The purpose of this prospective, cross-sectional study was to evaluate the selective activation of the infraspinatus during external rotation exercises in participants with rounded shoulder postures and compare the different exercise positions. The fifteen (7 males and 8 females) participants with rounded shoulder posture were recruited for this study. The EMG activations of the middle trapezius, posterior deltoid and infraspinatus muscles in the dominant limb were recorded during exercises in standing external rotation (SER), side-lying position (SDER), scapular plane (SPER) and muscle architecture-based (MABER) positions.

Inclusion Criteria:

• without shoulder pain,
• totally able to perform overhead activities with no pain or discomfort,
• without a history of shoulder injuries
• with rounded shoulder posture

Exclusion Criteria:

• a history of shoulder muscle injury
• bone fractures in shoulder region
• luxation or subluxation
• cervical dysfunction radiating to upper limbs
• neurologic or musculoskeletal disorders that would prevent shoulder external rotation in the testing postures.

Fifteen (7 males and 8 females) participants without shoulder pain, totally able to perform overhead activities with no pain or discomfort, without a history of shoulder injuries, and with rounded shoulder posture were recruited for this study.