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 (LM) and percentage force generation (Force).

RESULTS

The iLPC group had significantly lower LM (17%) than the NoLBP group (P<.05). No significant difference was seen in Force between the NoLBP and iLPC groups (P>.05). No significant correlation was seen between LM and Force (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.