Popsugar Health & Fitness Workouts Plank Ab Workout I Trained With J Lo's Trainer, and Now I Know the Secret Behind Her 6-Pack 21 September 2018 by Tamara Pridgett View On One Page Photo 3 of 4 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 3 Circuit Two: Elbow Plank With Knee Drive Start in an elbow plank, and bring your right knee into your nose; your pelvis will rise toward the ceiling. Place right foot back on the ground. Alternate sides, and bring your left knee into your nose. Place right foot back on the ground. This counts as one rep. Complete 15 reps on each side. Previous Next Start Slideshow 15-Minute WorkoutsBodyweight WorkoutsIntermediate WorkoutsCore ExercisesAb WorkoutsCelebrity TrainersPlankStrength TrainingWorkouts