The effects of 250µs transcutaneous electrical nerve stimulation on the hip joint range of motion

Abstract

Background/Objectives: Although a transcutaneous electrical nerve stimulation (TENS) pulse duration of 100-150 Μs has been used conventionally to stimulate sensory nerve fibers, this pulse duration is not sufficient for stimulating motor nerve fibers. Therefore, this study was designed to test a new TENS protocol for stimulating motor nerve fibers. Methods/Statistical analysis: Fifteen males in their twenties with no lower back or pelvic orthopedic abnormalities and no contraindications for TENS participated in this study. A variable pulsation TENS machine was used. Using a high pulsating current of 250 Μs, as in acupuncture-like TENS, each segment of the longissimus and iliocostalis muscles on both sides was contracted as much as possible, without causing pain. Afterwards, a stainless steel goniometer was used to measure the hip joint range of motion (ROM) during an active straight leg raise (ASLR) test. Findings: Conventional TENS controls pain through the stimulation of sensory nerves and it is effective for diverse diseases, such as increase of blood flow and acute or chronic pain. The existing TENS that is being broadly used is not appropriate for stimulating motor nerve that has high threshold. In this study,ES-420 (ITO, Japan) was used where pulsation variables can be freely controlled. Using high pulsating current of 250us following the acupuncture-like TENS mechanism, each segment of longissimus and iliocostalis on both sides erector spinae muscles of the subjects were contracted as much as possible within the range of not causing pain. Afterward, The ASLR test results showed that the active straight leg raise test was left hip joint ROM increased conducted where the range of motion of left-side hip joint significantly, increased from 75.40±8.13° to 81.80±9.99° (p<0.05), and the right hip joint and the range of motion of right-side hip jointincreased significantly, increased from 70.53±10.92° to 81.00±12.97° (P<0.05). Not only electrical muscle stimulation (EMS), but also TENS with high pulse duration of 250us can stimulate motor nerve that has high threshold, which consequently produces effects of reducing muscle tension and enhancing muscle strength. Improvements/Applications: TENS with high pulse duration of 250us can stimulate motor nerves that have high threshold. TENS is expected to become a new protocol that promotes functional enhancement, such as reduction of muscle tension and enhancement of muscle strength muscle.