Smartphone Addiction and Isometric Strength of Rotator Cuff Muscles

Inclusion Criteria: \- 1- This study will comprise healthy volunteers between the ages of 18 and 30 who needed to use a smart phone. 2- Subjects who put in more than 4 hours per day using smartphone. Exclusion Criteria: * Patients will rule out if 1. They had any medical condition that could cause shoulder pain (such as impingement, subacromial bursitis, rotator cuff damage, or traumatic or degenerative supraspinatus tendonitis). 2. Anyone with a positive Neer sign, a positive Hawkins sign, discomfort during shoulder elevation, pain at the location of the rotator cuff tendon, pain with resisted isometric shoulder abduction, or a history of pain in the C5 dermatome will be ruled out. 3. Any individual who had previously suffered a musculoskeletal injury or surgery that could have influenced the measurement will be also eliminated.