The Effect of Expertise on Postural Control in Elite ju-jitsu Athletes

Background: The testing of athletes in ecological conditions is based on the concept that sport-specific adaptations in postural control are observed mostly in positions or tasks that are related to the practice of a specific movement. Due to the high postural control demands of ju-jitsu, it is likely that long-term ju-jitsu training may influence the process of maintaining a stable posture, especially in positions directly related to combat. The purpose of this study was to examine the postural sway characteristics of elite ju-jitsu athletes in ecological and non-ecological conditions with an approach not previously used in martial arts.Methods: The study was conducted on eleven male elite ju-jitsu athletes and ten non-athletes. The data was collected with the use of a force plate under two conditions: quiet standing and ju-jitsu combat stance. Apart from the standard analysis of the spatial-temporal parameters of COP, sensitive methods in COP data processing were used, namely rambling-trembling and sample entropy. The non-parametric U Mann-Whitney test was used to compare both positions.Results: The main findings of the study showed that in quiet standing, elite ju-jitsu athletes and non-athletes had comparable postural control in both the anterior-posterior and mediolateral planes. In contrast, elite athletes had lower values of postural sway and higher values of sample entropy in comparison to the non-trainees in the combat stance (p<0.05). The rambling-trembling decomposition of the COP data did not exhibit additional differences between groups beyond the standard analysis.Conclusions: Our results confirmed the importance of a sport-specific environment in investigating the subtle differences in the postural regulation of elite athletes. The sample entropy results indicated more irregular characteristics of postural sway in the elite ju-jitsu athletes, representing more automated postural control.