Abstract
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.
Highlights
Soccer is a team sport that is played in a dynamic environment, with considerable demands on the perceptual-motor skills of the players [1,2,3]
The aims of this study were to: (1) analyze the percentage (%) of playing time that soccer players spend in different trunk inclinations in match play; (2) analyze the G-forces that soccer players experience in different trunk inclinations; (3) analyze the trunk inclination required for different speeds thresholds; and (4) analyze the effect of playing position on the time percentage that soccer players spend in different trunk inclinations, G-forces that the players experience in different trunk inclinations, and trunk inclination required for different speeds thresholds
FW showed the lowest time percentage (~36%) in match play. These differences may be due to the positional demands (i.e., WMF tend to run with the ball for longer times than FW) [27], these results suggest that these postural demands need to be considered when designing specific training drills [28]
Summary
Soccer is a team sport that is played in a dynamic environment, with considerable demands on the perceptual-motor skills of the players [1,2,3]. As in other team sports in which the ball, teammates, referees, or opposition players are continually in motion, it is suggested that the understanding of the postural demands met by the players when performing sports-specific skills would provide coaches and performance analysts with meaningful information about their performance in perception and action [4]. The downward orientation of the head and the trunk may restrict the ability to perform in the field of regard [4,5]. Soccer players usually play the ball with the feet, which may increase the trunk flexion and move the field of regard down [4]. The trunk kinematics have a significant effect on knee and hip energetics in running [7], hamstring injury [8], patellofemoral joint stress [9], and low back pain in professional soccer players [10]
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