Lie flat on the bench so that your head, upper back, lower back, and both feet are firmly pressed against the bench and ground at all points while holding two dumbbells at your sides with a neutral grip.
Keeping your upper arm by your side, exhale and raise both dumbbells up towards your shoulders by flexing your arms and simultaneously rotating your palm inward so that your palm is facing you.
Continue until your arms are fully flexed and the dumbbells cannot be curled any further.
Inhale and lower the dumbbells down, returning to the starting position.