The purpose of this study is to evaluate the ability of blood flow restriction therapy to improve strength of shoulder muscles during the sidelying external rotation (ER) exercise versus a control group who only performs the sidelying ER exercise.

The purpose of this study is to determine if blood flow restriction (BFR) therapy is superior at increasing strength of the shoulder (supraspinatus, infraspinatus, posterior deltoid, and middle deltoid) and increasing tendon size of the supraspinatus and infraspinatus (as determined by diagnostic ultrasound) while performing the sidelying external rotation exercise compared to those who only perform the sideyling external rotation exercise without BFR.

Subjects will be randomized to one of two treatment groups: exercise with BFR or exercise alone. Recruitment will be a sample of convenience consisting of healthy adults (age range 22 to 45). Subjects will perform the sidelying external rotation exercise 2 times a week for an 8 week period.

Inclusion Criteria:

1. Healthy adult (age 18 and older) with no current shoulder pathology

Exclusion Criteria:

1. Current neck, shoulder (or general upper extremity), and/or thoracic spine pathology
2. Shoulder surgery (or general upper extremity surgery) during the prior 6-month time period
3. Cervical/thoracic spine surgery during the prior 1 year
4. Subject having one or more contraindications for BFR training.

Outcomes assessors are blinded to group allocation.