Mountain climbers should start in the plank position. That means your shoulders are down (no shrugging), your core is braced, and your back is neutral. When you tuck your knees in, it is important to remember these cues, as you might compensate for lack of core stability and hip flexor strength by rounding your shoulders and lower back.
You should also be flat as a board as you use your hip flexors and abs to pull your knees towards your chest. Once you have this technique down, you can up the difficulty of the move, increasing both your heart rate and the stabilisation demands of the exercise. Need some inspiration...
In the video above, PT Gerren Liles, shows you six variations, from the cross-body mountain climber, that nails your obliques, to the feet-to-wall mountain climber, that shifts the emphasis to the muscles in your shoulders.
Mix these variations into your regimen and you'll not only unveil core muscles you never knew existed, you'll also tighten your posture and boost your athleticism.
A version of this story originally appeared on Menshealth.com