七歲男女生足弓相關指標之雙峰分布

Abstract

背景與研究目的 雖然扁平足常見於小朋友，而且很多家長非常擔心孩子扁平足造成的影響，但目前文獻上對於扁平足精確的定義，甚至健康照護仍無共識。扁平足常常被認為是造成體育活動與體適能表現較差的原因，因此有很多治療與處置方法介入。本研究的目的是為了探究在控制年齡與性別後，扁平足相關的足弓指標與體適能的關係。 方法 本研究通過倫理委員會審查後，研究者從新北市市區的三所小學招募一年級兒童，採集足印與量測三項體適能：立定跳遠、20公尺衝刺與棒上單足站。從採集到的足印量測並計算兩種足弓指標Chippaux-Smirak Index (CSI) and Staheli’s arch index (AI)。藉由統計方法獨立t檢定與相關性來探討足弓指標與體適能的關係，回歸用來判定是否有顯著的因子能解釋不同足型兒童的體適能表現。 結果 研究者採集829位7歲兒童的足印，得到的兩種足弓指標皆呈現雙峰分佈(bimodal distribution)，波谷值分別為CSI: 0.55，AI: 1.0。接著使用波谷值把兒童分成兩組，足弓較扁的兒童呈現較大的身體質量指數(BMI)與較差的棒上單足站，但只有女生的棒上單足站達顯著差異。男生BMI比女生大且扁平足的人數較女生多。體適能與兩種足弓指標(CSI、AI)、身體質量指標(BMI)的相關性非常低，且回歸方法顯示只有身體質量指數(BMI)能微量解釋體適能表現(r2= 0.02~0.09)。 結論 研究結果或許可以解釋為什麼扁平足小孩呈現出體適能表現比較差，但是相關性與回歸方法卻顯示扁平足不是重要影響體適能的因子。把年齡控制在一個小範圍之後，兩種足弓指標呈現雙峰分佈，顯示在兒童的發展，可能自然存在兩種足弓分組。不同於大部份的身體測量通常都是鐘型分佈，足弓的雙峰型分佈其特徵與生理意義需要更進一步的研究。

Background and purpose. Although a large proportion of foot type in children is flexible flatfoot (FFF) and a matter of great concern for parents, the ‘precise’ definition of flatfoot as well as health care remain no consensus. Flatfoot is often regarded as a cause for inferior performance in sports and fitness; therefore several models of managements have been applied. This study was to investigate the association between flatfoot related parameters and physical fitness after controlling the confounding effects of age and gender. Methods. After being proven by institutional review board, researchers collected foot prints and three tests of physical fitness, including standing long jump, 20-meter dash, and standing on one foot, from first grade students in 3 urban elementary schools. Chippaux-Smirak Index (CSI) and Staheli’s arch index (AI) were computed from foot prints and their association with physical fitness was studied using independent t test and correlation. Regression was used to identify the factors that could significantly explain physical fitness. Results. The two flatfoot indices computed from 829 children (mean age 6.7 years, SD 0.33) were in bimodal (two-peak) distribution, and the trough value was 0.55 in CSI and 1.0 in AI. When divided by the trough value, children with flatter feet had greater body mass index (BMI) and inferior one leg balance (p<0.05). Boys had greater BMI and more flatfeet than girls, but only girls with flatfeet showed inferior performance in fitness. The correlations between physical fitness and CSI, AI, BMI are very low. Regression revealed physical fitness could only be explained in a minimal amount by BMI after control of gender (r2= 0.02~0.09). Conclusion. The results may explain why flatfoot children presented with inferior physical fitness. However, correlation and regression are against flatfoot as a significant factor for physical fitness. By controlling age in a small range, the two flatfoot indices revealed that in child development there might exist two divergent groups of children. This characteristic is different from normal bell shaped distribution seen in other body measurements, and its physiological significance requires further longitudinal study.