Activity-based Therapies (ABT) hinge on the premise that the central nervous system, inclusive of the brain and spinal cord, is plastic and that it reorganizes in response to sensory stimulation and motor practice. Thus, ABTs (body weight supported treadmill training, gait training, load bearing, e-stim assisted cycling, e-stim assisted functional activities, etc.) focus on improving muscle function and sensory perception below the level of injury while minimizing compensation or maladaptive accommodation after a spinal cord injury. In layman’s terms: if a neurologically disabled person aims to recover movement, ABT will try to do this by “activating” the right muscles through performing specific tasks repeatedly.
Intense physical activity has been shown to improve physiological function and health outcomes in individuals with chronic spinal cord injury and other neurological impairments (Jones, Michael L. et al, 2017). Physical activity has decreased the incidence of repeated hospitalization due to fractures secondary to osteoporosis, urinary tract infections, pressure sores and other secondary sequelae after such devastating neurological impairments.
ABT refers to interventions that combine functional training with physical exercise to target activation of the neuromuscular system below the level of lesion with the goal of retraining the nervous system to recover specific motor tasks such as standing, walking, and grasping without compensation (Jones, Michael L. et al, 2017).
The philosophy underlying these interventions is that sensory stimulation (such as load bearing) complemented by massed practice of a non-compensatory task assists in optimizing the state of excitability of the central nervous system, which allows the spinal cord to respond to or access the diminished but existent descending supra spinal input from the cerebral cortex and regain functional movement. To put it simply, it is thought that ABT works because all of the inputs going into the patient’s body (all the repeated movements and stimuli) cause changes to occur in the CNS on a molecular level that allow for regeneration.
ABTs originated from extensive research in animal models that suggested that the use of intense and repetitive sensory stimulation coupled with motor practice result in an increase in brain-derived neurotrophic factor (BDNF) in the CNS that correlates with increased arborization of motor neuron dendrites, axonal sprouting, and synaptic recovery after a spinal cord injury. Furthermore, various lines of evidence suggest that neural plasticity along the neural axis in humans directly correlates with intense practice of specific tasks such as walking. Evidence from patient populations with incomplete spinal cord injuries, stroke, and multiple sclerosis suggests that intense, focused, repetitive active movement of impaired limbs, especially when combined with sensory augmentation, appears to improve function without compensation and induces neural changes in the cerebral cortex
Over the last decade there has been a growing trend towards incorporating ABT principles into the standard, traditional model of neurological physical therapy. This is partly due to an increase in consumer demand for maximizing potential for neuromuscular recovery, but also to clinical evidence that supports the use of ABT principles for recovery of function in the affected/paralyzed parts of the body in individuals with varying forms of paralysis. This has led to the growing advent of outpatient programs that provide intense therapies to individuals with various neurological disabilities in different settings ranging from large hospital systems to privately owned facilities all over the country.