Crank up your core strength with plank variations Boost your results with these plank variations by Holly Barker.Side plank with knee touchElevate your side plank by dropping your top elbow and raising your top knee towards each other. Perform 10 reaches per side, holding at the crunch and coming back to side plank each time.Basic plank with mountain climberElevate the basic plank by dropping your body down to a push-up position, elbows bent, and reaching one knee towards the same side elbow. Repeat one side after the other. Perform 10 touches per side with quick switches from side to side.Looking for more ab workouts? Grab a bench and try these workouts.