Biology subjects

Kizuka, T.

Publications and source records attributed to Kizuka, T..

6 recordsLinked to original sources

bioRxiv2026

Task- and experience-dependent modulation of head-eye coordination during ball interception

Head-eye coordination during ball interception depends on both task demands and motor experience. The purpose of this study is to determine how these factors influence head-eye contributions to gaze control. Twenty-five female university students (novices with no ball sport experience, n = 13; experienced softball players, n = 12) performed two tasks: visually tracking an approaching ball (tracking task) and, in addition, moving the hand to the ball's landing position (reaching task). Head, eye, and gaze velocities, cross-correlation coefficients between gaze and head velocity, and gaze-head lag time were analyzed using linear mixed models. The results showed that although gaze velocity remained unchanged regardless of tasks or groups, decomposing gaze into head and eye components revealed task-dependent contributions. Compared with the tracking task, the reaching task showed significantly larger head velocity and smaller eye velocity, indicating complementary adjustments that were not revealed by gaze movements alone. The cross-correlation between head and gaze was significantly higher in the reaching task than the tracking task, indicating stronger temporal coupling under greater task demand. Furthermore, the experienced group showed greater task-dependent modulation of eye velocity than the novice group, demonstrating greater flexibility in adjusting the magnitude of head-eye movements to task demands. In addition, the experienced group showed a consistently near-zero gaze-head lag regardless of task, whereas the novice group showed a prolonged gaze-leads-head interval. These findings suggest that ball sport experience shapes two distinct aspects of head-eye coordination: task-dependent flexibility in movement magnitude, and stable, temporally synchronized gaze-head control.

physiology↗

bioRxiv2026

The effects of force constraint during preparatory phase on the explosive force generation of base stealing in baseball.

BackgroundExplosive force generation during the initial acceleration phase is critical for successful base stealing in baseball. Preparatory balance control preceding movement onset may facilitate this process by constraining horizontal ground reaction force (GRF) toward a task-specific direction. However, its contribution to ballistic sprint initiation remains unclear. Research questionDoes preparatory force constraint influence explosive force generation during base stealing, and when during the preparatory phase is this influence greatest? MethodsFourteen baseball players performed 3-m maximal sprints simulating base stealing under time-constraint (Time) and self-paced (Self) conditions. GRF around movement onset were recorded. Peak rate of force development (peak RFD) was computed from onset to take-off. A 250-ms window before the onset was divided into 50-ms bins, and mean resultant length (Rlen), which represents the extent of force constraint, of each bin was calculated. Using statistics analyses, Differences between conditions were tested, and the relationship between the interaction (Rlen x condition) and peak RFD was assessed. ResultsThe peak RFD was greater under the Self condition than under the Time condition, accompanied by a larger Rlen. Furthermore, Results indicated that the force constraint in the 150-100 ms interval preceding the movement onset most strongly influenced the peak RFD. SignificanceThese findings demonstrate that temporally organized preparatory force constraint plays a critical role in explosive sprint initiation during base stealing. Identifying the specific preparatory timing linked to superior force production provides novel mechanistic insight into preparatory balance control and may inform targeted training strategies for ballistic athletic movements.

neuroscience↗

bioRxiv2025

Eye-Head Coordination During Rapid Gaze Shifts in Soccer Scanning

The visual exploratory behavior involving rapid gaze shifts that supports cognitive processes is called "scanning." Scanning in soccer is a foundational behavior that enables players to explore their environment, supporting rapid and accurate decision-making. However, since most previous studies have focused on head movements, the coordination structure of gaze shifts, including the ocular contribution, is insufficiently understood. This study aimed to determine the coordinated roles of the eye and head during scanning. Twenty male collegiate soccer players performed a passing task paired with video-based situational judgments while eye and head movements were recorded by a 200 Hz sampling rate using an eye tracker system with a built-in gyroscope. We detected eye and head velocities and amplitudes during rapid gaze shifts. As a result, peak eye velocity was significantly higher than peak head velocity (d = 4.09, p < .001). The cross-correlation (CC) between gaze and eye velocities (0.98) was significantly greater than that between gaze and head velocities (0.90). These results indicate that gaze shifts were driven primarily by eye movements rather than head movements. Furthermore, eye and head velocities were negatively correlated (r = -.60, p = .005), whereas their velocity-control profiles (mean velocity normalized by amplitude) were positively correlated (r = .90, p < .001), indicating individual strategy-dependent allocation of effort while preserving control capability of eye and head movements. Our findings provide a characterization of the eye-head coordination structure of gaze shifts in soccer scanning, suggesting the need for comprehensive assessments beyond head-motion metrics alone.

neuroscience↗

bioRxiv2024

Predictive visual patterns during table tennis forehand rallies

The purpose of this study was to clarify predictive visual patterns of skilled table tennis players during forehand rallies. Collegiate male table tennis players (n = 7) conducted forehand rallies at a constant tempo (100, 120 and 150 bpm) using a metronome. In each tempo condition, participants performed a total of 30 strokes (three conditions). Gaze fixation time, gaze targets and saccade eye movements were detected by video footage of an eye tracking device. We found that participants gazed at a ball approaching them only 20 % of the total rally time. Participants tended to gaze at the ball when the opponent hit the ball and move their gaze away from the ball after that. Furthermore, saccades were directed toward the opposite side of the court including the opponent after tracking the ball. These findings suggest that focusing on the opponent motion is important for successful forehand table tennis rallies. Taken together, skilled table tennis players are likely to use unique visual patterns for interceptive sports players to estimate spatiotemporal information about the ball.

physiology↗

bioRxiv2024

The effects of pressure on anticipatory postural adjustments during a jump shot in basketball

BackgroundAnticipatory postural adjustments (APAs) play an important role in feedforward control of dynamic movement, such as jump shot performance in basketball. It is known that jump shot performance declines under pressure from a defender (shot blocker). Research questionDoes pressure from a shot blocker affect APAs of a jump shot in basketball? Is jump shot performance in basketball associated with APAs? MethodsFourteen healthy male university basketball players performed jump shots under pressure and non-pressure (free) conditions by a shot blocker. Using a force plate, the APAs were defined as occurring until the point of thrust (TH) phase, and ground reaction force (GRF) and center of pressure (COP) at that moment were assessed. To assess jump shot performance, the maximum GRF during the TH phase (THmax), jumping height, and success score of the shot (accuracy score: AS) were measured by using the vertical component of the force plate. Two-way ANOVA examined the effects of the phase and condition on APA duration. Pairwise t-tests analyzed pressure effects on subjective pressure intensity, AS, and kinetics measures. Relationships between condition changes in AS and COP or GRF variables were assessed via Pearson correlations. Differences between the pressure and free conditions were denoted by {Delta}. ResultsThe APA duration was shorter under the pressure condition compared to the free condition. The THmax and jump height values were greater under the pressure condition relative to the free condition. Across conditions, changes in COP variables were significantly and negatively correlated with AS. SignificanceThe results of this study suggest that pressure from a shot blocker shortens APA duration and decreases jump shot performance. Additionally, by measuring players APAs and evaluating relationships with jump shooting proficiency, APA variables could potentially serve as indicators of skill expertise.

physiology↗

bioRxiv2023

Importance of head movements in gaze tracking during table tennis forehand stroke

The purpose of this study was to clarify the properties of gaze and head movements during forehand stroke in table tennis. Collegiate table tennis players (n = 12) conducted forehand strokes toward a ball launched by a skilled experimenter. A total of ten trials were conducted for the experimental task. Horizontal and vertical movements of the ball, gaze, head and eye were analyzed from the image recorded by an eye tracking device. The results showed that participants did not always keep their gaze and head position on the ball throughout the entire ball path. Our results indicate that table tennis players tend to gaze at the ball in the initial ball-tracking phase. Furthermore, there was a significant negative correlation between eye and head position especially in the vertical direction. This result suggests that horizontal VOR is relatively suppressed than vertical VOR in ball-tracking during table tennis forehand stroke. Finally, multiple regression analysis showed that the contribution of head position to gaze position was significantly higher than that of eye position. This result indicates that gaze position during forehand stroke could be associated with head position rather than eye position. Taken together, head movements may play an important role in maintaining the ball in a constant egocentric direction in table tennis forehand stroke.

neuroscience↗