Also known as a “switch,” this simple but challenging movement primarily works the abdominals, glutes, abductors, quadriceps and hamstrings, and also engages the lats, deltoids, obliques and calves. While all these muscle groups are doing their thing, the high intensity aspect of mountain climbers will get your heart and lungs churning, too.

Since climbing any mountain begins with the first step, please allow me to introduce the proper form:
Begin on your hands and knees on the floor and then step back into what looks and feels like a yoga plank position (or the “up” phase of a push-up). Hands about shoulder-width apart, toes pointed downward, spine is long and strong. Bend your left leg and bring your left foot forward so your knee and foot are in line below your chest.

Check that your hands remain flat on the ground (weight evenly distributed on all ten fingers), your core is braced and your butt isn’t sticking up in the air.

From this starting position, execute a mini jump in which you switch leg positions, driving your right knee forward and the left leg back. Stop and check that all the directions above hold—except with your right knee under your chest and left leg fully extended behind you.

Congratulations, you’ve just performed a single mountain climber. If that felt okay, begin switching left-right, left-right—keeping your legs under you as you drive alternating knees forward—at whatever speed initially works for you. Choose a repetition number and count each time your left knee comes forward.

Cautions and variations: Obviously, form is crucial, so you may want to line yourself up near a mirror (side view) the first few times you try this exercise. If the range of motion in your hips doesn’t allow for the movement as described above, place your hands on a raised surface and execute mountain climbers that way until your hips adjust. For those feeling too much pressure on their wrists, try placing two dumbbells or push-up bars on the floor and use that grip instead. In the name of intensity, I suggest you super-set mountain climbers with crunches on a stability ball.

Mountain climbers are a fun and effective addition to your workout, and since no equipment is needed, they can be done just about anywhere.

Final note: The advice presented above is not meant for anyone with contraindicated health problems. Please consult a medical or fitness professional.

The first major achievement in mountain climbing is widely considered to be the ascent of Mont Blanc—the highest mountain in the Alps—in 1786.