UNIT 2 Flashcards
internal forces
muscle pull, joint reaction force
external force
gravity/weight of the body segment, ground reaction force
Net force
sum of all internal and external forces (equal to 0 when static)
5 steps in a Free Body Diagram
identify and isolate body segment
define a reference frame
add forces and moments as vectors
draw joint reaction force
label
kinetic measurements
forces acting on the body
kinematic measurements
spacial and temporal measurements
velocity, acceleration, position (angle)
Imaging systems
position and time data collected through video
Electrogoniometers
position and time data are collected through taped electrodes to skin detecting change in voltage with movement
Inertial Measurement Units IMUs
accelerometer and gyroscope
collects acceleration data
position vs time curves
velocity vs time curves
acceleration vs tim graphs
Force Platforms
measures forces in all directions (X, Y, Z)
limitation: cannot determine two separate contacts on a single point (one foot per plate)
What is EMG
recordings and interpretations of the electrical activity from muscles during movement
What does EMG represent
sarcolemmal potential changes (action potentials)
Clinical EMG use (4)
temporal muscle activity
relative exertion level
muscle fatigue
biofeedback
Functional task determinants of movement
person: cognitive, behavior, physical
environment: physical, informational, psychosocial
Task: goal of the movement
Task related determinants of a sit-to-stand
- generate anterior momentum of the head arms and trunk
- control anterior displacement of whole COM over new BOS
- generate vertical momentum to raise whole COM
- arresting forward and vertical momentum of whole COM
Task related determinants of a forward reach
- generate anterior momentum pf head arms and trunk COM
- generate momentum of one upper extremity to elevate it forward
- control whole COM forward momentum adjustments
- coordinate COM momentum for each of the trunk arm and hand to reach target
Task related determinants of supine to stand
- generate momentum to displace the whole body COM over feet
- orient head arms and trunk to place whole COM over feet
- establish new base of support with feet on floor
- generate vertical momentum to raise whole body COM
- arresting forward and vertical momentum of whole body COM
Define gait
a pattern, style, or manner of locomotion
8 phases of gait
initial contact
loading response
mid stance
terminal stance
pre swing
initial swing
mid swing
terminal swing
define step
initial contact to opposite limb initial contact
define stride
initial contact to subsequent same limb initial contact
Define Foot progression angle
angle to foot turns outward during walking
10-14 degrees
Define Step rate
number of steps taken per time
115 steps/minute
Typical adult walking gait speed
1.4 meters/sec
how to calculate gait speed
step rate x step length
Pelvic movement in the frontal plane
lateral tilt when foot hits the ground about 2 inches
peak muscle activity of hip flexors
pre swing and initial swing
peak muscle activity of hip extensors
loading response
peak muscle activity of knee flexors
terminal swing and loading response
peak muscle activity of knee extensors
loading response
peak muscle activity of ankle plantarflexors
terminal stance
peak muscle activity of ankle dorsiflexors
early loading response
functional task of weight acceptance during gait
high rate of loading at all joint
absorbs ground reaction force
functional task of single limb support during gait
full weight on single limb
progression of COM forward
