Step Response of Human Motor System as a Measure of Postural Stability in Children

Neuromuscular performance of balance and posture control in childhood and adolescence

“…From age 9, significant differences were no longer detectable. This is in accordance with other studies that found stability control in 11 years old girls to be as stable as in young adults ( Błaszczyk et al., 2020 ; Nolan et al., 2005 ). For boys, there were significant differences between the oldest age group (15–17 years) and the younger ones.…”

“…Assuming that body posture on this basis is controlled in a combination of open-loop (feedforward) and closed-loop (feedback) mechanisms ( Collins and De Luca, 1995 ; Schmitz et al., 2002 ), it is safe to suppose that the quality of posture control depends on the formation of a valid body schema and also on the optimization of control loops ( Figure 1 ). For example, with a well-developed internal representation, the CNS can compensate for the effects of changes in body position by anticipatory movements, thereby keeping the COG stable above the supporting surface of the feet ( Błaszczyk et al., 2020 ). Although we were not able to find any clear dependency on athletic activity (i.e., participants with long-term praxis in demanding types of sport with a high share of coordinative and balance skills and an intense control of body tension did not exhibit improved posture control ability), it must be remembered that the control system worked successfully in all cases, which means the test persons did not lose their balance even with closed eyes.…”

“…By analyzing the reaction to disturbing stimuli, the control properties of a system can be understood. E.g., Błaszczyk et al. (2020) have investigated the motor response to toe stand upright and have shown that the trajectory of toe stand position depends on individual characteristics of the children studied, such as muscle strength, anthropometry and neuromuscular development.…”

“…He was able to show that anticipatory postural adjustments are related to both balance control and postural stabilization. Postural stability (in the sense of balance control) can be defined as an adequate response to disturbances of the center of mass (COM) caused by body sway, motor activity or conscious interaction with the environment ( Błaszczyk et al., 2020 ). It is known that both balance control and postural control are interlinked dynamic processes ( Massion, 1992 ) that use signals of the same receptor systems ( Chiba et al., 2016 ; Danis et al., 1998 ) and the same actuators - both regulate the activity of the postural musculature ( Figure 1 ).…”

“…It is known that both balance control and postural control are interlinked dynamic processes ( Massion, 1992 ) that use signals of the same receptor systems ( Chiba et al., 2016 ; Danis et al., 1998 ) and the same actuators - both regulate the activity of the postural musculature ( Figure 1 ). Therefore, controlling posture while ensuring its stability is a fundamental task of the CNS ( Błaszczyk et al., 2020 ; Sousa et al., 2012 ). By systematically activating the muscles, the central nervous system (CNS) is able to stabilize the biomechanically unstable body segments and at the same time keep the stabilized system in equilibrium ( Assaiante et al., 2005 ; Sousa et al., 2012 ; Massion, 1992 ).…”