This is an excerpt from Functional Training Anatomy by Kevin Carr & Mary Kate Feit.
The body has evolved to develop a great many interconnected systems that allow people to move dynamically throughout daily life. An athlete’s ability to run, jump, and throw can be attributed to the body’s amazing network of bones, muscles, tendons, and fasciae that allow them to flex, extend, and rotate as an integrated unit and produce force with a single coordinated outcome.
Although people are traditionally taught strength training and anatomy in isolation, single-muscle functions and single-joint exercise do not accurately represent real-life movement. Nothing in the body occurs in a silo. The body functions as an interconnected unit, all pieces interdependent on one another, constantly adjusting function to carry out the desired task. In designing functional training programs, one must take into consideration not just the anatomy of the human body but also how anatomy functions in an integrated way in specific sporting environments.
Consider the function of the hamstring muscles during running. Traditionally one is taught that the biceps femoris, semimembranosus, and semitendinosus muscles function primarily as knee flexors—and in an isolated setting, such as on a leg curl machine, they would.
However, when you consider the function of a hamstring when you are on your feet, standing, running, or walking, the functionality of the hamstring is much different. A biarticular muscle group, crossing both the hip and knee, the hamstring muscles must carry out numerous actions during the gait cycle in conjunction with the obliques and glutes (see figure 1.3).