Adaptation Through Size and Density

Trained individuals exhibit significant muscular adaptations with muscle fibers being 30% larger and fiber numbers 34% greater compared to untrained individuals. Interestingly, while the individual myofibrils in trained individuals are smaller, their density is notably higher, with about 50% more myofibrils packed tightly together. This suggests a possible phenomenon of hyperplasia, where an increase in muscle fiber count occurs, although the interpretation of results might be influenced by the method of biopsy used. The choice of using fusiform muscles, like the biceps, is strategic, as their parallel fiber arrangement minimizes measurement artifacts that could arise from biopsy angles.