This study aims to investigate the effects of pes planus deformity on gait spatiotemporal parameters and pelvic kinematics during walking on different inclines. Participants will include healthy adults aged 18-35 years with flexible bilateral pes planus and normal body mass index. Pes planus severity will be evaluated using the Jack's toe-raise test and the navicular drop test. Gait parameters such as walking speed, cadence, stride length, stance and swing phase percentages, gait cycle duration, as well as pelvic tilt, obliquity, and rotation symmetry will be measured using the BTS-G wireless sensor system. Assessments will be performed on both flat and inclined treadmill conditions. The findings are expected to provide new insights into the biomechanical adaptations of pes planus during walking and contribute to the development of an individualized rehabilitation protocol.