title: The effect of starting velocity on maximal acceleration capacity in elite level youth football players
Creators: name: Breddy, Scott
Publisher: name: University of Glasgow
Year: 2018
Subjects: subject: GPS, accelerations, football, sport science.

description: Due to advancements in performance monitoring technology (GPS and Accelerometry), practitioners are able to measure accelerations and decelerations with a view to quantifying their impact on training load in team sports. In practice, the magnitude of these accelerations has typically been categorized into low, moderate and high threshold bands (similar to often-quoted speed and distance parameters).
Research suggests a value of greater than 2.78 m.s-2 (Varley and Aughey, 2013) as a high acceleration threshold, based on data measuring maximal acceleration capacity from a standing start. 
However, there has only been one study to our knowledge that directly examines the effect of starting speed on the capacity to maximally accelerate (Sonderegger et. al, 2016). Further, the research fails to examine accelerations, measured via GPS or Accelerometry in football specific context. 
Therefore, the aim of this study is to quantify, via GPS and Accelerometry, the impact of different commencement velocities on the maximum voluntary acceleration capacity of individuals during maximum efforts. A secondary aim of the study is to analyse more dynamic situations involving a stretch-shortening cycle by determining the impact of changing entry speed and deceleration on the acceleration capacity of individuals making maximum voluntary efforts.
Fifteen male football players from the Development Squad of a Scottish Premier League club took part in the study during the pre-season phase of the 2015/2016 season.
Subjects wore Catapult OptimEye X4 10-Hz GPS units with in-built tri-axial accelerometer, gyroscope and magnetometer sampling frequencies of 100-Hz
The players were asked to complete three different running tests that would require them to accelerate maximally from either a standing start position, from five increasing run-in speeds or after a period of deceleration. 
The data collected for analysis was; peak acceleration at point of change of pace and peak deceleration at point of deceleration. These were measured by both Doppler GPS method and from the Vector of the tri-axial accelerometer data. 
The results showed that peak accelerations achieved during progressively increasing starting velocities were 2.34±0.35, 1.85±0.31, 1.5±0.26, 1.12±0.18 and 0.92±0.21 m.s-2 (Doppler derived values). Accelerations were reduced to 1.42±0.57, 0.83±0.51, 0.61±0.26, 0.47±0.37 and 0.33±0.32 m.s-2 (Doppler derived values) when the effort was preceded by a rapid deceleration after similar entry speeds.
The reduction in observed acceleration with increased running speed will be important in situations where the context changes player behaviour, such as in; pitch-dimensions, number of players and relative playing area. The consequences of this misinformation may be that players initiate an acceleration effort and pay metabolic cost but get further load applied because that effort was not recorded. This could potentially result in training overload.