Effects of obesity on dynamic plantar pressure distribution in Chinese prepubescent children during walking☆
Highlights
► We compare the gait between obese and non-obese children with larger sample size. ► We use a precise and comprehensive dynamic plantar pressure measurement system. ► The obese children have weaker walking stability and the larger foot axis angle. ► The obese children have dynamic plantar pressure distribution changes. ► The obese children have differences in foot balance compared to non-obese children.
Introduction
The concern of childhood obesity is one of international issues and an area of medical practice demanding further research. Obesity is associated with numerous health problems such as dyslipidemia, hypertension, and type II diabetes [1]. Obesity is also associated with orthopedic problems due to the overload on musculoskeletal structures. Especially for children and adolescents who are growing rapidly, overweight and obesity will negatively affect the normal development of their bones, muscles and joints. Childhood obesity is reported to have a detrimental impact on biomechanical parameters of children's gait [2]. Gait analysis in obese children showed the changes of spatiotemporal parameters similar to those in obese adults, with longer gait cycle [3], stance phase duration and reduced cadence [2], [3], [4]. Nantel et al. [5] analyzed the kinetic characteristics of locomotion in obese children and found a greater amount of mechanical energy involved during locomotion in obese children when compared with their normal-weight counterparts. The reduction of the postural stability limited the progression velocity of the obese adolescents [6].
Feet, as the body's base of support, often endure ground reaction forces during daily activities. Obese children were at an increased risk of developing foot discomfort and/or foot pathologies due to increased plantar loads. Furthermore, continual bearing of excessive mass by children appears to flatten the medial midfoot region during walking [7]. Hills and Parker [3] also reported flatter foot pattern at heel contact. Some studies examined the effects of obesity on foot structure [8], [9], plantar pressure patterns [9] and plantar pressure distribution [3], [10] in prepubescent children. They have found that obese children displayed lower footprint angle values and higher Chippaux-Smirak index values and generated higher plantar pressures in the medial midfoot and forefoot regions compared to their non-overweight counterparts. However, a previous study [11] found that the obese children generated higher peak pressure and force in all anatomical areas except medial toes. Though higher pressure and force have been found in different foot regions, people speculated that higher plantar pressures may increase loading on the developing foot, resulting in foot discomfort and possibly deformity [9].
At present, there are 12 million children and adolescents in China who are overweight and obese. The percentage of obese children is approximately 10%, and is increasing with 8% per year [12]. Obesity has already become a major problem affecting the health of children in China. Previous studies have been conducted to assessing dynamic and static postural stability in obese children [13]. Kinematic parameters, including gait cycle, stride length, stride speed, stride frequency and joint angle [14], [15], [16], and plantar pressure distribution variables [15], [16] such as peak plantar pressure, impulse percentage in obese children have been also investigated.
The results of previous studies with small sample size may not reflect true plantar pressure distribution characteristics of obese children, thus further comprehensive researches pertaining to the effects of obesity in children on plantar pressure distribution with larger sample sizes are warranted to ascertain if higher plantar pressures in some regions are typical for obese children. In addition, it is important to identify if higher foot pressures in different locations have implications for foot deformities to be likely developed.
This study was to compare the dynamic plantar pressure distribution during walking at their preferred speed between obese and non-obese prepubescent children with relatively larger sample size by using a precise and comprehensive dynamic plantar pressure measurement system.
Section snippets
Participants
Fifty obese prepubescent children (age: 9.62 ± 1.61 years; height: 142 ± 11 cm; BMI = 23.68 ± 3.00 kg/m2) and fifty non-obese subjects (age: 10.26 ± 0.72 years; height: 139 ± 7.5 cm; BMI: 17.08 ± 1.25 kg/m2) were recruited.
Inclusion criteria were age (7–12 years) and BMI (greater than 95th percentile for age for obese group).
Children were excluded if they had musculoskeletal, neuromuscular, and/or cardiopulmonary conditions. Written consents from their parents were obtained prior to data collection. Children were
Subphases during foot-ground contact duration
Statistical analyses indicated no significant difference for duration of the heel-strike phase between obese and non-obese subjects (p = 0.05). Duration of the midstance phase was statistically much longer in the obese subjects (left foot: 49.45 ± 7.72; right foot: 49.36 ± 7.90) compared to their non-obese counterparts (left foot: 43.06 ± 10.60; right foot: 45.37 ± 10.03) (p = 0.004). However duration of the propulsion phase was statistically shorter in obese subjects (left foot: 41.81 ± 7.80; right foot:
Discussion
Hennig et al. [24] found no difference between boys and girls for plantar peak pressures and impulse, so we did not consider gender influences in this study.
High frequency (300 Hz) digital sampling technique has been used in this study for precise and comprehensive dynamic plantar pressure measurements and the examination of gait differences between obese children and non-obese. It has been reported that through high frequency digital sampling techniques, a detailed registration and analysis of
Conclusions
This study has examined the dynamic plantar pressure distribution of obese prepubescent children comprehensively. Obese subjects showed flatter foot pattern, larger foot axis angle and differences on dynamic plantar pressures compared to the non-obese subjects. Obesity children more likely feel pain and discomfort in the lower extremities including foot, ankle joints and knee joints with weaker stability of walking.
Conflict of interest
The authors have no financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work.
Acknowledgments
The authors would like to thank financial support provided by Educational Administration of Beijing, PR China, and to thank the subjects participating in this study and the teachers providing help from YuLin Elementary School, District Fengtai, Beijing.
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