Angular Kimematics - Joint Angles In Running Flashcards
5 assumptions when digitising
Skin markers represent underlying bone and joint movements ( could surgically insert markers but is invasive)
Skin movement is 0
No ‘wobbly’ mass
Segments of body are Rigid and are represented by straight lines joining skin markers
2D joint rotations only ( in a Sagittal plane)
5 positions of markers when analysing joint angles in running
HIP 1cm posteriorly KNEE 1cm anteriorly (lateral epicondyle) ANKLE on the bone MTP base of big toe HEEL calcaneus
In degrees, what is absolute zero?
What does it look like?
180 degrees
Completely straight leg
Phases of ground contact in knee (in order)
Foot strike
Initial support
Mid stance
Toe off
Describe foot strike of knee (flex, ext, angle value)
10 degrees flexion
Describe initial support of knee
Cushioning flexion
Reduces shock wave
Describe mid stance of knee (flex, ext, angle value)
Peak/max flexion
38 degrees
Describe toe off in knee (flex, ext, angle value)
13 degrees extension
Phases of ground contact in ankle (in order)
Foot strike
Initial support
Mid stance
Toe off
Describe foot strike in ankle (flex, ext, angle value)
90 degrees flexion
Describe initial support in ankle
Small amount of plantar flexion
Describe mid stance in ankle (flex, ext, angle value)
108 degrees dorsal flexion
Describe toe off in ankle
Plantar flexion
Swing phase
Flexion following the extension to get the next step
Max amount of flexion as leg is pulled up into next step
Draw knee angle time history
X axis = time (m/s) 0 to 60
Y axis = knee angle (degrees) 0 to 200
Max angle = max knee flexion (when the angular convention is in front of the knee)
Curve = 10 degrees until 40, up to 50 degrees at 100, down to 200
Draw ankle angle time history
X axis = ankle angle (degrees) 0 - 130
Y axis = time (m/s) 0 - 100
Max angle = maximum ankle flexion. (When angle convention is underneath the foot)
Curve = 105 degrees at 5, 95 degrees at 25, up to 115 at 50, flat to 100, down to 200
What to consider when drawing knee/ankle time histories
If convention is in front of knee, regular time history
If convention is behind knee, flip time history upside down
If convention is below foot, regular time history
If convention is above foot, flip time history upside down
Why might Line in time history be bumpy?
When data is raw or unfiltered.
This means it isn’t standardised relative to the standing position
(subject may be standing straight with 10 degrees knee flexion)
Angular velocity of thigh time history
X axis - time
Y axis - degrees
Horizontal line with shallow dip in middle of time. Line rises back up to just below original position
Angular acceleration time history for thigh
X axis time
Y axis degrees
Angle dips to start and then rises gradually to a plateau higher than initial position
In angular acceleration time history, what does the polarity of acceleration show?
Polarity (-ve / +ve) shows the rate at which the angle is changing
NOT showing the angle itself getting bigger or smaller
Peak ankle Dorsi-flexion velocity?
6.5 rad per sec
Peak knee flexion velocity?
9.5 rad/s
Sagittal plane angles in sprinting:
Is it viable to test sprint running on treadmills?
Not for the start of the sprint but as the study goes on, peak values start to coincide with expected results
Also not at the end when person slows down
Uphill running and its effects on claves?
An increase in Doris flexion =
Reduction in initial knee extension & Reduction in knee flexion velocity =
Tight calves
Achilles’ tendon study author and year
Dixon and Kerwin
1999
Achilles’ tendon study aims (X2)
Influence of heel lift manipulation on Sagittal plane kinematics in running
Ways to reduce strain using inserts in shoes
Achilles’ tendon study results
Inserts shortened the length and stretch of Achilles’ tendon due to reduction in dorsi-flexion
NO CHANGE in knee angle
REDUCTION in ankle dorsi-flexion
Literature comparisons of changes in angles during running gait cycle : considerations of different results from different authors?
Comparison of results is influenced by:
Variability between subjects
Differences in marker placements
Different angular conventions
Description of joint angle changes in the THIGH during running
Foot strike - angle positive indicating hip flexion
Initial support - little change in angle of hip/thigh
Mid stance - angle negative indicating hip extension
Toe off - max extension of thigh
Swing phase - thigh is flexed
Description of KNEE joint angle changes during running
Foot strike - flexion
Initial support - flexion to cushion ground impact
Mid stance - begins to extend
Toe off - continued extension
Swing phase - initially flexed then extended
Description of ANKLE joint angle changes during running
Foot strike - angle at 90 degrees
Initial support - small amount of plantar flexion
Mid stance - Dorsi flexion peak
Toe off - plantar flexion
Swing phase - plantar flexion through to dorsi flexion
Name 1 thing that influences the size of the angle
Angular conventions