burning muscle - Tilted Forum Project Discussion Community

FaderMonkey · 03-10-2004, 06:47 PM

So, I've been told by a few people that when doing aerobic workouts you should watch your heartrate and not let it get too high. I'm told that once your heartrate goes too high you start to burn muscle instead of fat.

I guess I'm just wondering how true this is. When I mention this to some friends they say they've never heard of it. Anyone know details behind this? Is it just a way to sell heartrate monitors or is it for real?

cait987 · 03-10-2004, 07:54 PM

Pretty much, when you run, your body cant keep up with the intensity and then naturally turns to the greatest energy source (carbs), however, what happens when carbs run out? Well naturally your wonderful body goes to the next best thing, Muscle! Muscle provides aprox 17x the energy that fat does so the body naturally relies on muscle due to cartigens(SP?) being released to bring more energy to the body part that is lacking.

However, by keeping your heart rate at a steady pace (65% aprox) your body can keep up with the intensity in a sense and instead of being forced to massively devour muscle/carbs it can rely entirely on fat once the carbs run out, pretty much, your body beleives its going to die and just like animals storing all their food as fat for when they get hungry, your body digests anything it can get ahold of for the most energy so you dont collapse dead which is carbs -> muscle/fat at high intensity
carbs -> fat -> muscle at medium intensity

Now dont get me wrong, high intensity workouts do work, why? Because you deplete your carb stores in your body so naturally all those extra carbs are then burned off and arent stored as fat like they would naturally be, however, go to long and fat isnt the only thing you are losing ...

hannukah harry · 03-11-2004, 10:43 AM

this is some of the worst information i've heard...

Originally posted by cait987
Pretty much, when you run, your body cant keep up with the intensity and then naturally turns to the greatest energy source (carbs), however, what happens when carbs run out? Well naturally your wonderful body goes to the next best thing, Muscle! Muscle provides aprox 17x the energy that fat does so the body naturally relies on muscle due to cartigens(SP?) being released to bring more energy to the body part that is lacking.

1) unless you are on atkins, there's no chance of running out of carbs for energy when doing high intensity exercise. you'll fatigue due to lactic acid accumulation long before that ever happens.

2)muscle does not provide 17x the energy of fat. i don't know where you got that, but it's wrong. one gram of fat gives 9 calories, while 1 gram of protein gives 4. muscle is made up of protiens, and when it is broken down for energy, it is broken down to protein which is then converted into glucose.

3)the body turns to fat long before it turns to muscle because fat is more calorie dense.

4) cartigens? i have no idea what your talking about. do you mean cortisol? cortisol (sp?) is produced in your body by stress, and does promote muscle catabolism, but it is not a concern until you've been doing about an hour of cardio. if you're doing less than that, don't worry about it.

5) have you ever seen an olympic sprinter and marathoner? which is more musculer? which performs a more intense workout? point made?

However, by keeping your heart rate at a steady pace (65% aprox)

65% of what? max heart rate? heart rate reserve? vo2max? vo2max reserve?

your body can keep up with the intensity in a sense and instead of being forced to massively devour muscle/carbs it can rely entirely on fat once the carbs run out,

giving out the arbitrary 65% is meaningless. everyone is different and at different fitness levels. you may be able to work out at that level, while someone who is very out of shape has to start out working out at 40%, but it's relatively the same intensity for the two of you.

your body is never just burning carbs or just burning fat. there's something called the respitory exchange ratio (RER) that can be used to determine how much of each is being burned at one time. an RER of .7 means your buring only fat, while an RER of 1.0 means all carb. at above 1.0 your starting to hyperventilate. at .85 your burning equal amounts carb/fat. somewhere around 60-65% of your vo2max is where you hit .85 (might be a bit lower, i'd have to look it up). so when you're running at a slow easy pace, you're using mainly fat as energy, but when you go at a high intensity, you burn mainly suger. protein is not normally used for energy unless you have entered "starvation mode" or are running a marathon. in a marathon, towards the end, you will have burned up all the glycogen stores and then protein will start being burned, for about 15-20% of the energy used with the rest coming from fat.

pretty much, your body beleives its going to die and just like animals storing all their food as fat for when they get hungry, your body digests anything it can get ahold of for the most energy so you dont collapse dead which is carbs -> muscle/fat at high intensity
carbs -> fat -> muscle at medium intensity

i've already said what's wrong with this, i do believe.

Now dont get me wrong, high intensity workouts do work, why? Because you deplete your carb stores in your body so naturally all those extra carbs are then burned off and arent stored as fat like they would naturally be, however, go to long and fat isnt the only thing you are losing ...

that's part of it, along with EPOC (excess post-exercise oxygen consumption, although recent studies suggest that may be much less of a contributor than previously beleived.).

to answer the original question, you don't need to worry about burning muscle unless you have long cardio sessions. intensity won't burn muscle, duration will. higher intensity will fatigue you quicker before muscle is ever started being burned.

edited for format

EleqTrizi'T · 03-11-2004, 01:30 PM

My trainers over time have all told me the basic same thing... stop working out when you burnt your glycogen stores.

One trainer believed you trained hard for 45 minutes and stopped. Another believed when you started feeling fatigued everywhere (not just the muscles you're working), you should stop.

I do the latter, not entirely sure that is the right choice. But I gauge my tiredness on my ability or inability to do two pushups in a row. Sometimes I just drop and give it a shot, if I can't, I shower.

Lunchbox7 · 03-11-2004, 08:06 PM

hannukah harry Well said. I was about to say basicaly the same thing though I wouldnt of said it anywhere near as well as you did.

Aleqtrizi'T dont worry about the glycogen stores. It is just part of the process of producing glucose (suger) from other energy sources. You cant possibly measure when you glycogen stores are at unless you have access to the best equipment. When your glycogen stores run out you die. As hannukah harry said your body tries to survive. That is why muscle is used last as you need to your muscle to help you survive. You will stop excercising through fatige along time before all your energy stores are used up.

hannukah harry · 03-11-2004, 08:43 PM

Quote:

Originally posted by Lunchbox7
Aleqtrizi'T dont worry about the glycogen stores. It is just part of the process of producing glucose (suger) from other energy sources. You cant possibly measure when you glycogen stores are at unless you have access to the best equipment. When your glycogen stores run out you die. As hannukah harry said your body tries to survive. That is why muscle is used last as you need to your muscle to help you survive. You will stop excercising through fatige along time before all your energy stores are used up.

i actually never said anything about glycogen stores running out and you dying from it. cause that won't happen. as long as there's something to be converted for energy, your body will do it. marathon runners will empty their glycogen stores, and they don't die. the body burns fat rather efficiently, so without glycogen, we'd still survive. we'd be rather lethargic and not really be able to perform intense activity (anaerobic glucolysis is used for that because fat burns too slow).

thingstodo · 03-13-2004, 10:07 AM

I do know from riding a racing bike for 100 mile that you need carb replacement every 30-45 minutes or you will do something called a "bonk", which means your mind stops working effectively and you can even pass out. I've almost done that before. But I was never concerned with burning muscle. That might happen if you worked out for days at a time but you'd probably bonk many times before hand!

03-10-2004, 06:47 PM	#1 (permalink)
FaderMonkey Psycho Location: Orlando, FL	burning muscle So, I've been told by a few people that when doing aerobic workouts you should watch your heartrate and not let it get too high. I'm told that once your heartrate goes too high you start to burn muscle instead of fat. I guess I'm just wondering how true this is. When I mention this to some friends they say they've never heard of it. Anyone know details behind this? Is it just a way to sell heartrate monitors or is it for real?

03-13-2004, 10:07 AM	#7 (permalink)
thingstodo A Storm Is Coming Location: The Great White North	I do know from riding a racing bike for 100 mile that you need carb replacement every 30-45 minutes or you will do something called a "bonk", which means your mind stops working effectively and you can even pass out. I've almost done that before. But I was never concerned with burning muscle. That might happen if you worked out for days at a time but you'd probably bonk many times before hand! __________________ If you're wringing your hands you can't roll up your shirt sleeves. Stangers have the best candy.

03-10-2004, 07:54 PM	#2 (permalink)
cait987 Insane	Pretty much, when you run, your body cant keep up with the intensity and then naturally turns to the greatest energy source (carbs), however, what happens when carbs run out? Well naturally your wonderful body goes to the next best thing, Muscle! Muscle provides aprox 17x the energy that fat does so the body naturally relies on muscle due to cartigens(SP?) being released to bring more energy to the body part that is lacking. However, by keeping your heart rate at a steady pace (65% aprox) your body can keep up with the intensity in a sense and instead of being forced to massively devour muscle/carbs it can rely entirely on fat once the carbs run out, pretty much, your body beleives its going to die and just like animals storing all their food as fat for when they get hungry, your body digests anything it can get ahold of for the most energy so you dont collapse dead which is carbs -> muscle/fat at high intensity carbs -> fat -> muscle at medium intensity Now dont get me wrong, high intensity workouts do work, why? Because you deplete your carb stores in your body so naturally all those extra carbs are then burned off and arent stored as fat like they would naturally be, however, go to long and fat isnt the only thing you are losing ...

03-11-2004, 10:43 AM	#3 (permalink)
hannukah harry Junkie	this is some of the worst information i've heard... Originally posted by cait987 Pretty much, when you run, your body cant keep up with the intensity and then naturally turns to the greatest energy source (carbs), however, what happens when carbs run out? Well naturally your wonderful body goes to the next best thing, Muscle! Muscle provides aprox 17x the energy that fat does so the body naturally relies on muscle due to cartigens(SP?) being released to bring more energy to the body part that is lacking. 1) unless you are on atkins, there's no chance of running out of carbs for energy when doing high intensity exercise. you'll fatigue due to lactic acid accumulation long before that ever happens. 2)muscle does not provide 17x the energy of fat. i don't know where you got that, but it's wrong. one gram of fat gives 9 calories, while 1 gram of protein gives 4. muscle is made up of protiens, and when it is broken down for energy, it is broken down to protein which is then converted into glucose. 3)the body turns to fat long before it turns to muscle because fat is more calorie dense. 4) cartigens? i have no idea what your talking about. do you mean cortisol? cortisol (sp?) is produced in your body by stress, and does promote muscle catabolism, but it is not a concern until you've been doing about an hour of cardio. if you're doing less than that, don't worry about it. 5) have you ever seen an olympic sprinter and marathoner? which is more musculer? which performs a more intense workout? point made? However, by keeping your heart rate at a steady pace (65% aprox) 65% of what? max heart rate? heart rate reserve? vo2max? vo2max reserve? your body can keep up with the intensity in a sense and instead of being forced to massively devour muscle/carbs it can rely entirely on fat once the carbs run out, giving out the arbitrary 65% is meaningless. everyone is different and at different fitness levels. you may be able to work out at that level, while someone who is very out of shape has to start out working out at 40%, but it's relatively the same intensity for the two of you. your body is never just burning carbs or just burning fat. there's something called the respitory exchange ratio (RER) that can be used to determine how much of each is being burned at one time. an RER of .7 means your buring only fat, while an RER of 1.0 means all carb. at above 1.0 your starting to hyperventilate. at .85 your burning equal amounts carb/fat. somewhere around 60-65% of your vo2max is where you hit .85 (might be a bit lower, i'd have to look it up). so when you're running at a slow easy pace, you're using mainly fat as energy, but when you go at a high intensity, you burn mainly suger. protein is not normally used for energy unless you have entered "starvation mode" or are running a marathon. in a marathon, towards the end, you will have burned up all the glycogen stores and then protein will start being burned, for about 15-20% of the energy used with the rest coming from fat. pretty much, your body beleives its going to die and just like animals storing all their food as fat for when they get hungry, your body digests anything it can get ahold of for the most energy so you dont collapse dead which is carbs -> muscle/fat at high intensity carbs -> fat -> muscle at medium intensity i've already said what's wrong with this, i do believe. Now dont get me wrong, high intensity workouts do work, why? Because you deplete your carb stores in your body so naturally all those extra carbs are then burned off and arent stored as fat like they would naturally be, however, go to long and fat isnt the only thing you are losing ... that's part of it, along with EPOC (excess post-exercise oxygen consumption, although recent studies suggest that may be much less of a contributor than previously beleived.). to answer the original question, you don't need to worry about burning muscle unless you have long cardio sessions. intensity won't burn muscle, duration will. higher intensity will fatigue you quicker before muscle is ever started being burned. edited for format

03-11-2004, 01:30 PM	#4 (permalink)
EleqTrizi'T Insane	My trainers over time have all told me the basic same thing... stop working out when you burnt your glycogen stores. One trainer believed you trained hard for 45 minutes and stopped. Another believed when you started feeling fatigued everywhere (not just the muscles you're working), you should stop. I do the latter, not entirely sure that is the right choice. But I gauge my tiredness on my ability or inability to do two pushups in a row. Sometimes I just drop and give it a shot, if I can't, I shower.

03-11-2004, 08:06 PM	#5 (permalink)
Lunchbox7 Addict	hannukah harry Well said. I was about to say basicaly the same thing though I wouldnt of said it anywhere near as well as you did. Aleqtrizi'T dont worry about the glycogen stores. It is just part of the process of producing glucose (suger) from other energy sources. You cant possibly measure when you glycogen stores are at unless you have access to the best equipment. When your glycogen stores run out you die. As hannukah harry said your body tries to survive. That is why muscle is used last as you need to your muscle to help you survive. You will stop excercising through fatige along time before all your energy stores are used up.