Context:The stability of the scapula in relation to the entire moving upper extremity is the key in the throwing sequence. The importance of scapular positioning in volleyball players has been well documented in the literature, but no one has compared scapular positioning between volleyball players and sedentary people.Objective: To compare measurements of scapular mobility obtained using the lateral scapular slide test between volleyball players and sedentary participants without shoulder impairments and to compare changes in scapular mobility in players according to the number of years of sport participation.Design: Cross-sectional study. Setting: University research laboratory. Patients or Other Participants:A total of 121 people at a single university volunteered. Of these, 67 were sedentary (age = 24.3 ± 2.34 years, height = 1.69 ± 0.09 m, mass = 65.1 ± 11.91 kg); 54 were volleyball players from 4 professional teams and were separated into 2 groups according to their years of sport participation. The first group was named young players (n = 31; age = 17.7 ± 2.58 years, height = 1.83 ± 0.10 m, mass = 68.3 ± 12.21 kg, sport participation ≤ 9 years), and the second group was named old players (n = 23; age = 26.9 ± 3.39 years, height = 1.95 ± 4.38 m, mass = 90.7 ± 5.75 kg, sport participation ≥ 10 years).Main Outcome Measure(s): Study participants completed a rating scale for pain and a questionnaire about demographic and shoulder problems. One assessor performed the lateral scapular slide test and additional flexibility measurements around the shoulder girdle. Flexibility (external rotation, internal rotation) and scapular position (1, 2, 3) were compared among groups (young players, old players, sedentary people) and between sides (dominant, nondominant).Results: In sedentary participants, we found differences for position 1 (t 66 = 3.327, P = .002), position 2 (t 66 = 2.491, P = .004), position 3 (t 66 = 2.512, P = .006), and internal rotation (t 66 = 2.592, P = .001) between the dominant and nondominant sides. In old players, we found differences for position 2 between the dominant and nondominant sides (t 22 = 2.956, P = .004). For position 2 (F 2,118 = 4.265, P = .02) and position 3 (F 2,118 = 4.702, P = .01), we found differences between young and old players. For internal rotation, we found differences between sedentary and old players (F 2,118 = 6.578, P = .002) and between young and old players (F 2,118 = 3.723, P = .01).Conclusions: Clinicians evaluating overhead athletes need to remember that asymmetric scapular posture between the dominant and nondominant sides in unilateral overhead athletes might be normal and not necessarily related to injury.Key Words: upper extremity, shoulder, internal rotation Key Points • Measurements obtained with the lateral scapular slide test cannot be used to assess the presence or magnitude of scapular asymmetry.• Clinicians evaluating overhead athletes must remember that asymmetric scapular posture between the dominant and nondominant sides in unilateral overhead ath...