A compound exercise, pullups require that you use numerous muscles in the upper body to pull yourself up to a bar. You mainly rely on the latissimus dorsi muscle of the back to perform a pullup, but you also use the muscles in your shoulders. To train your entire shoulder area, you need to make a change in hand placement on the bar during pullups and use additional shoulder exercises.
Work out your shoulders once or twice a week on non-consecutive days beginning with three sets of six to 12 repetitions of close-grip pullups or chin-ups. Perform pullups at the beginning of your workout. Compound exercises such as pullups require the use of many secondary muscles, so it is better to do them at the beginning of your workout when you are fresh. If you wait until the end of your workout, you might not be able to complete as many repetitions.
Place your hands closer together during the pullups -- or perform chin-ups -- to target the rear deltoids. You typically perform pullups using an overhand grip with hands placed greater than shoulder-width apart. This position does not target the rear deltoids as much as narrower hand placement does.
Follow your pullups with one or two compound shoulder exercises for three sets of six to 10 repetitions. Finish your shoulder workout with one or two isolation exercises for three sets of 12 to 15 repetitions. Compound exercises such as military press, overhead dumbbell press or Arnold press target the entire shoulder area. Front raises with dumbbells isolate the front deltoids, lateral raises isolate the middle deltoids, and bent-over lateral raises isolate the rear deltoids.
Avoid swinging or relaxing your muscles too much during the hanging position of the pullup or chinup. Relaxing your muscles too much in the down position can place unwanted stress on the shoulder joint, which may result in injury.