Does the body start to burn muscle instead of fat after 90 minutes of exercise?

Question

If so, how much muscle are we talking about and does it depend on the intensity of exercise? Someone told me this the other day and I have a hard time believing it.

Answer 1

This is not true. I think what they were trying to tell you is that after so much aerobic exercise your body will switch to anaerobic exercise where it starts burning sugar rather than oxygen. This is why after so much exercise you feel "the burn". Its due to build up of lactic acid in your muscles.

The body can burn your muscle tissue for energy but it is never because of exercise. Your body starts with your sugar (glucose) reserves for energy then moves to fat. Only in extreme cases of starvation would your body resort to the horribly inefficient method of breaking down amino acids in muscle tissue for energy.

Answer 2

This is a first! I have never heard of burning muscle!
This was most likely misinterpreted. I believe as long as you do an intense body workout for 30 minutes are more, you will burn fat. Not muscle.

Here is something I thought might interest you, it's from Fitness Freakz, He is 26, and has been training for over 6 years and works with various types and age groups but mostly athletes. Located in Orange County, his occupation is Sports Coach. Here is what he has to say on the matter:

Fact- muscle can never be burned. You will always have muscle They size may decrease but never burn muscle. There is no such thing. Plenty of people especially athletes have a great amount of muscle and do intense cardio. Footballs players, baseball players, basketball players- it's just that not everyone works out to strictly bulk up. Most athletes will.

Answer 3

I'm going to speak in general terms...

Your body has a certian amount of stored glycogen (aka. sugar/fat) that it uses for energy. Typically the glycogen stores are burnt out within 45 minutes of heavy weight training and about an hour of cardio training. Upon depletion of glycogen stores your body switches to using the 2nd most readily available energy source, MUSCLE.

If you are spending more than 45 minutes in the gym and are not on any anabolic/androgenic steroids (anti-catabolic in nature and prevent the deterioration of muscle tissue) you are most likely being counterproductive to the muscle building process.

I can go deep into this topic, but for general purposes just remember 45 minutes of weight training until you are a very advanced athlete. If you are taking 1 minute intervels between sets, you will be VERY exhausted with this timeframe.

If doing cardio the same days as weights, it's best to do your cardio training in the morning and weight training in the afternoons. Can everyone adhere to this? NO. But it is the optimal way of training.

Also, not more than 4 days a week in the gym for commone enodomorphs and ectomorphs, mesomorphs are something all together different. Look them up if you don't know what the heck I'm talking about.

Answer 4

you should give me the 10 points because that is bullshit, and ill tell you why. look there is a way to burn your muscle, that is when you work a muscle for too long, if you do biceps a lot in one day you might burn it, but that is to the extreme, and you dont burn it to the point of loosing it, you burn it in a way that lets say you **** it up so that it wont grow more and you dont want that, but after 90 min impossible, i work out 3 hours a day and you could too, but i do two diferent pars, but i have worked 2 hours or more with one muscle and believe me it didnt get burned so it is really hard to do it, just be carefull

Answer 5

It really depends on what you are doing, how long, how hard and how much stored energy you have. In general 99% of people don't push it to the point that it starts deteriorating the muscle. If you ran 20 miles at a 6 min. pace, you would jsut start to run out of your stored up energy and then you would start breaking down the muscle. Anything short of that and you are fine.

Answer 6

This all depends on the person and your work out routine. It's never good to do the same excercise daily. Your body will get used to it and you won't be burning anything. Also you may be able to damage your muscles but you can't really burn them...

Answer 7

muscle tissue is never "burned"

after just 20 minutes of exercise at a moderate level, the body switches from burning glycogen, i.e. sugars to burning fat

muscles tissue either enlarges from exercise or decreases in size from atrophy

Answer 8

The only way you'll lose muscle is by not exercising. You don't burn muscle if you work above your target heart rate.

Answer 9

I don't know but I hope not because I walk all up hill in the morning before work for 2 hours straight! Than, after work, I go bike riding for 10-15 minutes. I also do crunches every day. It would suck if this is true!

Answer 10

I think intensity has something to do with it, as well as your target heart rate. You can over-train. Your muscles grow by breaking them down, and then resting. You have to get adequate rest if you workout. There are plenty of heath magazines that address this topic.