There are countless supplements available (thanks to their classification keeping them out of the purview of the FDA), but the study focused on the more common ones which includes whey protein, creatine and L-carnitine. Protein powder is a bulking agent, thought to provide extra calories and amino acids to people putting their muscles through the wringer. Creatine, on the other hand, helps people lift more (and more often) by aiding in muscle recovery. L-carnitine is an amino acid that provides energy and aids in muscle development.
The last few years I have not used any supplements. The only one I did use last was creatine. The bottle was the plain powder kind that cost $15 or less and it lasted over a year. A teaspoon a day was all that I needed and I would cycle the usage.
What supplements do you use and why?