Dumbbell lying supination on floor

Lie flat on your back on the floor with your legs extended and your arms by your sides, holding a dumbbell in each hand. Rotate your palms to face up, keeping your elbows close to your sides. Slowly curl the dumbbells towards your shoulders, squeezing your forearms. Pause for a moment at the top, then slowly lower the dumbbells back down to the starting position. Repeat for the desired number of repetitions.