Injury risk factors in young soccer players detected by a multivariate survival model

Soccer is a popular game practiced all around the world by teenagers. However, despite being a relatively safe sport, muscle-strain injuries during competitive matches are common compared to other team-sports. Few studies, to date, have investigated risk factors for soccer injuries using a multivariate survival model (e.g., Cox regression). The aim of this study was to use a multivariate survival model to investigate factors associated with an increased risk of thigh muscle strains, in young soccer players. A multivariate Cox regression was used to evaluate survival probability predictors for thigh muscle strains. 84 young male soccer players (16.4 ± 1.6 years) were followed for a season. Baseline tests were performed for body size, body composition, endurance, flexibility, and jump height from both a static position (SJ), and with a countermovement (CMJ); the percentage difference between the two types of jumps was also calculated (ΔJH). Cox regression result (hazard ratio; C.I. 95%) showed that: previous injuries (2.80; 1.19–6.54), ΔJH (0.79; 0.71–0.87), and stature (1.17; 1.06–1.25) were significantly correlated to thigh-strain survival probability. This study confirms that previous injuries are an important risk factor. However, we also report that a negative ΔJH and an elevated stature increased the probability of thigh strain. This could be explained by poor player coordination, influencing jumping ability, which may be even more evident in tall young players.