On your next arm day, try out this circuit for a new way to hit those curls. It's engineered to help you build up cannonball-sized biceps, so you'll be glad you switched up your routine.

Prone cobra

To maximize your arm exercises and prevent injury, don't let your shoulders roll forward. Prone cobras will strengthen your shoulders and the stabilizing muscles in your back.

Lie facedown on the floor with your legs straight, arms at your sides, and palms down. Drive your hips into the floor. Contract your glutes, raising your legs off the floor.

Simultaneously inhale and tighten the muscles in your upper back, raising your chest, head, and arms off the floor; rotate your thumbs toward the ceiling as you do this.

Hold for 4 seconds, and then return to the start. That's 1 rep. Do 2 sets of 10.

Do 3 rounds of this muscle-building circuit. Rest 1 minute between each round. Start with medium-weight dumbbells; aim for 12 reps in the first two rounds, 10 in the last round. Focus on flawless form.

Tall kneeling hold curl

Kneel on your shins, thighs perpendicular to the floor, holding dumbbells with an underhand grip. Curl the weights until your forearms are parallel to the floor; this is the start.

Without moving your left arm, lower your right arm to your side. Do one full curl. Lower to the start. Repeat with your left arm. That's 1 rep; do 10 to 12.

Floor JM press

Lie faceup on the floor holding dumbbells above your chest, arms straight, and palms facing in.

Bend your elbows so the dumbbells end up directly over your shoulders and the points of your elbows are near your ribs.

Pause and return to the starting position. That's 1 rep; do 10 to 12.

Wall curl

Stand with your back pressed against a wall, holding two 20-pound dumbbells with an underhand grip.

Curl them upward toward your chest as you keep pressing your back and upper arms into the wall.

Squeeze your biceps at the top of the curl; then lower the dumbbells. That's 1 rep; do 10.

Close-grip pushup hold

Assume a pushup position, your hands directly under your shoulders.

Keeping your elbows close to your body, lower your torso until your chest is 2 inches from the floor. Hold 4 seconds; return to the start.

That's 1 rep; do as many as you can before the time's up or your form fails.

Test Your Cannonball Strength

You can turn the workout into a fun challenge to gauge your arms' strength. Set a timer for 2 minutes per round. Do 3 rounds of the circuit total, resting 1 minute between each. Track the number of close-grip pushup holds you complete in total; that's your score.

SCORECARD

<6 Off to a good start

7-12 That's serious strength

>13 Now you've got sleeve-busting biceps!