When it comes to getting results from your workout, intensity encourages efficiency. Often, self-appointed fitness experts -- in other words, muscle heads -- will tell you that increasing weight is the only way to enhance intensity. Not true: exercises such as the pullup don't entail any added resistance yet are highly intense on their own. The pullup simultaneously works many muscles across your upper body to drive the movement. This makes the pullup intense and efficient.
While your arms do most of the moving during pullups, the exercise actually targets your back. The pullup's primary target is the latissimus dorsi, or the lats, which stretch from your upper to lower torso on the right and left sides of your back. These muscles play a starring role in nearly everything your arms do, as they perform extension, rotation and adduction of your arms from the shoulder joints. Other back muscles worked by the pullup include the rhomboids, levator scapulae and trapezius.
If you're looking for strong, toned shoulders, the pullup should be part of your arsenal of exercises. Your shoulders provide a significant amount of the force that pulls your body upward, thanks to the actions of muscles such as the teres minor, posterior deltoid and infraspinatus, also known as the rotator cuff. These muscles assist in the rotation and extension of your arms backward and out to the sides. Such movements are crucial for exercises such as swimming.
The pullup may be the ultimate arm exercise, as it works muscles of both your upper and lower arms. Your triceps, located on the back of your upper arms, are the sole muscles responsible for stabilizing your arms throughout the pullup to eliminate any rocking or swaying motion. Meanwhile, your other upper-arm muscles -- the biceps and brachialis -- along with the brachioradiales of your lower arms assist the shoulders and back to lift your body.
While the pullup mostly challenges your back muscles, your chest muscles are less of a focus during pullups than in other exercises, such as the pushup. However, your pectoralis minor, the smaller muscle of your chest, does play a role in pullups. This muscle helps rotate and move down the scapulae, or shoulder blades, which allows for the up-and-down motion of the pullup.
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