Accels and Decels – How do they influence injury risk and performance outcomes?

Many soccer teams monitor high speed running (HSR) as a key indicator for load. Yet in competition such as the English Premier League HSR and sprinting account for only 10% of the total game distance, whereas decelerations and accelerations occur every 9 seconds during a 90 minute match. On average, players perform 656 accelerations (>0.5m/s/s) and 612 decelerations (<-0.5m/s/s) during a game. Some research actually indicates that accelerations and decelerations can place a greater physiological demand on players than constant speed straight line running.

By identifying movements such as acceleration and deceleration, particularly those of a higher intensity during games and training, backroom staff will be able to develop a greater awareness and control of the overall external demands of matchplay. Having a better understanding of how these movements contribute to the overall physiological cost and their contribution to player fatigue could potentially play an important role in optimising performance throughout the playing season.

As such the team at Kitman Labs investigated the data of four soccer teams, an American Football team and an Ice Hockey team to quantify how accelerations and decelerations influenced performance and injury risk.

In all four soccer cases, a decrease in the number of recent decelerations from the individual athlete’s norm, increased game injury risk, suggesting players were underprepared for the demands placed upon them. However, research from other sports (ice hockey) suggests that players who are exposed to too many decelerations in practice, which contributes to overall player load have a decrease in match performance (reduced chance of winning).

Soccer

• -1 SD – Total Decelerations
• 25% Increase Injury Risk
  • Injury risk increases by 25% when Total Decelerations over the last 7 days decreases by 1 standard deviation from an individual athlete’s average.

Hokey

• <80 Total Decelerations
• 64% Increase in games won
  • Number of games won increases when the number of Decelerations over 3 days prior to a game is less than 80 for an individual athlete.

For accelerations, only in one case did an increase in accelerations from the individual athlete’s norm result in increase in injury risk. This was also true of the American Football research and of even more interest is that for the soccer teams, it seems there is a “sweet spot” when it comes to accelerations, where doing too little or too much can influence performance (games won).

Soccer

• +1.25 SD – Total Accelerations
• 1.8x Increase Injury Risk
  • Injury risk increases when Total Accelerations over the last 7 days increases by 1.25 standard deviations from an individual athlete’s average.

American Football

• >150 Total Accelerations
• 2.5x Increase in Injury Risk
  • Injury risk increases when Total Accelerations over the last 7 days ins greater than 150 for an individual athlete.

In order to optimise performance throughout the season, teams should consider how accelerations and decelerations may contribute to the overall physiological cost and contribution to player fatigue within their environment. Follow us on twitter and check out a highlight of our insights for accels and decels.