On the big screen, the antagonist typically plays a devious role. His or her goal is to undermine the lead character, creating drama and conflict. But in the weight room, it's a different story. Every time you perform a movement—whether it’s a squat, curl, press, row, raise, lunge, deadlift, or dip—all of your muscles, including the “antagonists,” work together to get the job done.
In the context of your body, an antagonist is a muscle that opposes the action of the targeted muscle. When you do a dumbbell curl, your triceps are the antagonists, for example. Their primary job is to extend the elbow, but they relax enough to allow your biceps (i.e., the “agonists”) to flex your elbow and lift the weight while still producing enough opposing force to help keep the movement controlled. When you do a triceps extension, the roles are reversed—your biceps are the antagonists and your triceps are the agonists.
This muscular collaboration plays out every time you move a joint, and if you know how to capitalize on it in your workouts, you can supercharge your gains while slashing your training time in half.
Your move: Pair exercises that target opposing muscle groups in back-to-back sets known as supersets. Using this classic bodybuilding strategy, you might alternate sets of the bench press (pecs) and bent-over row (lats, traps, rhomboids), or the dumbbell curl (biceps) and the skull crusher (triceps).
The key here is that you’re working one muscle group while allowing the opposing one to recover. In so doing, you can eliminate the need for rest between sets, shortening your workouts without sacrificing your gains.