Epidemiology and prediction models of injuries in elite futsal

Resumen

Futsal (the five-a-side indoor version of associated football) requires players to perform on a reduced (usually indoor) pitch size (40 x 20 m) and during two x 20-minute periods (with time stopping at every dead ball and unlimited substitutions) a substantive number of repeated high intensity multiplanar movements such as sudden acceleration and deceleration, rapid changes of direction, tackling and kicking. At elite levels, the combination of these high physical demands alongside exposure to contacts and stress and anxiety caused by the congested match calendar might place futsal players at high risk of injury. In fact, futsal has been suggested as one of the top 10 most injury prone sports, all of this despite the substantive effort made by the scientific community and physical trainer practitioners to reduce their number and severity. The inefficacy of the preventive measures applied might be caused, in part, by the limitations present in the literature which hinder: a) the accurate estimation of the most frequent futsal-related injuries; b) the identification of team sport athletes at high risk of injury; and c) the identification of the factors and their interactions that play a main role on the adoption of altered movement patterns during dynamic actions. Therefore, and based on these limitations, the main objectives of the current doctoral thesis were: 1) to describe injury incidence, characteristics and burden in futsal; 2) to examine the criterion-related validity of five kinematic measures of frontal plane knee alignment and hip and knee motion in the sagittal plane using a 2D video analysis and a 3D motion analysis system during bilateral drop landings through a contemporary statistical approach; 3) to analyze and compare the individual and combined ability of several measures obtained from different questionnaires and field-based tests to prospectively predict lower extremity soft-tissue injuries after having applied supervised Machine Learning techniques; and 4) to analyze the relationships between several parameters of neuromuscular performance with dynamic postural control using a Bayesian Network Classifiers based analysis. To achieve these objectives, a systematic literature review and meta-analysis, a prospective epidemiological study, a validation study and two multivariable prediction model studies were conducted. The main findings of the studies one and two report that male and female futsal players are exposed to a substantial risk of sustaining injuries, especially during matches. In particular, and in both sexes, lower extremity injuries are, by far, the most frequent. Although the most common injury mechanism reported was by non-contact, it should be highlighted that a remarkable number of injuries (around 30%) were caused by a contact mechanism. For females, the injuries with the highest injury burden were those that occurred at the knee (31.9 days loss per 1000 hours of futsal exposure), followed by quadriceps (15.3 days loss per 1000 hours of futsal exposure) and hamstring (14.4 days loss per 1000 hours of futsal exposure) strains. On the other hand, the results of study three confirm that the knee medial displacement (standardized TEEST = 0.53 [small], r = 0.88 [moderate to high], kappa statistic = 0.72 [high]) and knee flexion range of motion (standardized TEEST = 0.56 [small], r = 0.87 [moderate to high], kappa statistic = 0.74 [high]) measures calculated during a bilateral drop vertical landing and using a cost-effective, technically undemanding and portable 2D video analysis procedure might be considered as valid and feasible alternatives to their respective 3D criterion to quantify knee kinematics and to detect futsal players who demonstrated aberrant movement patterns in the frontal and sagittal planes, respectively. Study four demonstrated that lower extremity soft-tissue injuries can be predicted with moderate accuracy through a combination of easy to employ field-based tests in elite futsal players using machine learning techniques. The best performing model, which was built with just four ROM measures, reported an area under the curve score of 0.767 with true positive and negative rates of 85.1% and 62.1% respectively. Finally, the Bayesian network built in study five showed that dynamic postural control has strong relationship with the abilities to flex the hip, knee and ankle, and with the control of the core structures during static but mainly dynamic tasks. Overall, both the results and methodology used in the present doctoral thesis might be used by coaches, physical trainers and clinicians to improve the decision-making process to reduce the number and impact of injuries in futsal.