Abstract
[Purpose] To investigate the relationship between footwear characteristics and motor development in toddlers walking independently. [Participants and Methods] A total of 13 toddlers (mean age: 26.5 ± 4.5 months) were included. Footwear characteristics, including size, presence of a heel counter, and flex point alignment, were assessed. Motor development was evaluated using the Enjoji Analytical Developmental Test. [Results] Improperly fitted footwear was frequently observed. A significant positive correlation was identified between appropriately sized footwear and locomotor development. [Conclusion] These findings underscore the importance of correctly fitted footwear to support optimal motor development in toddlers.
Keywords: Toddlers, Footwear, Locomotor development
INTRODUCTION
Early childhood is a critical period of human development, characterized by rapid progress across multiple developmental domains. Understanding the factors that influence this stage and providing targeted support are essential for promoting optimal growth and long-term well-being. Recent studies increasingly indicate that environmental and physical factors, such as footwear, play a crucial role in early development. Proper footwear for toddlers is hypothesized to require appropriate sizing, a heel counter (HC), flexibility at the ball of the foot, and secure fasteners1). Such footwear is believed to support not only foot health and growth but also overall developmental outcomes.
Despite these considerations, limited research has examined whether toddlers wear appropriate footwear in daily life. Moreover, few studies have explored the association between footwear appropriateness and early childhood development.
In this study, we investigated the characteristics of footwear worn by toddlers who had acquired independent walking, specifically assessing size, the presence of an HC, flexibility, and fasteners. Additionally, we examined the association between footwear size appropriateness and developmental outcomes assessed using the Enjoji Analytical Developmental Test.
PARTICIPANTS AND METHODS
The participants were enrolled from multiple daycare centers operated by a corporation in Nagoya City, Japan. Eligible participants were toddlers aged 1–2 years who had achieved independent walking and engaged in daily walking activities. Exclusion criteria included the presence of developmental disorders, such as autism spectrum disorder or attention deficit hyperactivity disorder, intellectual disabilities, neurological diseases, and orthopedic conditions. This study was conducted in accordance with the principles of the Declaration of Helsinki. The purpose and methods of the study were thoroughly explained to the parents or guardians, and informed consent was obtained before participation. The study protocol was approved by the Ethics Committee of Tokyo University of Technology (approval number: E22HS-021).
To evaluate the developmental status of the toddlers and the characteristics of their footwear, the following procedures were conducted. The developmental status of participants was assessed using the Enjoji Analytical Developmental Test, which comprehensively evaluates child development across motor skills (locomotor and manual movements), social skills (basic habits and interpersonal relationships), and language skills (speech and language comprehension)2). Previous studies have demonstrated its reliability and validity in assessing developmental milestones in young children2). In this study, daycare teachers who routinely cared for the participants conducted these assessments. To enhance inter-rater reliability, all assessors received prior training on the standardized application of the test. Subsequently, the difference between the chronological and developmental ages of participants in each domain, as assessed using the Enjoji Test, was calculated (hereafter referred to as the “developmental age discrepancy”).
Participants were seated with their hip and knee joints flexed at 90°. Using a foot gauge, the linear distance from the heel point to the tip of the longest toe (either the first or second toe) was measured (Fig. 1a). The average lengths of the left and right feet were then calculated. The insole was removed from each shoe, and the straight-line distance between the heel point and the tip of the toe of the insole was measured (Fig. 1b). The flexion point of the shoe should align with the ball of the foot (the base of the toes)1), a key indicator in footwear selection. Proper alignment is essential for toddlers to achieve and maintain a natural walking pattern. The flexion point was assessed by a physical therapist with more than 10 years of experience, who applied a dorsally directed bending force to the forefoot of the shoe. The shoes were evaluated on a three-point scale: “flexes anywhere”, “flexes only at the ball flexion line”, and “does not flex”.
Fig. 1.
Methods for measuring the foot (a) and sole (b) lengths.
a: Linear distance from the heel point to the tip of the longest toe (either the first or second toe). b: Linear distance from the backmost point to the foremost point of the insole.
The heel counter (HC) is an essential support feature of toddler footwear, providing stability to the heel. The presence or absence of an HC was determined by fixing the shoe’s rear section with both hands and pressing the HC with a finger to evaluate firmness. Shoes were classified as “HC present” if rebound force was detected and as “HC absent” if no rebound force was detected and the rearfoot section of the shoe deformed under pressure. Fasteners were classified as “present” if the shoes had laces or Velcro straps and as “absent” if these features were not present.
The association between foot length and insole length was analyzed using Spearman’s rank correlation coefficient. For variables that showed significant correlations in the Spearman analysis, a quadratic regression model was applied to explore potential non-linear relationships. Statistical analyses were performed using SPSS statistical software (version 27.0, IBM), with statistical significance set at p<0.05.
RESULTS
A total of 13 participants were enrolled in this study, with a mean chronological age of 26.5 ± 4.5 months (Table 1). The mean foot length was 13.6 ± 0.8 cm, whereas the mean insole length was 14.2 ± 1.1 cm. The difference between foot length and insole length was 0.6 ± 1.0 cm.
Table 1. Characteristics and results of the Enjoji Analytical Developmental Test.
| Characteristics | |
| Participants (n) | 13 |
| Height (cm) | 85.0 ± 5.0 |
| Weight (kg) | 11.7 ± 1.2 |
| Mean chronological age (months) | 26.5 ± 4.5 |
| Mean foot length (cm) | 13.6 ± 0.8 |
| Mean insole length (cm) | 14.0 ± 1.1 |
| Difference between foot and insole length (cm) | 0.5 ± 1.0 |
| Enjoji Analytical Developmental Test | |
| Locomotor movements (months) | 26.4 ± 6.0 (−0.2 ± 3.2) |
| Manual movements (months) | 26.0 ± 7.8 (−0.5 ± 6.0) |
| Basic habits (months) | 24.3 ± 6.1 (−2.1 ± 3.3) |
| Interpersonal relationships (months) | 27.5 ± 5.0 (1.2 ± 6.0) |
| Speech (months) | 23.5 ± 7.0 (−3.0 ± 5.5) |
| Language comprehension (months) | 25.3 ± 6.0 (−1.4 ± 5.9) |
Values are presented as mean ± standard deviation (mean age discrepancy ± standard deviation).
The results of the Enjoji Analytical Developmental Test indicated the following mean developmental ages (± standard deviation [SD]) and mean age differences (± SD) for each domain:
-Locomotor movements: 26.4 ± 6.0 months (age difference: −0.2 ± 3.2 months)
-Manual movements: 26.0 ± 7.8 months (age difference: −0.5 ± 6.0 months)
-Basic habits: 24.3 ± 6.1 months (age difference: −2.1 ± 3.3 months)
-Interpersonal relationships: 27.5 ± 5.0 months (age difference: 1.2 ± 6.0 months)
-Speech: 23.5 ± 7.0 months (age difference: −3.0 ± 5.5 months)
-Language comprehension: 25.3 ± 6.0 months (age difference: −1.4 ± 5.9 months).
Statistical analyses did not identify a significant association between foot length and insole length (Spearman correlation coefficient: r=0.12, p>0.05). Among the evaluated footwear, 36% (five pairs) had the flex point at the ball flex line, while 64% (nine pairs) were classified as having overall soft soles. Additionally, 50% (seven pairs) had an HC, whereas 50% (seven pairs) lacked an HC. Fasteners were present in 93% (13 pairs) of the footwear samples and absent in 7% (one pair) (Table 2).
Table 2. Footwear characteristics.
| Footwear characteristics | Number (n=14) | Percentage (%) |
| Flexes at ball flex line | 5 | 36 |
| Overall soft sole | 9 | 64 |
| HC present | 7 | 50 |
| HC absent | 7 | 50 |
| Fastener present | 13 | 93 |
| Fastener absent | 1 | 7 |
HC: heel counter.
The correlation analysis indicated a significant positive association between the difference in shoe size and foot length, while locomotor movement was the only developmental domain that showed a significant positive correlation (r=0.61, p<0.05). No significant associations were found for the other developmental domains (Table 3). Additionally, a quadratic regression analysis was conducted to investigate a potential U-shaped relationship between shoe–foot length difference and locomotor development. However, this analysis did not reveal a significant U-shaped association.
Table 3. Correlation between the difference in shoe and foot size and the Enjoji Analytical Developmental Test.
| Enjoji Analytical Developmental Test | r | Significance |
| Locomotor movements (months) | 0.61 | * |
| Manual movements (months) | 0.41 | |
| Basic habits (months) | 0.49 | |
| Interpersonal relationships (months) | −0.07 | |
| Speech (months) | 0.44 | |
| Language comprehension (months) | 0.17 |
r: Spearman’s correlation coefficient. *p<0.05. n.s.: not significant
DISCUSSION
This study aimed to explore the association between footwear characteristics and motor development in toddlers who had achieved independent walking. To achieve this, we examined footwear attributes such as size, the presence of a HC, flex point alignment, and fasteners alongside motor development. Additionally, we analyzed the correlations between differences in shoe size, foot length, and developmental outcomes. The findings did not indicate a significant association between foot and insole lengths. Moreover, a substantial proportion of the footwear failed to align the flex point with the ball flex line, and half of the evaluated shoes lacked an HC. These results suggest potential inadequacies in the design or selection of footwear commonly used by toddlers. Correlation analysis indicated a significant positive association between shoe size and foot length, while developmental domains assessed using the Enjoji Analytical Developmental Test showed a significant positive correlation exclusively with locomotor movements. However, correlation does not imply causation, and further research is needed to clarify the nature of this relationship. No significant associations were observed for the other developmental domains. These findings suggest that appropriate footwear sizing may be beneficial for locomotor development; however, its influence on other developmental domains appears to be minimal.
The lack of a significant correlation between foot and insole lengths suggests that toddlers often wear improperly sized shoes, either excessively large or too small. Ideally, shoes should provide sufficient room in the forefoot area to allow free toe movement1). For adults, an excess space of more than 20 mm is considered excessive3), and a typical allowance of 10–15 mm is recommended. However, for a child with a foot length of 150 mm, an allowance of 15 mm would correspond to approximately 10% of the foot length. Shoes that are excessively large relative to foot size can reduce walking efficiency and increase effort during walking5). Conversely, shoes that are too small may result in toe injuries or hinder foot growth. Ochiai et al.1) reported that the ideal allowance for children’s shoes is approximately half the width of the toe, whereas Sato et al.4) suggested that 5–6 mm of extra space in the forefoot provides an optimal fit. Based on these recommendations, it is likely that approximately half of the toddlers in our study were wearing improperly sized shoes. Additionally, approximately half of the participants used shoes without an HC or with overly flexible soles, which may negatively affect gait mechanics. The HC is essential for maintaining heel stability during walking and weight-bearing activities, whereas overly flexible soles have been reported to reduce walking speed efficiency5). These findings suggest that toddlers may frequently wear footwear that does not adequately stabilize the heel during walking or support efficient walking speeds.
A significant positive association was observed between the difference in shoe size and foot length and locomotor movement. The mean age of the participants was 27.4 ± 4.5 months, and locomotor tasks in the Enjoji Analytical Developmental Test at this age include independent walking, running, ascending and descending stairs while holding onto a railing, and jumping with both feet off the ground simultaneously. Successfully performing these tasks requires dynamic lower limb movements, including toe mobility.
When the difference between shoe size and foot length is small, toe movement may be restricted, potentially resulting in lower locomotor domain scores in the Enjoji Test. However, as this study employed a cross-sectional design, it remains unclear whether the relationship between footwear size appropriateness and development changes over time. Additionally, although the significant positive correlation suggests that a larger difference between shoe size and foot length may be linked to higher locomotor scores, excessively large shoes, as previously discussed, could negatively impact motor abilities by reducing walking efficiency or causing instability. Further research with a larger sample size is necessary to better understand these relationships and determine whether an optimal shoe size range exists.
The present study investigated the relationship between footwear characteristics and motor development in toddlers who had achieved independent walking. The findings indicate that many toddlers frequently wore footwear that did not align with recommended fit criteria, particularly regarding size, the presence of an HC, and flex point alignment. Additionally, a significant positive association was observed between appropriate footwear size and locomotor development, underscoring the potential importance of selecting properly fitted footwear for toddlers.
In contrast, no significant correlations were found in other developmental domains, such as manual movements, basic habits, interpersonal relationships, speech, or language comprehension. The factors influencing these domains may differ from those affecting locomotor development. For instance, language and social development are primarily shaped by environmental factors such as caregiver interactions and early learning experiences, rather than physical factors such as footwear fit. In addition, we conducted a quadratic regression analysis to examine the potential for a U-shaped relationship between shoe–foot length difference and locomotor development; however, this analysis did not reveal any significant U-shaped association. Given these limitations—particularly the small sample size, which may have reduced the statistical power to detect associations in some developmental domains—and the cross-sectional design, caution must be exercised when interpreting these findings.
Conference presentation
This study was based on data presented at the 11th Annual Meeting of the Japanese Society of Pediatric Physical Therapy.
Conflicts of interest
The authors declare that there are no conflicts of interest relevant to this study.
REFERENCES
- 1.Ochiai T, Yamada T, Suzuki H: Shoes suitable for children. MB Orthop, 2018, 31: 15–22. [Google Scholar]
- 2.Kurokawa T, Moriyama Y, Nishimura K: On the Enjoji Analytical Developmental Test for infants. Cogn Neurosci, 2021, 23: 45–51. [Google Scholar]
- 3.Nakamura Y, Tanaka K, Suzuki K: Basic knowledge of footwear and orthoses for foot disorders. J Jpn Foot Care Soc, 2019, 17: 1–6. [Google Scholar]
- 4.Sato M, Tanaka I, Takahashi A: Development of children’s feet and children’s footwear. Kawa Hakimono, 2008, 145: 2–6. [Google Scholar]
- 5.Akimoto M, Takahashi Y, Kimura M: Effects of oversized shoes on children’s gait. Life Support, 2015, 27: 3. [Google Scholar]