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Avatar
02-06-2001, 03:00 PM
Alright, its my understanding that the body does the following things in this order when performing cardio:
1. Burns energy you've obtained from food
2. When food has been burnt, fat stores beging to get burnt off
3. Muscle stores start to get burnt

Now I can understand why its best to workout on an empty stomach because you skip #1 and jump right to #2, but whats stopping your body from burning fat and burning muscle simutaneously and if #1, #2, and #3 above are in the correct order, what tells the body to go to #2 before #3 and what tells it when its time to switch.

Hope that wasn't too confusing :)

David
02-06-2001, 07:52 PM
Originally posted by Avatar

Hope that wasn't too confusing :)


...not as confusing as chris mason and mac sloan's debate on the "Wondering where this myth came from" thread.

After reading that thread i am totally confused on how to train. :confused:

Maki Riddington
02-06-2001, 09:26 PM
Triple P don't be,use what works for you and when it stops change it.If what Chris advocates brings lots of success your way then by all means continue on.


Avatar your body uses different energy sytems for different tasks,all are used at one time,it's just that one is more dominantly used than the rest.There is a short term,intermediate and long term systems and the body will use all these systems.

Your 2 MAIN sources of energy during exercise are carbs(glycogen,glucose) and fats(tryglyceride)

When a meal is eaten, predominantly higher in carbs it appears that the body will rely heavily on carbohydrates and less on fat,this is probally due to insilun playing a role in regulating the mixture of fats and carbs oxidized during your exercise.

There are predominantly 2 places fat is oxidized from,addipose tissue and intramuscular fat as far as the ratio during exercise I don't think there has been any studies that have shed light on this.You see there are aprox 50 000 - 60 000 kcals of energy stored as fats in all the adipose cytes in your body(thats alot of fat!)Because of this large amount of enrgy that is stored in a small amount od space you can see how this is a great way for people to carry fuel as they move from place to place.
When food stores are burnt the workrate that you are working determines whether it will use predominanly more carbs or fats.Again you will always be using carbs no matter what,your body doesn't just use one source.If you just used fat I would be suprised how you got to the gym let alone get yourself out of the house.

Protein is not a readily used source of fuel,meaning that you need not worry about the catobolizing(sp) effect that everyone talks about so much.I would start to worry if you had been fasting fro more than 12 hours then your body would start to readily dip into your protein stores.

It's a complex subject and I hope I answered the question,if not let me know.

Avatar
02-07-2001, 08:44 AM
Originally posted by mac sloan

Protein is not a readily used source of fuel,meaning that you need not worry about the catobolizing(sp) effect that everyone talks about so much.I would start to worry if you had been fasting fro more than 12 hours then your body would start to readily dip into your protein stores.

So what your saying here is when doing cardio, muscle is rarely used as an energy source? Is this true even if you've been jogging for 45+ minutes? because as you say there is so much fat, you should never stop burning that as the main source after carbs have been used up.

Maki Riddington
02-07-2001, 07:58 PM
Avatar amino acids contribute roughly (this ia a rough aproximation)5-15% of the energy that is consumed during exercise(Exercise Metabolisim,Mark Hargraves)


It has been estimated that amino acids contribute anywhere from 3-18% of the total energy required for a long exercise bout.(Brooks,G.A.Amino acid and protein metabolisim during exercise and recovery.Med.Sci.Sport.19:S150-S156;1987)
(Poortmans,J.R.Protein turnover and amino acid oxidation during and after exercise.Med.Sports Sci,17:130-147;1984)

That is not to say that your free to exercise for extended periods of time and not lose any muscle mass,if your diet is off you'll suffer,if you have been exercising and then do some cardiovascular exercise and your cals are close to your resting rate then you'll suffer.

Scotty the Body
02-08-2001, 10:52 AM
Your body will use energy sourses depending on what your heart rate is at durring exercise.

To burn the optimum amount of fat over useing muscle(protien) for energy you need to be doing your cardio in your target heart range.

To figure your target heart range or THR, you need to get your Max heart rate or MHR. Use the following.

MHR = 210-(1/2 your age)-(.05 x your body weight)+4
THR = 70 to 80% of your MHR

Once you've done your cardio, try to wait 1 hour before eating as your body will continue to use fat to restore glycogen stores.