Week 6 Flashcards
Movement Analysis Framework includes…
- Preparation
- Observation
- Evaluation of Performance
- Intervention
The two key elements of successful tennis stroke
- Accuracy increase (intermediate to advanced)
- Shot speed increase (high performance to professional)
Ball Speed is dictated by…
- 25% incoming ball speed
- 75% racket head speed
Determinants of Hitting Mechanics
- Elastic Energy
- Distance of Racquet Swing
- Kinetic Chain
- Linear and Angular Movement
- Equipment Selection
- Physical Development
Elastic Energy
Muscle pre-tension consisting of
1. Concentric = power
2. SSC = more power
Maintain
- Minimal pause time
- stretch magnitutde elastic yet comfortable
- speed of stretch fast
- stable base
Distance of Racquet Swing
Speed = distance / time
How to increase speed
- increased racket swing distance
- decrease time to move same distance
Kinetic Chain
more segments = more speed
more unit synchronization = more accuracy
- work from groud up
- strength and coordination to execute stroke under static and dynamic balance
Linear and Angular Movement
Trunk rotation correlated with raclet speed (open and square)
- Angular velocity
- Linear velocity
- Linear
- Angular
Equipment Selection
- racquet swing (lighter = swing faster and higher speed but less momentum to ball)
- swingweight (mass near racket tip = higher SW but is slower yet more powerful)
- head size (weight where wider faces = more resistance to long-axis twisting)
- racquet stiffness (less energy lost bending racquet)
- stringing tension (lower tension = energy storage generating high ball speed)
Physical Development
- base (good legs and base to inititate kinetic chain)
- funnel (core and cuff - energy transfer from lower body to core to upper body)
- engine (driver muscles and individual muscle contributions)
Movement Characteristics
- joint angular speeds
- movement planes
- kinetic chain optimization
qualitative analysis
- systematic observation and introspective judgement
- simple and minimal equipment
- best suited for coaching
- depends on coaching quality
quantitative analysis
- describe full/partial movement in numerical terms
- specialised equipment and performed in high performance settings
High Speed 2D Video Cameras
- easily deployable
- good camera and high frame rates
- only in one plane
- quick and effective feedback
studies serves of word class players in-competition
Radar Gun
- easily deployable and measurement for speeds
- tracks fastest moving object with quick quantitative feedback
Wearable Sensors
- inertial measurement units (IMUs)
- estimate kinematics throughout performance e.g. Xsens and Babolat Pop
Attachable Sensors (racquet)
- portable and easily deployable for large capture area
- measures number of shots, ball impact location, swing type/speed and ball speed
- real time feedback
not evaulated as gold standard
Force Platforms
- gold standard for GRF
- force magnitude and direction of force by leg drive
- lower limb contributions to kinematic chain
Electromyography
- measure muscle contractions and contributions to technique execution
- criterion standard measure for muscle activity
- assess limb contributions to kinematic chain
- not practical in competition
3D Marker-Based Motion Analysis
- criterion standard for 3D motion analysis
- record over 1000 FPS
- need controlled environment
- expensive and time consuming
3D Marker-Less Motion Analysis
- advances in computer vision tech
- multiple 2D video cameras
- used in-competition
- still needs validation
- 50/60 FPS
Features of Video Recording
- field of view
- shutter speed/exposure time
- frame rate
- depth of field
- lens distortion
How did players improve based on certain feedback?
- receiving augmented feedback such as radar gun speed
