The semi-supinated, or neutral-grip, chin-up is a popular body weight exercise. To perform any form of chin-up or pull-up you need to be able to lift your own body weight using only your arms. If you are unable to do this, lat pull-downs provide a viable alternative. Also, there are assisted chin-up machines that counterbalance a percentage of your body weight to make this exercise easier. With regular training, some exercisers may become so strong that they have to strap extra weight around their waists to make chin-ups sufficiently challenging. Whether you are a chin-up expert or merely a beginner, the muscles used during performance of this exercise are the same.
Latissimus Dorsi
Your latissimus dorsi muscles, or lats for short, are located on the side of your back. These large, wing-shaped muscles are responsible for pulling your arms down and back into extension as you pull your chin up toward the bar. Attaching your arms to your spine, latissimus dorsi are the agonist or prime mover when performing any variation of chin-ups or pull ups.
Biceps Brachii and Brachioradialis
The biceps brachii, often referred to simply as biceps, is the main muscle responsible for elbow flexion. In many cases, smaller, weaker biceps will fatigue before the larger, more powerful lats. The neutral or semi-supinated hand position used in this chin-up variation increases the demand placed on the brachioradialis muscle but also places it in a mechanically advantageous position. For this reason, some exercisers find the neutral grip chin-up slightly easier than the pronated grip pull-up.
Trapezius
Running from the base of your skull, out toward your shoulders and then down to your middle spine, the trapezius covers a large amount of your upper back. The trapezius can be divided into three regions: upper, middle and lower. While the upper region of trapezius is not very active in chin-ups, the middle region is responsible for holding your shoulders back and the lower region holds your shoulders down. Keeping your shoulders pulled down and back during this exercise is one of the keys to minimizing the risk of shoulder injury.
Muscles of the Forearm
A strong grip is essential for performing supinated grip chin-ups. Each of your fingers is controlled by one or more muscles that work together to keep your hands tightly wrapped around the handles. Some people perform chin-ups wearing wrist wraps. While this does improve your grip, wearing wrist wraps disguises rather than treats the problem of a weak grip. Your main forearm gripping muscles are the flexor digitorum and flexor pollicis muscles, which control the fingers and thumb respectively.
References
- "Atlas of Skeletal Muscles"; Robert J. Stone and Judith A. Stone; 2008
- "Anatomy of Exercise: A Trainer's Inside Guide to Your Workout"; Pat Manocchia; 2009
- "Strength Training Anatomy"; Frederic Delavier; 2010
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