> ## Documentation Index > Fetch the complete documentation index at: https://docs.uplift.ai/llms.txt > Use this file to discover all available pages before exploring further. # Track and Field: Discus > Biomechanical analysis of discus throw movements, including events, phases, and discrete metrics. ## Overview The discus throw is a track and field throwing event in which the athlete rotates one and a half turns within a circle to accelerate a discus before releasing it at speed and at an optimal angle. The thrower begins with a preparatory wind-up, pivots off the non-dominant foot into an airborne turn, plants the dominant foot in the center of the circle, and drives through the legs and trunk before releasing the discus off the fingers with the arm extended. Distance depends on release speed, release angle, and the sequencing of the legs, hips, and trunk ahead of the arm. Biomechanical analysis of the discus throw can address foot-off and foot-down timing through the turn, hip-shoulder separation built during the turn, arm and shoulder positioning at release, and release speed, height, and angle. ## Dimensions Required inputs for processing are not yet defined. When supported, typical dimensions may include: * **handedness:** the handedness of the athlete \['left', 'right'], which determines throw direction and rotation ## Output Variables ### Generic Outputs Every capture includes session metadata, standard joint angle/velocity time series, and 3D keypoint positions common to all movements. See [Generic Outputs](/biomechanics/activities/generic_outputs) for the full list. ### Events | Metric | Acronym | Description | | --------------------- | ------- | --------------------------------------------------------- | | Peak Backswing | PB | the peak backswing position prior to the throw | | Dominant Foot Off | DFO | the instance when the dominant foot leaves the ground | | NonDominant Foot Off | NDFO | the instance when the nondominant foot leaves the ground | | Dominant Foot Down | DFO | the instance when the dominant foot touches the ground | | NonDominant Foot Down | NDFO | the instance when the nondominant foot touches the ground | | Release | R | release of the discus | ### Phases and Stages of the Discus Throw | Phase | Start | End | | ----------- | ----- | ---- | | Preparation | PB | DFO | | Entry | DFO | NDFO | | Airborne | NDFO | DFD | | Transition | DFD | NDFD | | Delivery | NDFD | R | ### Discrete Metrics | Metric | Units | Description | | ---------------------------------- | ------- | --------------------------------------------------------------------------------- | | Handedness | N/A | Calculated handedness of the athlete ('right' or 'left') | | Preparation Phase | seconds | Time between peak backswing and dominant foot off | | Entry Phase | seconds | Time between dominant foot off and non-dominant foot off | | Airborne Phase | seconds | Time between non-dominant foot off and dominant foot down | | Transition Phase | seconds | Time between dominant foot down and non-dominant foot down | | Delivery Phase | seconds | Time between non-dominant foot down and release | | Speed at DFO | m/s | Speed of the discus at dominant foot off | | Speed at NDFO | m/s | Speed of the discus at non-dominant foot off | | Speed at DFD | m/s | Speed of the discus at dominant foot down | | Speed at NDFD | m/s | Speed of the discus at non-dominant foot down | | Speed at Release | m/s | Speed of the discus at release | | Horizontal Release Speed | m/s | Horizontal component of discus speed at release | | Vertical Release Speed | m/s | Vertical component of discus speed at release | | Hip-Shoulder Separation at DFO | degrees | Transverse angle between hips and shoulders at dominant foot off | | Hip-Shoulder Separation at NDFO | degrees | Transverse angle between hips and shoulders at non-dominant foot off | | Hip-Shoulder Separation at DFD | degrees | Transverse angle between hips and shoulders at dominant foot down | | Hip-Shoulder Separation at NDFD | degrees | Transverse angle between hips and shoulders at non-dominant foot down | | Hip-Shoulder Separation at Release | degrees | Transverse angle between hips and shoulders at release | | Arm Elevation Angle at DFO | degrees | Angle of throwing arm relative to horizontal at dominant foot off | | Arm Elevation Angle at NDFO | degrees | Angle of throwing arm relative to horizontal at non-dominant foot off | | Arm Elevation Angle at DFD | degrees | Angle of throwing arm relative to horizontal at dominant foot down | | Arm Elevation Angle at NDFD | degrees | Angle of throwing arm relative to horizontal at non-dominant foot down | | Arm Elevation Angle at Release | degrees | Angle of throwing arm relative to horizontal at release | | Shoulder-Arm Separation at DFO | degrees | Angle between shoulder line and arm at dominant foot off | | Shoulder-Arm Separation at NDFO | degrees | Angle between shoulder line and arm at non-dominant foot off | | Shoulder-Arm Separation at DFD | degrees | Angle between shoulder line and arm at dominant foot down | | Shoulder-Arm Separation at NDFD | degrees | Angle between shoulder line and arm at non-dominant foot down | | Shoulder-Arm Separation at Release | degrees | Angle between shoulder line and arm at release | | Base of Support Width | meters | Distance between ankles at non-dominant foot down | | Relative Release Height | meters | Vertical distance between discus and shoulder at release | | Height at Release | meters | Absolute height of discus at release | | Release Angle | degrees | Angle of discus trajectory at release | | Distance | meters | Estimated distance thrown | | Trunk Flexion at Release | degrees | Trunk sagittal flexion angle at release (forward = positive, backward = negative) | | Release Style | N/A | Classification of release style ('Reverse' or 'Fixed Foot') | ## Notes * Kinematic data typically captured at 240Hz