT could be tough on them. But for Calorie burning and developing a high cardiovascular capacity, HIIT is probably the king.

Impressive! Thanks for all the useful information, you are like a walking fitness encyclopedia :)

thank you ..bro! very useful tips & article...:neener:

Impressive! Thanks for all the useful information, you are like a walking fitness encyclopedia :)
Agreed. :)

[QUOTE]There should be some amount of low intensity steady state (LISS) which is a bit better at recruiting mitochondria to the muscles than HIIT is.[QUOTE]


Can you shed a little more light on the "mitochondria" thing?

Also, if I understand you right, I can keep a steady flow of carbs coming in while doing longer durations of cardio to keep up the energy and continue burning more and more fat cals. I know there is a lot more to the "formula" but is that the basic idea, or will you continuously be burning the carbs you're feeding into your system?

Thanks. Sorry if my questions sound elementary. I don't have time to do two-a-days, but on my cardio only days, I'd like to make the best use of them.

Peace,
Brian