TY - JOUR T1 - Is it necessary to adjust current creatine kinase reference ranges to reflect levels found in professional footballers? JF - BMJ Open Sport & Exercise Medicine JO - BMJ OPEN SP EX MED DO - 10.1136/bmjsem-2017-000282 VL - 4 IS - 1 SP - e000282 AU - Jamie Mahmutyazicioglu AU - Julian Nash AU - Andrew Cleves AU - Len Nokes Y1 - 2018/01/01 UR - http://bmjopensem.bmj.com/content/4/1/e000282.abstract N2 - Objective We aimed to explore the validity of applying current reference ranges of the enzyme creatine kinase (CK) when analysing the medical status of professional footballers and to offer a more functional CK reference range for professional footballers.Methods A sample of 27 professional male footballers competing in The Football League Championship was analysed. The single sample Wilcoxon signed-rank test was used to compare the CK distribution of the study group with that of a control group of military personnel reported in the literature.Results The median values for study group and the published control group were 284 U/L and 124 U/L, respectively (P<0.001) suggesting that the average CK activity of professional footballers is higher than that of the normal healthy military population.Conclusion Ethnicity, sex, age and physical exercise are factors that likely influence CK levels among various populations. From our analysis, we recommend a new 95% reference interval of 64.9 U/L to 1971.7 U/L for professional footballers. ER -