Popsugar Fitness Workouts Posterior Core Exercises Get Your Strongest Core Ever by Adding These Ab-Strengthening Exercises Into Your Routine 27 December, 2019 by Tamara Pridgett View On One Page Photo 5 of 8 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 5 Bird Dog Get on all fours, with your knees under your hips and your hands under your shoulders. Remember to keep abs engaged and keep your back flat. Reach out with your right hand and extend your left leg out behind you. Round your back and head to connect your right elbow with your left leg under your body. This completes one rep. Previous Next Start Slideshow Trainer TipsFitness TipsAb ExercisesStrength Training