Much like the chin up, a pull-up is a compound, pull-type exercise that works a large number of muscles in your back, shoulders, and arms.
1. Approach the pullup bar and extend your arms, taking a shoulder width, overhand grip on a pullup bar, i.e., palms facing away from you. Likely, you will need to jump up to grab the bar or reach if from a bench.
2. Hang extended from the bar then, inhale as you begin to pull upward, sticking your chest out.
3. Pull until your chin is level with the bar.
4. Exhale as you complete the movement, lowering yourself to the starting position then, repeat the next repetition.
This is a difficult exercise for most to perform. When beginning, take a narrower grip on the bar. As you become more conditioned and experienced, take a wide grip. The wider the grip the more the exercise will work the traps and lats.
This exercise develops the lats and teres major. It also places intense focus on the biceps (though not as much as a chin up) and brachialis. It is usually incorporated in exercise programs that focus on training the arm regions.
Other secondary muscles involved include the trapezius (both middle and lower portions), rhomboids, and pectorals.
Because this exercise requires great strength and muscle conditioning, it is advisable to use a resistance pull-up machine before attempting the full exercise. The resistance machine will help you develop a strength foundation for this exercise and adequately condition your muscles.