32 male patients with shoulder instability undergoing arthroscopic anterior shoulder stabilization surgery were randomized to receive either a cross-education (CE) training program targeting the non-operative shoulder (n=16) or standard postoperative rehabilitation (n=16). The primary outcome was rotator cuff muscle strength, assessed at 3 and 6 months postoperatively. Secondary outcomes included functional performance (Closed Kinetic Chain Upper Extremity Stability Test, Y-Balance Test–Upper Quarter) and patient-reported shoulder function (Western Ontario Shoulder Instability Index). At 6 months, CE training improved rotator cuff muscle strength, particularly internal and external rotation at higher angular velocities, but had no significant effect on functional performance or patient-reported outcomes. Overall, the study suggests that CE can enhance postoperative strength recovery, offering a complementary strategy to standard rehabilitation protocols.