Anatomy and Physiology

To reduce the energy cost of gait, the movement of the center of mass should be minimized. The most important mechanism is the virtual lengthening of the lower extremity by ankle dorsiflexion at heel strike and ankle plantar flexion at pre-swing. Without ankle plantar flexion motion, the center of mass movement and, consequently, the energy cost of gait increase. Proactive balance is necessary for countering potentially destabilizing internal and external forces. This can be used interchangeably with anticipatory balance. Movement of one part of the body changes the location of the center of mass, and the body is moved without intention if there is no counteracting muscle contraction. Almost all mobility tasks involve not only horizontal movement but also vertical movement of the center of mass (through lower extremity flexion and extension). Thus, tests and training should include components of vertical movement of the center of mass.