Lie in a straight line with the side of one foot and the same side forearm on the floor with the elbow bent to 90 degrees. Keeping the abs and glutes tight to ensure your body remains in a straight line, lift your hips up into a side plank position and hold momentarily before bringing the hips down to lightly touch the floor, and repeat.
 
Purpose
The side plank is simply a repetitive lift up into a side plank rather than an isometric hold in the plank position that strengthens the obliques and quadratus lumborum to help with lateral trunk stability.
 
Programming
The side plank lift can be done unweighted for high-rep sets (upwards of “maximal”—not to actual concentric failure) or with added weight for sets of 10-15 reps. It can be done unweighted during a warm-up as a trunk preparation exercise, or at the end of a workout with more intense trunk strength work.
 
Variations
Side plank lifts can be done from on the hand with a straight arm rather than the elbow, can be weighted with a dumbbell or plate on the hip, can be done with extended pauses in the plank position, and can be done without allowing the hips to touch the floor between reps to maintain continuous tension.