Validity Of Two-Dimensional Static Footprint To Evaluate Medial Longitudinal Arch And The Characteristics Of Athlete’s Footprint

ObjectiveMedial longitudinal arch is an important part of foot movement function, the relationship between medial longitudinal arch and athletic ability has always been the topic of academic debate, measurement and evaluation of medial longitudinal arch is also the focus point. Two-dimensional static footprint analysis is one of the commonly used evaluation method of medial longitudinal arch. However, there are no unified standards for the acquisition and evaluation of footprint. The purpose of this paper is to explore the validity of two dimensional static footprint analysis to evaluate medial longitudinal arch, and to study the characteristics of athlete’s footprint. Then provide a basis for the evaluation and selection of athletes.MethodsExperiment 1: 29 high level athletes and 40 normal university students were selected. X-ray was taken and measured Calcaneal Inclination Angle, Calcaneal–First Metatarsal Angle and the ratio between the height of arch and the length of arch. Then collected two-dimensional static footprints and measure the width of ball, arch, heel,and length of footprint, toe, Chippaux-Smirak Index(CSI) and Staheli Index(SAI).Using interclass correlation coefficient(ICC) to evaluate the reliability of those indicators, Pearson correlation coefficient to evaluate the correlation of those indicators.Experiment 2: 106 high level athletes and 104 normal university students were selected. Collected two-dimensional static footprints and measure the width of ball,arch, heel, and length of footprint, toe, Chippaux-Smirak Index(CSI), the ratio between the length of toe and footprint length, the ratio between the width of ball and footprint length and the ratio between footprint length and height. The comparison between each indicators were processed with independent t-test or paired t-test.Results1. Single measure ICC and average measure ICC of Calcaneal Inclination Angle,Calcaneal–First Metatarsal Angle, the ratio between the height of arch and the length of arch, the width of ball, arch, heel, and length of footprint, toe,Chippaux-Smirak Index(CSI) and Staheli Index(SAI) were greater than 0.800,indicated that all the indicators’ reliability are great.2. No matter athletes or normal people, men or women, the correlation between CSI,SAI and Calcaneal Inclination Angle, Calcaneal–First Metatarsal Angle, the ratio between the height of arch and the length of arch were statistically significant(P﹤0.05).3. CSI differences between male athletes and normal people were not statistically significant, but the mean of athletes’ CSI is smaller than normal people. Female athletes’ CSI is smaller than normal people, differences were statistically significant(P﹤0.05), the right CSI was highly significant difference(P﹤0.01).4. Normal people, no matter men or women, their bilateral CSI differences were statistically significant(P﹤0.05), and CSI of right foot is greater than the left foot. However the bilateral CSI differences were not statistically significant in the athletes.5. No matter men or women, the differences of the ratio between the length of toe and footprint length, the ratio between the width of ball and footprint length and the ratio between footprint length and height between athletes and normal people were no significant difference.ConclusionsTwo-dimensional static footprint indexes indicators, namely Chippaux-Smirak Index(CSI) and Staheli Arch Index(SAI) have good reliability. The correlation between CSI, SAI and Calcaneal Inclination Angle, Calcaneal–First Metatarsal Angle,the ratio between the height of arch and the length of arch were statistically significant,both of them can be used to evaluate the medial longitudinal arch.Female athletes’ medial longitudinal arch are significantly higher than normal people. Although it can’t directly prove the medial longitudinal arch relative height is directly related to run, jump and other athletic ability, it’s enough to explain that the medial longitudinal arch relative height is an important indicator in track and field.There is no difference on the bilateral of medial longitudinal arch of athletes.However, the medial longitudinal arch relative height of right foot are lower than the left foot among normal people.No matter men or women, the differences of the ratio between the length of toe and footprint length, the ratio between the width of ball and footprint length and the ratio between footprint length and height between athletes and normal people were no significant difference.