If you've ever watched men's gymnastics during the Olympics, you were probably impressed at the upper-back development of the gymnasts who competed in the still rings. In these athletes' training, chinups are essential. This one simple exercise actually does a lot of body sculpting, including working the latissimus dorsi, teres major, posterior deltoid, rhomboids, the sternal portion of the pectoralis major, the lower portions of the trapezius, and the elbow flexors. They also stimulate growth in the biceps, brachialis, brachioradialis, and pronator teres.
Chinups have lost favor with many bodybuilders in recent years, but it's easy to get hooked on them when you see the tremendous gains you'll make in upper-body strength and size by performing them on a regular basis. The best type of chinup is always the one you're not doing. You can't optimally work a muscle's entire strength curve with just one exercise, so it's important to keep things fresh and try new techniques. Lats are big and powerful, and as such, you need to train them from a variety of different angles to stimulate all the motor unit pools of this muscle group.
Just to be clear, chinups are performed with either a semi-supinated grip (palms facing each other) or a supinated grip (palms facing your body). Pullups are a variation of chinups and are performed with a pronated grip (palms facing away from you). Add one of these expert-approved chinups in your next workout and move through the variations every other week. Master them all and your upper back will never look better.