What is Acceleration Generation 2 (Gen2)?
Acceleration Generation 2 (Gen2) is designed specifically to detect acceleration efforts and has been developed to improve accuracy in reporting of acceleration events (efforts) in training and competition.
Acceleration (Gen2) Effort detection is the standard acceleration effort detection for OpenField customers since May 2018. For earlier OpenField customers, it is an opt-in module and must be added to your account. Please contact support if you want to add the module to your account.
How is Acceleration (Gen2) applicable?
The capacity to quickly accelerate and decelerate is an essential component of performance in most sports. Acceleration (Gen 2) enables users to quantify the number of acceleration and deceleration efforts performed by athletes within defined bands. It provides the opportunity for more detailed analysis such as parameters measuring duration of efforts and distance covered in efforts.
How are Acceleration Generation 2 (Gen2) Efforts Calculated?
An effort is registered when a specified acceleration band is reached before returning to a lower acceleration band. For more information on Bands, please see our Bands article. Acceleration (Gen2) is only available in OpenField Console version 1.18 or later and is recommended to supersede Acceleration Generation 1 (Gen1) effort detection.
Criteria for Acceleration (Gen2) Efforts Detection
- Only data points above a velocity of 5km.h-1 are used to ensure low speed movements are excluded from the analysis to improve accuracy. This is termed the Low Speed Threshold.
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Acceleration Efforts are calculated using multiple data points (9 @ 0.1s intervals = 0.9 seconds). An Acceleration effort with a duration less than 0.9 second would not be reported as an acceleration effort. This ensures the reported efforts are movements over a minimum of 3 to 4 meters (= ~3 steps). Unlike Velocity (Gen2) the Dwell time for an acceleration cannot be altered for Acceleration (Gen2).
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The algorithm uses 9 data points on a Line of Best Fit methodology. The gradient of the line is used to calculate acceleration.
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The Correlation coefficient of the line is also used to determine if the acceleration is a reasonably smooth acceleration. If the co-efficient of the Line of Best Fit is less than 0.8 an acceleration will not be reported – this to exclude noisy/poor quality data.
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The time between Efforts cannot be less than 1 second. If a new effort meets all criteria except that it occurred less than 1 second after a previous effort, the effort will continue from the previous effort and will report as a single effort.
How to set Bands for Acceleration (Gen2) Parameters
For instructions on how to set Bands for Acceleration (Gen2), please see our Bands article. The user will have to set bands for the "Gen2Acceleration" Parameter.
Acceleration (Gen2) bands include: 3 Deceleration bands and 3 Acceleration Bands and the bands are organised as follows:
You will notice that the upper limit and lower limit of bands 4 and 5 respectively are blocked out. Acceleration data tends to be quite noisy around zero, so to minimise noise we do not allow users to report on bands that drop to zero. Band 1 and Band 3 are the highest and lowest intensity of deceleration bands respectively and Band 6 and Band 8 are the lowest and highest intensity of acceleration bands respectively.
How to Display Acceleration Efforts (Gen2) in the OpenField Console
One of the features of Acceleration (Gen2) is the Events / Efforts table widget in the console. This widget enables you to display information about each individual acceleration effort within and above a specified band. The tables of efforts and events feature is only available POST session and will not display any data live for any of the metrics. For instructions on how to create an Events / Efforts table, please see our Table of Efforts / Events article.
We can see that for all of the accelerations the athlete had a peak acceleration of 3.49 m.s2 with an average recovery time of 16.7 seconds.
The Acceleration (Gen2) effort table average line returns an average value for that field, except for ‘Max Vel’ which returns a maximum from the table below. NOTE: The average values returned are based on the values visible in the table for the individual athlete, the selected band and period. Please check and adjust your selections as required.
Acceleration (Gen2) Parameter Definitions
Acceleration/Deceleration Band 1-3 Average Efforts (Session) (Gen 2)
The total number of Acceleration/Deceleration effort count in in the specified Band(s) divided by the session count
Acceleration/Deceleration Band 1-3 Distance (Gen 2) (m)
The Distance covered in an Acceleration/Deceleration Effort in the specified Band(s)
Acceleration/Deceleration Band 1-3 Duration (Gen 2)
The total time involved in an Acceleration/Deceleration Effort in the specified Band(s)
Acceleration/Deceleration Band 1-3 Efforts (Gen 2)
The number of Acceleration/Deceleration Efforts counted in the specified Band(s)
Acceleration/Deceleration Band 1-3 Total Efforts (Gen 2)
The number of Acceleration/Deceleration Efforts counted in the specified Band(s)
Max Acceleration/Deceleration
Practical Example of Acceleration (Gen2) Effort Detection
In the following example, 1 set of 10 x 30m sprints was performed with rest in between each sprint. A total of 10 accelerations and 10 deceleration events were registered as outlined by both the Acceleration and Deceleration Bands shown below.
As outlined in the illustration above, 4 accelerations were recorded in Acceleration Band 2 (2 to 3m/s 2) and 6 accelerations were recorded in Acceleration Band 3 (3 to 10m/s 2), whereas all deceleration events occurred in Deceleration Band 3 (-3 to -10m/s 2). The graph shows that sprints 1-5 and 7 were Acceleration Band 3 efforts, while sprints 6, 8, 9 and 10 were Acceleration Band 2 efforts.