Multijoint Musculoarticular Stiffness Derived From a Perturbation Is Highly Variable

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• Musculoarticular stiffness assessment offers insights into multijoint elastic properties.
• Existing research predominantly focuses on single-joint stiffness quantification.
• The reliability of multijoint stiffness measurement using perturbation techniques requires further investigation.

Purpose of the Study:

• To quantify the test-retest reliability of multijoint musculoarticular stiffness.
• To evaluate stiffness derived from the perturbation technique across bench pull, bench press, and squat movements.

Main Methods:

• Eight resistance-trained men performed maximal effort lifts (bench pull, bench press, squat).
• A perturbation protocol was applied to the barbell during each movement.
• Barbell displacement and force data were collected using a force plate and linear position transducer to derive stiffness.

Main Results:

• Musculoarticular stiffness measurements exhibited high variability and poor test-retest reliability (Intraclass Correlation: -0.58 to -0.89).
• Significant variations were observed across different movements and testing days.
• Squat data analysis was excluded due to inconsistent perturbation detection.

Conclusions:

• The perturbation technique for measuring multijoint musculoarticular stiffness in the bench pull and bench press demonstrates considerable limitations in reproducibility.
• Practitioners should exercise caution when interpreting musculoarticular stiffness data derived from this method.
• Further research is needed to refine perturbation-based methods for reliable multijoint stiffness assessment.