Effects of shoulder external rotation exercises that use ultrasound imaging in adult baseball players

INTERVENTION: D005081 Rehabilitation, rotator cuff exercise shoulder external rotation exercises that use ultrasound imaging feedback CONDITION: D000070599 Shoulder Injuries ; throwing injury, SLAP injuries, rotator cuff injuries throwing injury, SLAP injuries, rotator cuff injuries PRIMARY OUTCOME: Kerlan‐Jobe Orthopaedic Clinic Shoulder and Elbow Score (KJOC) SECONDARY OUTCOME: 1) Patient‐based questionnaire (Japanese society for surgery of the hand version of the quick disability of the arm shoulder, and hand (Quick DASH‐JSSH) questionnaire, Pitching performance score); 2) Physical function evaluation: joint range of motion (angle), muscle strength (Nm), and muscle activity (% maximal voluntary contraction); 3) Pitching performance evaluation: pitch speed and rotation rate, elbow valgus stress, and arm swing speed INCLUSION CRITERIA: 1) Persons aged 18 to 39 years who belong to a baseball club 2) Persons who practice or play games on two or more days a week 3) Persons who can perform external rotation exercises continuously for one month 4) Persons who freely provide informed consent prior to participation after the study is sufficiently explained to them