Joint torque variability and repeatability during cyclic flexion-extension of the elbow

Area of Science:

• Biomechanics
• Human Movement Analysis
• Orthopedics

Background:

• Joint torques are critical for evaluating surgical outcomes and functional capacity.
• Standardizing upper limb functional evaluation is an ongoing clinical need.
• Non-invasive methods using kinematics and inverse dynamics are employed for torque calculations.

Purpose of the Study:

• To assess the variability of calculated maximal elbow joint torque during cyclic movements.
• To evaluate the test-retest repeatability of these measurements in healthy young adults.

Main Methods:

• Twelve healthy young adults performed cyclic elbow flexion-extension movements.
• Participants used five different dumbbell weights (0-4 kg) and three frequencies (0.5, 0.33, 0.25 Hz).
• Peak elbow joint torques were calculated using non-invasive kinematic and inverse dynamics methods.

Main Results:

• The variability coefficient of trial peak torques was consistently below 4% across all conditions.
• Bland and Altman analysis demonstrated good test-retest repeatability for weights up to 3 kg, irrespective of movement frequency.

Conclusions:

• The high repeatability of peak elbow flexion-extension torques is a significant advancement.
• This supports the standardization of functional upper limb evaluations.
• Provides a reliable method for assessing elbow joint torque in clinical settings.