"Just" Cardio

fteale

running actually decreases muscle size, more so if you are in a caloric deficit (look at long distance runners, thin as rakes)

Long distance running is a different thing, as the milage they do mean the body needs to fuel itself from other sources than most people. You can't store enough glycogen to run a marathon.

Also, professional runners keep themselves intentionally as light as possible to increase their speed.

liftingbro

Cardio does not build muscle. Why? Because running,cycling and the like recruit slow twitch muscle fibers, lifting weights recruits fast twitch muscle fibers. ST muscle fibers do not hypertrophy very much (maybe 5% of of what fast twitch does).

99% of the "building muscle" people think is happening when they run or cycle is a combination of just simply lowering BF% and muscle being more dense. A lean leg will look larger than a fat leg even if the measurements prove that wrong. FT and ST muscle fibers will become more dense with training and will make the muscle feel harder but in fact they may not be larger.

The one exception is sprinters and that's because sprinting activates fast twitch fibers.

liftingbro

cardio tones muscle, and yes you will lose muscle if you don't eat properly. With that being said, you will uncover all the muscle that you already have if you were to only do cardio. If you are trying to burn any amount of fat, you need to do cardio quite a bit. If you want to build your muscles, you would need some sort of lifting routine in order to fatigue those muscles properly.

Now that just isn't true. You don't need a specific "lifting routine" to build muscle. You have to have a weight aspect to your exercise regime, but that can be rowing, cycling, press ups, rock climbing, any one of 100s of sports that have a similar effect. Look at olympic swimmers. They have incredible bodies, and not from lifting weights.

Or tennis player's legs. I'm sure tennis is probably considered cardio, but D*** those tennis dudes have some fantastic legs.

Lean? Yes. Big? No.

Tennis does activate FT muscle fibers so they are somewhere between a distance runner and a sprinter as far as that goes.

fteale

It's pretty apparent that if people could only build muscle by lifting weights, most of us would be blobs on the floor. All sorts of daily activities, including running and rowing and cycling, build and then maintain muscle. They MUST, or runners simply wouldn't have any muscle.

Running and the other sports I have mentioned are NOT "just" cardio. They have a weight aspect. I am still waiting for someone to give me an example of a sport that is purely cardiovascular with no muscle weight bearing effect.

bcattoes

Cardio does not build muscle. Why? Because running,cycling and the like recruit slow twitch muscle fibers, lifting weights recruits fast twitch muscle fibers. ST muscle fibers do not hypertrophy very much (maybe 5% of of what fast twitch does).

99% of the "building muscle" people think is happening when they run or cycle is a combination of just simply lowering BF% and muscle being more dense. A lean leg will look larger than a fat leg even if the measurements prove that wrong. FT and ST muscle fibers will become more dense with training and will make the muscle feel harder but in fact they may not be larger.

The one exception is sprinters and that's because sprinting activates fast twitch fibers.

Hmm, I think that all sounds interesting. But it doesn't explain my Zumba legs.

liftingbro

From what I've read you have to put a load on the muscle equal to or greater than 60% of the maximum load it can handle to recruit a significant amount of FT muscle fibers to see a significant amount of hypertrophe.

Running (outside of sprints) will not do that.

erickirb

Cardio does not build muscle. Why? Because running,cycling and the like recruit slow twitch muscle fibers, lifting weights recruits fast twitch muscle fibers. ST muscle fibers do not hypertrophy very much (maybe 5% of of what fast twitch does).

99% of the "building muscle" people think is happening when they run or cycle is a combination of just simply lowering BF% and muscle being more dense. A lean leg will look larger than a fat leg even if the measurements prove that wrong. FT and ST muscle fibers will become more dense with training and will make the muscle feel harder but in fact they may not be larger.

The one exception is sprinters and that's because sprinting activates fast twitch fibers.

100% agree with this

liftingbro

Cardio does not build muscle. Why? Because running,cycling and the like recruit slow twitch muscle fibers, lifting weights recruits fast twitch muscle fibers. ST muscle fibers do not hypertrophy very much (maybe 5% of of what fast twitch does).

99% of the "building muscle" people think is happening when they run or cycle is a combination of just simply lowering BF% and muscle being more dense. A lean leg will look larger than a fat leg even if the measurements prove that wrong. FT and ST muscle fibers will become more dense with training and will make the muscle feel harder but in fact they may not be larger.

The one exception is sprinters and that's because sprinting activates fast twitch fibers.

Hmm, I think that all sounds interesting. But it doesn't explain my Zumba legs.

Sure it does. More lean=look more muscular. More dense=feels a lot harder.

Simple as that. I would seriously doubt your legs got bigger doing Zumba unless you gained weight.

SaraSweetheart

I don't think there's anything as "just" cardio... but keep in mind, it's important to cross-train... especially if you are a runner. Lift weights working all areas of the body to avoid injury. I like the exercises Jillian Michaels does with weights on her DVDs, and I am a fan of the leg press. I have shorter tendons and muscles on the right side of my body than I do on the left side, and my bones are of poor quality. The doctor said I need to lift weight so I get more balanced and my bones get stronger. I'm also a runner and haven't had an injury yet! Also, do yoga to keep your muscles from getting to tight once or twice a week.

meglar287

cardio tones muscle, and yes you will lose muscle if you don't eat properly. With that being said, you will uncover all the muscle that you already have if you were to only do cardio. If you are trying to burn any amount of fat, you need to do cardio quite a bit. If you want to build your muscles, you would need some sort of lifting routine in order to fatigue those muscles properly.

Now that just isn't true. You don't need a specific "lifting routine" to build muscle. You have to have a weight aspect to your exercise regime, but that can be rowing, cycling, press ups, rock climbing, any one of 100s of sports that have a similar effect. Look at olympic swimmers. They have incredible bodies, and not from lifting weights.

Olympic swimmers all lift weights as part of their training program.

fteale

From what I've read you have to put a load on the muscle equal to or greater than 60% of the maximum load it can handle to recruit a significant amount of FT muscle fibers to see a significant amount of hypertrophe.

Running (outside of sprints) will not do that.

I would have thought that the average force a runner produces with their legs when they hit the ground would easily reach 60% of max.

bobbybdoe

Mcrow is 100% right in here. All professional (or even regular) athletes do lift weights, even runners. Look, I learned this in Biology.

In the first 20 minutes of exercise, your body uses ATP as it's first energy source. ATP only lasts about 20 minutes of use before the source is depleted. Afterwards, the body uses the fats and carbohydrates that were stored in the body from previous meals. The thing is, after your fat and carb sources are depleted, your body begins to burn fat (stored in the body -- the fat that makes us look -- well, fat), but for runners, they usually don't have this stored fat, so they have to use muscle stored in the body, which is why THIS kind of intense cardio burns muscle.

The thing is, cardio can help you gain and maintain muscle if you do it right and in the right amounts.

meglar287

maybe i'm not an olympic swimmer, but i swam in high school and my muscles got WAY bigger without weight lifting. just sayin

trelm249

Cardio is basically any sustained exercise that keeps the heart rate elevated for a long period. Typically associated with walking, running, biking, lap swimming, etc.)

These activities do not stimulate the fast twitch muscle fibers that are more prone to dramatic hypertrophy (increase in size/strength).

Cardio uses slow twitch muscle fibers. These do not grow as dramatically due to what they are used for.

fteale

Mcrow is 100% right in here. All professional (or even regular) athletes do lift weights, even runners. Look, I learned this in Biology.

In the first 20 minutes of exercise, your body uses ATP as it's first energy source. ATP only lasts about 20 minutes of use before the source is depleted. Afterwards, the body uses the fats and carbohydrates that were stored in the body from previous meals. The thing is, after your fat and carb sources are depleted, your body begins to burn fat (stored in the body -- the fat that makes us look -- well, fat), but for runners, they usually don't have this stored fat, so they have to use muscle stored in the body, which is why THIS kind of intense cardio burns muscle.

The thing is, cardio can help you gain and maintain muscle if you do it right and in the right amounts.

RUNNING can help you build and maintain muscle.

CARDIO is purely about heart rate.

That is the distinction most people seem to miss on this site.

ninerbuff

Perhaps some of it is genetics, but I can tell you that they were NEVER pure muscle until I started running. So, obviously running is what did it. Nothing anyone says will change my mind - sorry. I've watched how they've changed since I started running. They look like completely different thighs.

I don't do any kind of work on my legs because I run every single time I go to the gym. My thighs are still larger, but they are pure muscle. There isn't any fat left to them.

*shrug*

There is fat on every muscle in the body. Percentage is the difference. If you had no fat, then your legs should look like they only have skin over them. Look a competitive bodybuilder in contest. Ripped to the bone and you can see every detail. And they are at about 5% bodyfat all over.
The misconception is that your legs were fat once. Now you can see muscle so somehow you believed you "built" it. It's been there all along, you just couldn't see it. Without muscle you couldn't walk. So really all you did was activate them and made their purpose more continous.

bobbybdoe

Perhaps some of it is genetics, but I can tell you that they were NEVER pure muscle until I started running. So, obviously running is what did it. Nothing anyone says will change my mind - sorry. I've watched how they've changed since I started running. They look like completely different thighs.

I don't do any kind of work on my legs because I run every single time I go to the gym. My thighs are still larger, but they are pure muscle. There isn't any fat left to them.

*shrug*

There is fat on every muscle in the body. Percentage is the difference. If you had no fat, then your legs should look like they only have skin over them. Look a competitive bodybuilder in contest. Ripped to the bone and you can see every detail. And they are at about 5% bodyfat all over.
The misconception is that your legs were fat once. Now you can see muscle so somehow you believed you "built" it. It's been there all along, you just couldn't see it. Without muscle you couldn't walk. So really all you did was activate them and made their purpose more continous.

Hit the nail right on the head there.

charlene77

Cardio WILL build muscle! If it didn't my thighs wouldn't be pure muscle since the only work I really do on my legs is running (and running is cardio).

That can also be a function of genetics, not due to the running. I have thin legs and did even when I was dead lifting and squatting double my body weight for multiple reps.

Perhaps some of it is genetics, but I can tell you that they were NEVER pure muscle until I started running. So, obviously running is what did it. Nothing anyone says will change my mind - sorry. I've watched how they've changed since I started running. They look like completely different thighs.

I don't do any kind of work on my legs because I run every single time I go to the gym. My thighs are still larger, but they are pure muscle. There isn't any fat left to them.

*shrug*

I don't have all the answers but, you said... "There isn't any fat left to them".....Your muscles will look alot different as your cardio exercises burn the fat. You now are revealing what was there I know I have pipes...I am a muscular person...my arms and legs for sure.....but the fat is hiding them Heck maybe I have a six pack hiding under there....I am now jogging, yes I am feeling stronger as I am activing and strengthening my muscles, and can't wait for what the fat disappearing, reveals

ninerbuff

What I am saying is how can there be such a things as pure "cardio"? I can't think of any exercise that raises your heart rate with no muscular force. And muscular force WILL build muscle.

Not true. It takes muscular force to lift a coffee cup. To wink your eyes. To type on a computer. How much muscle are you building there?
To build muscle you need to OVERLOAD it over a duration of time. Running doesn't overload it since your weight doesn't change, with the exception of going down, which would UNLOAD more weight.

ChantalGG

Well there is resistance with just gravity so you will build muscle. Also having extra pounds on you if like using resistance bands in a way. you will get sculpted if you are doing the right kind of cardio.