Human movement occurs thanks to the “kinetic chain.” Kinetic means force, and chain is defined as a system that is linked together. Throughout this book, when we refer to the kinetic chain, we are referring to the system of interconnected body segments that allows the body to move. For our purposes, the kinetic chain includes the parts of the body which directly or indirectly impact the positioning, alignment, strength, endurance and performance of proximal or distal segments of the body. The nervous system, the musculoskeletal system, as well as the cardiovascular system, all work together to transfer energy or force through the body to the extremities in order to cause movement. The majority of this text is focused on the lower kinetic chain, which for our purposes refers to all of the muscles, bones, ligaments, tendons, joints and all associated neurological input systems that influence those structures from the chest (pectoral muscles) to the feet.