Time 1

shank

thigh Knee

Segment Angles are ABSOLUTE ANGLES, measured with respect to a (stationary) global vertical or horizontal reference axis.

Joint Angles are RELATIVE ANGLES, measured between two adjacent segments with the angle’s vertex at the joint center.

Angular Kinematics

Time 1 Time 2

shank = shank 2 - shank 1

shank 2

Shank segment angular velocity ()

Shank = shank 2 - shank

1

time 2 - time 1

time

=

Segment Angular Velocity ()

Calculating Segment Angular Position with segment endpoint coordinate data (x, y)

(0.65, 0.90)

(0.85, 0.50)

(0, 0) +X

+Y

Calculating JOINT Angular Position with Segment Angular Position Data

+Y

(0, 0) +X

Adjacent joint angle-angle diagrams are used to characterize joint coordination

patterns

Knee

Hip

Knee

Ankle

100

120

140

160

180

200

100 120 140 160 180 200

Knee angle (degrees)

Hip

an

gle

(d

eg

rees)

Similar knee-hip coordination patterns during push phase

Hurdle Take-off

Long jump Take-off

HLJ

Analysis - Total Body Level Initial horizontal position of TBCM relative to foot at touchdown is significantly related to ground contact duration

-500

-250

0

250

500

750

1000

1250

0.000 0.050 0.100 0.150 0.200 0.250

Time (s) after contactH

oriz

onta

l GR

F (

N)

CMxCMx

Foot CMxFoot CMx

CMxCMx

Foot CMxFoot CMx

1) How is TBCM position controlled or repositioned relative to the foot?

2) Why?

Assessing Segment Contribution to Joint Motionin order to understand the primary source of

observed joint motion

Shank

Time 1Time 1 Time 2Time 2

kneeknee

Shank

Knee

Thigh

Ankle

Foot

Shank rotation during impact phase significantly delays peak thigh rotation post-impact (p<.01)

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

0.000 0.050 0.100 0.150 0.200 0.250

-500

-250

0

250

500

750

1000

1250

0.000 0.050 0.100 0.150 0.200 0.250

time (s) after contact

Hor

izon

tal G

RF

(N

)Se

gmen

t an

gula

r ve

loci

ty (

rad/

s)

Shank sav

Thigh savAA

B

Segment contribution to TBCM control

80

100

120

140

160

180

40 60 80 100 120 140ankle jap (deg)

kn

ee j

ap (

deg

)

pt16

cs11

AA

B

Adjacent Joint Coordination: Angle-Angle Diagrams

Ankle angle (deg)K

nee

angl

e (d

eg)