Allright, so how much is too much? After my track and cross-country days, I never ran more than 20 miles a week tops. Do you have anything specific in this regard?
i would imagine any activity that is primarily aerobic in nature. this could be lifting pink dumbbells like gene does, or jogging or running long distances.
energy systems come into play here, although if you listen to coach you should do every energy system at once.
science tells us we should split up training, keeping the energy systems as far apart as possible.
specifically to bodybuilding - studies show cardio and weights together interfere with each other.
i do both together because it can't be helped with my time management and its simply convenient for me. however it is not optimal for muscle and strength gains nor endurance/cardiovascular gains either.