Are you a workout-warrior looking for a challenge? You've come to the right place. Last week we launched a new series to test your mettle and your abilities. Each week, our fitness expert, CrossFit competitor and owner of Reebok CrossFit 5th Ave., Nathan Forster will lay out a quick and specific workout that focuses on a variety of areas: strength, speed, power, endurance and skill. Think you've got what it takes to 'One-Up' our guy? Get ready to throw-down and let's see what you got...

For this week, Forster's challenge consists of four movements at varying repetitions ranges that you must complete as fast as you can.

> Complete the prescribed number of repetitions for each exercise as fast as possible.

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Kettlebell Swings: Don't swing the weight with just your arms, make sure to 'pop' your hips to explosively raise the weight. Finish with the bell at eye-level for one complete rep.

Med Ball Slams: Be sure to use the power in your legs to explode upwards and down with the ball on the slam. The med ball must be overhead for a rep to be complete.

Lunges: Don't over-extend your lunge, the knee on your lead leg should align with your ankle and be perpendicular with the floor.

Sit-Up: When in the start position, open up your hips and turn your knees outward to reduce the strain on your lower back. Your hands must touch your sneaker to be a complete rep.