Kinematic analysis Of Performance 2

Question 1

Phases of tennis serve (6)

Answer 1

Ankle flexes/extends
Knee flexes/extends
Upward movement begins with GRF (ground reaction force)
Trunk rotates
Arm flexes/extends
Ball strike

Question 2

Order of peak flexion in tennis serve

Answer 2

Ankle, knee, hip, shoulder, elbow, wrist

Question 3

Order and magnitude of peak velocities in tennis serve

Answer 3

Ankle, knee, hip, shoulder, elbow, wrist

Question 4

Describe kinematic chain in terms of velocities

Answer 4

Over time there’s a build up of velocity

Whatever end point velocity is, is what’s transferred into the ball

Question 5

Describe contributions in kinematic chain to serve velocity

Esp. Leg and trunk functions

Answer 5

Every segment has its own velocity contribution

Legs and trunk provide good base for other segments to rotate upon

Question 6

Contributions to serve velocity (figures)

Segment rotation - legs and trunk?

Answer 6

10-20%

Question 7

Contributions to serve velocity (figures)

Segment rotation - upper arm?

Answer 7

10%

Question 8

Contributions to serve velocity (figures)

Segment rotation - forearm?

Answer 8

40%

Question 9

Contributions to serve velocity (figures)

Segment rotation - hand?

Answer 9

30%

Question 10

Force in the system:

What is force produced by/ what triggers the K chain?

Answer 10

Ground reaction force (GRF) muscles

Question 11

2 vital pieces of information you need to know when analysing performance using K chain?

Answer 11

1) proximal to distal timing of peak joint flexion

2) proximal to distal timing of peak velocities

Question 12

Purpose of kinematic chain?

Answer 12

Each segment accelerates then decelerates and stabilises, providing a base of acceleration for next segment in chain

Question 13

When should peak velocity be attained in the K chain?

Answer 13

Peak velocity is desired to coincide with impact/release

Question 14

Consequences of injury to Kinematic chain?

Answer 14

‘Chain is only as strong as the weakest link,
Segment drop out can cause over compensation by other segments
Reduces the accumulation of motion
Reduces end point velocity

Question 15

Units of
Vt
r
angular velocity

Answer 15

Vt = m.s-1
r = m
Angular velocity = rad.s-1

Question 16

If radius length or angular velocity is increased, ……………… Increases

Answer 16

Tangential velocity increases

Question 17

How to convert degrees to radians

Answer 17

x degrees / 57.3

Question 18

Convert revs into radians

Answer 18

1 Rev = 360 degrees
x revs X 360 = x degrees
x degrees / 57.3 = radians

Question 19

Another name for linear velocity

Answer 19

Tangential velocity

Question 20

Literature example of linear and angular velocity:
Author and year
Nature of study (what’s involved)
Results (X3)

Answer 20

Dörge et al 2001

Dominant vs non dominant footed kicking

Foot velocity influenced by knee linear velocity and shank angular velocity

Faster ball velocity in dominant foot
Similar knee velocity
Faster shank angular velocity in dominant foot

Question 21

Ascending order of Linear velocities for novice kicker

Answer 21

Hip, knee, ankle, foot

Question 22

Limitation of analysing tennis serve

Can result in…

Answer 22

In 2D analysis, joint ventures are out of view as the serve moves into the 3D plane therefore needs to be observed in 3D with the use of multiple cameras
Results in inaccurate angle measurements