Shoulder rotators electro-mechanical properties change with intensive volleyball practice: a pilot study

Area of Science:

• Sports Medicine
• Biomechanics
• Exercise Physiology

Background:

• High-level athletes often develop sport-specific adaptations.
• Shoulder strength and muscle activation are crucial for overhead sports like volleyball.
• Understanding muscle imbalances can inform injury prevention strategies.

Purpose of the Study:

• To evaluate the impact of intensive volleyball training on shoulder muscle strength and activation.
• To compare muscle strength and activation during internal and external shoulder rotations between professional and amateur volleyball players.
• To identify potential muscle deficits associated with high-level volleyball practice.

Main Methods:

• Pilot study involving 14 male volleyball players (7 professional, 7 amateur).
• Maximal isometric, concentric, and eccentric isokinetic shoulder rotations were performed.
• Torque production and muscle activation of PECTORALIS MAJOR and INFRASPINATUS were measured.
• Torque ratios for external/internal rotations were calculated.

Main Results:

• No significant differences in muscle activation or co-activation between professional and amateur players.
• No significant difference in internal rotation torque production.
• Amateur players showed higher external rotation torque than professionals during isometric contractions.
• Professional players exhibited significantly lower external/internal rotation torque ratios, indicating an external rotator deficit.

Conclusions:

• Intensive volleyball practice is associated with a significant deficit in shoulder external rotator strength.
• This deficit is more pronounced in professional volleyball players compared to amateurs.
• The findings suggest a need for targeted training to address external rotator weakness in volleyball athletes.
• Results highlight differences compared to other overhead sports like swimming, baseball, or tennis.