4. Balance And Posture.pdf

TOPIC 4: BALANCE AND POSTURE Balance Balance: ability to maintain the line of gravity within the base of support with minimal postural sway. Equilibrium: all acting forces are cancelled by each other resulting in a stable balanced system. It improves in case of: -Wider base of support -Lower center...

TOPIC 4: BALANCE AND POSTURE Balance Balance: ability to maintain the line of gravity within the base of support with minimal postural sway. Equilibrium: all acting forces are cancelled by each other resulting in a stable balanced system. It improves in case of: -Wider base of support -Lower center of gravity -Longer distance between the line of gravity and the border of the base of support. Posture Attitude assumed by the body either with support during the course of muscular activity. Standing posture Small base of support High center of mass External forces: gravity and ground reaction forces. Internal forces: muscle activity, tension of noncontractile structures Line of gravity: On or close to joints axis: -Compressive forces are distributed. -Less passive tension or muscle activation. Postural control Complex sensorimotor skill, interaction of -Musculoskeletal system -Somatosensory system: Vision Vestibular Proprioception Cutaneous or tactile -Central nervous system integration and processing: Afferent (sensory), Efferent (motor) Postural sway: the unconscious, small movements that happen around the body’s center of gravity in order to maintain balance. Continuous muscle activation with an stabilizer role: Ankle Knee Hip Spine Standing Postural Control Multiple muscle groups maintain an “isometric” activation: Ankle: plantar flexion VS dorsiflex gravitational moment Knee: posterior joint capsule VS extension gravit. moment Hip: ligaments and psoas VS extension gravit. moment Lumbar: ligaments VS extension gravit.moment Thoracic: ligaments + extensors VS flex. gravit. moment Cervical: ligaments VS extension gravit. moment Other Static postural control To identify muscle groups activation: -Base of support -Line of gravity -Gravitational moment: opposing muscle activations. Postural Control Mechanisms Sensorimotor control under load pertubances: Feedback control: stimulation of a corrective response after sensory detection. Feedforward control: CNS predicts the effect that a voluntary movement will have on the body and plans a sequence of anticipatory muscle activity in order to be prepared for this perturbation.