A pull-up is an upper body strength exercise where you hang from a bar with an overhand grip, then pull yourself up until your chin is level with the bar, engaging primarily your latissimus dorsi (lats) muscles in your upper back, as well as your biceps and shoulders; essentially, it involves hanging from a bar and pulling your body up using your arm muscles to reach your chin to the bar. Pullups can be a good exercise to challenge your arm, shoulder, and back muscles. They may also improve your overall body strength and fitness, physical health, and mental health.