Mountain Climber

A plank with the knees driving alternately toward the chest. It keeps the midline under load while the heart rate climbs, and it needs nothing but a patch of floor.

Standard: A valid rep drives one knee toward the chest and returns it while the hands stay planted and the hips stay level with the shoulders.

How to do the Mountain Climber

1. Set up in a high plank with the hands under the shoulders.
2. Brace the midline so the hips sit level, not high and not sagging.
3. Drive one knee toward the chest without letting the hips rise.
4. Return that foot and drive the other knee through.
5. Keep the shoulders stacked over the hands the whole time.

Common faults

• Hips bouncing up and down so the movement comes from the back rather than the legs.
• Hands creeping forward until the shoulders are behind them.
• Feet slapping the floor rather than moving under control.
• Speeding up until the knees stop travelling anywhere near the chest.

Scaling & progressions

• Slow the tempo right down and treat it as a moving plank.
• Raise the hands onto a box or bench to reduce the load on the shoulders.
• Step the feet rather than driving them for a lower-impact version.
• Shorten the intervals and rest properly between them.