I just started deca/test cycle. I'm trying to stay realitively lean through this cycle so I am doing some cardio, running, bike, etc. How much is too much cardio before it begins to hinder muscle gains?
I wouldn't do more than 20 minutes 2-3 times a week... If you eat clean you dont have to worry about gaining a lot of fat, therefore you can concentrate on bulking and forego any kinda cardio.
I consider walking up a flight of stairs too much cardio while bulking, so you can probably guage my response to something like running. Why are you running if your trying to add muscle mass. When was the last timne to saw a jacked up 250 pound ethiopian marathon runner? Running and muscle mass don't mix.