Sit on a bench with an incline of 30 to 45 degrees. Hold the dumbbells at each side with your arms suspended and your hands. Perform a bicep curl by lifting your arms to the height of your lower pectorals. When lifting your arms, you should twist your wrist to adopt a supine grip at the end of the positive phase of the movement. From this position, exhale to lower the dumbbells and return your arms to the starting position.