RESUMO
OBJECTIVE: To investigate changes in lumbar multifidus (LM) and deep lumbar stabilizing abdominal muscles (transverse abdominis [TrA] and obliquus internus [OI]) during transcutaneous neuromuscular electrical stimulation (NMES) of lumbar paraspinal L4-L5 regions using real-time ultrasound imaging (RUSI). METHODS: Lumbar paraspinal regions of 20 healthy physically active male volunteers were stimulated at 20, 50, and 80 Hz. Ultrasound images of the LM, TrA, OI, and obliquus externus (OE) were captured during stimulation at each frequency. RESULTS: The thicknesses of superficial LM and deep LM as measured by RUSI were greater during NMES than at rest for all three frequencies (p<0.05). The thicknesses in TrA, OI, and OE were also significantly greater during NMES of lumbar paraspinal regions than at rest (p<0.05). CONCLUSION: The studied transcutaneous NMES of the lumbar paraspinal region significantly activated deep spinal stabilizing muscle (LM) and the abdominal lumbar stabilizing muscles TrA and OI as evidenced by RUSI. The findings of this study suggested that transcutaneous NMES might be useful for improving spinal stability and strength in patients having difficulty initiating contraction of these muscles.