You finished a brutal session — maybe a HYROX race, a long marathon training run, a fitness competition prep block, or a 55-minute Pace & Press class that left your legs shaking. A percussion massage gun is one of the fastest ways to short-circuit the soreness coming tomorrow. But only if you use it correctly. Here's the no-fluff guide to the 10 most common types of post-workout muscle soreness — DOMS, IT band tightness, sled-push quads, post-marathon calves and more — plus exactly how to fix each with a Hypervolt massage gun.