Author(s): KAWATA, Y., YAMANAKA, K., HATA, H., NAKAMURA, M., HAYASHI, H., NAKADA, M., NORO, H., KAI, M., YAMADA, Y., KUDO, Y., YANAGIYA, T., ICHII, Y., NIWA, S., YUKIMATSU, S., WAKI, H., Institution: JUNTENDO UNIVERSITY, Country: JAPAN, Abstract-ID: 1744

INTRODUCTION
Although international standards for arena illuminance exist, indoor sports have shown a trend toward higher illuminance levels, driven by the widespread adoption of high-resolution broadcasting technologies aimed at delivering more visually compelling content to audiences. These lighting designs primarily aim to optimize the visual media quality; however, their effects on athletes’ perceptual–motor performance remain insufficiently examined. Volleyball attack reception is a highly demanding skill that requires the rapid perception of ball trajectories, anticipation of the attacker’s intent, and appropriate response actions, all of which may be strongly influenced by visual environmental conditions. Therefore, this study examined the effects of arena illuminance on volleyball attack reception performance using an immersive virtual reality (VR) environment.

METHOD
Participants included 30 male volleyball players (expert group) and 30 adult males (control group). A VR-based volleyball attack reception task was conducted under precisely controlled illuminance conditions. The task employed a temporal occlusion paradigm with six occlusion timings relative to ball contact (−160 ms, −120 ms, −80 ms, −40 ms, ±0 ms, and 40 ms). The participants performed repeated reception responses for 18 min while wearing a head-mounted display under three illuminance conditions: low (2000 lx), medium (4000 lx), and high (6000 lx). The accuracy of receive-course prediction and gaze behavior (gaze velocity) were measured.

RESULTS AND DISCUSSION
Illuminance significantly affected attack reception performance. Compared with the low illuminance condition, prediction accuracy for the −80 ms occlusion task was significantly lower under high illuminance. Time-series analyses revealed that both the prediction accuracy and gaze velocity declined during the later phase of task performance under high illuminance. These findings suggest that high illuminance may increase susceptibility to mental fatigue over time, impairing rapid and accurate decision-making and gaze control. The results indicate that athletic performance is not simply enhanced by brighter lighting and that an optimal range of illuminance for maximizing performance may exist.

CONCLUSION
Under high illuminance conditions, declines in prediction accuracy and changes in gaze behavior became more pronounced over time, particularly in the −80 ms temporal occlusion condition. This timing represents a critically important phase in volleyball attack reception. The present findings suggest that excessively high illuminance may impair perceptual–motor performance during key anticipatory decision-making phases. These results indicate that arena illuminance should not be determined solely by prioritizing improvements in image quality or broadcasting conditions but should instead be optimized with careful consideration of sport-specific performance demands.