Balance and Postural Stability

Flashcards on Balance and Postural Stability

Balance and Postural Stability

Keeping the center of mass over the base of support.

Center of Mass

The point of perfect weight equilibrium; the center of the body's mass.

Base of Support

The contact area between the body and the surface supporting it.

Center of Gravity

The vertical projection of the center of mass to the ground.

Limit of Stability

The point at which a person has to move their base of support to avoid losing their balance.

Neuromuscular and Musculoskeletal Systems Contributors

Visual, Vestibular, and Somatosensory (Proprioceptive) Systems

Visual System

Tells us where our head is in space and can compensate for inadequate vestibular or proprioceptive input.

Vestibular System

Gives us information about the position and movement of our head in relation to gravity.

Somatosensory (Proprioceptive) System

Provides information about joint position sense; receptors within the muscle spindle are primarily responsible.

Ankle Strategy

Small motions at the ankle to keep the center of mass over the base of support; used for anterior or posterior perturbations.

Anterior Perturbation (Ankle Strategy)

Muscles on the posterior aspect of the body contract in a distal to proximal fashion (gastrocs, hamstrings, paraspinals).

Hip Strategy

Large perturbations that rapidly flex or extend the hips to move the center of mass closer to the base of support; muscle activation is proximal to distal.

Stepping Strategy

Large force displaces the center of mass beyond the limits of stability, requiring a step forward or back.

Suspension Strategy

Quick lowering of the center of mass by flexing the knees, causing hip flexion and ankle dorsiflexion.

Weight Shift Strategy

Displacement of the center of mass comes from the side, so the body takes a step to the opposite side.

Perturbation

Deviation from a regular or normal position caused by an outside influence.

AP

Anterior-Posterior, also known as forward-back or sagittal plane motion.

Balance During Lifting

The body leans forward towards the load, displacing the center of mass forward, and the central nervous system generates a backwards horizontal linear momentum to maintain balance.

Key Principles for Initiating Balance Intervention

Identify the activity/movement with the balance deficit, identify the contributing structure/system, and start at a challenging but achievable level.