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Prone Scaption Above 90 Degrees in External Rotation (The Prone Y)

Ronai, Peter M.S., RCEP, CEP, EP-C, FACSM, CSCS-D

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ACSM's Health & Fitness Journal: July/August 2016 - Volume 20 - Issue 4 - p 28-30
doi: 10.1249/FIT.0000000000000219
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The prone scaption in external rotation or shoulder Y is a single-joint, open kinetic chain upper-body exercise that activates and strengthens the posterior muscles of the shoulder girdle.


The prone scaption in external rotation or shoulder Y exercise is part of an exercise series known as the prone T-Y-I-W series designed to provide dynamic stability, optimal muscle length and tension, and proper positioning of the scapula and shoulder girdle on the thorax during upper-extremity activities (2,3,6,7,11,12).


Exercises to promote shoulder girdle stability are integral components of strength and conditioning, rehabilitation, and postrehabilitation exercise programs for clients who perform repetitive overhead motions during sports or occupational activities (2,3,6–12). Functional imbalances between the upper trapezius and the lower trapezius, middle trapezius, and the serratus anterior muscles have been associated with conditions like shoulder instability and subacromial impingement syndrome, which can cause shoulder pain and dysfunction (2–4,6–12). This article is not meant to help readers diagnose or treat shoulder pain or injuries. Clients should be free of shoulder or upper-extremity injuries and related pain before performing these exercises. The onset of injury-related pain warrants termination of exercise and immediate client consultation with a physician, physical therapist, or other health care provider.


Supraspinatus, infraspinatus, deltoid (middle and posterior fibers), trapezius (upper, middle, and lower fibers), rhomboids, and levator scapula. The prone Y exercise has been identified as a primary exercise for activating the lower fibers of the trapezius muscle (2,3,6,7,11,12) (Figure 1).

Figure 1:
Shoulder girdle muscles activated. (Reprinted from: Premkumar K. The Massage Connection: Anatomy and Physiology. Copyright © 2004 Lippincott Williams & Wilkins. Used with permission.)


The prone Y exercise can be performed on a matted floor, plynth (treatment) table, or a multipurpose training bench. Plynth tables typically enable clients to place their faces within a cutout hole, which facilitates breathing and in-line stabilization of the cervical and thoracic (neck and upper back) spine (Figure 2). A video of this exercise can be viewed here ( A small pillow placed under the top of the pelvis and hips can provide additional alignment and support to the lower back. Clients also can place their foreheads on a small hand-rolled towel and place a small pillow under their waist and hips to achieve similar alignment if they are lying prone on the floor (Figure 3). The use of the floor or a plynth table provides the shoulder girdle with additional extrinsic support and reduces the distance in which the arms must be lifted from the starting position as compared with a multipurpose training bench (10,11). Exercise intensity can be increased by progressing from a supportive surface like the floor or treatment table to a multipurpose training bench where the arm is raised and lifted through a greater range of motion. Clients should exhale during the lifting phase and inhale during the lowering phase of each exercise. External loading should never prevent clients from performing each exercise in a controlled manner.

Figure 2:
Prone Y exercise performed on a plynth table.
Figure 3:
Prone Y exercise performed on the floor with extrinsic support.


Starting Position

Clients lie prone and maintain a straight-line position between their head, neck, and spine with their elbows fully extended and their glenohumeral (shoulder) joint in external rotation (thumbs are pointing up toward the ceiling). If performing the prone Y on the floor or a plynth table, the arms are placed diagonally overhead in a position of approximately 130 degrees so that they are in line with the fibers of the lower trapezius muscle (2–4,6–8,11,12). At this point, the arms assume and maintain a position resembling the letter Y throughout the exercise. The arms hang down perpendicular with the floor at the beginning of the exercise if it is performed on a multipurpose training bench. (The starting- and ending-phase positions from a training bench appear in Figure 4.)

Figure 4:
Prone Y exercise starting- and ending-phase positions.

Upward Phase

By concentric actions of the upper, middle, and lower trapezius; rhomboids; infraspinatus; teres minor; supraspinatus; and deltoid, the scapulae are actively retracted (adducted) and posteriorly tilted, and the upper arms are raised diagonally in an action referred to as scaption until they are level with the plynth, floor, or training bench. The arms maintain the Y position throughout the exercise and are in line with the fibers of the lower trapezius muscle (2–4,6–10). The scapulae and arms are held in this position for a count of three. Clients should be cued to raise and lower their arms in a controlled manner, to avoid swinging their arms, and to refrain from lifting their head/neck or back throughout the exercise. (The upward-phase position appears in Figure 5.) A video of this exercise can be viewed here (

Figure 5:
Prone Y exercise upward-phase position.

Downward Phase

The arms and scapulae return to the starting position in a controlled manner by eccentric actions of the upper, middle, and lower trapezius; rhomboids; infraspinatus; teres minor; supraspinatus; and deltoid (2–4,6–10). Clients should be cued to lower the weight in a controlled manner and to avoid dropping their arms.

Exercise load and intensity selection can be based on the individual goals of each client (12). Although lighter loads and higher repetitions have typically been recommended for scapulohumeral stability exercises, results from a few studies suggest that it might not be necessary to limit the amount of weight used with these exercises if performed by healthy individuals without a history of shoulder pathology (1,5,12).


The prone horizontal abduction in external rotation/full can (prone Y exercise) is part of a series of exercises known as the T-Y-I-W series and is intended to improve scapulothoracic joint and glenohumeral joint muscle function and shoulder girdle stability. Exercises can be performed without external loading in clients who either are unaccustomed to doing them or are deconditioned. External resistance can be added in the form of dumbbells or cuff weights as tolerated by clients as their strength and endurance improves.

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Suggested Reading:

Ekstrom RA, Donatelli RA, Soderberg GL. Surface electromyographic analysis of exercises for the trapezius and serratus anterior muscles. J Orthop Sports Phys The. 2003;33(5):247–58.
    McCabe RA, Orishimo KF, McHugh MP, Nicholas SJ. Surface electromyographical analysis of the lower trapezius muscle during exercises performed below ninety degrees of shoulder elevation in healthy subjects. NAJSPT. 2007;2(1):34–43.

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