Persistent biomechanical deficits observed in professional soccer players with a history of hamstring injury during a reactive functional test

Objectives: The aim of the study was to estimate hip extensor muscle stretching capacity as a function of previous hamstring injury during a for-purpose, standardised test permitting unrestricted full-body movement, including hamstrings, adductors and gluteal muscle length evaluated using a musculoskeletal modelling approach. Method: Twenty-seven professional footballers, distributed in two groups (control or previously injured), performed a reactive functional test to one of four targets from a standing start and performed a knee and plantar extension on target. Joint kinematics served as input data of a musculoskeletal model, and joint angles and hip extensor muscle lengths were calculated Results: A reduced range of motion of anterior pelvis, hip and knee joints at the peak of BFlh length was observed associated with a lesser ability to actively stretch the posterior muscle chain. Additionally, a shorter time-to-peak length in was found in previously-injured compared to non-previously-injured players during the functional test. Conclusion: Persistent biomechanical deficits can be observed in athletes with HSI even after undergoing rehabilitation and returning to a full competition and training schedule. Musculoskeletal modelling allowed the analysis of musculoskeletal function in greater detail than using kinematics assessment alone. These findings contribute to assist medical practitioners, sport physicians and physiotherapists to design efficient programmes for diagnosis and management of HSI injury.