Author(s): SCHRAPF, N., KINZER, C., TILP, M., Institution: INSTITUTE OF HUMAN MOVEMENT SCIENCE, SPORT AND HEALTH, Country: AUSTRIA, Abstract-ID: 1794

INTRODUCTION:
The spike attack is the most commonly performed movement in volleyball. The analysis of various elements of this movement was therefore in the focus of previous studies. Seminati et al. (2015) and Giatsis et al. (2019) examined the use of various arm swing techniques during spike attacks. They focused on biomechanical aspects of the movement regarding performance and injury prevention. For a better understanding of the various techniques, it would be helpful to examine the activation of the muscles involved during the movement, which has not yet been investigated. Therefore, the aim of the present study is to analyze the muscle activation patterns during spike attacks using different arm swing techniques.
METHODS:
The muscle activation from spike attacks using different arm swing techniques of seven professional male volleyball players were examined by means of electromyography (EMG). Based on the classification of Seminati et al. (2015), the players performed both the traditional and the alternative technique. The start of the movement was defined at the beginning of the cocking phase at 45° shoulder flexion and the end was defined at a shoulder flexion of 135° in the acceleration phase. The activation of the muscles was recorded using a Noraxon Ultium EMG system for the following muscles: M. pectoralis major, M deltoideus (pars clavicularis, acromialis and spinalis), M. infraspinatus, M. trapezius (upper and middle part), M. latissimus dorsi. To compare the EMG signals of the subjects, they were normalized based on the maximum voluntary contraction of the muscles. Differences in the muscle activation were examined using a paired t-test of an statistical parametric mapping (SPM) analysis.
RESULTS:
SPM analysis revealed different activation patterns for the M. deltoideus (pars clavicularis) and the M. infraspinatus. In the first part of the cocking phase (about 10% of the movement), EMG amplitude of the infraspinatus muscle was higher in the traditional technique compared to the alternative technique (p<0.004). In contrast, the M. deltoideus (pars clavicularis) showed higher EMG amplitudes in the alternative technique compared to the traditional technique in the acceleration phase (p<0.001). For the other muscles no significant differences were observed.
CONCLUSION:
The higher activation of the M. infraspinatus could be due to greater external rotation of the shoulder in the cocking phase of the movement. The higher activation of the M. deltoideus is surprising, as the acceleration phase is similar in both techniques. To understand whether this higher activation is a result of the different chocking phase, further research needs to be done.
REFERENCES:
Giatsis et al. (2019). Analysis of the arm swing technique during the spike attack in elite beach volleyball, Int. J. Perform. Anal. Sport, 19:3, 370-380.
Seminati et al. (2015). Shoulder 3D range of motion and humerus rotation in two volleyball spike techniques: injury prevention and performance. Sports Biomech, 14:2, 216-231.