All aerobics

Mountain climber

Plank with quick knees

1 min roundsHarder

How to do it

  1. 1Set your hands under the shoulders and step back to a straight plank.
  2. 2Drive one knee toward the chest, then switch.
  3. 3Hips stay level. Don't bounce them up.
  4. 4Keep the hands planted.
  5. 5Work 20–30 seconds.

Tip

Slow the knees down if the plank starts to break.

Avoid

Letting the hips sag, or hopping both feet at once.