Relationship between Untouched-Toes and Heel Load in Preschool Children

doi:10.4236/ape.2013.34027

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Advances in Physical Education

2013. Vol.3, No.4, 165-168

Published Online November 2013 in SciRes (http://www.scirp.org/journal/ape) http://dx.doi.org/10.4236/ape.2013.34027

Open Access 165

Relationship between Untouched-Toes and Heel Load in

Preschool Children

Shigeki Matsuda1, Shinichi Demura2, Kosho Kasuga3, Hiroki Sugiura4

1Gifu Shotoku Gakuen University, Gifu, Japan

2Kanazawa University, Kanazawa, Japan

3Gifu University, Gifu, Japan

4Fukui Prefectural University, Fukui, Japan

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

[email protected]

Received September 6th, 2013; revised October 6th, 2013; accepted October 13th, 2013

Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the

original work is properly cited.

Although the number of children with untouched-toes, which do not touch the floor while standing, is in-

creasing in Japan, the cause of untouched-toes and its effect on the body have been rarely investigated.

This study aims to examine the relationship between untouched-toes and heel load in preschool children.

The subjects were 691 preschool children aged 4 - 6 years (328 boys and 363 girls). The contact surface

area of the soles of the feet was pictured to evaluate the untouched-toes. The posterior foot pressure ratio

in both feet was used to evaluate the heel load. During the entire childhood period, the posterior foot

pressure ratio was significantly larger in children with over two untouched-toes than in children without

untouched-toes for the left foot, and in children with over two untouched-toes than in children without

untouched-toes and with one untouched-toe for the right foot. In addition, this ratio was significantly lar-

ger in children aged 4 years than in children aged 6 years for the left foot, and in children aged 4 years

than in children aged 5 and 6 years for the right foot. In conclusion, children with over two un-

touched-toes tend to have greater heel load than children without untouched-toes.

Keywords: Foot Shape; Untouched-Toes; Foot Pressure Load; Heel Load; Posture; Children

Introduction

Untouched-toes are the toes that do not touch the floor during

normal standing. Recently, it has been reported that the number

of children with untouched-toes is increasing in Japan (Harada,

2001; Uchida et al., 2001; Matsuda et al., 2009, 2011a). Toes

are an important component in supporting the body and play a

central role in maintaining the body’s balance when standing

and initiating walking movements (Chou et al., 2009). Consid-

ering the role of toes, untouched-toes may have a negative ef-

fect on the body and physical activity. However, the cause of

untouched-toes and its effect on the body have been rarely in-

vestigated.

Physique, physical fitness, balance ability, shoes, heel load,

exercise quantity, and usage frequency of toes have been noted

as factors related to untouched-toes (Harada, 2001; Uchida et

al., 2001). Previous examination of the relationships between

untouched-toes and physique, physical fitness, and balance

ability indicates that there is little relationship between these

three factors (Chou et al., 2009; Matsuda et al., 2010, 2011b).

The relationship between untouched-toes and the quantity of

outdoor exercise has also been examined, and it was reported

that children who belonged to a nursery with more outdoor

exercise had fewer cases with untouched-toes.

Uchida et al. (2002) noted that the heel load, in which the

center of gravity is in a posterior position, is a primary reason

for untouched-toes and Harada (2001) pointed out the same as

one of the reasons for untouched-toes. The magnitude of toe

pressure while standing is affected by the change of the position

of the center of gravity; the more posterior the position is, the

smaller the toe pressure becomes (Fujiwara et al., 1984). Hence,

there may be a relationship between the untouched-toes and

heel load; however, this relationship has been rarely examined.

This study aims to examine the relationship between the un-

touched-toes and heel load in preschool children.

Methods

Subjects

The subjects consisted of 691 preschool children aged 4 - 6

years (328 boys and 363 girls). Table 1 shows the number of

subjects and their physical characteristics. Children were re-

cruited from two kindergartens located in Gifu and Yamagata

cities, Gifu, Japan. The population of Gifu (city) and Yamagata

is approximately 410,000 and 30,000, respectively.

The purpose and procedure of this study were explained to

the subject’s parents in detail and informed consent was ob-

tained before the measurement.

In addition, the consent of the participants for the measure-

ment was obtained at the time of measurement. This experi-

mental protocol was approved by the Ethics Committee on

Human Experimentation of Faculty of Human Science, Kana-

zawa University (2012-05).

S. MATSUDA ET AL.

Table 1.

Number of subjects and their physical characteristics.

Age-4 Age-5 Age-6Total

n 127 101 100 328

Height MEAN 102.8 109.3 115.4 108.6

(cm) SD 4.1 4.7 4.7 6.9

Body mass MEAN 15.7 16.9 19.0 18.8

Boys

(kg) SD 1.6 1.8 2.4 2.8

n 145 127 91 363

Height MEAN 102.3 109.3 114.0 107.7

(cm) SD 4.3 4.1 6.3 6.8

Body mass MEAN 15.4 16.7 18.9 18.4

Girls

(kg） SD 1.4 2.0 2.4 2.7

Measurement Methods

Anterior-Posterior Foot Pressure Ratio

The heel load was evaluated by calculating the anterior-pos-

terior foot pressure ratio. This ratio refers to the pressure dis-

tribution between the anterior and posterior parts of the foot. In

the case of the left foot illustrated in Figure 1, the anterior and

posterior ratios are 26% and 74%, respectively. The line divid-

ing the foot into the anterior and posterior parts was formed at

the center of the foot length, which is defined as the distance

from the back of the heel to the front of the longest toe.

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

anterior–posterior foot pressure ratio. This measurement device

can calculate the anterior-posterior foot pressure ratio of each

foot using all foot pressures obtained from the area of the foot

that is in contact with the device while the subject is in a stand-

ing position (Figure 1). For the purposes of the present study,

the sampling frequency was 20 Hz.

The anterior-posterior foot pressure ratio was measured us-

ing a previously described method (Matsuda et al., 2012; Ma-

tsuda & Demura, 2013). The subjects stood barefoot on the

Footview Clinic measurement device, with their feet 5 cm apart

and their hands relaxed at the side of the body. Before the

measurement of the anterior-posterior foot pressure ratio, a

stationary picture of the contact area of the sole of the foot was

recorded using the device to obtain their foot length, which was

necessary for analysis. Because of the fact that some children

were unable to touch their toes, a tester pushed the subject’s

toes downward temporarily during the recording of the station-

ary picture. Subsequently, a 10-s measurement was initiated

after the tester confirmed that the child’s posture was stable.

The subjects were instructed to look at a mark located at eye-

level and to remain still as long as possible during the meas-

urement. Each subject was measured three times.

In addition, it is important to note that some young children

could not maintain a stable posture or continuously keep their

eyes on the mark as directed. Such children were excluded from

this study in advance.

Contact Surface Area of the Sole

A pedoscope (Sakamoto, Japan) was used to record the con-

tact surface area of the soles of the subjects’ feet, which was

used for the analysis of untouched-toes. The subjects stood in

the same posture as that for the measurement of the anterior-

Figure 1.

Anterior-posterior foot pressure ratio.

posterior foot pressure ratio. After a tester confirmed the sub-

ject’s postural stability, a picture of the contact surface area of

the soles of their feet was recorded. Each subject was sequen-

tially measured five times while standing. Untouched-toes are

defined as the toes that did not emerge in more than four pic-

tures among the five recorded pictures.

Evaluation Variables

The posterior foot pressure ratio was selected as a variable to

evaluate the heel load, and the mean of a 10-s measurement was

used for analysis. It was reported in a previous study that the

second and third trials have high reliability (Matsuda et al.,

2012); therefore, they were used for this analysis.

The number of untouched-toes in both feet was selected as a

variable to evaluate the untouched-toes. Three groups were

established on the basis of the number of untouched-toes: a

group without untouched-toes, a group with one untouched-toe,

and a group with two or more untouched-toes. When a group

with three or more untouched-toes was established, the number

of the subjects in this group was extremely small in comparison

with the other groups. Hence, only the above three groups were

formed.

Statistical Analysis

Trial-to-trial reliability was examined using intraclass corre-

lation coefficient (ICC). A two-way analysis of variance

(ANOVA) was used to test the mean differences among the

groups according to different number of untouched-toes and

age (4 - 6 years) in the posterior foot pressure ratio. Owing to

the fact that a significant age difference in the posterior foot

pressure ratio of preschool children has been documented (Ma-

tsuda et al., 2012), the factor of age was set as an independent

factor. If a significant difference was found in the main effect

or interaction, Tukey’s honestly significant difference test was

used for a multiple comparison test. In addition, because there

were no sex differences in the number of untouched-toes and

posterior foot pressure ratio in this study as well as previous

studies (the number of untouched-toes: t = 1.77, p = .08; foot

pressure ratio (right foot): t = −.89, p = .38; (left foot): t = .25, p

= .80) (Matsuda et al., 2009, 2012), the combined data of boys

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S. MATSUDA ET AL.

Open Access 167

and girls were used for the above analysis. When a significant

difference was found, the effect size was calculated to examine

the size of the mean difference. The level of statistical signifi-

cance was set at p < .05.

Results

Intraclass correlation coefficients (ICC) for the posterior foot

pressure ratio were .88 and .86 for the left and right feet, re-

spectively. Table 2 shows the results of the two-way ANOVA

and a multiple comparison test for the posterior foot pressure

ratio. Significant differences among the means of the groups

according to different number of untouched-toes and age were

found in both feet. The posterior foot pressure ratio was sig-

nificantly larger in children aged 4 years than in children aged 6

years for the left foot and in children aged 4 years than in chil-

dren aged 5 years and 6 years for the right foot. The effect sizes

were .36 for the left foot, and .22 in children aged between 4

and 5 years and .44 between 4 and 6 years for the right foot.

Regarding the number of individuals with untouched-toes, the

posterior foot pressure ratio was significantly larger in the

group with over two untouched-toes than in the group without

untouched-toes for the left foot and in the group with over two

untouched-toes than in the groups without untouched-toes and

with one untouched-toe. The effect size was .32 for the left foot,

and .39 between the groups with over two untouched-toes and

the group without untouched-toes for the right foot, and .33

between the groups with two untouched-toes and the group

with one untouched-toe for the right foot.

Discussion

Matsuda et al. (2012) reported that the ICC between the sec-

ond and third trials was high, with a value of .85 for the ante-

rior-posterior foot pressure ratio in preschool children. This was

consistent with the result in our study (.88, .86). Hence, the

reliability of data used in this study is considered to be high.

Although the heel load has been noted as one of the factors

related to the occurrence of untouched-toes (Harada, 2001;

Uchida et al., 2002), the relationship between them has not

been examined. This study evaluated the heel load by calculat-

ing the anterior-posterior foot pressure ratio on the basis of the

line that was established at the center of the foot length and

examined the above relationship. During the entire childhood

period, the posterior foot pressure ratio was significantly larger

in children with over two untouched-toes than in children with-

out untouched-toes and with one untouched-toe. Therefore, it is

considered as one of the reasons of this result that the load of

the toes decreased largely by having over two untouched-toes.

In addition, posture may be related to the present result. Fu-

jiwara et al. (1984) examined the relationship between the ante-

rior-posterior position of the center of gravity and toe pressure

when posture changed from posterior inclination to anterior

inclination. As a result, it was reported that the more anterior a

posture was, the more anterior the position of the center of

gravity was and the larger the toe pressure was. Hence, the

posture of children with over two untouched-toes may be of a

more posterior inclination than that of children without un-

touched-toes. A posterior inclination in the standing posture

induces an increase of muscle activity in the tibialis anterior

muscle, which contains more fast muscle fibers, and is consid-

ered unfit for postural maintenance. In addition, it is considered

that a posterior inclination imposes an inappropriate burden on

other antigravity muscles and has a negative effect on postural

maintenance. The deterioration of posture is noted as a physical

problem of modern young children in Japan (The national net-

work of physical and mental health in Japanese children, 2009).

Untouched-toes may have some relationship with postural in-

clination and the problem regarding postural deterioration. In

future studies, it will be necessary to examine the above prob-

lems.

Matsuda & Demura (2013) reported that the posterior foot

pressure ratio decreases with age in young children. The present

result had a tendency similar to the above previous study. Fur-

ther, in studies that examined an age-related change in the ante-

rior-posterior position of the center of gravity, it was reported

that the position moves anteriorly from childhood to adulthood

Table 2.

Results of the two-way ANOVA and a multiple comparison test for the posterior foot pressure ratio.

Age-4 Age-5 Age-6 Two-way ANOVA

U-toes

U-toe

Over 2

U-toes

U-toe

Over 2

U-toes

U-toe

Over 2

U-toes Age Num

er of

U-toes Interaction

Tukey’s

HSD

(ES)

n 103 65 104 105 49 74 72 50 69

M 70.8 69.1 73.0 68.4 69.6 71.6 63.7 69.4 69.5F5.317.29 1.97

Age-4 >

Age-6

(.36)

The posterior

foot pressure

ratio in the left

foot SD 10.1 12.0 10.4 12.1 11.0 10.3 12.4 11.69.8 p.01*.00* .10

over 2

U-toes >

0 U-toes

(.32)

M 68.4 68.6 72.2 66.3 65.5 70.0 61.1 65.4 67.9F9.6410.84 .90

Age-4 >

Age-5,

Age-6

(.22, .44)

The posterior

foot pressure

ratio in the right

foot SD 11.7 11.9 10.2 13.2 10.59.8 14.2 12.9 10.0p.00*.00* .46

over 2

U-toes >

1 U-toe,

0 U-toes

(.39, .33)

Noe: U-toe: Untouched-toe, M: Mean, SD: Standard deviation, *p < .05, ES: Effect size. t

S. MATSUDA ET AL.

(Kojima & Takemori, 1980; Usui et al., 1995). Hence, it is

considered that children with over two untouched-toes had a

different tendency from general ones on the development proc-

ess of foot pressure.

In this study, three groups according to the number of un-

touched-toes were formed because of the limit of the number of

subjects. Considering the present results, there is a possibility

that the greater the number of untouched-toes is, the more

marked the tendency of heel load becomes. In addition, it has

been reported that an untouched-toe occurs predominantly in

the fifth toe (Matsuda et al., 2009). If a group having over three

untouched-toes is formed, the effect of the number of un-

touched-toes on the heel load may become notable because it

comprises a group of children with untouched-toes other than

the fifth toe. In future studies, an examination similar to the

present study will be necessary after increasing the number of

subjects and establishing a group with over three untouched-

toes. In addition, the effect of untouched-toes on the heel load

may differ by the part of the untouched-toes. Although the

above effect could not be examined in this study because of the

limit of the number of subjects, it will be necessary to examine

the above effect in future.

Although the relationship between the untouched-toes and

heel load was examined in this study, the movement mass and

type of shoes worn have also been noted as factors related to

the occurrence of untouched-toes (Harada, 2001; Uchida et al.,

2002). To clarify the cause of untouched-toes and its effect on

the body, it will be necessary to examine the above problem.

Conclusion

In conclusion, this study examined the relationship between

the untouched-toes and heel load by studying 691 preschool

children (328 boys and 363 girls) aged 4 - 6 years. Children

with over two untouched-toes have heel loads higher than chil-

dren without untouched-toes. Because the posterior foot pres-

sure ratio decreases with age in young children, the heel load

related to the untouched-toes may not be desirable in terms of

age-related change of foot pressure.

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