gms | German Medical Science

Objective: A cascade of adaptive changes such as glenohumeral internal rotation deficit – GIRD, symptoms of SICK scapula syndrome and muscular imbalances develop in dominant shoulders of overhead athletes and represent a shoulder at risk. Our goal was to isolate adaptive changes that are critical for injury developtment. We wanted to find correlation between career duration and the expressiveness of adaptive changes and injuries and how does the (a)symmetry of hand use in a specific field position of overhead athletes influence the developtment of adaptive changes and injuries of the dominant shoulder.

Material/Methods: Participants were 36 competitive female overhead athletes (21 handball players and 15 volleyball players), devided in 2 groups by symmetry of hand-use (symmetric, group 1: setters in volleyball, goal-keepers in handball; asymmetric, group 2: other than group 1 - hitters and throwers). All completed medical questionaire, detailing shoulder injury and pain in the past year. Clinical examination of the shoulders was performed, including SICK scapula signs, passive internal (IR) and external rotation (ER), GIRD evaluation and special shoulder clinical tests. Isokinetic testing of IR and ER was performed in concentric (c) and eccentric (e) mode at two testing speeds (60°/s, 150°/s). Fatigability of IR and ER was measured. Stability spiking (eER/cIR) and cocking ratios (eIR/cER) were calculated.

Results: All players showed decreased IR and increased ER ROM in the dominant shoulder (p>0,001). Average GIRD was 20,6°, greater GIRD was correlated with lower cIR peak torques (p=0,026 and p=0,008). Players with increased passive ER and more SICK scapula signs had lower eIR peak torques and hence lower cocking ratios (p=0,019, p=0,035 and p=0,04). Dominant hand eER peak torques were lower (p=0,015, p=0,04) and the spiking ratios were also lower on the dominant side (p=0,002 and p=0,006). Players with previous injury showed more passive scapular abduction on their dominant side (p=0,05), increased passive ER (p<0,001) and lower cocking ratios (p=0,023). Players with objective or subjective glenohumeral instability shower more SICK scapula signs (p<0,05) than players without instability. Setters, goalkeepers and liberos (symmetrical hand-use) had lower fatigability of IR and ER (p=0,019 and 0,01).

Conclusion: Several adaptive changes were found in the dominant shoulders of our participants (GIRD, increased passive ER, signs of SICK scapula, muscular imbalances), regardless of career duration or field position. Pronounced scapular abduction, increased passive ER and low cocking ratios were correlated to the history of injury. Players with GH instability had more SICK scapula signs on their dominant side, mainly protraction and abduction. Hitters and throwers showed more fatigability of IR and ER, probably due to higher percentage of faster, type 2, muscle fibers, which is noticed in other overhead sports as well.

Because of delicate balance between mobility and stability of the overhead athlete's shoulder, adaptive changes need to be recognized, regularly followed and controled with proper preventive training, focusing on the stretching of posterior capsule, dynamic GH stability exercises, scapular stability exercises and eccentric training for GH rotator muscles.