Inter-Limb Asymmetries in Volleyball Players: Differences between Testing Approaches and Association with Performance

Area of Science:

• Sports Science
• Biomechanics
• Human Movement

Background:

• Inter-limb asymmetries are common in athletes and can impact performance and injury risk.
• Assessing these asymmetries requires reliable and valid testing protocols.

Purpose of the Study:

• To investigate the prevalence of inter-limb asymmetries in young volleyball players.
• To compare asymmetry outcomes across diverse strength and power tests.
• To evaluate the commonly used >10% asymmetry threshold.

Main Methods:

• 54 young volleyball players (25 males) underwent tests for jumping, change-of-direction, and isometric knee extension torque.
• Calculated inter-limb asymmetry indexes for each test outcome.
• Assessed agreement in classifying participants as symmetrical or asymmetrical.

Main Results:

• Average inter-limb asymmetry magnitude varied significantly (2.0-31.2%) across different tests.
• Poor agreement in classifying participants as symmetrical/asymmetrical using the >10% threshold, except within similar tasks.
• Inter-limb asymmetry in rate of torque development scaling factor (RTD-SF) showed weak association with change-of-direction performance.

Conclusions:

• Multiple strength and power testing protocols are essential for a comprehensive evaluation of athlete imbalances.
• The >10% asymmetry threshold requires reconsideration and further investigation.
• Rate of force development scaling factor (RFD-SF) is proposed as a novel measure for coaches and researchers.