How Does TestRX Work? Stack on Pounds of Lean, Hard Muscle at Any AgeGet Your Libido Back and Improve Bedroom Performance! TestRX helps guys build bigger muscles, boost aerobic performance, lose weight, and even shifts your sex drive into high gear. The short version of how TestRX works is that it encourages your body to make more testosterone. Testosterone boosts the rate of protein synthesis, which helps build muscle mass. I...