Timed Mountain Climbers

How to do it

1. Begin in a pushup position, with your weight supported by your hands and toes. Flexing the knee and hip, bring one leg until the knee is approximately under the hip. This will be your starting position.
2. Explosively switch legs at a steady pace until the timer runs out: extend the bent leg onto the toe while bringing the other knee in. Keep the hips down and the core braced.

Common mistakes

• Hips piked high — the abs barely work.

Tips

• Shoulders over wrists, knees to chest at a fast but steady pace.