Exercise! Yes, it's the obvious answer, but we wanted to preface with that first. Without exercise, no supplement will make you gain muscle. Period. And the best complement to exercise is good nutrition from a healthy, balanced diet.

As far as supplements to take with exercise, any type of protein is the first thing because your body needs that protein to build up the muscle after the exercise breaks it down. After that, L-Arginine is a great option because it's a simple amino acid (a building block of proteins) that helps circulation so it helps in the warm up and helps to prevent lactic acid from building up (that build-up is why the muscles hurt).

There's another category for energy products... Ribose, L-Carnitine, and Creatine are major players there. Any simple sugar (even honey, syrup, or table sugar) can give you a quick boost, but it's followed by a quick crash. Ribose and Creatine help more for sustained energy to keep the workout going. L-Carnitine is an amino acid that helps your body convert fat into energy so many people use it for exercise and/or weight loss support.