Neuromuscular responses to combined neuromuscular electrical stimulation and motor control exercises in a patient with recurrent low back pain: A single subject research report.

BACKGROUND: Previous studies have demonstrated changes in lumbar multifidus muscle (LM) contractility after motor control exercises (MCE), and it has been hypothesized that adding neuromuscular electrical stimulation (NMES) may help to re-activate motor units. OBJECTIVE: To present the effects of combined NMES and MCE on LM contractility, spatial and temporal motor unit recruitment, and movement control in a patient with recurrent low back pain (rLBP). METHODS: Motion tracking system was used to measure quality of movement (smoothness) during an active forward bend, while ultrasound imaging and decomposition electromyography were used to measure the LM contractility and motor unit recruitment during the Sorensen test. These data were collected pre and post intervention. Perceived improvement was also recorded. RESULTS: Improved movement smoothness post intervention was found, with increases in LM contractility from 68.1% to 97.7%, and from 74.2% to 86.7% on the right and left sides, respectively. Number of motor unit increased from 14 to 18 units, while mean firing rate decreased from 10.9 to 7.1 pulses/second post intervention. The patient also reported a perceived improvement of +2 on the Global Rating of Change (GROC). However, this change was not greater than +3 to be considered as minimal clinically important difference. CONCLUSION: These findings indicate improvements in movement control, LM contractility, and changes in spatial and temporal motor unit recruitment in the study patient, suggesting the potential clinical utility and the need for further research on combined NMES and MCE in the treatment of patients with rLBP.

Individuals With Impaired Lumbopelvic Control Demonstrate Lumbar Multifidus Muscle Activation Deficit Using Ultrasound Imaging in Conjunction With Electrical Stimulation: A Cross-sectional Study.

OBJECTIVE: To determine lumbar multifidus (LM) muscle activation deficits in individuals with impaired lumbopelvic control (iLPC) based on musculoskeletal ultrasound in conjunction with electrical stimulation approach and the correlation between back extension force and LM activation. DESIGN: A cross-sectional study design. SETTING: A university laboratory. PARTICIPANTS: Fifty participants (25 iLPC and 25 no low back pain [NoLBP]) were recruited from the university physical therapy clinic and surrounding areas. MAIN OUTCOME MEASURES: The musculoskeletal ultrasound was used to measure LM thickness at rest, maximum voluntary isometric contraction (MVIC), and electrical stimulation combined with MVIC, and a handheld dynamometer was used to record force during MVIC and electrical stimulation combined with MVIC. These data were used to derive LM activation (LMACT) and percentage force generation (ForceGEN). RESULTS: The iLPC group had significantly lower LMACT (17%) than the NoLBP group (P<.05). No significant difference was seen in ForceGEN between the NoLBP and iLPC groups (P>.05). No significant correlation was seen between LMACT and ForceGEN (P>.05). CONCLUSIONS: The findings support the utility of our protocol to determine LM activation deficits. The lower LM activation in iLPC group suggests that individuals with iLPC were unable to fully recruit the motor units available in LM. Force generation measurements may not be an appropriate approach to determine such deficits in LM.

Combined neuromuscular electrical stimulation with motor control exercise can improve lumbar multifidus activation in individuals with recurrent low back pain.

Motor control exercise (MCE) is commonly prescribed for patients with low back pain. Although MCE can improve clinical outcomes, lumbar multifidus muscle (LM) activation remains unchanged. Neuromuscular electrical stimulation (NMES) can be used to re-activate motor units prior to MCE which should result in increased LM activation. Therefore, this study aimed to explore the immediate effects of NMES combined with MCE on LM activation and motor performance. Twenty-five participants without low back pain (NoLBP) and 35 participants with movement control impairment (MCI) were recruited. Participants with MCI were further randomized to combined NMES with MCE (COMB) or sham-NMES with MCE (MCE) group. Ultrasound imaging was used to measure LM thickness at rest, maximum voluntary isometric contraction (MVIC), and NMES with MVIC. These data were used to calculate LM activation. Quadruped rocking backward was used to represent motor performance. LM activation and motor performance were measured at baseline and after one-session of intervention. Results showed that both COMB and MCE groups had significantly lower (P < 0.05) LM activation compared with NoLBP group at baseline. Additionally, both COMB and MCE groups demonstrated significant improvement (P < 0.05) in motor performance while COMB group demonstrated significantly greater improvement (P < 0.05) in LM activation compared with MCE group. Individuals with MCI still have persisting LM activation deficit. Our key findings suggest that combined NMES and MCE may have better ability to improve LM activation in individuals with MCI. These findings would support the utility of NMES to induce a priming effect before MCE.

Using neuromuscular electrical stimulation in conjunction with ultrasound imaging technique to investigate lumbar multifidus muscle activation deficit.

Lumbar multifidus muscle (LM) activation deficit has been proposed as a potential underlying mechanism responsible for recurrence episode of low back pain (LBP). The quantification of voluntary LM activation can provide a better understanding of the role of muscle activation deficit in LBP. The objective of this technical report is to propose a new approach using neuromuscular electrical stimulation (NMES) in combination with the ultrasound imaging technique (USI) to investigate the ability of individual to voluntarily activate the LM. We recruited ten participants with a recurrent LBP (rLBP) and twelve participants with no history of LBP (NoLBP). Theoretically, the superimposition of NMES on the LM during maximum voluntary isometric contraction (MVIC) should activate all motor units available in the LM. The percentage of LM activation (%LM) can be calculated by the changes of LM thickness during MVIC, divided by the changes of LM thickness during the combination of MVIC and NMES. This %LM was used to compare between groups. The individuals with rLBP had significantly lower %LM (p < 0.05) compared with the NoLBP counterpart (%LM = 72.4 and 92.9, respectively). Results demonstrate that this new approach can potentially differentiate %LM among individuals with rLBP and NoLBP. This new approach can be potentially used to 1) determine the extent of LM activation deficit, 2) identify the existence of muscle activation deficit in the LM, and 3) objectively measure the effect of the intervention designed to address the LM activation deficit.