The Influence of Injury History on Countermovement Jump Performance and Movement Strategy in Professional Soccer Players: Implications for Profiling and Rehabilitation Foci.

CONTEXT

Professional soccer players who have sustained a lower limb injury are up to 3× more likely to suffer a reinjury, often of increased severity. Previous injury has been shown to induce compensatory strategies during neuromuscular screening tests, which might mask deficits and lead to misinterpretation of readiness to play based on task outcome measures.

OBJECTIVE

To investigate the influence of previous injury in professional soccer players on countermovement jump (CMJ) performance and movement strategy.

DESIGN

Cross-sectional.

SETTING

Professional soccer club competing in the English Championship (tier 2). Patients (or Other Participants): Outfield players with a minimum of 6 years as a professional.

INTERVENTION(S): Players were categorized as previously injured (n = 10) or not injured (n = 10). All players completed double- and single-leg CMJ trials.

MAIN OUTCOME MEASURES

CMJ performance was quantified as jump height and flight time:contraction time ratio. CMJ movement strategy was quantified as force-time history, differentiating eccentric and concentric phases and CMJ depth.

RESULTS

Double-leg CMJ was not sensitive to previous injury in performance or movement strategy. In contrast, single-leg CMJ performance was impaired in players with previous injury, who generated significantly lower eccentric and concentric peak force and rate of force development, and a deeper countermovement. Impaired single-leg CMJ performance was also evident in the nonaffected limb of previously injured players, suggesting cross-contamination. Hierarchical ordering revealed that the eccentric phase of the CMJ contributed little to performance in previously injured players. In noninjured players, the eccentric rate of force development and concentric peak force were able to account for up to 89% of the variation in CMJ performance.

CONCLUSIONS

Single-leg CMJ is advocated for player profiling, being more sensitive to previous injury, and negating the opportunity for interlimb compensation strategies. Movement strategy deficits in previously injured players suggest rehabilitation foci specific to eccentric force development.