Balance is an important aspect of the health of preschool children and a fundamental condition in their motor development [
1]. Based on different standards, balance capacity can be divided into two (static and dynamic balance) [
2], three (static, dynamic, and symmetric balance) [
3], or four types (static, dynamic, active, and reactive balance) [
4]. In recent years, the relationships between different types of balance have garnered attention. Researchers have explored the relationship between static and dynamic balance among people of different ages, such as children over 7 years old, teenagers, middle-aged, and older adults [
5], and of different occupational groups, such as professional sports, dancers, and other professionals [
6,
7]. At the same time, the correlation between the four types of balance in people over six years old has also been explored: static, dynamic, reaction, and active balance [
8]. The results obtained were similar; that is, there is little to no correlation between the different types of balance abilities. However, there is still a lack of correlation research on the different types of balance in children under six years of age. Before the age of 6, balance develops rapidly, especially at 4–5 years of age when balance control shifts from visual dominance to the same proprioceptive dominance mode as in adults. At this time, balance has notable characteristics, the fastest development speed, and greatest variability of all the stages in life [
9]. Therefore, it is difficult to generalize the research results of people over 6 years old to the preschool children group. Given that the targeted samples of previous studies were mostly children over 7 years, adults, and older adults, it is important to investigate the relationship between static balance and dynamic balance in preschool children under 6 years old. A better understanding of their association helps to give an insight into the development mechanisms of various balance abilities in the early years. Meanwhile, such an understanding might also assist physical activity and health professionals, teachers, and coaches in implementing precise balance intervention programs for preschool children.
In recent years, with the development of Micro-Electro-Mechanical Systems (MEMS), wearable sensors have gradually been applied for the detection of human balance [
10]. Wearable sensors can accurately measure the static and dynamic balance of preschool children under different sensory conditions or sports states and can make up for the many defects in the “gold standard” plantar pressure test of balance [
11]. The plantar pressure test evaluates human posture by collecting center of pressure (COP) data. COP is different from center of mass (COM), and COM is more suitable as an indicator of changes in body posture [
12]. This study used wearable sensors in combination with a modified clinical test of sensor interaction and balance (mCTSIB), and a balance beam walking test was employed to explore the correlation between static and dynamic balance in preschool children aged 4–5 years.
The wearable sensor combined with the mCTSIB can measure the shaking speed and amplitude of the COM under normal conditions, as well as shielding vision, interfering with proprioception, and sensor conflict. Combined with the balance beam test, it can measure the speed of walking on the balance beam, and the shaking speed and amplitude of the COM when walking on the balance beam. This study will, therefore, show the correlation between static and dynamic balance in preschool children from multiple perspectives through indicators such as shaking speed and amplitude of the COM under various sensory conditions and different movement states. This research aimed to further understand the early physical development of children and provide a reference for promoting balance and motor development in children.