How long cardio to lose fat but not muscle?

I've been weight lifting for over 4 years now, and I'm definitely making alot of gains, but I still don't really know about cardio... I never do cardio, and I'd like to start doing it. I just want to know how long sessions of cardio should I do to burn fat, so I could get and stay lean.. but I don't want to lose any muscle. I don't really want to lose weight, I just want to burn all this little fat around me (NOT MUSCLE)

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Recommanded Answer:
Its not about how long you do, it is more important the type you do.

Doing cardio can actually help with muscle growth if you do it right. You do not want to be going for an hour cycle or go jogging. You want to be doing extremely high intensity cardio in bursts.

This will achieve everything long easy pace cardio will do however it can increase testosterone and hgh. As it should increase these two, it will probably out way the downsides cardio does to muscle growth.

Sprint as far as you can go ( probably only about a minute ) then walk until you are ready to go again. Keep doing it for as long as you want.

• Its very hard to lose muslce with cardio
• Cardio will not burn muscle unless you go to the extreme and run a marathon every day.
  The reason why some people lose muscle when doing heaps of cardio is because they are't compensating for the calories burned during the exercise. If you eat enough calories to compensate for the cardio, you won't lose anything.
  
  See Scooby's video for more details:
  http://www.youtube.com/watch?v=nTDQVARSDNc