Reliability and Sex Differences in the Foot Pressure Load Balance Test and Its Relationship to Physical Characteristics in Preschool Children

doi:10.4236/ape.2012.22008

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Advances in Physical Education

2012. Vol.2, No.2, 44-48

Published Online May 2012 in SciRes (http://www.SciRP.org/journal/ape) http://dx.doi.org/10.4236/ape.2012.22008

Reliability and Sex Differences in the Foot Pressure Load Balance

Test and Its Relationship to Physical Characteristics in Preschool

Children

Shigeki Matsuda1, Shinichi Demura2, Kosho Kasuga3, Hiroki Sugiura2

1Gifu Shotoku Gakuen Un i versity, Gifu, Japan

2Graduate School of Natural Science & Technology, Kanazawa Uni ver sity, Kanazawa, Japan

3Gifu University, Gifu, Japan

Email: [email protected], demura@ed.kanazawa-u.ac.jp, kasug [email protected],

[email protected]

Received April 1st, 2012; revised May 4th, 2012; accepted May 15th, 2012

This study aimed to examine the trial-to-trial reliability and sex differences in a foot pressure load balance

test and its relationship to physical characteristics in 396 preschool children (201 boys and 195 girls). The

subjects were asked to maintain an upright standing posture for 10 seconds three times on the Footview

Clinic, an instrument designed to calculate the right-left and anterior-posterior ratios of foot pressure load.

The ratios of the left and anterior foot pressure loads in right and left feet were selected as variables. In-

tra-class correlation coefficients between the second and third trials in all variables were high (intra-class

correlation coefficients = 0.70 - 0.90). The above variables showed insignificant sex differences and little

relationships with physique. When measuring foot pressure load balance, it is desirable to use a mean of

the second and third trials as a representative.

Keywords: Foot Pressure Load Balance; Preschool Children; Sex Difference; Reliability

Introduction

Toes play an important role in propelling the body forward

when walking and running and in maintaining posture while

standing (Hughes et al., 1990; Kulthanan et al., 2004; Chou et

al., 2009; Tanaka et al., 1996; Hutton & Dhanendran, 1979). In

the case of children’s toes, problems related to toe deformities

such as curly and overlapping toes are sometimes found (Asir-

vatham, 2001; Wenger & Leach, 1986). It was recently reported

that many young children in Japan have an “untouched-toe”,

referring to the case in which a toe does not touch the floor

while standing (Matsuda et al., 2009, 2011; Harada, 2001).

Harada (2001) reported that the rate of occurrence of untouched

toes in children was about 5% - 10 % in 1980, but the ratio

increased rapidly to about 50% in 2000. Although a child with

untouched-toes does not require surgery as with the case of curly

toes and other foot disorders (Asirvatham, 2001; Wenger &

Leach, 1986), a great deal of attention has been paid to this

condition because the rate of occurrence has increased so markedly

(Matsuda et al., 2009, 2011; Harada, 2001). A decrease in toe

use frequency along with decreases in movement mass, type of

shoes worn, and heel load etc. have been noted as factors re-

lated to the occurrence of untouched-toes (Harada, 2001), the

relationships between the above factors and the occurrence of

untouched-toes have not been examined.Above all else, because

heel load is considered to play a role in posture deterioration, it

is necessary to clarify the relationship between the occurrence

of untouched-toes and heel load. When evaluating heel load, it

is necessary to evaluate the anterior-posterior balance of foot

pressure load after dividing the foot pressure load into the ante-

ri or and posterior parts. However, because a method to adequa t e l y

evaluate the anterior-posterior balance of foot pressure load has

not been established, the relationship between the untouched-

toes and heel load has not been examined.

On the other hand, human’s body has functional asymmetries

such as a dominant hand, a dominant leg, and a dominant eye.

Previc (1991) stated that many people depend on the left side of

their bodies for posture maintenance because the left otolith

function, which is an organization related to balance sense in

inner ear, is superior to the right one. Because there is a large

possibility that there is also some asymmetry in foot pressure

load balance, the examination of the asymmetry is needed.

Recently , a device (The Foot view Clinic, Nitta, Japa n) designed

to measure the right-left and anterior-posterior balances of foot

pressure load was developed, thereby allowing foot pressure

load balance to be determined easily. We can examine the rela-

tionship between untouched-toes, anterior-posterior balance of

the foot pressure load and the asymmetry of the foot pressure

load through the use of this device. However, the human body

always sways while standing, measured values will also vary.

In addition, because young children are not always able to fully

understand the measurement procedure, many trials are needed

to get stable measured values. It is necessary to examine the

reliability of the measured values calculated by the above device.

Because the contact area of the soles of the feet is the area

supporting the body weight, foot pressure and sole shape are

affected by the body weight. The amount of pressure exerted on

the feet is greater for obese people than for people of a normal

body weight (Hills et al., 2001) and, accordingly, sole shape (e.g.

the prevalence of flat-footedness) differs between these two

groups. Hence, variables related to foot pressure load balance

may be affected by physique. If this is true, it will be nec essary

S. MATSUDA ET AL.

to examine whether the effect should be taken into consideration.

On the other hand, because foot pressure load balance in

young children has not been measured, possible sex differences

in their relevant variable have not been determined. Matsuda et

al., (2007) reported that the contact area and the middle part of

the foot width of preschool children are larger in boys than in

girls. Hence, sex differences may be found also in the foot pres-

sure load variables. This study aims to examine the trial-to-trial

reliability and sex difference in foot pressure load balance vari-

ables and their relationships to physique in preschool children.

Methods

Subjects

The subjects consisted of 396 preschool children aged 3 to 6

years (201 boys and 195 girls) who commute to two kindergar-

tens (Table 1).

The purpose and procedure of this study were explained to

the parents of participants in detail and informed consent was

obtained before the measurement. In addition, the consent of

the participants for the measurement was obtained at the time of

measurement. This experimental protocol was approved by the

Ethics Committee (Kanazawa University Health & Science

Ethics Committee).

Measurement Device

The Footview Clinic (Nitta, Japan) was used to measure the

foot pressure load balance. This device is designed to calculate

the right-left and anterior-posterior balances of foot pressure

load from the area of the foot that is contact with the device

during standing (Figure 1). The sampling frequency was 20 Hz.

The right-left and the anterior-posterior balances refer to the

proportion of pressure distribution between the left and right

foot (In a case of Figure 1: left foot 55 and right foot 45) and

the proportion of pressure distribution between the anterior and

posterior parts of foot (In a case of left foot in Figure 1: ante-

rior part 26 and posterior part 74), respectively. The line divid-

ing the foot into anterior and posterior parts was set at the cen-

ter of the foot length, which was defined as the distance from

the back of the heel to the front of the longest toe. The foot

length was calculated using a personal computer.

Measurement Procedure

The subjects stood barefoot on the measurement device with

Table 1.

Physical characteristics of subjects.

Age-3Age-4 Age-5 Age-6Total

n 16 58 55 72 201

Height MEAN 98.7 102.6 109.5 114.8109.8

(cm) SD 3.9 4.0 5.0 4.7 6.3

Body mass MEAN 15.8 16.8 19.0 20.519.2

Boys

(kg) SD 1.9 1.7 2.5 2.4 2.6

n 10 70 57 58 195

Height MEAN 98.0 103.3 108.2 115.2106.6

(cm) SD 3.0 3.6 4.8 4.2 7.3

Body mass MEAN 15.8 17.0 18.6 21.118.0

Girls

(kg) SD 1.6 1.8 2.6 2.3 2.8

Figure 1 shows the right- left and anterior-posterior balances of foot press ure load.

In case of Figure 1, the ratios of left foot pressure load, the anterior part of left

foot pressure load , and the anterior p art of the right foot pressure load are 55, 26,

and 37, respectively.

Figure 1.

Balance of the foot pressure load.

their feet 5 cm apart and their hands relaxed at the side of the

body. They were instructed to look at a mark located at eye-level

and to stabilize their posture for as long as possible during the

measurement. After confirming posture stability, a ten second

measurement was started. Each subject was measured three

times. Here it is important to note that some young children

were unable to maintain stable posture or were not able to con-

tinuously keep their eyes on the mark as directed. Such children

were excluded from this study in advance.

Evaluation Vari ables

It will be necessary to examine the relationship between the

anterior-posterior balance of the foot pressure load and untou-

ched-toes and the asymmetry in the foot pressure load in pre-

school children. Hence, the ratios of left foot pressure load (left

foot load), the anterior part of left foot pressure load (left-anterior

load), and the anterior part of the right foot pressure load (right-

anterior load) were selected as foot pressure load balance vari-

ables. Each of these variables refer to the ratios of the left foot

with respect to the right foot when consi dering the pressure loa d i n

both feet, the anterior part of the left foot in its pressure load,

and anterior part of the right foot in its pressure load, respect-

tively. Incidentally, the ratios of the right foot pressure load and

the posterior part of the left foot pressure load were defined as

the difference of the left foot load and 100 and the difference of

the left-anterior load and 100, respectively (Figure 1). The

means for a 10 second measurement in all variables were used

for analysis. The measurement device is also able to calculate

the total sway length. Because this variable adversely affects

the trial-to-trial reliability of the foot pressure load balance

variables, it was selected as a variable.

Statistical Analysis

Basic statistics of all variables in each trial were calculated.

To test mean differences between trials, one-way analysis of the

S. MATSUDA ET AL.

variance was used. If a significant difference was found, Tukey’s

HSD test was used for a multiple comparison test. Trial-to-trial

reliability was examined using intra-class correlation coeffi-

cients (ICC). ICC is widely used when examining the stability

of measured values between trials (Shrout & Fleiss, 1979; Landis

& Koch, 197 7). After selectin g a representat ive value, an un paired

t-test was used to test for a sex difference with respect to the

foot pressure load balance variables. Peason’s correlations were

calculated to examine relationships between the foot pressure

load balance variables and height, body mass, and BMI.BMI

(body weight/height2) was calculated by reference to Cole

(2000).The level of statistical significance was set at p < 0.05.

Results

Table 2 shows basic statistics, test results of mean differ-

ences between trials, and ICC for each variable. After testing

mean differences between trials,there were no significant dif-

ferences between the mean values for all trials for boys. How-

ever, the mean for girls was significantly higher in the first trial

than in the third trial for the left-anterior and right-anterior

loads. There was a significant difference in the mean of total

sway length between trials for both boys and girls in that it was

significantly higher in the first trial than in the second trial for

boys and significantly higher in the first trial than in both the

second and third trials for girls. After calculating ICCs to ex-

amine trial-to-trial reliability, ICC of the second and third trials

was the highest in all foot pressure load balance variables. ICCs

for boys and girls were 0.70 and 0.73 in left foot load, 0.90 and

0.87 in left-anterior load, and 0.86 and 0.85 in right-anterior

load, respectively.

The means of the second and third trials were used as repre-

sentative values of the foot pressure load balance variables in

subsequent analyses. After testing sex differences with respect

to the foot pressure load balance variables, there were no sig-

nificant sex differences in the foot pressure load balance vari-

ables (Table 3). When examining relationships between the

foot pressure load balance variables and physique, significant

correlations were found between left-anterior and/or right-anterior

loads a nd height and b ody mass in boy s, and between le ft-anterio r

load and BMI in girls, but their values were low (Table 4).

Discussion

The ratios of the left foot pressure load, and the pressure

loads of the anterior parts of the left and right feet were selected

as variables for the foot pressure load balance in this study.

Because the human body always sways while standing, meas-

ured values also vary. Foot pressure load balance variables

trial-to-trial reliability has not been examined. In addition, be-

cause some of the young children had trouble understanding the

measurement method, multiple trials were needed in order to

obtain stable measured values. Reliability between the second

and third trials was the highest for all foot pressure load balance

variables and their ICCs were over 0.7. Jackson et al., (1980)

judged that reliability is good when ICC is over 0.7. In addition,

significant differences between the first and third trials were

found in two foot pressure load balance variables in girls.

Namely, it was suggested that stable measured values could be

obtained after the second trial. Hence, foot pressure load bal-

ance in young children is required to measure more than two

trials and when measuring three trials, it may be adequate to use

the mean of the second and third trials as a representative value.

Based on the present results, the mean of the second and third

trials were used in this study. The total sway length showed

insignificant difference between the second and third trials but

was significantly longer in the first trial than in the second and

third trials (Table 3). Namely, it is inferred that bodily posture

is more unstable in the first trial than in trials after the second

one. Because this was the first time the subjects had their foot

pressure load balance measured, they may have been uneasy

and inexperienced at the first trial. It is inferred that they gradu-

ally got used to the measurement and could maintain a stable

posture after the second trial.

Three trials were performed in consideration of the effects of

fatigue. Hence, trial-to-trial reliability after the fourth trial is

unclear for the foot pressure load balance variables. Although

the subject’s unease and inexperience may decrease after the

fourth trial, there is a possibility that fatigue and practice effects

could affect measurement results.

On the other hand, in preschool children, the figure of the

contact area of the feet differed between boys and girls (Ma-

tsuda et al., 2007). Sex difference may be found also in the foot

pressure load balance variables. Hence, it was necessary to

confirm their difference. The present results did not show sex

differences in all foot pressure load balance variables. Hence,

data can be analyzed without having to distinguish between

which measurements came from of boys and girls.

It was reported that obese people experience greater foot

pressure and are more likely to have flat feet than people of a

normal weight (Hills et al., 2001; Riddiford-Harland et al.,

Table 2.

Basic statistics, test results of mean differences between trials, and ICC for each variable.

1st trial 2nd trial 3rd trial One-way ANOVAICC

M SD M SD M SD F p

Tukey’s

HSD 1-2 trials 1-3 trials2-3 trials

Boys Left foot load 50.0 6.8 50.6 7.3 50.6 7.1 1.20 0.30 0.62 0.60 0.70

Left-anterior load 31.3 10.6 30.8 11.0 30.7 11.6 1.02 0.36 0.85 0.81 0.90

Right-anterior load 33.9 11.2 33.7 11.7 33.5 12.5 0.32 0.70 0.85 0.76 0.86

Total sway length 14.7 4.8 13.9 4.8 14.3 5.6 3.81 0.03 1 > 2 0.66 0.59 0. 63

Girls Left foot load 51.5 6.2 51.6 5.8 51.9 6.6 0.48 0.62 0.67 0.57 0.73

Left-anterior load 31.7 11.0 30.9 11.0 30.5 10.9 3.48 0.04 1 > 3 0.81 0.80 0.87

Right-anterior load 35.3 11.7 34.4 12.7 33.8 12.0 4.74 0.01 1 > 3 0.85 0.78 0.85

Total sway length 13.2 5.0 12.5 5.1 12.3 5.8 5.88 0.00 1 > 2, 3 0.74 0.76 0.79

S. MATSUDA ET AL.

Table 3.

Sex differences in foot pressure load balance va riables.

Boys Girls t p

MEAN 50.6 51.7 –1.76 0.08

Left foot load SD 6.7 5.8

MEAN 30.7 30.7 0.06 0.42

Left-anterior load SD 11.0 10.6

MEAN 33.6 34.1 –0.42 0.73

Right-anterior load SD 11.6 11.9

Table 4.

Relationships be tween foot pre ssure load bala nce variables and p hysique.

Boys Girls

Height Body

mass BMI Height Body

mass BMI

r –0.09 –0.10–0.04 0.07 0.02–0.07

Left foot

load p 0.21 0.14 0.54 0.35 0.730.32

r –0.16* –0.130.03 0.00 0.070.15*

Left-anterior

load p 0.02 0.08 0.71 0.96 0.330.03

r –0.17* –0.17*–0.05 0.07 0.120.12

Right-anterior

load p 0.01 0.01 0.45 0.32 0.090.11

Note: *p < 0.05.

2010; Mickle et al., 2006). Because body mass or BMI affects

foot pressure load and the shape of the contact area of the foot

sole, it was hypothesized that foot pressure load balance vari-

ables are affected by physique. Although height, body mass,

and BMI showed significant correlations with foot pressure

load balance variables, their relationships were very low. Hence,

it was judged that physique affects little foot pressure load balance.

The number of young children with an untouched-toe has in-

creased in Japan (Matsuda et al., 2009, 2011) and heel load has

been cited as one of the many factors related to it. If the rela-

tionship between the untouched-toe and heel load is clarified, a

better understanding of why its occurrence has recently in-

creased may be obtained.

Humans have some functional asymmetries (Dittmar, 2002)

with the lower limbs being divided into a supported-leg (which

supports the body) and a functional-leg which has superior

manipulation abilities (Peters, 1988). However, the upper limbs

as compared with the lower limbs have clear asymmetry. In

addition, the functional asymmetry of the lower limbs has not

been thoroughly studied. Because of the present results, it now

possible to examine the asymmetry of the foot pressure load

balance. It will be needed to examine the age difference of the

foot pressure load balance variables, the relationships between

the variables and posture, the shape of the contact area of the

foot sole, and so on in the future.

Conclusion

This study examined the trial-to-trial reliability, sex differ-

ence in the foot pressure load balance variables and their rela-

tionship with physique in preschool children aged 3 to 6 years

(201 boys and 195 girls). Significant differences between the

second and third trials were not found in any of the foot pres-

sure load balance variables and their intra-class correlation co-

efficients were high (intra-class correlation coefficients = 0.70 -

0.90). The above variables showed no sex differences and little

relationship with physique. The measurement of the foot pres-

sure load balance is desirable to conduct more than two trials

and it may be adequate to use a mean of the second and third

trials as a representative value when performing three trials.

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