Optimizing the methodology for precise estimation of skeletal muscle fiber type proportions in humans

• Published in: Scientific reports Vol. 15; no. 1; pp. 30006 - 10
• Main Authors: Serrano, Nathan, Buras, Matthew R., Roust, Lori R., De Filippis, Eleanna, Katsanos, Christos S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.08.2025; Nature Publishing Group; Nature Portfolio
• Subjects: 631/1647; 631/1647/767; Accuracy; Adult; Biopsy; Electrophoresis, Polyacrylamide Gel; Female; Gel electrophoresis; Glycerol; Heterogeneity; Humanities and Social Sciences; Humans; Male; Metabolism; multidisciplinary; Muscle fibers; Muscle Fibers, Skeletal - cytology; Muscle Fibers, Skeletal - metabolism; Muscle phenotype; Musculoskeletal system; Myosin; Myosin heavy chain; Myosin Heavy Chains - metabolism; Number of fibers; Physiology; Protein Isoforms; Quadriceps Muscle; Science; Science (multidisciplinary); Selection of fibers; Skeletal muscle; Sodium lauryl sulfate; Myosin heavy chain; Accuracy; Number of fibers; Muscle fibers; Selection of fibers; Muscle phenotype
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-025-15163-w

Isolating individual muscle fibers and characterizing their myosin heavy chain (MHC) content using SDS-PAGE has become an increasingly common method for describing skeletal muscle fiber type proportions. In this study, we aimed to assess how the number of muscle fibers analyzed, and whether they are characterized in the order of isolation or randomly selected from a larger pool of muscle fibers, affects the precision of fiber type proportion estimates. A total of 170 individual muscle fibers were isolated from vastus lateralis biopsies from each of eight human subjects, and their MHC isoform content was analyzed using SDS-PAGE. To evaluate the precision of fiber type proportion estimates, we employed a resampling approach, varying both the muscle fiber sample size (25, 50, or 100 fibers) and the selection method (ordered vs. random selection). Our results indicate that when analyzing a small number of muscle fibers, precision improves if the fibers are randomly selected from a larger pool rather than characterized in the order they were isolated. These findings have important implications for designing experiments to assess skeletal muscle fiber heterogeneity and its role in health and disease.