Karen

Karen is a conditioning workout: 150 wall-ball shots done for time. It trains your quadriceps and shoulders hard, with your glutes and core backing you up. The goal is to keep moving through a lot of reps while your form holds up.

Stand facing a wall, about an arm's length away. Hold a medicine ball at chest height with both hands, elbows tucked under and in. Set your feet about shoulder-width apart, toes turned out slightly, and look at the target on the wall.

Drop into a full squat, sending your hips down until they sit below your knees. Drive up hard, use your legs and arms to throw the ball up to the target, then catch it on the way back down. Pull the ball straight back to your chest and go right into the next squat. Repeat until all reps are done.

Breathe in and brace your core at the top of each rep, then exhale as you throw. If your depth or full overhead extension fades, lower the ball weight or target height so every rep stays complete. To raise the challenge, move faster only if your form stays solid.

Fault: The ball drifts out in front of you and pulls you forward. Fix: Keep your elbows under the ball and close to your chest, aim right at the target, and catch the ball high and tight.

Fault: Squats get shallow as you get tired. Fix: Scale the ball weight or target height so you can still hit full depth and a full finish overhead every rep; smaller sets are better than bad reps.

Fault: You hold your breath or relax at the bottom of the squat. Fix: Inhale and brace before you descend, keep your core tight through the bottom, and exhale as you throw the ball.