Question

Perform a chin-up (palms supinated) and determine which muscles are the prime movers, stabilizers, and synergists. Is there a difference with a pull-up (palms pronated)? If so, what are the differences? Do as many chin-ups as possible. Which muscles inhibit your ability to perform more repetitions? What does this say about the chin-up as an effective exercise for the latissimus dorsi? List as many variations of pull-ups and chin-ups as possible. Describe how what you have learned during this experience will help you in your future training.

Answer 1

Prime movers: Pullups primarily target the latissimi dorsi. They start in the ribs and vertebral column and insert just underneath the humerus. The lats are responsible for controlling movements in the shoulders and assist with the depression, rotation and adduction of the scapula.

Stabilizers: Themuscles that contract during exercises. These musclesdo not significantly lengthen or shorten. Dynamic stabilizers are muscles that provide support to the joint during the full range of motion during the lift with subtle shortening at the target joints and lengthening at the adjacent joints. During a pullup the triceps brachii serve as dynamic stabilizers to the latissimi dorsi.

Synergists: The muscles other than the primary target that help complete the movements. As with most body-weight exercises, pullups require a multiple synergists to support the body throughout the movement. The biceps, deltoids, rhomboids, trapezii and a number of other smaller muscles in the back and arms help support the latissimi dorsi to enable you to complete a full pullup.

Pull Ups compared to chin ups

Pull ups: A pronated grip where palms point outwards so that they are facing away from one the most common grip width is just slightly wider than shoulder width.

Chin Ups: A supinated grip where your palms point inwards so that they are facing you the most common grip width is shoulder width.