Lower-limb damping characteristics during various repetitive jumping forms: Reliability and sensitivity analysis

Area of Science:

• Biomechanics
• Human Movement Science
• Sports Science

Background:

• Controlling impact forces is crucial for jumping performance.
• The damping ratio quantifies oscillation decay and is a key measure of impact control.
• Understanding the reliability and sensitivity of damping ratios is essential for biomechanical analysis.

Purpose of the Study:

• To assess the intra-session and inter-session reliability of damping ratios at various lower-limb anatomical landmarks.
• To evaluate the sensitivity of damping ratios in distinguishing between different repetitive jumping forms (CMJ, BL HOP, UL HOP).
• To establish a specific methodological approach for reliable damping ratio analysis.

Main Methods:

• Twenty-three participants performed maximal countermovement jumps (CMJs) and bilateral (BL) and unilateral (UL) hopping (HOP).
• Ten wireless inertial measurement units recorded data from five bilateral lower-limb anatomical landmarks.
• Damping ratios were calculated and analyzed for reliability and sensitivity across different jump types and anatomical locations.

Main Results:

• Damping ratios showed good intra-session and inter-session reliability for CMJ and HOPUL, and moderate reliability for HOPBL.
• Significant differences in damping ratios were observed between CMJ, HOPBL, and HOPUL across most anatomical landmarks.
• CMJ exhibited the highest damping ratios, HOPBL the lowest, and HOPUL intermediate values, influenced by joint stiffness, displacement, and stretch-shortening cycle utilization.

Conclusions:

• A methodological approach using 20 repetitions per intra-session trial and averaging bilateral data for inter-session reliability is acceptably reliable and sensitive.
• Damping ratios are a valuable metric for biomechanical analysis of jumping and hopping, with potential applications in sports training and rehabilitation.
• This metric can contribute to developing theoretical models and enhancing practical biomechanical assessments.