by Men's Health

This workout revs your metabolism while bulking up your triceps and biceps. Celebrity trainer Mark Jenkins says that doing this workout once a week will chisel your arms and ignite a total-body fat burn. It's the smartest way to spend 15 minutes. Well, almost.

First, perform a superset of eight to 12 repetitions of the squat. Then, without rest, move on to a set of shoulder presses. Rest a minute and repeat the superset. Then do the triceps-and-biceps superset three times, resting a minute after each superset.

Muscles worked: arms, shoulders, legs, and core

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1) Squat

Stand holding a pair of dumbbells at your sides, palms facing in. Lower your body to a sitting position, so that your thighs are parallel to the floor. Pause, then push yourself back up to the starting position.

The key to big guns is working your biceps and triceps from every angle. Add 2 inches to your arms with this workout.

2) Shoulder Press

Stand holding a pair of dumbbells just above your shoulders with an overhand grip, palms facing forward. Press the weights straight up. Pause, then lower them to your shoulders.

No matter how many curls you do, if you have weak muscles in your upper back, shoulders, and core, you won't build muscle. Click here to learn the better way to bigger biceps.

3) Swiss-Ball Incline Triceps Extension

Grab a pair of dumbbells and sit on a Swiss ball. Roll your back down the ball, keeping your stomach tight, until your shoulders are pressed firmly against the ball and your butt is off the ball. Hold the weights with straight arms, angled so the weights are over your forehead. Keeping your upper arms still, bend at the elbows to lower the weights until they're even with the top of your forehead. Pause, then straighten your arms.

4) Swiss-Ball Biceps Curl

Set dumbbells on a bench in front of a wall, or ask someone to hand them to you. Place a Swiss ball against the wall a few feet up from the floor and stand with your lower back against the ball, holding it in place. Hold the dumbbells with palms facing the sides of your thighs. Curl the weights up, rotating your wrists upward so your palms face you by the time the weights reach your shoulders.

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