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