Background The Nine Plus screening battery test (9+) is a series of 11 tests, used to assess limitations in fundamental movement patterns assumed to predispose athletes for injury.
Objective To examine the association of the 9+ with lower extremity injuries, and to identify the optimal cut-off point for risk screening.
Design Prospective cohort study.
Setting Professional football league.
Participants Male professional football players in Qatar.
Interventions The 9+ test was performed prior to the 2013 and 2014 seasons. Time-loss injuries and exposure in training and matches were registered prospectively by club medical staff during 2 consecutive seasons. Univariate and multivariate regression analyses were used to calculate odds ratios (ORs), risk ratios (RR) and 95% confidence intervals (CIs). Receiver operating characteristics (ROC) curves were calculated to determine sensitivity and specificity, and identify the optimal cut-off point for risk assessment.
Main Outcome Measurement Lower extremity injuries.
Results In total, 363 players completed the 9+ and had injury and exposure registration. There were 527 injuries among 204 players (56.2%) during the 2 seasons; injuries to the thigh were most frequent. There was no association between 9+ total score and the risk of lower extremity injuries (OR, 1.02; 95% CI, 0.98–1.06; P=0.44), even when adjusted for exposure (RR, 1.04; 95% CI, 0.98–1.12; P=0.21) or other factors in a multivariate analysis (OR, 1.04; 95% CI, 0.97–1.06; P=0.60). ROC curve analysis revealed an area under the curve of 0.48 for lower extremity injury. No optimal cut-off point to distinguish between injured and non-injured players could be determined.
Conclusions The 9+ total score was not associated with lower extremity injury. The 9+ total score was no better than chance for classifying injured and non-injured players. Therefore, the 9+ test cannot be recommended as a screening tool in this population.