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.