Contents of Article
What is Acceleration (Gen1)?
Acceleration (Gen1) parameters are based on the rate of change of Velocity.
Acceleration (Gen1) versus Acceleration (Gen2) effort detection
Acceleration (Gen1) is designed to capture discreet changes in speed that would potentially be missed when using an effort detection assessment (Gen2) where a duration threshold (Dwell Time) must be met in order for an acceleration to be detected (typically 0.4 – 0.6s). In addition to this, acceleration effort detection uses a set of ‘rules’ to quantify an acceleration effort and categorizes them into effort bands whereas Acceleration Gen1 based parameters are calculated using all accumulated acceleration values.
How is Acceleration applicable?
How is Acceleration Calculated?
Acceleration is calculated from smoothed velocity data. From the smoothed velocity data, resultant acceleration values are derived at 0.1s intervals.
Raw vs Smooth Data
It is important to understand that Catapult uses a smoothed velocity stream to calculate acceleration and therefore Acceleration Load and derivatives. The image below provides an example of why we use smoothed and not ‘raw’ velocity data. As is well documented, raw forms of positional data can be susceptible to noise, and the smoothing of this signal ensures we can eliminate as much of this noise as possible, giving a more realistic representation of changes in speed.
The raw velocity as displayed above is showing many sudden peaks and troughs representing a potentially unrealistic representation of changes in speed. When used in conjunction with Acceleration parameter calculations, this would provide much higher numbers. The smoothed velocity data (as shown above) is used to calculate Acceleration and is a representation of a less noisy data stream.
How is Acceleration Load Calculated
The acceleration load value is the accumulation of acceleration values over the specified period. Acceleration Load treats all acceleration (+ve) and deceleration (-ve) activity as a positive value and as such, the acceleration and deceleration values accumulate and contribute equally to the overall and absolute value of the acceleration load.
Acceleration Load was developed following a research paper by Duthie and Delaney (2015) titled "Acceleration-Based Running Intensities of Professional Rugby League Match-Play." The research used average acceleration values to better reflect the work of athletes in small spaces in comparison to open spaced performances. Please see the References section of this article for more information.
How to set Bands for Acceleration
Acceleration Bands can be set by following the steps in our Bands article. Please select 'Acceleration' as the parameter from the drop down menu. Any negative Acceleration Band thresholds are Deceleration.
Acceleration Parameter Definitions
For a list of Acceleration (Gen1) cloud parameters, please see our OpenField Cloud Parameter Definitions article. The definitions can be found under the Acceleration section.
- Delaney, J.A., Duthie, G.M., Thornton, H.R., Scott, T.J., Gay, D., Dascombe, B.J. 2015. Acceleration-Based Running Intensities of Professional Rugby League Match-Play. International Journal of Sports Physiology and Performance.