Influence of Image Acquisition and Biologic Variability on Measurement Reproducibility of Vastus Lateralis Muscle...

Area of Science:

• Biomechanics
• Musculoskeletal Ultrasound
• Exercise Physiology

Background:

• Accurate measurement of muscle architecture is crucial for understanding muscle function and adaptation.
• Ultrasonography (US) is a common tool for assessing muscle architecture, but its reproducibility can be influenced by various factors.
• Standardized protocols are essential for reliable and valid US-based muscle assessments.

Purpose of the Study:

• To compare the reproducibility of two distinct ultrasonography (US) protocols for measuring vastus lateralis muscle architecture.
• To evaluate the influence of single versus multiple image acquisitions on measurement variability.
• To determine the impact of protocol choice on key muscle architecture parameters: cross-sectional area (CSA), muscle thickness (MT), fascicle length (FL), and pennation angle (PA).

Main Methods:

• Two reproducibility protocols were compared: a single image acquisition (1X) and two separate image acquisitions (2X), both with 72-hour intervals.
• Muscle architecture parameters (CSA, MT, FL, PA) of the vastus lateralis were measured using US in 104 experimental units from 54 subjects.
• Reproducibility was analyzed using typical error (TE), coefficient of variation (CV), minimum detectable change (MDC), and Bland-Altman plots.

Main Results:

• The 1X protocol consistently yielded lower TE and CV values for all measured muscle architecture parameters compared to the 2X protocol.
• Significant differences between protocols were observed for fascicle length (FL) and pennation angle (PA) (p < 0.001 and p < 0.026, respectively).
• The 2X protocol exhibited greater variance across all parameters, indicating lower measurement reliability.

Conclusions:

• The single image acquisition (1X) protocol offers superior reproducibility for vastus lateralis muscle architecture assessment via ultrasonography.
• Protocol selection significantly influences measurement variability, impacting the reliability of muscle architecture data.
• These findings underscore the need to consider evaluator and biological variability when interpreting US-based muscle assessments.