Neuromuscular and Kinematic Dynamics in Human Movement Adaptation

The field of motor adaptation and development has long been a subject of intense study, particularly in the context of the degrees of freedom available to the central nervous system (CNS) for executing tasks. The concept of degrees of freedom refers to the multitude of potential solutions from which the CNS must select to efficiently meet particular task requirements. For instance, in a Sit-To-Stand task executed in a three-dimensional space, joint control is primarily directed towards the sagittal plane—involving hip and knee flexion and extension. Movements along the frontal and transverse planes, such as hip abduction/adduction and rotation, are often minimized despite being valid alternatives within the solution space. This practice of reducing redundant kinematic dimensionality to reach optimal task solutions has given rise to the motor redundancy theory in motor control. However, a complementary notion views the presence of redundant degrees of freedom as advantageous. This perspective has gained traction among researchers, leading to the development of the motor abundance theory. This theory suggests that the CNS introduces additional degrees of freedom, such as variability in joint kinematics, to efficiently meet task requirements, rather than reducing the degrees of freedom for an optimal solution. Researchers from both perspectives have shown that degrees of freedom tend to either freeze or become free during movement adaptation. This contributes to the ongoing debate about abundance versus redundancy during adaptive or developmental changes in human motion. Despite this conflict, it’s important to note that both of these degrees of freedom theories offer valuable insights into system dynamics. More specifically, the methods used in these theories, when paired with suitable experimental designs and cutting-edge technology (such as EMG, EEG, Motion Capture, IMUs, etc.), allow for the observation of adaptive and developmental changes in motor behavior. Furthermore, they assist researchers in determining which of the three constraints—Task, Neural, or Environmental—leads to adaptive changes in specific situations.

This Research Topic aims to enrich the literature about the impact on neuromuscular and kinematic degrees of freedom, especially during adaptive or developmental changes in movement. We invite contributions from the proponents of abundance and redundancy theories to provide insight into adaptive and developmental changes in human movement behavior. This could assist the scientific community in developing more effective rehabilitation methods.

To gather further insights into the boundaries of motor adaptation and development, we welcome articles addressing, but not limited to, the following themes:
- Biomechanics
- Electromyography
- Neural Engineering and Rehabilitation
- Motor Neuroscience
- Motor Learning and Motor Control
- Motor Adaptation and Development
- Physical Therapy