154 - Framework for Biomechanical Analysis of Non-Typical Skeletal Muscles

Poster Board Number: 254
There are separate poster presentation times for odd and even posters.
Odd poster #s – first hour
Even poster #s – second hour

Abstract Body : Introduction: The structure and arrangement of skeletal muscle fibers is the primary determinate of muscle function. While analysis of morphologic parameters to elucidate muscle structure-function relationships dates to the 17th century, considerable variability in methodology and technique to quantify these relationships exists within the literature. Additionally, applications to assess the impact of non-typical musculoskeletal anomalies on structure-function relationships are limited. This study aims to present a framework of combined methods and techniques for efficient and comprehensive evaluation of the biomechanical impact for non-typical skeletal muscle morphologies.

Methods: A literature review was conducted to identify existing skeletal muscle biomechanical formulas and experimentally determined acceptable values for typical fast-acting skeletal muscle. The different methods were ordered in a stepwise, comprehensive framework with accepted values for standardized variables associated with human skeletal muscle. The associated formulas, optional steps, and possible techniques for completing necessary measurements will be delivered in the full presentation of the framework.

Results: The assembled framework presents a comprehensive, ordered process with mathematical formulas for measuring skeletal muscle parameters and calculating the following biomechanical aspects of a skeletal muscle: 1) fascicle length normalization (FLn) from measurements of observed fascicle length, sarcomere length, and using the accepted value of 2.64 µm for optimal human sarcomere length; 2) physiological cross-sectional area (PCSA) from measurements of muscle mass, pennation angle, FLn, and accepted value of 1.055 g/cm3 for skeletal muscle density; 3) maximal isometric force (Fmax) from PCSA and the accepted value of 22.5 N/cm2 for specific tension; 4) torque (𝜏) from Fmax and measurements of the angle of attachment on a leveraged bone and distance from the associated joint; and 5) difference index between two muscles (δ2,1) from measurement of muscle belly length and use of previously named or calculated variables.

Conclusions: This study presents an efficient and comprehensive framework of combined methods and techniques for investigators to evaluate the biomechanical impact of skeletal muscle variations. The practical and cost-effective use of this framework should optimize project efficiency and spending, increase study rigor, and minimize procedural variation across different studies if used consistently. Furthermore, understanding the impact of non-typical musculoskeletal anomalies may benefit clinical implications involving non-typical musculoskeletal morphologies.