H-reflex Responses to High-Velocity Low-Amplitude Manipulation in Adults With Chronic Non-specific Low Back Pain

Osteopathic Manipulative Treatment (OMT) is a health science that addresses treatment to somatic dysfunction among other conditions. High-Velocity Low-Amplitude (HVLA) manipulation is a known technique, defined as a quick and short force applied to a segment with movement restriction.

Somatic Dysfunction (SD) is the impaired or altered function of the components of the somatic system: skeletal, articular and myofascial elements with their vascular, lymphatic and neural related structures. The palpatory diagnosis of the SD is based on the presence of any of the 4 TART (Tenderness, Asymmetry, Range of motion and Tissue texture change) criteria, taking into account the information provided about pain and discomfort.

There is no evidence to support the use of the term 'somatic dysfunction' and moreover, the diagnosis is based on palpatory skills. Therefore, the investigators chose the term Restriction of Movement (RM) to describe the subjectivity of the palpatory examination.

HVLA manipulation produces neurophysiological and mechanic effects. The mechanical effects described in the literature are: meniscoids release, intervertebral disc material and segmental adhesions. The neurophysiological effects occur through the stimulation of mechanoreceptors and nociceptors located in the paravertebral tissues, including the skin, muscles, tendons, ligaments, zygapophyseal joints and intervertebral discs. This changes the influx of sensory information into the Central Nervous System (CNS), and this effect can be measured by the H-reflex (reflex analogous to the spinal stretch reflex). Thus, this is a valuable tool in the assessment of α-motor neuron excitability.

Studies show a transient attenuation of α-motor neuron excitability after HVLA manipulation in asymptomatic participants. According to studies, HVLA spinal manipulation increases joint mobility by blocking afferent impulses in the muscle spindle and the small-diameter free nerve, decreasing the γ-motor neuron activity.