There are no official guidelines to assist in answering this question. I will search for relevant research papers instead.
From the Research
Shoulder Muscles Prone to Strain
The shoulder muscles prone to strain during gymnastics include:
- Rotator cuff muscles, specifically the supraspinatus, infraspinatus, and subscapularis 1
- Deltoids, particularly the middle deltoid, which provides significant abduction torque 1
- Scapular muscles, such as the serratus anterior, which contributes to scapular upward rotation, posterior tilt, and external rotation 1
Common Injuries in Gymnasts
Common injuries in gymnasts include:
- Multidirectional instability and musculotendinous injury, which are the most common types of shoulder injuries in female artistic gymnasts 2
- Structural lesions of the shoulder and shoulder girdle, such as biceps tendon anchor, long head of the biceps tendon, and tendon of the supraspinatus muscle, which can arise due to high repetitive support and swing forces during exercises on the rings 3
- Chronic overuse injuries, which account for 60% of injured shoulders in high-level male gymnasts 4
Risk Factors and Mechanisms
Risk factors and mechanisms for shoulder injuries in gymnasts include:
- Asymmetric bars, which are the most frequent mechanism of shoulder injury in female artistic gymnasts 2
- Excessive shoulder stretching, hyperlaxity, and instability, which are significant potential risk factors for shoulder injuries in female artistic gymnasts 2
- Traction of the arm in forced flexion-rotation while using suspension equipment with locked hands on the bars or the rings, which is the mechanism of injury in 90% of injured shoulders in high-level male gymnasts 4