Kinetic analysis

1. KINETIC ANALYSIS
By:H.a.maaz
OPT

2. Forces acting on the body During gait.
- - External forces: gravitational force,
ground reaction force and inertia.
- - Internal forces: active muscle
force, passive (ligaments, tendons,
capsules, bony components).

3. 1- gravitational force
- point of application : COG
-Line of action: LOG.
-Direction: vertical downward.
- Magnitude: W

4. LOG: imaginary vertical line
passes perpendicularly in the
body through the COG.
Pathway from lateral view:
Vertex
-mastoid process
-anterior to atlantooccipital joint
-behind cervical spine
-anterior to the body of dorsal
vertebrae
-posterior to the body of lumbar
vertebrae
-anterior to the second sacral
vertebrae
-behind or through the hip joint

5. Effect of gravitational force on body segments
- Depends on location of the LOG relative to axis
of motion.
- Through the axis: no torque
- At a distance: gravitational torque produced that
causes motion of the body segment around the
axis of rotation.
- Gravitational torque tends to cause anterior
motion of the proximal segment.
- magnitude of torque depends on the distance
between LOG and the joint axis.
- The gravitational torque is opposed by a
counterbalancing torque by active muscle
tension and passive tension in ligaments and
joint capsules.

6. 2- ground reaction force
- point of application :
COP
-Line of action: GRFV.
-Direction: upward.
-Magnitude: ma

7. COP

8. GRFV

9. GRFV

10. Pathway of GRFV
IC LR MS TS PS
Hip A A P P P
Knee A P A A P
ankle P P A A A

11. Gait

12. Frontal plane

13.  Prime movers
 Stabilisers
 Muscle contraction
mode:
• concentric
• eccentric
• isometric
Internal forces: primarily by the muscles. Assisted
by ligaments, tendons, capsules, bones.
To counterbalance the moment created by the GRFV.

15. Analysis of muscle activity during
Gait
General principles:
- Identify the acting muscle and the type of muscle
contraction.
1- identify the pathway of the GRFV and the moment
resulting from this passage. The muscle in the opposite
direction is acting to counterbalance.
2-determine the normal joint motion during this subphase of
gait.
3- * joint motion occurs in the same direction with the
muscles…………Concentric.
*joint motion occurs in one direction and the acting
muscle works in opposite
direction…………………….Eccentric.

16. Analysis of Gait – sagittal plane analysis.
Ankle joint.
IC LR MS TS PS
Ankle P P A A A
0
dorsiflexion
15
Plant Flex
5-10
Dorsi flex
10
Dorsi flex
20-30
Planter flex
10
Plante
Flex
0 0

17. Analysis of Gait – sagittal plane analysis.
Knee joint
IC LR MS TS PS
Knee A P A A P
0
extension
15-20
Flex
5
flexion
0
extenson.
35-40
flexion
40- 60
Flex
65-30
Flex
0
exten

18. Analysis of Gait – sagittal plane analysis. Hip
joint
IC LR MS TS PS
Hip A A P P P
30
Flex
25
Flex
0 20
Hyper ext.
0
20
Flex
30
Flex
30
Flex

19. Pathway of GRFV: Frontal plane
IC LR MS TS PS
Hip L M M M L
Knee L M M M N
ankle N L L M N