Hi and welcome to Zurich. My boyfriend is a bodybuilder too and we both work out a lot. A lot of the bodybuilders go to our gym- TC Gym in Airgate, Oerlikon. Its 5 minutes walk from Bahnhof Oerlikon and has squash courts, Sauna,Massage,etc. I like it because it seems quite big (high ceilings) and the atmosphere is nice there. The staff mostly speak English (I dont speak German). Otherwise, alot of the other hardcore people go to Nordfit which is slightly closer to Bahnhof Oerlikon, but I never liked the look of that place. As for buying protein powders an etc, you can try XXXFitness in the city, or there is another shop near bahnhof Wiedikon...if you want the name and address of the places, get back to me, as I will have to ask my boyfriend.