When it comes to the best muscle building supplement, you may want to try a testosterone based product which can help build both muscle and strength. Gaining muscle is not just about looking huge (although this helps!) it is also about gaining muscular strength and endurance so that you can get the most out of your fitness regime. Once your endurance is boosted, our stamina and our ability to work out for longer will improve too. The supplements that you take can determine how much you can benefit from your workout – a performance enhancer can give you the boost that you need!