Biomécanique et Bioingénierie

Amyotrophic Lateral Sclerosis (ALS) and myopathy are debilitating neuromuscular disorders that require accurate and timely diagnosis for effective management. Traditional electromyography (EMG)-based diagnostic methods rely on manual interpretation, which is time-consuming and prone to variability. This study proposes an approach that directly classifies EMG signals using a one-dimensional convolutional neural network (1D-CNN) without feature extraction, addressing the limitations of existing methods that depend on handcrafted features and focus primarily on binary classification. The proposed model is evaluated on a publicly available EMG dataset, achieving an overall accuracy of 99.27%, with macro and weighted precision, recall, and F1-scores exceeding 99% across ALS, myopathy, and healthy subjects. Unlike previous approaches that require extensive preprocessing, our method maintains high classification performance while reducing computational complexity, offering a clinically relevant multiclass classification framework. Although our method achieves high classification performance, it also maintains a strong balance between sensitivity and specificity, ensuring reliable and accurate neuromuscular disorder diagnosis, making it a practical tool for clinical applications. Future research will focus on improving model generalizability, expanding dataset diversity, and integrating real-time deployment for enhanced diagnostic utility.

Abstract Skeletal muscle formation involves tight interactions between muscle cells and associated connective tissue fibroblasts. Every muscle displays the same type of organisation, they are innervated in the middle and attached at both extremities to tendons. Myonuclei are heterogeneous along myotubes and regionalised according to these middle and tip domains. During development, as soon as myotubes are formed, myonuclei at muscle tips facing developing tendons display their own molecular program. In addition to molecular heterogeneity, a subset of tip myonuclei has a fibroblastic origin different to the classical somitic origin, highlighting a cellular heterogeneity of myonuclei in foetal myotubes. To gain insights on the functional relevance of myonucleus heterogeneity during limb development, we used 2D culture and co-culture systems to dissociate autonomous processes (occurring in 2D-cultures) from 3D-spatial environment of tissue development. We also assessed the role of mechanical parameters in myonucleus heterogeneity in paralysed limb muscles. The regionalisation of cellular heterogeneity was lost in 2D cell culture systems and paralyzed muscles. The molecular signature of MTJ myonuclei was also lost a dish and paralysed muscles indicating a requirement of spatial and mechanical input for MTJ formation. Tip genes that maintain their expression in a dish are involved in myofibrillogenesis and myotube attachments. The behaviour of regionalized markers in cultured myotubes and paralyzed muscles allows us to deduce whether the genes intervene in myogenesis, myotube attachment or MTJ formation.HighlightsThe regionalisation of cellular heterogeneity of myonuclei is lost in cultured myotubesBMP signalling regulates fibroblast nucleus incorporation into cultured myotubesThe molecular signature of MTJ myonuclei is lost in cultured myotubes and paralysed musclesTip genes involved in myofibrillogenesis maintain their regionalised expression in cultured myotubes

The aim of this study was to investigate the effect of aging and resistance training with a moderate load on the size and mechanical properties of the patellar (PT) and Achilles tendon (AT) and their associated aponeuroses; medial gastrocnemius (MG) and vastus lateralis (VL). Young (Y55; 24.8 ± 3.8yrs, n = 11) and old men (O55; 70.0 ± 4.6yrs, n = 13) were assigned to undergo a training program (12weeks; 3 times/week) of moderate slow resistance training [55% of one repetition maximum (RM)] of the triceps surae and quadriceps muscles. Tendon dimensions were assessed using 1.5T magnetic resonance imaging before and after 12weeks. AT and PT cross sectional area (CSA) were determined every 10% of tendon length. Mechanical properties of the free AT, MG aponeurosis, PT, and VL aponeurosis were assessed using ultrasonography (deformation) and tendon force measurements. CSA of the AT but not PT was greater in O55 compared with Y55. At baseline, mechanical properties were generally lower in O55 than Y55 for AT, MG aponeurosis and VL aponeurosis (Young's modulus) but not for PT. CSA of the AT and PT increased equally in both groups following training. Further, for a given force, stiffness and Young's modulus also increased equally for VL aponeurosis and AT, for boths groups. The present study highlights that except for the PT, older men have lower tendon (AT, MG aponeurosis, and VL aponeurosis) mechanical properties than young men and 12-weeks of moderate slow resistance training appears sufficient to improve tendon size and mechanical adaptations in both young and older men. New and Noteworthy: These novel findings suggest that short-term moderate slow resistance training induces equal improvements in tendon size and mechanics regardless of age.

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