Architectural model for muscle growth during maturation

Stefan Papenkort,Markus Böl,Tobias Siebert

doi:10.1007/s10237-021-01492-y

Stefan Papenkort, Markus Böl + Show 1 more

Open Access

https://doi.org/10.1007/s10237-021-01492-y

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Abstract

Muscle architecture, which includes parameters like fascicle length, pennation angle, and physiological cross-sectional area, strongly influences skeletal muscles' mechanical properties. During maturation, the muscle architecture has to adapt to a growing organism. This study aimed to develop an architectural model capable of predicting the complete 3D fascicle architecture for primarily unipennate muscles of an arbitrary age, based on fascicle data for an initial age. For model development, we collected novel data on 3D muscle architecture of the rabbit (Oryctolagus cuniculus) M. plantaris of eight animals ranging in age from 29 to 106 days. Experimental results show that plantaris muscle belly length increases by 73%, whereas mean fascicle length and mean pennation angle increases by 39 and 14%, respectively. Those changes were incorporated into the model. In addition to the data collected for M. plantaris the predictions of the model were compared to existing literature data of rabbit M. soleus and M. gastrocnemius medialis. With an error of −1.0 ± 8.6% for relative differences in aponeurosis length, aponeurosis width, muscle height, and muscle mass, the model delivered good results matching interindividual differences. For future studies, the model could be utilized to generate realistic architectural data sets for simulation studies.

Highlights

The muscle’s architecture strongly influences the skeletal muscle’s mechanical properties (Gans and Gaunt 1991; Wickiewicz et al 1984; Woittiez et al 1983). It is commonly characterized by parameters like the fascicle length, the physiological cross-sectional area (PCSA), the angle of pennation, and aponeuroses’ dimensions (Kupczik et al 2015; Papenkort et al 2020)
From 29 to 106 d, muscle belly length increased by 73%, whereas mean fascicle length increased by 39% (p = 0.0037)
The scaling in muscle length, where fascicles are shifted in the aponeurosis length direction, was motivated by similar increases in muscle belly length (73%) and aponeurosis length (76%)

Summary

Introduction

The muscle’s architecture strongly influences the skeletal muscle’s mechanical properties (Gans and Gaunt 1991; Wickiewicz et al 1984; Woittiez et al 1983). It is commonly characterized by parameters like the fascicle length, the physiological cross-sectional area (PCSA), the angle of pennation, and aponeuroses’ dimensions (Kupczik et al 2015; Papenkort et al 2020). The free tendon length (if present) is often considered when the entire muscle-tendoncomplex’s (MTC) mechanical behavior is of interest. Muscles with comparatively long fascicles show higher contraction velocities due to many sarcomeres in series. MTCs with long tendons are, for example, able to store and recover large amounts of elastic energy during periodic movements

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