W3 & 4 - Kinematic Analysis of Performance

Question 1

What would allow you to use kinematic analysis to improve performance of a skill?

Answer 1

Identifying key points of a skill + compare variables with that of an elite performer

Question 2

Will a small variation in the timing of ball contact in golf have little or large influence on the length of the put?

Answer 2

Little

Question 3

If a coach wants to quantitatively compare performance of a maximal football kick for two players.

What approach may be useful?

Answer 3

Compare joint angles or angular velocities at key parts of the skill.

Question 4

If the kinematic chain breaks down …

Answer 4

Then there’s a ⬇️ in end point force + end point velocity

Question 5

What is the kinematic chain?

Answer 5

Co–ordinated activation of segments

Question 6

What is the purpose of the kinematic chain?

Answer 6

To place the end segment in the optimal position for the skill.

Question 7

In which way does the ideal kinematic chain work?

Answer 7

Proximal to distal

Question 8

What does the kinematic chain produce?

Answer 8

Max force when timing the segments in a proximal to distal order.

Question 9

In boxing the ideal kinematic chain starts and ends where?

Answer 9

Starts at the legs, then trunk, shoulder, elbow + ends at the wrist.

Question 10

A hammer thrower achieves an angular velocity of 4 rad/s just prior to release. Calculate the linear velocity of the hammer assuming the hammer cable is 1m in length and the hammer throwers arms are 0.75m in length to the axis of rotation.

Answer 10

Vt = r x w

r = 1 + 0.75 x 4

= 7m/s

Question 11

A gymnast swings round the high bar and achieves an angular velocity of 300 deg/s just prior to release. If the distance from the gymnast’s mass centre to the bar is 0.8m, what is the linear velocity at release?

Answer 11

300 / 57.3 = 5.235 radians

0.8 x 5.235 = 4.2m/s

Question 12

A golfer swings the driver with a angular velocity of 14 rad/s. If the club is 0.7m in length (from grip to ball contact) and the golfers arms are straight at ball contact, what is the linear velocity of the ball? (golfer arms are 0.65m)

Answer 12

(0.7 + 0.65) x 14 = 18.9 m/s

Question 13

What is the relationship between angular + linear motion?

Answer 13

Angular motion is used to prod linear motion

Question 14

What must happen to ⬆️ linear velocity in relation to radius of rotation?

Answer 14

To ⬆️ linear velocity = ⬆️ radius of rotation

Question 15

What must happen to ⬆️ linear velocity in relation to angular velocity ?

Answer 15

To ⬆️ linear velocity = ⬆️ angular velocity

Question 16

How can we increase angular velocity?

Answer 16

By training the kinematic chain

Question 17

What comes under training the kinematic chain?

Answer 17

Incl training drills to target ind parts of the chain so when put back together we have elevated levels of perf.

Question 18

What is training the kinematic chain about?

Answer 18

Improving the proximal distal timing of the peak angular velocities of each segment.

Question 19

What happens to projectiles when the radius of rotation increases?

Why?

Answer 19

Projectiles travel further

Due to an ⬆️ in radius of rotation resulting in an ⬆️ in the tangential (linear) velocity of the projectile.

Question 20

Phases for the KINEMATIC analysis of kicking

Answer 20

Take back

Acceleration phase

Ball contact

Follow through

Question 21

Literature example for a performance analysis on kicking

Answer 21

Right vs left footed Kicking (Dorge et al., 2002)

Overall - foot velocity influenced by: knee linear velocity + shank angular velocity.

Main determinant between dominant + non-dominant kicking leg is that the dominant has a higher shank angular velocity.

Question 22

In tracker, what could be the difficulties in digitising the tennis serve?

Answer 22

Difficulty viewing joint centres out of view.

3D movement but analysed in 2D

Question 23

Give an example of a motion analysis system that can be used for a tennis forehand

Answer 23

Passive marker system i.e Vicon

Question 24

Examples of active marker systems under motion analysis system

Answer 24

CODA motion

• Have drive boxes + markers (both taped to body).

Question 25

What are the 3 phases into which many ‘ballistic’ sports movements can be subdivided into?

Answer 25

Preparation (i.e backswing)

Action (hitting)

Recovery (Follow-through)