We live in a Golden Age of fitness science. Studies come out every month that confirm one or another fundamental truth about how to get in shape — the power of rest and recovery, the importance of mental toughness, or the unbeatable efficiency of high-intensity interval training. Still, buried within all those studies are subtleties and finer points that can make all the difference in how strong, fast, and healthy you feel and look. And that’s where we come in. We raided the latest research, talked to leading experts, and honed five workout upgrades that you can make right now. The tweaks may be simple, but follow the advice faithfully and the results will be nothing short of genius.