The purpose of this study is to compare the clinical effectiveness and outcomes between current evidence based clinical care and use of personalized blood flow restriction training in the treatment of lateral epicondylalgia ("tennis elbow").

Background: Lateral Epicondylalgia, or "tennis elbow", has been shown to affect up to 3% of the population and is a common musculoskeletal condition which also affects military service members. This study will compare clinical effectiveness of two treatment programs in individuals with lateral elbow pain.

Design: Prospective randomized controlled clinical trial

Methods: Participants, between the ages of 18-65, presenting to the NMCSD or NHCP Occupational or Physical Therapy Clinics with complaint of lateral elbow pain will be eligible for consideration to participate in this research. Patients that meet the inclusion criteria and elect to participate in the study will be randomized to either (1) a standardized, evidence based rehabilitation program or (2) an exercise volume matched group using personalized blood flow restriction (BFR) exercise.

Upon entry to the program subjects will complete measurements of height, body weight, physical activity level (Marx Activity Scale), annotation of their dominant upper extremity (UE), the patient-rated tennis elbow evaluation (PRTEE) questionnaire, Numerical Pain Rating Scale (NPRS), Patient-Reported Outcome Measurement Information System version 1.2- Global Health (PROMIS scale v1.2- Global Health), and grip strength using the JAMAR dynamometer. At the end of each treatment session subjects will complete the Numerical Pain Rating Scale (NPRS) and the OMNI-Resistance Exercise Scale (OMNI-RES) rating of perceived exertion (RPE) survey.

The standard rehabilitation group will perform active wrist extension, forearm supination, and gripping. These exercises may include isometric, concentric, or eccentric forms of strengthening contingent upon clinical decision making. Specifics of exercise performance (to include magnitude of resistance and volume of exercise) will be documented in the treatment record.

The Delphi Personalized Tourniquet System (PTS) will be utilized for the BFR exercises. The Delphi PTS measures an individual's personalized tourniquet pressure (PTP) using doppler technology similar to a blood pressure cuff. In the BFR exercise condition, subjects will perform a 30-15-15-15 repetition progression of 1-3 exercises as selected by the therapist.

Participants will be provided in-clinic treatment for a maximum of 12 sessions, one to three treatment sessions weekly, and may be discharged prior to that based upon shared decision making between the participant and therapist. The NPRS, grip strength, PROMIS scale v1.2- Global Health, and PRTEE will be completed at the last clinical appointment, as well as three and six-week, and three and six month follow up appointments. Twelve months following completion of occupational/physical therapy clinical care participants will be contacted and asked to complete a verbal NPRS, PROMIS scale v1.2- Global Health and the PRTEE outcome scale. Additionally, at 12 months following discharge from Physical or Occupational Therapy, the participants' EMR will be reviewed for follow-up visits related to the same condition (LET).

Data Analysis: A mixed effects longitudinal model will be utilized to assess for differences in the primary outcome measures (grip strength, NPRS, and PRTEE) between the time points of intake, end of occupational/physical therapy treatment, and three and six months post completion of treatment. Secondary analysis of change in OMNI-RES RPE and NPRS during the course of treatment will also be analyzed with a mixed effects longitudinal model. Healthcare provider(s) will be analyzed as a co-variate. Microsoft Excel and SPSS will function as the main data analysis instruments.

Clinical Implications: Results of this study are expected to guide clinician's selection of rehabilitation techniques to improve outcomes (increase strength, improve function, and decrease pain), improve mission readiness by earlier return to duty, reduce healthcare service costs, and also reduce lost duty/work time.

Inclusion Criteria:

1. Diagnosis of lateral elbow pain (e.g. "tennis elbow" or wrist extensor tendinopathy)
2. Between the ages of 18-65
3. Elbow pain for 4 weeks or more

Exclusion Criteria:

1. Ligamentous elbow sprain, osteoarthritis of elbow and cervical radiculopathy in the affected limb will be excluded from the study.
2. Any history of ligamentous, bony or other soft tissue reconstruction surgery at the affected elbow.
3. Vascular disorders to include: history of DVT, history of endothelial dysfunction, peripheral vascular disease
4. Current fracture in affected arm
5. History of crush injury to affected arm
6. Any surgery on affected arm in last 1 year
7. Surgery within last year on contralateral upper extremity
8. History of lymphectomy (such as axillary exploration with breast surgery, lymph node biopsy in the affected axilla/arm)
9. Pregnancy
10. Active infection
11. Current cancer diagnosis/treatment
12. Sickle cell anemia or trait
13. Kidney dialysis
14. History of syncope/passing out with pressure to body (such as massage, or blood pressure cuff).
15. Inability to consent
16. Thromboembolism
17. Varicose veins
18. Cardiovascular disorders
19. Taking anti-coagulant medications
20. Bleeding disorder
21. Instructed by a physician or medical practitioner that they are not cleared to exercise

Treating therapists and patient will be aware of treatment. Grip strength objective measure will be performed by a clinician blinded to the participant's treatment group. All other outcome measures are patient-reported on outcome forms.