The impact of different Body Mass Indexes on plantar pressure

Purpose: The aim of this study is to investigate the relationship between body mass index (BMI) and plantar pressure in college students and to provide reference indicators for the application of plantar pressure analysis. Methods: For the experiment, 96 young college students were recruited as test subjects, including 44 men and 52 women between the ages of 18 and 21. They were divided into three groups based on their body mass index (BMI) values. The overweight group (BMI > 25 kg/m², n=27), the underweight group (BMI < 18 kg/m², n=40) and the normal weight group (BMI 18-25 kg/m², n=20). Tests on natural gait were carried out in the three groups of test subjects using the Zebris pressure distribution measuring plate. The analysis included the maximum force value, peak pressure, and proportion of time in each support phase during the dynamic walking task. A Pearson correlation analysis was performed to examine the relationship between these parameters and different Body Mass Index values. Results and Discussion: The overweight group had the highest maximum force value and peak pressure in the left foot, midfoot, and hindfoot. The order of maximum force value and peak pressure from high to low was overweight group > normal weight group > underweight group. This suggests that as BMI increases, the maximum force value and peak pressure also increase. Within each BMI group, the maximum force value and peak pressure were highest in the forefoot, followed by the hindfoot and midfoot. The correlation between the maximum force value and the overweight group showed a significant difference, while the peak pressure in the left midfoot of the normal weight group also showed a significant correlation with BMI. In addition, there was a significant correlation between BMI and the phase of arch support in the normal weight group, indicating that there were significant differences in the correlation between different BMI groups and the time proportion of each stage of the support phase. Conclusions:The overweight group, with a higher BMI, experiences increased maximum force value and peak pressure during walking, which can lead to pathological changes in the foot over time. The increased BMI in obese individuals leads to flattening of the arch of the foot, prolonged metatarsal-to-ground contact, and an increased risk of developing flat feet. Arch support time decreases with increasing BMI, resulting in a relatively larger proportion of time in the forefoot propulsion phase. This is because people with a higher BMI require a longer time to push off the ground to generate sufficient momentum.