Reliability of an instrument to determine lower limb comfort in professional football

AIMS AND OBJECTIVES This study extends previous work in the field of injury awareness using a novel lower limb comfort index (LLCI), which was developed to assess comfort in professional football. Participants rated comfort for designated anatomical segments of the lower limb utilizing a seven point Likert scale. The aims of the study were (i) to assess the reliability of the LLCI in a competitive football environment (Australian Rules and Rugby League), and (ii) to assess whether LLCI measurements were responsive to changes in lower limb comfort over time. METHODS AND RESULTS THE RELIABILITY OF THE LLCI WAS OBSERVED IN TWO PROFESSIONAL FOOTBALL ENVIRONMENTS: Training Week (mean difference 0.1 point, intra-class correlation coefficient, ICC 0.99) for n = 41 participants; and Match Day (mean difference 0.2 points, ICC 0.97) for n = 22 players. Measurements of lower limb comfort were responsive to changes in comfort over time. Within-player differences were not significant for periods 0-8 hrs (P > 0.05) but, generally, significant for time periods 0-24 hrs (P < 0.05), and significant between 24-96 hrs (P < 0.01). The results indicate that the LLCI was reliable when tested for repeated measures and indicated how the index measures lower limb comfort changes over time. CONCLUSION This study shows that the use of a lower limb comfort index, when used in a competitive football environment, is both reliable and responsive to change during both a training week and under match day conditions.