Muscle pain code: a novel tool for screening the risk of time-loss muscle injury in professional male football players.

OBJECTIVE To investigate the association of a novel post-match muscle pain map, named Muscle Pain Code (MPC), with the risk of subsequent time-loss muscle injury in a cohort of professional football (soccer) players. METHODS The MPC classifies pain in four codes: code 0, 'no pain;' code 1, 'generalized muscle pain;' code 2, 'diffused site muscle pain;' and code 3, 'specific site muscle pain.' Over four consecutive seasons, MPC was collected on the second post-match day and players were followed for occurrence of time-loss muscle injury over the next five days. Players exposed to at least 45 minutes in two consecutive matches within seven days were included as cases for analysis. RESULTS Eighty players participated in the study. Of 1,656 cases analyzed, 229 resulted in time-loss muscle injuries. Only 2% of cases with codes 0 and 1 resulted in time-loss muscle injuries. Conversely, 63% and 78% of codes 2 and 3 were followed by time-loss muscle injuries, respectively. Compared with the reference scenario (i.e. code 0 on MPC), the risk of subsequent time-loss muscle injury was significantly higher when players recorded code 2 (odds ratio, 4.29; 95%CI, 3.62 to 4.96) or code 3 (odds ratio, 5.01; 95%CI, 4.05 to 5.98) on MPC, but not when they recorded code 1 (odds ratio=-0.27; 95%CI, 1.05 to 0.56). CONCLUSIONS Players experiencing well-outlined pain area on the second post-match day were more likely to incur a time-loss muscle injury in the subsequent days compared to those experiencing spreading pain or no pain.