The Comparison of the Difference in Foot Pressure, Ground Reaction Force, and Balance Ability According to the Foot Arch Height in Young Adults

Background. Human feet have important roles in supporting, moving and balancing the body. The feet must not only support the weight of the body but must also have the elasticity to absorb the burden associated with supporting excessive body weight. Objectives. The purpose of this study was to compare the difference of foot pressure, ground reaction force, and balance ability according to change of the foot arch during the weight loading. Methods. Total 60 healthy young adults were divided into flexible flat foot group (FFFG, n = 30) and normal foot arch group (NFAG, n = 30) by screening navicular drop test. To compare the foot pressure, the rate of change was calculated by measuring the foot contact area when walking against the foot contact area when standing. The ground reaction force measurement was performed to calculate the contact time of the foot, vertical force peak, and total GRF time-integral value during walking. Besides, a one-leg standing test was performed to measure postural instability according to the height of the foot arch. Results. The FFFG showed a significantly higher contact area than that of the NFAG. Also, there was a significant increase in contact area ratio in FFFG (p < 0.05). The vertical force peak results revealed no significant differences between the two groups. However, for contact time and total GRF time-integral values, the FFFG values were higher than those for the NFAG (p < 0.05). The FFFG had significantly greater COP, velocity, COP path length, and area values than those of the NFAG (p < 0.05). Conclusion. These results show that the flexible flat foot may reduce energy efficiency and increase instability during the dynamic performance and has a high risk of causing secondary problems.