Chinups focus on developing muscles of the upper back and the large muscles of the latissimus dorsi, the muscles that power much of your mid-back. Slightly different than a pullup, chinups also engage the biceps. Since you use multiple muscle groups in your upper body in this exercise, warm up your upper body and stretch the shoulders with gentle arm circles or weighted arm swings. With a proper warm up, you can focus on activating the correct muscles during the concentric and eccentric phases of the exercise.
Chinups require an under-hand, or supinated, grip. This grip places more emphasis on the biceps than the over-hand grip of a pullup but still targets the muscles of the upper back and latissimus dorsi. Some may consider the chinup “easier” in comparison to the pullup since the motion recruits extra help from the biceps as opposed to leaving the back to do most of the work alone.
A concentric contraction occurs when muscles shorten in length. The concentric phase of a chinup occurs as you bend your arms and pull your body upward. The work is felt predominantly in the biceps of the upper arm and latissimus dorsi on either side of your back surrounding the rib cage. But the movement of the shoulder joint also activates the muscles of the teres major; subscapularis and the rhomboids at the upper back; the pectoralis major in the chest and the triceps at the back of the upper arm. A full concentric movement involves taking the chin all the way up to the bar.
The eccentric phase of a movement is when the muscle lengthens again. The eccentric phase of a movement often involves maintaining muscular control during deceleration. In the case of chinups, the same muscles of the biceps, back and shoulders work to control the eccentric, downward movement of the body as during the concentric phase. The resistance during the eccentric phase feels markedly different due to the pull of gravity but the same muscles are working. You’ve hit the true bottom of the eccentric phase when your elbows are fully extended and your shoulder blades are released.
Chinups can be varied by changing the grip placement of the hands. Position your hands narrowly, about shoulder width apart, or wider than shoulder width. The variation in placement slightly alters which muscles are emphasized. A wider grip engages the pectoralis major only at the top of the concentric movement when the chin reaches the bar. A narrow grip engages the pectoralis major throughout the concentric and eccentric movement in addition to recruiting additional muscles of the shoulder. The infraspinatus and teres minor located along the shoulder blade, along with the deltoids of the shoulder are activated when using a narrow grip in addition to the other muscles of the shoulder, back and biceps.
- Men’s Fitness: Exercise: Face Off - Pull Ups vs. Chin Ups
- University of California-San Diego: Muscle Physiology – Types of Contractions
- Fitness Institute Australia: Exercise: Wide and Narrow-Grip Chin Up
- NASM Essentials of Sports Performance Training; Michael Clark
- Charles Poliquin: 12 Tips to Improve Your Chin Ups
- Photo Credit Comstock/Comstock/Getty Images