Biomechanics of skeletal muscle

Factors that influence muscle force: Directly measuring muscle force in the body is invasive and not practical. Accordingly, the factors that influence muscle force have mainly been derived from isolated muscle experiments. Although this may seem like a limitation, the experiments have provided details that would not otherwise have been identified. So, we can be very specific about these factors.  The factors that influence muscle force may be categorized as structural, mechanical, and neural.

Structural factors:

Muscle cross sectional area (CSA): As shown below, CSA refers to the girth or size of muscle within the transverse plane.  A muscle with a greater CSA contains more muscle cells and therefore a greater capacity for force generation.  Just like bone, if muscle is stressed sufficiently (i.e., 2/3 max) the CSA will increase mainly because of new myofibrils, not muscle cells!  What is an effective technique to stress the muscle and produce hypertrophy? (See interesting Fact # 2).