Characterising body postures by injury scenarios: a video review analysis of hamstring strain injuries in the National Football League.

Objectives: The purpose of this study was to (1) establish the agreement of multiple expert reviewers' identification of hamstring strain injury (HSI) scenarios and related body postures among National Football League (NFL) players and (2) determine the prevalence of each HSI scenario and associated body posture in the NFL between 2018 and 2022. Methods: Videos from 305 HSIs in the NFL were reviewed in a blinded fashion by two expert reviewers, who classified the injuries into seven predefined injury scenarios developed by a separate committee of experts. Lower extremity body postures were also identified. Cohen's Kappa coefficients were calculated to determine inter-rater agreement and used to select the subset of injuries to be described via injury scenario and body posture with the intent of minimising bias or ambiguity in reporting. Results: 137/305 (45%) injury videos met the criteria for inclusion in the final dataset based on assessment of classification agreement. Agreement in injury scenario and body posture ranged from poor to moderate. Sprinting injuries were the most common scenario (59/137, 43%). Unique scenarios specific to American football demonstrated the importance of excessive trunk flexion during contact, or during acceleration and change of direction (54/137, 39%). Conclusions: Using a systematic approach involving multiple expert reviewers, sprint-related injury scenarios were highlighted as the most common injury scenario for HSIs. Specific to American football; however, excessive trunk flexion during contact plays or during acceleration and change of direction may be important to consider for injury prevention or rehabilitation from HSIs.