Purpose: This study aims to determine the effectiveness of high physical activity (PA) on shoulder pain, functional recovery, and structural outcome in the early healing phase after arthroscopic rotator cuff repair (ARCR). Methods: Forty-two patients were included in this study according to inclusion criteria. Subjects were classified into high PA (HPA) group (n=22) and low PA (LPA) group (n=20) according to the classification criteria. Differences between groups according to the PA level were analyzed by comparing visual analogue scale (VAS), range of motion (ROM), American Shoulder and Elbow Surgeons Shoulder Score (ASES), and isokinetic strength before and 6 weeks, 3, and 6 months after surgery. Structural outcome was analyzed by evaluating magnetic resonance imaging performed 6 months after ARCR. Results: VAS, ROM, and ASES were significantly higher in the HPA group at 6 weeks and 3 months after ARCR with a significant interaction effect between time and group (p＜ 0.05). The isokinetic muscle strength was significantly higher in the HPA group at 3 months after surgery with a significant interaction effect on forward flexion and external rotation strength (p＜ 0.05). There was no significant difference in extension and internal rotation strength. In the structural outcome of 6 months after surgery, the retear rate was lower in the HPA group with a significant trend (p＜ 0.05). Conclusion In this study, higher PA levels in the early healing phase after ARCR were found to result in faster pain relief and restoration of shoulder function. In addition, higher PA level was associated with lower retear rates in structural outcomes related to tendon healing.