You’ve probably done a mountain climber. It’s basically a plank, but your knees take turns driving toward your chest.

And you may have done the cross-body version or even the feet-elevated variation.

Related: Check out Anarchy Abs for a rapid fat-burning, six-pack-shredding workout.

But you probably haven’t come close to trying all of these 52 mountain climber variations shown by Men’s Health Fitness Director B.J. Gaddour. He plays around with different tempos, body angles, directions, and equipment to challenge your core and melt serious fat.

If you want to use them in your next workout, chose a handful of these mountain climber variations. Perform each one for 30 to 60 seconds, resting 30 to 60 seconds between moves. Do this for 5 to 10 rounds.

You can also plug them into a total-body circuit as your core or cardio exercise.