Biomechanics of skeletal muscle

As you can see above, when the pennation angle decreases tendon force increases.  Remember it’s the tendon force that pulls on bone. So, why do pennate muscles generate more force than parallel fiber arrangements?   Answer: Pennate muscles pack more fibers in a given space than do parallel fibers (see illustration below). More fibers mean more force even though the pennation angle hampers its potential contribution. A benefit of parallel fiber arrangements is that they enhance muscle shortening velocity and range of motion. See interesting fact # 4.