Author(s): CHANG, C., CHAINOK, P., KO, B.J., HUNG, M.H., KERNLUEA, S., LIN, J.Z., Institution: NATIONAL TAIWAN UNIVERSITY OF SPORT, Country: TAIWAN, Abstract-ID: 1236

INTRODUCTION:
Refractive error is one of the most prevalent visual disorders worldwide [1] and reduces visual clarity. Approximately 26% of recreational runners engage in running without appropriate refractive correction [2], despite visual information playing a critical role in motor control and gait regulation. However, the influence of refractive blur on joint-level control during running remains unclear. Therefore, this study investigated the effects of different levels of refractive blur on joint control strategies during slow running in athletes.
METHODS:
13 male collegiate athletes with myopia (-2.26 diopters [D]) were recruited for this study. After full refractive correction, participants were randomly fitted with lenses of different diopters to simulate three visual conditions: mild hyperopia (+3.00 D), full correction, and mild myopia (-3.00 D). Under each visual condition, participants performed 30 seconds of barefoot running on a treadmill at a constant speed of 6 km/h. A continuous 10-second segment during steady-state running was extracted for trunk and lower-limb joint kinematic analysis. A one-way repeated-measures analysis of variance was conducted to examine differences among visual conditions.
RESULTS:
The results demonstrated that, compared with the fully corrected visual condition, athletes under the mild myopia condition exhibited a greater peak hip flexion during the stance phase and a higher mean ankle abduction during the swing phase (p < .05). In addition, across the entire gait cycle, the range of axial trunk-pelvis relative rotation was significantly greater in the fully corrected condition than in the mild myopia condition (p < .05).
CONCLUSION:
This study shows that even during slow running, different levels of refractive blur significantly alter lower-limb joint control strategies, underscoring the critical role of visual input in locomotor regulation. When visual quality declines, individuals adapt motor strategies to manage environmental uncertainty [3]. Compared with the fully corrected visual condition, mild myopia produced greater hip flexion during stance and increased ankle abduction during swing. Greater hip flexion may facilitate impact attenuation and prolong joint motion time, allowing temporal adjustments under visually degraded conditions. Likewise, ankle abduction may enhance ankle stability. These findings suggest that blurred vision modifies joint-level strategies to maintain gait stability, consistent with previous evidence that visual manipulation reorganizes gait strategies [4]. Furthermore, greater trunk–pelvis relative rotation under full correction may reflect more effective multi-joint coordination and movement efficiency [5]. Collectively, these results demonstrate that altered visual input influences joint control strategies during slow running, underscoring the importance of vision–motor integration in running mechanics.