STABILITY AND BALANCE

CENTER OF GRAVITY OR MASSThe point at which the entire mass or weight of the body may be considered to be concentrated.

CENTER OF GRAVITY OR MASS The point around which the body’s mass is

equally distributed in all directions

The place where torques acting on the system are balanced

The place where all the linear forces are balanced

LOCATING CENTER OF GRAVITY IN HUMANS The human body is not rigid, so, the location

of the COG depends on the location of the limbs.

Intersection of three planes locates COG.

The location is about 55-57% of your standing height.

STABILITYThe ability of an object to return to equilibrium or to its original position after being displaced.

FACTORS AFFECTING STABILITY Base of Support: Described by those parts of

the body in contact with supporting surfaces and the intervening area.

Height of the center of gravity above the base of support.

Weight of the object

The relationship between the BOS and the Line of Gravity.

WHAT CAUSES INSTABILITY?External Torques: Gravity, Inertia & External Forces

WHAT CAUSES STABILITY?Internal Torques: muscle forces, ligament

forces, distribution of mass and external forces

PROVIDING INFORMATION FOR INTERNAL STABILITYVision, Somatosensory and Vestibular

SOMATOSENSORY Muscle Spindles Joint Receptors Tendon Organs Mechanoreceptors

VESTIBULAR: THE INNER EARProvides Information About: Head Linear Acceleration Head Rotation (angular accelerations) Head Position

Meneres Disease Dizziness

WEIRD SCIENCE: TRIPPING GRANNIEShttp://app.discoveryeducation.com/search?Ntt=balance

MECHANISM OF MAINTAINING BALANCE Activate supporting musculature Activate synergistic muscles (the core)

DAY TO DAY BALANCE MANAGEMENT: THE QUIET STANCEPostural AlignmentJoint Stiffness/ LaxityMuscle Tone

THE ANKLE METHODFor Minimal Instability:Rotation at the ankle (inverted pendulum)

THE HIP METHODFor Greater Instability:Hip adjustment for increased translation

THE STEPPING METHODFor greatest instabilityMultiple segments involved causing slowest reaction time