How do Spinal Stabilization Exercises Relieve Back Pain? An Analysis of Potential Mechanisms of Analgesia Effected at Muscular, Spinal Cord and Supraspinal Levels

STUDY OBJECTIVE Spinal stabilization exercises have emerged as an effective treatment for low back pain (LBP), but the mechanism of analgesia obtained through these exercises is unknown. The objective of the present research was to derive viable hypotheses for this pain relief based on previously validated analgesic mechanisms. METHODS A literature review was conducted by first considering commonly known methods of both exogenous and endogenous pain control, and then selecting for deeper analysis those mechanisms which could conceivably be operative during the self‐generated, low amplitude movements involved in spinal stabilization exercises. The three chosen analgesic processes were related to perfusion, gate control, and endogenous analgesia. RESULTS Mechanism 1: Increased Perfusion Muscle contraction is known to increase perfusion of muscle tissue, leading to increased nutrient delivery and removal of waste products, and ischemia caused by atherosclerosis causes pain in multiple tissues including muscle. The lumbar blood supply derives from the abdominal aorta/lumbar artery system and blockages in this system have been linked to LBP. Gentle stabilization exercises targeting the core which activate these muscles may thus increase perfusion and thereby lessen pain related to ischemia. Mechanism 2: Gate Control‐Mediated Analgesia Since Melzack and Wall first proposed the Gate Control Theory, the existence of multiple specific pain‐inhibiting circuits linking dorsal horn laminae has been confirmed. Recent studies support a role for muscle spindles and golgi tendon organs in “closing the gate” to pain sensations, via muscle contraction. Pain relief during contract‐relax and resistance exercises has been achieved in at least 3 studies, possibly through activation of these receptors. This process may explain in part the achievement of pain relief obtained after a short course of spinal stabilization exercises. Mechanism 3: Exercise‐Induced Analgesia Exercise Induced analgesia (EIA) works through multiple endogenous systems that decrease pain perception, including the opioidergic, serotonergic, noradrenergic, endocannabinoid, and nitrergic systems. Numerous studies have shown EIA occurs with aerobic exercise in both humans and animals. The role of EIA in analgesia during isometric and core stabilization exercises is starting to be explored, including findings that both plasma β‐endorphin and serotonin levels increase after core exercises. CONCLUSIONS The manner in which spinal stabilization exercises achieve analgesia is unknown. The vascular, gate‐control, and exercise‐mediated mechanisms outlined above are known to elicit an analgesic effect, and could conceivably be evoked by the gentle, low amplitude movements of these exercises. Rigorous, prospective research on perfusion of the muscles involved in core stabilization, the activation of muscle proprioceptive pathways in dorsal horn pain synapses, and plasma levels of key hormones during and after core stabilization exercises, would help support or refute the existence of this link.