If you're the typical gym-going dude, there's a pretty good chance you've heard the term "eccentric exercise" tossed around. Sounds like a fancy term, but it's a simple concept: Simply put, eccentric exercise focuses on working muscles as they lengthen, rather than as they contract.
Picture yourself doing a basic dumbbell curl. Typically, most guys focus on doing work as the bicep contracts into the big cannonball everyone wants, and then relaxing the muscle as they lower the weight for the next rep. (That’s formally called concentric exercise.)
The eccentric portion of the move happens as you slowly lower the dumbbell, feeling the burn as your muscles resist the weight while still extending. Eccentric movements also factor heavily in activities like walking down steps or running down a hill, where your muscles act as a sort of braking system.