Plank Knee Tuck

A moving core drill performed from a high plank: the body holds its straight line while one knee is drawn in under the chest and sent back, alternating sides. Slower and more controlled than a mountain climber, it trains the abdominals and hip flexors while the shoulders and trunk stay braced.

How to do it

1. Set up in a high plank with the hands under the shoulders and the body in a straight line from head to heels.
2. Press the floor away and brace the trunk so the hips neither sag nor pike.
3. Draw one knee in towards the chest without letting the hips rise.
4. Extend the leg back to the starting position under control.
5. Repeat with the other leg and keep alternating for the desired number of repetitions.

Tips

• Keep the hips level with the shoulders; letting them lift turns this into a pike.
• Pull the knee in with the abdominals rather than by hopping off the supporting foot.
• Keep the shoulders stacked over the wrists and push the floor away so the upper body does not sink.

Muscles

Primary: Hip flexors, Abs

Secondary: Front deltoid, Obliques, Serratus, Transverse abdominis