Immediate Effects of TENS on Lumbar Erector Spinae Stiffness in Low Back Pain

Low back pain is frequently associated with increased tone and stiffness of the lumbar erector spinae muscles, which may contribute to pain and functional limitation. Transcutaneous electrical nerve stimulation (TENS) is a non-invasive, safe, and widely used modality for pain reduction, but its very short-term (immediate) effects on lumbar muscle stiffness have not been clearly demonstrated. This randomized controlled trial will compare a single 20-minute session of conventional TENS with a control/rest condition in patients with non-specific low back pain. The primary outcomes will be change in lumbar erector spinae muscle stiffness (Myoton) and change in pain intensity (VAS) from baseline to immediately after the intervention. We hypothesize that TENS will produce a greater immediate reduction in muscle stiffness and pain than control.