RESUMEN
The rapid growth of wearable sensors has allowed the analysis of trunk kinematics during the match, which is necessary for having a better understanding of the postural demands of soccer players. However, some contextual variables may have an impact on the physical demands of the players. This study aimed to analyze the effect of three contextual variables (playing position, match half, and match day) on the sagittal trunk inclination, G-forces, and locomotor efficiency experienced by soccer players in match play. Then, wearable sensors were used to collect the trunk kinematics during 13 matches. Firstly, positional differences were found on the trunk inclination (p = 0.01) and the G-forces experienced by the players (p < 0.001). For example, the greatest and lowest trunk inclination was found for FW (~34.01°) and FB (~28.85°) while the greatest and lowest G-forces were found for WMF (1.16 G) and CD (1.12 G), respectively. However, there were no positional differences in the locomotor efficiency (p = 0.10). Secondly, the match half had a significant effect on the trunk inclination (p = 0.01) and the G-forces experienced by the players (p < 0.001) with significantly lower values observed during the second half. No differences between halves were found on the locomotor efficiency for any playing position (p = 0.41). Finally, no significant effect of match day on any variable was observed. This investigation is one of the first steps towards enhancing the understanding of trunk kinematics from elite soccer players. The positional differences found on the trunk inclination and G-forces imply that the development of position-specific training drills considering the postural demands is necessary to prepare the players not only for the physical demands but also for successful performance in the field of regard. The resistance to fatigue needs to be trained given the differences between halves.
Asunto(s)
Rendimiento Atlético , Carrera , Fútbol/fisiología , Adulto , Atletas , Fenómenos Biomecánicos , Fatiga , Humanos , Masculino , Torso , Adulto JovenRESUMEN
The development of wearable sensors has allowed the analysis of trunk kinematics in match play, which is necessary for a better understanding of the postural demands of the players. The aims of this study were to analyze the postural demands of professional soccer players by playing position. A longitudinal study for 13 consecutive microcycles, which included one match per microcycle, was conducted. Wearable sensors with inertial measurement units were used to collect the percentage (%) of playing time spent and G-forces experienced in different trunk inclinations and the inclination required for different speeds thresholds. The inclination zone had a significant effect on the time percentage spent on each zone (p < 0.001, partial eta-squared (ηp2 = 0.85) and the G-forces experienced by the players (p < 0.001, ηp2 = 0.24). Additionally, a significant effect of the speed variable on the trunk inclination zones was found, since trunk flexion increased with greater speeds (p < 0.001; ηp2 = 0.73), except for midfielders. The players spent most of the time in trunk flexion between 20° and 40°; the greatest G-forces were observed in trunk extension zones between 0° and 30°, and a linear relationship between trunk inclination and speed was found. This study presents a new approach for the analysis of players' performance. Given the large volumes of trunk flexion and the interaction of playing position, coaches are recommended to incorporate position-specific training drills aimed to properly prepare the players for the perception-action demands (i.e., visual exploration and decision-making) of the match, as well as trunk strength exercises and other compensatory strategies before and after the match.