770 FO43 – Causal associations between pre-race injuries and performance-limiting musculoskeletal issues during world-largest cross-country running competition: establishment of a foundation for next-generation prevention programs

Background Although it has been established that the risk of musculoskeletal injury is substantial during cross-country running competitions, lack of knowledge regarding causes of performance-limiting issues restricts the possibilities for prevention. Objective To estimate body-systems level and location-specific causal associations between pre-race injuries and musculoskeletal race performance issues in cross-country runners. Design Cohort study with data collection from 4 weeks pre-race to 4 weeks post-race. Setting Lidingöloppet, world largest cross-country competition with 30.000 runners participating. Participants Runners stratified by age, gender and ranking randomly invited from Lidingöloppet 30k race participation list in years 2016–18. Assessment of Risk Factors Directed acyclic graphs were used for a model of causal associations. The model guided estimations of systems-level and anatomic location-specific associations between pre-race injuries and performance-limiting musculoskeletal issues during the cross-country race. Main Outcome Measurements Self-reported performance-limiting musculoskeletal issues. Results 3606 runners (30.1%) provided complete data; 23.7% of respondents reported a performance-limiting musculoskeletal issue (Figure, Table). A pre-race injury suffered at any location showed a meaningful causal association with experiencing a performance-limiting musculoskeletal issue at any location during the race (OR 2.4, 95% CI 2.0 – 2.9). The estimated location-specific effect of pre-race injuries on race issues originating from the same location was 6–26 times larger than the estimated systems-level effect (lower leg (OR 63, 95% CI 17 – 214), groin (OR 32, 95% CI 8.3 – 102), Achilles tendon (31, 95% CI 16 – 61), and hip/buttock (17, 95% CI 9.1 – 30)). Conclusions Pre-race injuries were meaningful causes of performance-limiting issues during a challenging cross-country race; the location-specific etiological contribution was consistently larger than the estimated effect at body-systems level. To prevent performance-limiting issues during cross-country races, runners should progressively make ready tissues exposed for increased loads during sloped running and strictly follow return-to-sports schemes when managing injury complaints.