W3 & 4 - Kinematic Analysis of Performance Flashcards
What would allow you to use kinematic analysis to improve performance of a skill?
Identifying key points of a skill + compare variables with that of an elite performer
Will a small variation in the timing of ball contact in golf have little or large influence on the length of the put?
Little
If a coach wants to quantitatively compare performance of a maximal football kick for two players.
What approach may be useful?
Compare joint angles or angular velocities at key parts of the skill.
If the kinematic chain breaks down …
Then there’s a ⬇️ in end point force + end point velocity
What is the kinematic chain?
Co–ordinated activation of segments
What is the purpose of the kinematic chain?
To place the end segment in the optimal position for the skill.
In which way does the ideal kinematic chain work?
Proximal to distal
What does the kinematic chain produce?
Max force when timing the segments in a proximal to distal order.
In boxing the ideal kinematic chain starts and ends where?
Starts at the legs, then trunk, shoulder, elbow + ends at the wrist.
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.
Vt = r x w
r = 1 + 0.75 x 4
= 7m/s
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?
300 / 57.3 = 5.235 radians
0.8 x 5.235 = 4.2m/s
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)
(0.7 + 0.65) x 14 = 18.9 m/s
What is the relationship between angular + linear motion?
Angular motion is used to prod linear motion
What must happen to ⬆️ linear velocity in relation to radius of rotation?
To ⬆️ linear velocity = ⬆️ radius of rotation
What must happen to ⬆️ linear velocity in relation to angular velocity ?
To ⬆️ linear velocity = ⬆️ angular velocity
How can we increase angular velocity?
By training the kinematic chain
What comes under training the kinematic chain?
Incl training drills to target ind parts of the chain so when put back together we have elevated levels of perf.
What is training the kinematic chain about?
Improving the proximal distal timing of the peak angular velocities of each segment.
What happens to projectiles when the radius of rotation increases?
Why?
Projectiles travel further
Due to an ⬆️ in radius of rotation resulting in an ⬆️ in the tangential (linear) velocity of the projectile.
Phases for the KINEMATIC analysis of kicking
Take back
Acceleration phase
Ball contact
Follow through
Literature example for a performance analysis on kicking
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.
In tracker, what could be the difficulties in digitising the tennis serve?
Difficulty viewing joint centres out of view.
3D movement but analysed in 2D
Give an example of a motion analysis system that can be used for a tennis forehand
Passive marker system i.e Vicon
Examples of active marker systems under motion analysis system
CODA motion
- Have drive boxes + markers (both taped to body).
