Neuromechanics
[3] In addition to participating in reflexes, neuromechanical process may also be shaped through motor adaptation and learning.
[4] The inverted pendulum theory of gait is a neuromechanical approach to understand how humans walk.
As the name of the theory implies, a walking human is modeled as an inverted pendulum consisting of a center of mass (COM) suspended above the ground via a support leg (Fig.
The velocity vector of the center of mass is always perpendicular to the ground reaction force.
[6] The inverted pendulum is stabilized by constant feedback from the brain and can operate even in the presence of sensory loss.
[7] During postural control, delayed feedback mechanisms are used in the temporal reproduction of task-level functions such as walking.
The nervous system takes into account feedback from the center of mass acceleration, velocity, and position of an individual and utilizes the information to predict and plan future movements.
[9] The six determinants of gait predict very high energy expenditure for the sinusoidal motion of the Center of Mass during gait, while the inverted pendulum theory offers the possibility that energy expenditure can be near zero; the inverted pendulum theory predicts that little to no work is required for walking.
[5] Electromyography (EMG) is a tool used to measure the electrical outputs produced by skeletal muscles upon activation.
Motor nerves innervate skeletal muscles and cause contraction upon command from the central nervous system.
EMG signal acquisition is dependent on distance from the electrode to the muscle fiber, so placement is imperative.
[10] Signal processing involves taking the recorded electrical impulses, filtering them, and enveloping the data.
[10] Latency is a measure of the time span between the activation of a muscle and its peak EMG value.
Latency is used as a means to diagnose disorders of the nervous system such as a herniated disc, amyotrophic lateral sclerosis (ALS), or myasthenia gravis (MG).
The use of EMG to identify nervous systems disorders is known as a nerve conduction study (NCS).
[12] This is a result of decreased nerve conduction or electrical stimulation at the site of the muscle.
[18] The central nervous system is presented with the opportunity to coordinate muscle movements, and it must choose one out of many.
[20] Adaptation in the neuromechanical sense is the body's ability to change an action to better suit the situation or environment in which it is acting.
[24] Additionally, not only can electromyography readings differ, but the physical path that joints travel along can be altered as well.
