Introduction. The main aim of the study was to assess the strength of the shoulder rotator muscles of a group of second-league volleyball players. These muscles are assumed to have a crucial impact on attack effectiveness in volleyball. Strength was assessed based on peak torque values obtained for the rotator muscles measured using the maximal voluntary contraction (MVC) method. Torque was measured in both limbs and the differences between the two limbs were examined. The torque values obtained for the volleyball players were also compared against those measured in a group of students who had never trained any sports.
Material and methods. The study involved 20 students (mean age = 20 ± 1 years) who played in the second league when the study was conducted. Their results were compared with those of a control group consisting of 30 students (mean age = 20 ± 1 years) who had not trained any sports. Peak torque of the shoulder rotator muscles was measured during external and internal rotation of the shoulder in isometric conditions. The assessment was performed on a special measuring station with the forearm in a vertical and horizontal position. The following basic statistics were calculated for the torque values obtained in the measurement: the mean, standard deviation, minimum value, and maximum value. The data were then subjected to statistical testing.
Results. Compared to the students, the volleyball players had higher torque values of the internal and external rotators of the right and left shoulders, in both positions of the forearm. When the results obtained for the right and left limbs were compared for the group of volleyball players, it was found that the torque values for the right limb, which was the dominant limb, were significantly higher than those recorded for the left limb. The study also showed that the position of the forearm had an impact on torque values: when the forearm was in a horizontal position, higher mean values were obtained for the external rotators of the right (p < 0.05) and left (p < 0.01) limbs, and when it was in a vertical one, the internal rotators were stronger compared to the external rotators.
Conclusions. The shoulder rotator muscles of the volleyball players were found to be considerably stronger than those of the students, and the rotators of the dominant limb were significantly stronger than those of the non-dominant limb in the group of volleyball players. The position of the forearm had a considerable impact on the strength of the internal and external rotator muscles. The maximal voluntary contraction method used in the study can be helpful in measuring the strength of the shoulder rotator muscles in any phase of the training process.
1. Fidelus K., Skorupski L. (1970). Muscle torque in particular joints in athletes from different sports disciplines. In “Symposium on Sports Technique Theory”, 26-28 November 1968 (pp. 128-140). Warszawa. [in Polish]
2. Tabor P., Mastalerz A., Ostrowska E., Iwańska D., Stachowicz M., Urbanik Cz. (2003). Assessing volleyball technique using cinematographic motion analysis. In Cz. Urbanik (ed.), Issues in sports biomechanics – movement technique (pp. 106-118). Warszawa: AWF. [in Polish]
3. Smith D. (2006). Incorporating kinetic-chain integration, Part 1: Concepts of functional shoulder movement. International Journal of Athletic Therapy & Training 11(4), 63-65.
4. Tetreault P., Levasseur A., Lin J.C., Nuno N., Guise J., Hagemeister N. (2011). Passive contribution of the rotator cuff to abduction and joint stability. Surgical and Radiologic Anatomy 33(9), 767-773.
5. Ignasiak Z., Domaradzki J. (2013). Anatomy of the locomotor system. Wrocław: Elsevier Urban & Partner. [in Polish]
6. Bober T., Hay J.G. (1991). Selecting angular positions for the measurement of peak torque in the joints. Zeszyty Naukowe AWF Wrocław 53, 5-15. [in Polish]
7. Zapolska J., Witczak K., Mańczuk A., Ostrowska L. (2014). Assessment of nutrition, supplementation and body composition parameters on the example of professional volleyball players. Roczniki Panstwowego Zakładu Higieny 65(3), 235-242.
8. Jain R., Puri S., Saini N. (2008). Dietary profile of sports-women participating in team games at state/national level. Indian Journal of Public Health 52, 153-155.
9. Garber C.E., Blissmer B., Deschenes M.R., Franklin B.A., Lamonte M.J., Lee I.M. et al. (2011). American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Medicine & Science in Sports & Exercise 43(7), 1334-1359.
10. Tabor P., Mastalerz A., Iwańska D. (2004). Biomechanical criteria of attack technique effectiveness in volleyball. Sport Wyczynowy 1-2, 469-470. [in Polish]
11. Swanik K.A., Swanik B., Lephart S.M., Huxel K. (2002). The effect of functional training on the incidence of shoulder pain and strength in intercollegiate swimmers. Journal of Sport Rehabilitation 11(2), 140-154.
12. Swanik K.A., Huxel K., Swanik B. (2001). Rotator-cuff muscle-recruitment strategies during shoulder rehabilitation exercises. Journal of Sport Rehabilitation 20, 471-486.
13. Kaplan N., Ertan H., Ünver F., Kirazci S., Korkusuz F. (2004). Factors affecting the shoulder proprioceptive sense among male volleyball players. Isokinetics and Exercise Science 12(3), 193-198.
14. Lizis P. (2011). Shoulder mobility in volleyball players and untrained persons. Wychowanie Fizyczne i Zdrowotne 9, 25-29. [in Polish]
15. Taljanovic M.S., Nisbet J.K., Hunter T.B., Cohen R.P., Rogers L.F. (2011). Humeral avulsion of the inferior glenohumeral ligament in college female volleyball players caused by repetitive microtrauma. American Journal of Sports Medicine 39(5), 1067-1076.
16. Reeser J.C., Joy E.A., Porucznik C.A., Berg R.L., Colliver E.B., Willick S.E. (2010). Risk factors for volleyball-related shoulder pain and dysfunction. The Journal of Injury, Function and Rehabilitation 2(1), 27-36.
17. Kapandji A.I. (2011). Functional anatomy of the joints. Upper extremities Volume 1. Wrocław: Elsevier Urban & Partner. [in Polish]
18. Hurd W.J., Kaufman K.R. (2012). Glenohumeral rotational motion and strength and baseball pitching mechanics. Journal of Athletic Training 47(3), 247-256.
19. Jonsson P., Wahlstrom P., Ohberg L. (2006). Eccentric training in chronic painful impingement syndrome of the shoulder: results of a pilot study. Knee Surgery, Sports Traumatology, Arthroscopy 14, 76-81.
20. Mohseni-Bandpei M.A., Keshavarz R., Minoonejhad H., Mohsenifar H., Shakeri H. (2012). Shoulder pain in Iranian elite athletes: the prevalence and risk factors. Journal of Manipulative and Physiological Therapeutics 35(7), 541-548.