The Strengthening Effect of Electrical Stimulation on Lumbar Paraspinal Muscles in the Sitting Position: A Randomized Controlled Trial

Background: Sedentary lifestyle, a prevalent finding in modern society, can lead to weakness of the lumbar trunk musculature. Electrical stimulation (ES), in addition to lumbar strengthening exercises, has been shown to increase muscle strength. Objective: To assess the strengthening effect of ES on, the lumbar paraspinal muscles during prolonged sitting. Design: Randomized, controlled, single-blind study. Setting: Tertiary hospital. Participants: Thirty healthy subjects without low back pain. Methods: Thirty participants were randomly assigned to the ES group (n = 15) or the control group (n = 15). ES was administered over the lumbar paraspinal muscles, while subjects maintained a seated posture, at a maximal tolerable intensity for 60 minutes per day, three times per week, for 4 consecutive weeks. An identical protocol was used in the control group with muscle stimulation provided at the minimal sensory threshold intensity. Main Outcome Measurements: The isokinetic strength of the lumbar paraspinal muscles was evaluated at baseline, 4 weeks after the initiation of ES, and 8 weeks after the initiation of ES with an isokinetic dynamometer (Biodex Medical Dynamometer System-4) at 60 degrees/s and 120 degrees/s angular velocities. Results: The extension and flexion peak torque at 60 degrees/s showed no significant interaction between the time and intervention or between the interventions. However, after 4 weeks of ES in the sitting position, the isokinetic extensor trunk muscle strength measured at 120 degrees/s angular velocity significantly increased in the ES group (P <.05) compared with that in the control group. This effect was not maintained when measured at 4 weeks after the cessation of ES. Conclusions: ES in a sitting position is a potentially effective and accessible rehabilitation treatment, which can lead to short-term improvement in the extensor trunk muscle strength of the lumbar paraspinal muscles.