1. Place your hands flat on the floor slightly wider than shoulder width apart
2. Fully extend your legs out so that only your toes and/or balls of your feet touch the floor
3. Keeping your hands firmly placed on the floor, contract your hip flexors and abdominal muscles to bring one knee in towards your chest, briefly planting your foot lightly on the floor below and taking great care not to knee yourself as you do so
4. Reverse this motion to place the foot back into the starting position before repeating the same motion on the other side while keeping your back straight and strong
The primary muscles used in Mountain Climbers are the Abs. The secondary muscles used are the Obliques and Shoulders.