Biomechanics - Intro to Video Data Collection Flashcards
(Knudson 2013) Four task model?
1.) Preparation
2.) Observation
3.) Evaluation and diagnosis
4.) Intervention
(Cyclical)
(example for deterministic model) What is the goal of movement for a tennis serve? What will it require?
To gain an advantage by making it difficult for the opponent to return the ball.
Requires a fast serve within the court in different locations.
(example for deterministic model) How is the goal of movement for a tennis serve achieved?
Velocity of ball at release.
Speed due to speed of racket (and ball) at contact.
Direction due to angle of racket and ball at contact.
Velocity?
Speed and direction.
What are critical features related to in relation to the deterministic model?
The technique that is required for the goal of movement to be achieved.
How many critical features should there be when analysing a movement?
Between 4-8.
(example for critical features) Rationale for grip being a critical feature for a tennis serve?
Determines the path of the racket and forearm/wrist action.
(example for critical features) Rationale for toss being a critical feature for a tennis serve?
Determines timing and proper racket path.
(example for critical features) Rationale for racket preparation being a critical feature for a tennis serve?
Affects timing and speed of the racket.
(example for critical features) Rationale for continuous being a critical feature for a tennis serve?
(Sequential coordination pattern) Determines effective ball trajectory.
(example for critical features) Rationale for follow through being a critical feature for a tennis serve?
Maximises racket speed and protects the body.
(example for critical features) Rationale for stance being a critical feature for a tennis serve?
Affects balance, accuracy and development of racket speed.
How does grip as a critical feature relate to biomechanical principles?
(B5) Is the athlete applying force in the correct direction?
How does toss as a critical feature relate to biomechanical principles?
(P1) Flight and projectile motion.
How does follow through as a critical feature relate to biomechanical principles?
(F2) Range of motion.
(B4) Is the athlete applying the right amount of muscular force over the appropriate time and distance?
How does racket preparation as a critical feature relate to biomechanical principles?
(C4) Stretch-shorten cycle.
(F2) Range of motion.
How does continuous as a critical feature relate to biomechanical principles?
(C2) Proximal-to-distal sequence of movements.
(B3) Is the athlete applying force with the muscles in the correct sequence?
How does stance as a critical feature relate to biomechanical principles?
(B1) Does the athlete have optimal stability when applying or receiving force?
(F6) Stability.
(B2) Is the athlete using all the muscles that can contribute to the skill?
How to write a kinematic description of the movement using the correct anatomical language?
Break the movement down into phases.
Individually consider the joints involved.
Describe the movement identifying the axis and plane (e.g. medial rotation about the longitudinal axis of the humerus).
Not always possible/useful to identify the plane for rapid movements (e.g. tennis serve).
What do you need to establish for the critical features and technique points in a movement?
A range of correctness.
Impulse formula?
Force x Time
(Knudson, 2013) Four task model - Extended observation?
Video footage of what is being observed and using slow mo/replay features/video analysis software e.g. dartfish/quintic.
Can also use multiple observers.
Good way to avoid conflict of opinions between the observer and performer?
Watch video footage of performer together.
Advantages of video analysis software? (dartfish/quintic)
Ability to display more than one screen at a time.
Use of drawing tools to emphasise coaching points.
Quick calculation of key variables/measurements (i.e. semi-quantitative analysis).
Create presentations and reports.
Qualitative analysis using video example?
View video at slow speed/frame by frame.
How is qualitative analysis extended to a semi-quantitative level?
By taking simple timings, (e.g. stride frequency) and displacement measures (e.g. joint angles at key times).
Quantitative analysis using video examples?
Involves coordinate digitisation/Quintic Digitising).
What does coordinate digitisation/Quintic Digitising involve?
Identification of body landmarks to estimate joint axis of rotation.
Coordinates of each point are stored in computer memory via computer mouse.
What can coordinate digitisation/Quintic Digitising obtain?
Many more variabes e.g. peak angle velocity.
Video recording requirements?
Accurate location of body landmark positions e.g. hip - 2cm superior to and 1cm anterior to the greater trochanter of the femur.
Correct size and clarity of marker.
3-4-5 triangle set up for camera?
3m = plane of movement. 4m = adjacent. 5m = hypotenuse.
Data collection considerations for obtaining quantitative measurements?
Mount camera on tripod. 3-4-5 triangle. Zoom in to maximise image of performer. Focus/no movement of camera. Include calibration object. Plain background.
What features should the subject have?
Minimal clothing.
Habituation to markers e.g. zinc oxide tape.
Habituation to movement ie.e. a consistent performance.
