The glutes do more than just round out the back of your pants. They’re the strongest muscles in the body, and the main engine behind lifting huge amounts of weight on the squat and deadlift. Your butt helps you run faster and jump higher, too, so when this workout, designed by Michael Schletter, C.P.T., brings up your backside, remember that it’s not just for the ladies (though she'll definitely appreciate it).

How it works: We’ve added a little hamstring workout into the glute training to strengthen both muscle groups, because they work in conjunction to extend your hips, but this will also sharpen the distinction between the two where they meet on the back of the leg. Specifically, you’ll fatigue your hams with hip thrusts on the ball, and then finish them off with hamstring curls—your glutes will be firing as well to stabilize you. The butterfly hip thrust provides another challenge. This one targets the gluteus medius, which is commonly underdeveloped and can lead to instability and weakness in the entire lower body. When brought up, it can also make for firmer-looking buttocks, which no one complains about.

Directions: Perform the paired exercises (marked “A” and “B”) as supersets. So you’ll do one set of A, and then B before resting. Complete all the prescribed sets for the pair before moving on.