CHAPTER 9 FUNCTIONAL PROGRAMMING FOR STABILITY-MOBILITY AND MOVEMENT | ACE PERSONAL TRAINER MANUAL
IT IS IMPORTANT TO REMEMBER THAT ALL JOINTS DEMONSTRATE VARYING LEVELS OF STABILITY AND MOBILITY
It is important to remember that while all joints demonstrate varying levels of stability and mobility, they tend to favor one over the other, depending on their function within the body (Figure 9-2) (Cook & Jones, 2007a; Cook & Jones, 2007b). For example, while the lumbar spine demonstrates some mobility (approximately 15 degrees of rotation), it is generally stable, protecting the low back from injury. On the other hand, the thoracic spine is designed to be more mobile to facilitate a variety of movements in the upper extremity. The scapulothoracic joint is a more stable joint formed by collective muscle attachments between the scapulae and rib cage that provide a solid platform for pulling and pushing movements at the glenohumeral joint and must tolerate the reactive forces transferred into the body during these movements. The foot is unique, as its level of stability varies during the gait cycle. Given its need to provide a solid platform for force production against the ground during push-off (heel-off and toe-off instants), it is stable. However, as the foot transitions from the heel strike to accepting body weight on one leg (load- response instant), the ankle moves into pronation (with accompanying calcaneal eversion that increases the space between the tarsal and metatarsal bones), and the foot forfeits some stability in exchange for increased mobility to help absorb the impact forces. As the foot prepares to push off, the ankle moves back into supination (with accompanying calcaneal inversion that decreases the space between the tarsal and metatarsal bones), becoming more rigid and stable again to increase force transfer into motion.
Individuals who exhibit good posture generally demonstrate an improved relationship between stability and mobility throughout the kinetic chain, but concern arises when an individual exhibits bad posture. What happens when a joint lacks the appropriate level of mobility needed for movement? When mobility is compromised, the following movement compensations typically occur: • The joint will seek to achieve the desired range of motion (ROM) by incorporating movement into another plane. For example, if a client performs a birddog exercise with hip extension (sagittal plane movement) (see Figure
