Quadruped alternate shoulder flexion is a great exercise to enhance core strength, including both lower abdominal and lower back muscle strength. Upper body weight bearing during this exercise also helps keep the bones in your wrists and arms strong.
Begin by getting into a hands and knees position on your mat. Your hands should be directly below your shoulders, and your knees should be directly below your hips. Your back should be in a neutral position as if forming a tabletop.
Engage your lower abdominal muscles and elevate one arm forward. Your thumb should be pointed up toward the ceiling. Hold this position for 5 seconds. Return to the starting position. Repeat with the other arm