A side plank is an exercise where you balance your body on one arm while keeping the rest of your body straight and lifted off the ground, forming a straight line from your head to your toes. Full definition
The abdominal exercises used are the cross crawl, stability ball rollout, and side plank with dumbbell lateral raise. (turbulencetraining.com)
After crossing your legs, release them and step one leg across your body into a raised side plank position. (health.com)
First, complete 15 - second holds of side planks on each side, then finish the round with completing 15 seconds of a front plank on elbows. (fitnessandpower.com)