Table 1.
Definitions of common tracking metrics
| Level | Metric | Definition | Common Measures |
|---|---|---|---|
| 1 | Distance | Cumulative distance | Total, Relative, Distances in speed/acceleration/deceleration zones |
| 2 | Acceleration (2D) | Instantaneous peak rate of positive change in velocity | Maximal/Peak, Average, Distance/Efforts/Time in acceleration zones |
| Deceleration (2D) | Instantaneous peak rate of negative change in velocity | Maximal/Peak, Average, Distance/Efforts/Time in deceleration zones | |
| Change of Direction (2D) | Count and intensity of changes of direction derived from positional data | Total, Percentage Difference Left vs Right, Count in intensity zones | |
| 3 | Accelerometry-derived load | A manufacturer-specific, modified vector magnitude of 3D acceleration values (expressed in AU) | Total, Relative to time, Relative to distance, 2D (excludes vertical axis), 1D (absolute or relative contribution of individual axes) |
| Change of Direction (3D) | Count and magnitude (g) of changes of direction derived from inertial sensors | Total, Percentage Left v Right, Count in intensity zones | |
| Impacts | A manufacturer-specific metric that provides a count of 3D acceleration values (g) over a threshold | Count and Magnitude of Impacts | |
| Collisions/ Tackles | A manufacturer-specific metric that classifies collisions specific to the sport | Count and Magnitude of Collisions | |
| Stride Variables | Accelerometry-derived metrics estimating ground contact time | Contact Time, Flying Time, Vertical Stiffness (KN·m) | |
| Stride Imbalances | Accelerometry-derived metrics split by left and right side | Percentage Left v Right | |
| Hybrid | Speed | Instantaneous peak rate of position change | Maximal/Peak, Average |
| Sport-specific Metrics | Specific machine learning algorithms designed to quantifying movement demands per sport | AMF QB throws, Basketball court transition, IH skating strides, Rugby scrum detection, Soccer GK Left v Right Dive Count | |
| Metabolic Power | Estimates the energetic demands of high-intensity Level 1 and 2 actions via GPS or LPS data | Metabolic Energy (Cal·kg), Equivalent Distance (distance covered running at constant speed on flat terrain, for a given energy expenditure), Total Metabolic Power (ml·kg·min), Distance/Efforts/Time in Metabolic Power bands |
Level 1: distances covered in different velocity zones; Level 2: events related to changes in velocity (i.e. acceleration, deceleration, and changes in direction); Level 3: events derived from the inertial sensors; Hybrid = combination of levels (28)
2D, 2-dimensional; 3D, 3-dimensional; AU, arbitrary units; g, g force; kN, kilonewton; m, metre; AMF, American Football; IH, Ice Hockey; GK, Goalkeeper; Cal, calorie; kg, kilogram; ml, milliliter; min, minute