How does cardio cause muscle loss?

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Replies

  • SLHysell
    SLHysell Posts: 247 Member
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    This probably sums it up best.
    If you want to do only cardio like treadmill, elliptical, or running, and you enjoy it and can maintain such a routine, and such a routine has caused you to lose weight..........then great, you're already doing more than the next person doing nothing.

    As far as the physiology behind your question. If, for instance, all you are doing is running, then over time you are going to become a more efficient runner. Unfortunately, your body is going to work to strengthen those muscles needed to run to create an improved economy of motion, but those muscles not used in your selected workout are going to atrophy.......you body will adapt to improve your selected method of exercise by burning the muscle no longer needed.

    Yes, if you maintain a calorie deficit, you are going to appear more muscular-ish, but that is because the fat that previously covered those muscles is burning too.......it's kind of a lose/win.......you're burning fat, but you're also burning muscle which is probably a greater component in burning fat than that 30 minute run you just did.

    In the end, do what you want, do what you can maintain and consistently do, and anybody who wishes to tell you you're doing wrong can just go away.

    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.
  • LoneWolfRunner
    LoneWolfRunner Posts: 1,160 Member
    My running goes better when I also do weight training and my weight training goes better when also consistently run. Running definitely helps lean me down but I can see clearly in the mirror that I lose muscle mass if I am not regularly dining on early morning iron at the gym...
  • ThePhoenixIsRising
    ThePhoenixIsRising Posts: 781 Member
    SLHysell wrote: »
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    Being in a calorie deficit causes muscle loss (as well as fat loss) and cardio increases that deficit making the loss occur faster.

    There's more to it than this, but one reason muscle is lost in a deficit is that muscle requires more energy to maintain than fat does. So when your body is in a calorie deficit it will burn muscle for energy as well as fat in order to reduce energy expenditure and therefore reduce the deficit.

    Weightlifting also increases calorie expenditure and therefore the deficit, but unlike cardio it also encourages your body to hold on to the muscle (it thinks it needs it).

    So a lot of people prefer weightlifting to cardio for fat loss.

    A bit of both would be the ideal; weightlifting to keep the muscle, cardio to increase calorie deficit.

    This is the most informative and thought out answer I've see so far. I bolded part of it because that is the part that I've always had a problem with. Why on earth would the body burn muscle instead of fat since fat's purpose is to store energy for use when we don't have fuel. The bold text sort of answers that, but the question that then comes to mind is, how on earth is running 5 miles not teaching your leg muscles and your core muscles that they will be needed? Why would your body burn those muscles up? Obviously you are making a demand on them. To me, it doesn't really jive with the theory that resistance teaches your body to keep your muscles because it "thinks it needs it".

    EDIT: I did a couple of edits only to fix typos.

    There is only so much muscle your body needs to run, just look at distance runners.
  • sijomial
    sijomial Posts: 19,643 Member
    SLHysell wrote: »
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    Being in a calorie deficit causes muscle loss (as well as fat loss) and cardio increases that deficit making the loss occur faster.

    There's more to it than this, but one reason muscle is lost in a deficit is that muscle requires more energy to maintain than fat does. So when your body is in a calorie deficit it will burn muscle for energy as well as fat in order to reduce energy expenditure and therefore reduce the deficit.

    Weightlifting also increases calorie expenditure and therefore the deficit, but unlike cardio it also encourages your body to hold on to the muscle (it thinks it needs it).

    So a lot of people prefer weightlifting to cardio for fat loss.

    A bit of both would be the ideal; weightlifting to keep the muscle, cardio to increase calorie deficit.

    This is the most informative and thought out answer I've see so far. I bolded part of it because that is the part that I've always had a problem with. Why on earth would the body burn muscle instead of fat since fat's purpose is to store energy for use when we don't have fuel. The bold text sort of answers that, but the question that then comes to mind is, how on earth is running 5 miles not teaching your leg muscles and your core muscles that they will be needed? Why would your body burn those muscles up? Obviously you are making a demand on them. To me, it doesn't really jive with the theory that resistance teaches your body to keep your muscles because it "thinks it needs it".

    EDIT: I did a couple of edits only to fix typos.

    Unfortunately the difference between maintenance calories for muscle and fat is very small - 2 calories a day for a pound of fat and 6 calories for a pound of muscle. The difference is pretty much insignificant compared to the effects of training and energy actually expended during exercise.
  • SLHysell
    SLHysell Posts: 247 Member
    I should mention that although I do love to run and it is my preferred exercise, I also do 30 minutes of strength training at the gym 3 days a week. I really want the best of both worlds. I'm just seeking understanding in what is obviously a sometimes contentious subject.
  • kgeyser
    kgeyser Posts: 22,508 Member
    SLHysell wrote: »
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    This probably sums it up best.
    If you want to do only cardio like treadmill, elliptical, or running, and you enjoy it and can maintain such a routine, and such a routine has caused you to lose weight..........then great, you're already doing more than the next person doing nothing.

    As far as the physiology behind your question. If, for instance, all you are doing is running, then over time you are going to become a more efficient runner. Unfortunately, your body is going to work to strengthen those muscles needed to run to create an improved economy of motion, but those muscles not used in your selected workout are going to atrophy.......you body will adapt to improve your selected method of exercise by burning the muscle no longer needed.

    Yes, if you maintain a calorie deficit, you are going to appear more muscular-ish, but that is because the fat that previously covered those muscles is burning too.......it's kind of a lose/win.......you're burning fat, but you're also burning muscle which is probably a greater component in burning fat than that 30 minute run you just did.

    In the end, do what you want, do what you can maintain and consistently do, and anybody who wishes to tell you you're doing wrong can just go away.

    I'm guessing that legs kind of get the short end of the stick in strength training.

    Only if every day is upper body day. Legs get quite bit of work in squats, deadlifts, lunges, split squats, leg press, leg extension, hamstring curls, calf raises/presses, step ups, etc.
  • ndj1979
    ndj1979 Posts: 29,147 Member
    Its a load of rubbish promulgated by those who like to pick things up and put them down again. I have lost over 100lbs and believe me that was all fat. I now have more muscle than I have ever had and I haven't lifted anything. (Stands back and waits for flaming)

    so you trained your body to be 100% efficient and only burn fat...congrats as you are the only person on the face of the earth that can do that....you might want to copyright that process as it will make you a gazilllionaire..

    I lift heavy weight and I know I have lost muscle mass when in a calorie deficit...
  • erickirb
    erickirb Posts: 12,277 Member
    The body would burn muscle as a way of avoiding starvation. If you are in a deficit your body can shed muscle to lower you total energy output and save your fat stores so they last longer and you live longer in a situation of prolonged under eating.... it is essentially a survival mechanism, like fat storage for humans to survive when food was abundant and scarce. gain fat when it is there, to survive longer when it is not.
  • KylaDenay
    KylaDenay Posts: 1,585 Member
    Is there a minimum of resistance/strength training that one needs per week in order to help maintain current muscle mass? I mean I know why I should do it, but I now prefer to run then lift weights. I was lifting 3 times a week months ago, but would 2 full body days be enough? Are body weight exercises enough when eating in a deficit?
  • perseverance14
    perseverance14 Posts: 1,364 Member
    SLHysell wrote: »
    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.
    You think so? Try squatting 200 lbs. then come back and tell me that again. I can't do as much cardio as I used to along with my lifting because my leg muscles don't recover from the lifting then, they need a break to recover, things like squats all leg muscles and compound exercises are full body. You talk like somebody who has never done it, or you would know that is not true.

  • mustgetmuscles1
    mustgetmuscles1 Posts: 3,348 Member
    SLHysell wrote: »
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    This probably sums it up best.
    If you want to do only cardio like treadmill, elliptical, or running, and you enjoy it and can maintain such a routine, and such a routine has caused you to lose weight..........then great, you're already doing more than the next person doing nothing.

    As far as the physiology behind your question. If, for instance, all you are doing is running, then over time you are going to become a more efficient runner. Unfortunately, your body is going to work to strengthen those muscles needed to run to create an improved economy of motion, but those muscles not used in your selected workout are going to atrophy.......you body will adapt to improve your selected method of exercise by burning the muscle no longer needed.

    Yes, if you maintain a calorie deficit, you are going to appear more muscular-ish, but that is because the fat that previously covered those muscles is burning too.......it's kind of a lose/win.......you're burning fat, but you're also burning muscle which is probably a greater component in burning fat than that 30 minute run you just did.

    In the end, do what you want, do what you can maintain and consistently do, and anybody who wishes to tell you you're doing wrong can just go away.

    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.


    Im not sure what program you are doing but it should definitely include leg work.

    Running does not strengthen leg muscle beyond what it takes to run with your body weight which is not much.
  • SLHysell
    SLHysell Posts: 247 Member
    edited December 2014
    SLHysell wrote: »
    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.
    You think so? Try squatting 200 lbs. then come back and tell me that again. I can't do as much cardio as I used to along with my lifting because my leg muscles don't recover from the lifting then, they need a break to recover, things like squats all leg muscles and compound exercises are full body. You talk like somebody who has never done it, or you would know that is not true.

    Hey hey! I'm not looking for a fight, only understanding. I'm sure very serious people like yourself focus on their entire body, but I'd bet dollars to doughnuts that for most people, the legs are the bottom of the hierarchy when it comes to what is most important to them. I think this is especially true for guys. I don't hear a lot of people on here talking about how they want muscular thighs, but I do hear a ton of people talking about their abs and upper body. Just sayin'.

    And you are right. I don't do free weights just yet. I mentioned earlier that I prefer running, but I do hit the weight machines three times a week. Even so, this isn't a question about how you or I workout. It's about how muscle is built and/or burnt off. People often take things very personally when others are speaking in generalities. I'm trying to stick with generalities as much as I can on this one.
  • SteveJWatson
    SteveJWatson Posts: 1,228 Member
    SLHysell wrote: »
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    This probably sums it up best.
    If you want to do only cardio like treadmill, elliptical, or running, and you enjoy it and can maintain such a routine, and such a routine has caused you to lose weight..........then great, you're already doing more than the next person doing nothing.

    As far as the physiology behind your question. If, for instance, all you are doing is running, then over time you are going to become a more efficient runner. Unfortunately, your body is going to work to strengthen those muscles needed to run to create an improved economy of motion, but those muscles not used in your selected workout are going to atrophy.......you body will adapt to improve your selected method of exercise by burning the muscle no longer needed.

    Yes, if you maintain a calorie deficit, you are going to appear more muscular-ish, but that is because the fat that previously covered those muscles is burning too.......it's kind of a lose/win.......you're burning fat, but you're also burning muscle which is probably a greater component in burning fat than that 30 minute run you just did.

    In the end, do what you want, do what you can maintain and consistently do, and anybody who wishes to tell you you're doing wrong can just go away.

    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.


    There are two kinds of muscle - fast twitch and slow twitch. Distance running uses slow twitch muscle, essentially, you don't need much of it to propel your body at a steady pace for a long time. Fast twitch muscle is used for explosive movements, and can only fire for a short period of time. It is this muscle you are building when you lift weights.

    Quite a good illustration of muscle types can be found in fish - if you cook a fish and peel the skin off, the dark flesh along the lateral line is its slow twitch muscle, the rest is fast twitch. The contrast between the two is particularly noticeable in salmonids if you want to look.
  • NikonPal
    NikonPal Posts: 1,346 Member
    Its a load of rubbish promulgated by those who like to pick things up and put them down again. I have lost over 100lbs and believe me that was all fat. I now have more muscle than I have ever had and I haven't lifted anything. (Stands back and waits for flaming)

    Ditto -- Mine was all fat too....

    73641431.png

  • ndj1979
    ndj1979 Posts: 29,147 Member
    SLHysell wrote: »
    SLHysell wrote: »
    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.
    You think so? Try squatting 200 lbs. then come back and tell me that again. I can't do as much cardio as I used to along with my lifting because my leg muscles don't recover from the lifting then, they need a break to recover, things like squats all leg muscles and compound exercises are full body. You talk like somebody who has never done it, or you would know that is not true.

    Hey hey! I'm not looking for a fight, only understanding. I'm sure very serious people like yourself focus on their entire body, but I'd bet dollars to doughnuts that for most people, the legs are the bottom of the hierarchy when it comes to what is most important to them. I think this is especially true for guys. I don't hear a lot of people on here talking about how they want muscular thighs, but I do hear a ton of people talking about their abs and upper body. Just sayin'.

    And you are right. I don't do free weights just yet. I mentioned earlier that I prefer running, but I do hit the weight machines three times a week. Even so, this isn't a question about how you or I workout. It's about how muscle is built and/or burnt off. People often take things very personally when others are speaking in generalities. I'm trying to stick with generalities as much as I can on this one.

    most people neglect legs but do not realize that legs actually work your whole body and that you actually release more growth hormone by working your legs which helps build more muscle mass...

    AND working legs is hard work...
  • JeffseekingV
    JeffseekingV Posts: 3,172 Member
    Its a load of rubbish promulgated by those who like to pick things up and put them down again. I have lost over 100lbs and believe me that was all fat. I now have more muscle than I have ever had and I haven't lifted anything. (Stands back and waits for flaming)

    I wish I could have more muscles I've ever had w/o lifting anything
  • ndj1979
    ndj1979 Posts: 29,147 Member
    NikonPal wrote: »
    Its a load of rubbish promulgated by those who like to pick things up and put them down again. I have lost over 100lbs and believe me that was all fat. I now have more muscle than I have ever had and I haven't lifted anything. (Stands back and waits for flaming)

    Ditto -- Mine was all fat too....

    73641431.png

    not sure if serious or not....
  • SLHysell
    SLHysell Posts: 247 Member
    edited December 2014
    SLHysell wrote: »
    Jams009 wrote: »
    It doesn't cause it, it just does little to prevent it, and in certain circumstances can increase it.

    This probably sums it up best.
    If you want to do only cardio like treadmill, elliptical, or running, and you enjoy it and can maintain such a routine, and such a routine has caused you to lose weight..........then great, you're already doing more than the next person doing nothing.

    As far as the physiology behind your question. If, for instance, all you are doing is running, then over time you are going to become a more efficient runner. Unfortunately, your body is going to work to strengthen those muscles needed to run to create an improved economy of motion, but those muscles not used in your selected workout are going to atrophy.......you body will adapt to improve your selected method of exercise by burning the muscle no longer needed.

    Yes, if you maintain a calorie deficit, you are going to appear more muscular-ish, but that is because the fat that previously covered those muscles is burning too.......it's kind of a lose/win.......you're burning fat, but you're also burning muscle which is probably a greater component in burning fat than that 30 minute run you just did.

    In the end, do what you want, do what you can maintain and consistently do, and anybody who wishes to tell you you're doing wrong can just go away.

    This was helpful too. I think what you're saying is that running strengthens leg muscles, but doens't really do anything for the muscles that aren't really used much in running. That makes sense to me, but wouldn't the same apply to strength training? Calves and quads come immediately to mind. I'm guessing that legs kind of get the short end of the stick in strength training.


    There are two kinds of muscle - fast twitch and slow twitch. Distance running uses slow twitch muscle, essentially, you don't need much of it to propel your body at a steady pace for a long time. Fast twitch muscle is used for explosive movements, and can only fire for a short period of time. It is this muscle you are building when you lift weights.

    Quite a good illustration of muscle types can be found in fish - if you cook a fish and peel the skin off, the dark flesh along the lateral line is its slow twitch muscle, the rest is fast twitch. The contrast between the two is particularly noticeable in salmonids if you want to look.

    Now that is very interesting. So...with this in mind I'm extrapolating that you simply have more room for muscle building if you focus on lifting and such because there is naturally more of that type of muscle (fast twitch) to start with, and you can demand more of it since you can increase weights as much as the muscles can handle. On the other hand, with running, you don't really tax the muscles past a certain need (strength-wise) no matter what distance you add (after a certain distance, of course). That is a good piece of info. The puzzle is starting to come together.
  • No_Finish_Line
    No_Finish_Line Posts: 3,664 Member
    already answered well, calorie defecit sets you up for muscle loss, lifting does much more to prevent you from losing it then cardio. plus cardio would increase your defecit.

    its not really accurate to say that cardio eats muscle, but if your not eating enough then it can, more or less as a side effect, help contribute to muscle loss
  • No_Finish_Line
    No_Finish_Line Posts: 3,664 Member
    KylaDenay wrote: »
    Is there a minimum of resistance/strength training that one needs per week in order to help maintain current muscle mass? I mean I know why I should do it, but I now prefer to run then lift weights. I was lifting 3 times a week months ago, but would 2 full body days be enough? Are body weight exercises enough when eating in a deficit?

    you could probably get away with two. not considering a calorie deficit, your not supposed to lose performance if your working out with in 3 days of your last workout.

    performance/strength isn't the same thing as mass... but my opinion is that the mass would last at least some what longer then the ability.