Do any muscle work before cardio, and here's why:
Doing cardio before building muscle actually depletes your body of the energy it needs to work the muscles while lifting. If you work your muscles after your body is already void of some of the energy it needs, you will actually do more damage to your muscles than good. Think of it this way: In order to get the energy required to build your muscles, your body will have to use the muscles themselves for the energy, since what you used up doing cardio isn't there anymore.
The best plan is to just keep cardio days and lifting days completely separate.
