“Muscle size” refers to the goal of muscle mass gain (or hypertrophy), which occurs primarily as a result of an increase in the size and/or number of myofibrils (i.e., bundles of protein filaments within muscle fibers that produce muscle contraction).[1] “Muscle strength” refers to the ability to produce force against an external resistance.[2]
What are muscle size and strength?
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•Last Updated: May 16, 2025
Muscle size refers to the goal of increasing muscle mass through hypertrophy, which involves the growth of myofibrils within the muscle fibers. Muscle strength is defined as the capacity to generate force against external resistance.