Electrical stimulation on lumbar paraspinal muscle during prolonged sitting

Abstract

Introduction: Trunk muscle weakness is a risk factor for low back pain. Prolonged sitting, mainly due to the sedentary lifestyle of modern society, can cause trunk muscle weakness. Superimposed electrical stimulation (ES) over the back extensor during strengthening exercise has been proven to increase muscle strength. The objective of this study was to assess the strengthening effect of ES on the paraspinal muscle during prolonged sitting.

Methods: Thirty healthy subjects without low back pain were randomly assigned to an ES group (n = 15) or a control group (n = 15). ES was administered over the low lumbar paraspinal muscle in a seated posture at a maximal tolerable intensity for 60 min/day, three times a week, for 4 weeks. The same protocol was used in the control group, but at minimal intensity just over the sensory threshold. Isokinetic strength of the lumbar paraspinal muscles was evaluated at baseline, 4 weeks after ES, and 8 weeks after initiation of ES with an isokinetic dynamometer (Biodex Medical dynamometer system-4) at 60°/s and 120°/s angular velocities.

Results: After 4 weeks of ES in a sitting position, the isokinetic extensor trunk muscle strength measured at 120°/s angular velocity significantly increased in the ES group (P < 0.05) 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 an effective and accessible rehabilitation treatment to improve the extensor trunk muscle strength of the lumbar paraspinal muscle, although the effect is short-term.