In [[RealLife real life]], the size of a muscle is the determining factor in how much force a muscle can produce, as human muscle generally produces a constant amount of force per unit cross sectional area. [[note]] The mistaken idea that muscles can become larger without gaining functional mass via sarcoplasmic hypertrophy is commonly used as an explanation for why bodybuilders lack the functional strength of powerlifters. In reality, myofibrillar and sarcoplasmic hypertrophy never occur independently of one another, and in biopsy, human muscle cells are packed to capacity with myofibrils, regardless of their source. Aside from the fact that power-lifters are usually larger than bodybuilders, a key difference in functional strength lies in the neurological differences resulting from different types of training engaged in, not the quality of the muscle. In a very real sense, the bodybuilder builds muscle for show, while the powerlifter trains for performance.[[/note]] However, a person's strength takes into account significant factors such as neuromuscular response, which is essentially the percentage of muscle fascicles the person can 'recruit' or activate with a signal from the brain.

In works of fiction the writer or artist are not constrained by any such rules, thus a character of diminutive size with no visible muscle may possess enormous strength greater than the biggest burliest men.