Author(s): KATO, T., YAMADA, Y., TAKAMI, K., YAMAMOTO, H., SUGAJIMA, Y., Institution: ASAHI UNIVERSITY, Country: JAPAN, Abstract-ID: 1277

INTRODUCTION:
Shiko is a fundamental movement in sumo wrestling and is essential for maintaining proper posture and acquiring effective control of the center of gravity. However, beginners often lack trunk stability during shiko, resulting in uneven lifting and lowering motions of the legs. Although various factors may contribute to this issue, gaze behavior may be one such factor.
Accordingly, the purpose of this study is to investigate how gaze influences stability and postural control during shiko. In particular, this study aims to compare gaze dynamics, hip joint angles, and the duration of shiko posture between individuals with and without sumo experience in order to examine the role of gaze in mastering the shiko movement.
METHODS:
The participants consisted of 14 male students: seven members of the University sumo team and seven students from the Department of Health and Sports Science. Participants were instructed to wear eye-tracking device Tobii Pro Glasses 3 and perform the shiko movement under two conditions: a forward-gaze condition and a supporting toe-gaze condition. Each participant performed shiko once on each side under both conditions, for a total of four trials.
Movements were recorded simultaneously with gaze data, and the lifting and lowering phases were analyzed in 1/50-second. Video images were analyzed using Kinovea (Ver. 2025.1) to calculate shiko duration, stationary time, and maximum hip joint angles, and comparisons were made between the two groups.
RESULTS:
Under the supporting toe-gaze condition, the proportion of gaze directed toward the toes was significantly higher in the sumo group (81.2%) than in the inexperienced group (56.8%) (p < 0.05).
The sumo group showed significantly higher values for shiko duration 4.8 vs 1.7 sec, stationary time 2.0 vs 1.3 sec, and maximum hip joint angle 143.5 vs 106.6 deg (p<0.01) in a forward-gaze condition. In contrast, stationary time under the forward-gaze condition was 1.6 sec for the sumo group and 1.2 sec for the inexperienced group, with no significant difference observed (p = 0.068).
CONCLUSION:
The present study demonstrated that altering gaze direction during the shiko movement significantly changes the proportion of gaze fixation and influences movement stability and range of motion in the inexperienced group. Experienced sumo practitioners appropriately regulated their gaze even under the supporting toe-gaze condition. In contrast, the inexperienced group appeared unable to adequately support the trunk, possibly due to unstable gaze, and showed marked variability in their movements. However, no significant difference was observed in stationary time under the forward-gaze condition, suggesting that the disparity between the two groups may diminish depending on the gaze condition. These findings indicate that gaze is an important factor capable of modifying shiko performance and may serve as an effective instructional indicator for coaching beginners.