Mountain Climbers
Take position on the ground in a push up position with hands just outside shoulder-width apart, fingers facing forward and arms outstretched until the elbow joint is totally opened lifting the torso up. You should be up on your toes and with your body flat, not arched either way. This is the starting position.
The movement is performed by explosively bringing your right knee forward until it is under your body whilst keeping the left leg straight. Then alternate and bring the left knee up under the body while you simultaneously reverse the right leg back to push up position.
This is a fast paced exercise where you alternate each leg until the target duration is reached.