The impact of foot insole on the energy consumption of flat foot subjects during walking

The human foot contains one of the most variable structures of the body, namely the medial longitudinal arch. Decreasing the height of this arch is called flat foot. Although there is some evidence regarding the influence of flat foot on gait performance of subjects with flat arch, there is no strong evidence to support the effect of flat foot on energy consumption. Therefore, the aim of this study was to evaluate the contribution of flat foot in energy consumption. Two groups of 25 normal and flat-footed subjects were recruited in this research project. They were selected from the female staff and students of Isfahan University of Medical Sciences. The foot indexes of both groups were obtained using footprint method through Solid Work software. The physiological cost index of the subjects was measured by use of heart rate monitoring system (Polar Electro Finland). The difference between the PCI of subjects in the two studied groups was statistically determined via t-test. In addition, the influence of using insole was evaluated by use of paired t-test. The energy consumption of flat foot subjects differed significantly from that of normal subjects (the PCI of normal and flat arch subjects was 0.357 and 0.368 beats/m, respectively). Usage of foot insole improved the performance of the flat foot subjects during walking. The PCI of subjects affected by flat foot is more than that of normal subjects due to the misalignment of foot structure. Moreover, the application of foot insole improved foot alignment and decreased energy consumption.