Johann Windt1, Jan Ekstrand2, Karim M Khan3, Alan McCall4, Bruno D Zumbo5. 1. Department of Experimental Medicine, University of British Columbia, Canada; Centre for Hip Health and Mobility, University of British Columbia, Canada. Electronic address: johannwindt@gmail.com. 2. Division of Community Medicine, Department of Medical and Health Sciences, Linköping University, Sweden; UEFA Injury Study Lead Expert, Sweden; Football Research Group, Linköping University, Sweden. 3. Department of Experimental Medicine, University of British Columbia, Canada; Centre for Hip Health and Mobility, University of British Columbia, Canada. 4. Sport, Exercise and Health Sciences, School of Applied Sciences, Edinburgh Napier University, UK; Research & Development Department, Arsenal Football Club, UK. 5. Department of Educational and Counselling Psychology, University of British Columbia, Canada.
Abstract
OBJECTIVES: Player unavailability negatively affects team performance in elite football. However, whether player unavailability and its concomitant performance decrement is mediated by any changes in teams' match physical outputs is unknown. We examined whether the number of players injured (i.e. unavailable for match selection) was associated with any changes in teams' physical outputs. DESIGN: Prospective cohort study. METHODS: Between-team variation was calculated by correlating average team availability with average physical outputs. Within-team variation was quantified using linear mixed modelling, using physical outputs - total distance, sprint count (efforts over 20km/h), and percent of distance covered at high speeds (>14km/h) - as outcome variables, and player unavailability as the independent variable of interest. To control for other factors that may influence match physical outputs, stage (group stage/knockout), venue (home/away), score differential, ball possession (%), team ranking (UEFA Club Coefficient), and average team age were all included as covariates. RESULTS: Teams' average player unavailability was positively associated with the average number of sprints they performed in matches across two seasons. Multilevel models similarly demonstrated that having 4 unavailable players was associated with 20.8 more sprints during matches in 2015/2016, and with an estimated 0.60-0.77% increase in the proportion of total distance run above 14km/h in both seasons. Player unavailability had a possibly positive and likely positive association with total match distances in the two respective seasons. CONCLUSIONS: Having more players injured and unavailable for match selection was associated with an increase in teams' match physical outputs.
OBJECTIVES: Player unavailability negatively affects team performance in elite football. However, whether player unavailability and its concomitant performance decrement is mediated by any changes in teams' match physical outputs is unknown. We examined whether the number of players injured (i.e. unavailable for match selection) was associated with any changes in teams' physical outputs. DESIGN: Prospective cohort study. METHODS: Between-team variation was calculated by correlating average team availability with average physical outputs. Within-team variation was quantified using linear mixed modelling, using physical outputs - total distance, sprint count (efforts over 20km/h), and percent of distance covered at high speeds (>14km/h) - as outcome variables, and player unavailability as the independent variable of interest. To control for other factors that may influence match physical outputs, stage (group stage/knockout), venue (home/away), score differential, ball possession (%), team ranking (UEFA Club Coefficient), and average team age were all included as covariates. RESULTS: Teams' average player unavailability was positively associated with the average number of sprints they performed in matches across two seasons. Multilevel models similarly demonstrated that having 4 unavailable players was associated with 20.8 more sprints during matches in 2015/2016, and with an estimated 0.60-0.77% increase in the proportion of total distance run above 14km/h in both seasons. Player unavailability had a possibly positive and likely positive association with total match distances in the two respective seasons. CONCLUSIONS: Having more players injured and unavailable for match selection was associated with an increase in teams' match physical outputs.
Authors: Alberto Grassi; Luca Macchiarola; Matteo Filippini; Gian Andrea Lucidi; Francesco Della Villa; Stefano Zaffagnini Journal: Sports Health Date: 2019-12-04 Impact factor: 3.843