###### Abstract  
The aim of this study was to clarify the relationship between the landing position during consecutive straight jumps and standing posture stability of trampoline gymnasts with stable occlusal balance. Participants were 10 healthy men (BMI: 18.5-25.0) and 10 trampoline gymnasts (competition experience: \(\geq\)12 years), all of whom had stable occlusal balance. To assess postural control function, the displacements in the forward-backward (COP-FB) and the left-right directions (COP-LR) of the center of foot pressure were recorded under eyes-open and eyes-closed conditions. For the trampoline gymnasts, landing positions during 10 consecutive straight jumps were recorded. The horizontal displacements from the center of the bed in the forward-backward (H-FB) and the left-right directions (H-LR) directions were recorded. Differences in COP displacement between participant groups and between visual conditions were analyzed, along with the correlations between COP displacement and landing position. COP-FB in the eyes-open condition was significantly smaller in trampoline gymnasts than in healthy men (\(p<0.05\)). Significant strong positive correlations were observed between COP-FB and H-FB, and between COP-LR and H-LR (\(p<0.05\)). The postural control function of trampoline gymnasts was superior to that of healthy men in the eyes-open condition. The landing position during straight jumps of trampoline gymnasts with stable occlusal balance reflects standing postural control function.  
occlusal balance; postural control function; center of foot pressure; landing position; straight jump; trampoline +
Footnote †: journal: Medical  
moves synchronously with the body's center of mass (COM). In addition, the usefulness and validity of using COP as an index of COM has been reported [11].  
A trampoline competition is an event in which 10 jumps involving different techniques are continuously performed for a total flight time of about 20 s [12]. During flight, it is necessary to instantly recognize position with respect to the center of the bed, create an aerial posture, and control one's body movements. Therefore, sports vision, spatial awareness, and the ability to control minute shifts in posture are essential traits for gymnasts in trampoline competitions. The straight jump, which is the most basic exercise in trampoline competitions, uses the strong repulsive force of the bed transmitted from the soles of the feet to maintain a standing posture while in mid-air [13]. This exercise is presumed to be a technique that directly reflects the postural control function.  
A previous study examined the relationship of the occlusal contact state, which affects oral somatosensory input, with static postural control function, targeting trampoline gymnasts whose performance is influenced by fine balance and postural control [14]. It was clarified that equalization of the occlusal contact state by wearing a mouthguard contributed to the improvement of static postural control function in trampoline gymnasts. Furthermore, COP displacement was shown to decrease in all groups of untrained adults, weightlifters, and gymnasts when wearing mouthguards adjusted to equalize occlusal contact. Characteristically, gymnasts, the group with the best postural control without a mouthguard, showed the greatest reduction in COP displacement when wearing a mouthguard [15].  
The purpose of this study was to clarify the relationship between standing postural stability and performance in trampoline gymnasts. To this end, differences in COP between trampoline gymnasts and healthy men as well as the relationship between the landing position during consecutive straight jumps and the COP displacement were investigated. The null hypothesis was that there were no differences in COP between participant groups or between visual conditions, and that there was no correlation between landing position and the displacement of COP.