Interseason variability of a functional movement test, the 9+screening battery, in professional male football players

Background The Nine Plus screening battery test (9+) is a functional movement test intended to identify limitations in fundamental movement patterns predisposing athletes to injury. However, the interseason variability is unknown. Aim To examine the variability of the 9+ test between 2 consecutive seasons in professional male football players. Methods Asymptomatic Qatar Star League players (n= 220) completed the 9+ at the beginning of the 2013 and 2014 seasons. Time-loss injuries in training and matches were obtained from the Aspetar Injury and Illness Surveillance Program. No intervention was initiated between test occasions. Results A significant increase in the mean total score of 1.6 points (95% CI 1.0 to 2.2, p<0.001) was found from season 1 (22.2 +/- 4.1 (SD)) to season 2 (23.8 +/- 3.3). The variability was large, as shown by an intraclass correlation coefficient (ICC) of 0.24 (95% CI 0.11 to 0.36) and a minimal detectable change (MDC) of 8.7 points. Of the 220 players, 136 (61.8%) suffered a timeloss injury between the 2 tests. There was an improvement in mean total scores in the injured (+ 2.0 +/- 0.4 (SE), p< 0.001) group but not in the uninjured group (+ 0.9 +/- 0.5, p=0.089). The variability from season 1 to season 2 was large both in the injured (ICC 0.25, 0.09 to 0.40, MDC 8.3) and uninjured (ICC 0.24, 0.02 to 0.43, MDC 9.1) groups. Conclusions The 9+ demonstrated substantial intraindividual variability in the total score between 2 consecutive seasons, irrespective of injury. A change above 8 points is necessary to represent a real change in the 9+ test between seasons.