Unilateral YTW Shoulder Exercises by Dosage (EMG amplitude)

by Greg Lehman
Published on: May 10, 2020
Comments: No Comments

Audience: Therapists

Purpose: Ys, Ts and Ws are common exercises for shoulder rehabilitation.  A recent post by Mike Reinold has raised some concerns about performing these exercises bilaterally (click here).  Mike suggests performing the exercises unilaterally as bilateral performance may lead to some unwanted form errors and may not be ideal.  I can’t refute Mike’s claims, although I feel that the bilateral performance of the exercise on a swiss ball or standing with tubing can still be safely performed with appropriate cueing.

Regardless, it is important to train unilaterally and the points that were raised in his post are certainly worth thinking about.  Further, the research that looks at the EMG of these exercises was conducted unilaterally suggesting that the biomechanical evidence in existence supports the use of these exercises in the unilateral setting.

The following pictures demonstrate the performance of the unilateral exercise as well as giving the muscle activity of the important muscle groups.  The EMG values are taken from different studies so it is difficult to compare across studies.  But trends can be seen.

All amplitudes are expressed as a percentage of a maximum voluntary contraction.

Please feel free to use any pictures in patient handouts

The Y Exercise: Prone Horizontal Abduction at 135 degrees with External Rotation


Comment: while a bias to lower trap activity is evident you can not avoid upper trap activity.

The T Exercise: Prone Horizontal Abduction at 90 degrees with External Rotation

T exercise: Prone Horizontal Abduction





The W Exercise: Prone External Rotation at 90 Horizontal Abduction












Comment: Note the reduced upper traps activity yet excellent lower traps

The W: Prone External Rotation at 90 degrees Abduction


















But lets also compare these exercises with other common ones.  There are certainly a number of ways to train.

Sidelying External Rotation

Remember to place a towel under your elbow

Sidelying External Rotation (add towel between elbow and arm)















Comment: There is differences in amount of activity recorded between studies due to the different weight lifted.  One study had a ten repetition maximum (Reinold 2004) while the other achieved a 5 rep max (Townsend).  Even with these differences the patterns between muscles are not similar suggesting individual variations.  Caution should always be made when comparing EMG results across studies, between different body parts and even within the same person (e.g. between sides of the body).  Many factors influence EMG amplitude that are peripheral to force generation.



Scaption (30 degrees from sagital plane)



















Comments: Note the high amount of Upper Trapezius activity.

Standing Cable External Rotation

Standing Cable External Rotation






















Comment: The amount of muscle activity will obviously vary depending on the stiffness of the stretch cord or cable weight used.


All the  best,


Greg Lehman

Toronto Physiotherapy

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