Alasdair Dempsey

Introduction:
In recent decades, there has been an increase in the incidence of noncontact anterior cruciate ligament (ACL) injuries during sports, leading to high costs for athletes, sports teams, and the healthcare system. These injuries often occur during single-leg drop jump landing. There is a lack of studies available on a screening tool to assess multiple planes of motion during a single-leg drop jump landing in the field-based setting. One study has investigated the inter-session reliability of the Landing Error Scoring System (LESS) during double-leg drop jump landing tasks. However, no study has assessed the inter-session reliability using the Single-leg Landing Error Scoring system (SLESS) during single-leg drop jump landing tasks. This study investigated the inter-session reliability of single-leg drop jump landing tasks (dominant and non-dominant leg) using the SLESS and compared them to the double-leg drop jump landing tasks (cognitive loading drill with double-leg and double-leg) using the LESS. The study further examined the intra-rater and inter-rater reliability of single-leg drop jump landing tasks using the SLESS and compared it to the LESS across three sports and exercise science professionals.

Methods:
The study involved twenty participants aged 18- 40 years who were team sports players. Participants performed four variations of drop jump landing tasks during three testing sessions based on standard methodology. Tasks were dominant leg, non-dominant leg, double-leg, and cognitive loading drill with double-leg. Sessions 1 and 2 were conducted on the same day, and Session 3 was conducted a week later. Participants followed an individualised testing order in Session 1, and a 1-minute rest period was provided between landing tasks. Video cameras captured frontal and sagittal views of all landing tasks. Three sports and exercise science professionals (two exercise scientists and one physiotherapist) scored the participant's recorded trials using the standard SLESS and the LESS protocols. One scorer assessed both intra-session and inter-session reliability, while three scorers assessed inter-rater reliability. The reliability of single-leg and double-leg drop jump landing tasks was determined using intraclass correlation coefficient (ICC) with 95% confidence interval (CI) values. The ICC used a two-way mixed effects absolute agreement mean of measurements, two-way mixed effects absolute agreement mean of k raters, and two-way random effects absolute agreement, multiple raters/measurements ICC (2,k) (k= number of raters/measurements).

Results:
The study observed good to excellent inter-session reliability for single-leg and double-leg drop jump landing tasks using the SLESS and the LESS (SD: ICC = 0.916 [95% CI; 0.820-0.965], SN: ICC = 0.907 [95% CI; 0.792-0.962], DL: ICC= 0.754 [95% CI; 0.455-0.898], DC: ICC= 0.886 [95% CI; 0.752-0.952]). Good to excellent intra-rater reliability was also observed for single-leg and double-leg drop jump landing tasks using the SLESS and the LESS (SD: ICC= 0.949 [95% CI; 0.868-0.980], SN: ICC= 0.888 [95% CI; 0.566-0.963], DL: ICC= 0.853 [95% CI; 0.629-0.942], DC: ICC= 0.870 [95% CI; 0.678-0.948]). In addition, moderate to good inter-rater reliability was observed for single-leg, and double-leg drop jump landing tasks using the SLESS and the LESS (SD: ICC= 0.800 [95% CI; 0.358-0.929], SN: ICC= 0.882 [95% CI; 0.712-0.953], DL: ICC= 0.861 [95% CI; 0.706-0.942], DC: ICC= 0.730 [95% CI; 0.278-0.897]).

Discussion:
This study provides evidence of the reliability of the SLESS and the LESS in assessing drop jump landing tasks performed by team sports players. These results suggest that both the SLESS and the LESS can be used confidently to assess drop jump landing tasks in sports and exercise science research.

Impact/Application to the field:
These tools may identify athletes at higher risk of noncontact ACL injury and direct training programs to prevent future injuries in athletes in the field. While reliable, the SLESS still need to have both validity and the ability to predict ACL injuries assessed.