Evaluation of Trunk Muscle Activation During the Two Directions of Flexi-Bar Exercise in People with and without Low Back Pain

Introduction: The flexible-bar with a small amplitude of 5 Hz, which transmits vibrations to the trunk, enables the activation of the core muscles that can be used to rehabilitate subjects with low back pain. Two types of exercise direction that can affect trunk muscles of low back pain subjects similar control group are not known. This study aimed to evaluate and compare exercises with two directions of the oscillating flexible poles in people with and without low back pain (LBP). Materials and Methods: Twelve women with Mean±SD age of 28.75±2.92 years, and body mass index (BMI) of 22.31±2.10 kg/m2 and a history of low back pain, and 12 healthy subjects with Mean±SD age of 28.75±2.49 years and BMI of 21.59±1.50 kg/m2 voluntarily participated in this study. The electromyography (EMG) signals of trunk muscles were measured during two handheld oscillating flexible bars in two directions. The root means square (RMS) of signals for each muscle is normalized by the maximum RMS. Results: The results of comparing two types of exercise in two groups showed significant differences for left external oblique (P=0.017), right external internal oblique (0.002), and left internal oblique (0.008). Also, the difference in the interaction between group×exercise was significant only for left internal oblique (P=0.026). Conclusion: Muscle activity in the low back pain group appears different while performing exercises with a flexible-bar compared to the control group. This confirms motor control impairment in these populations and having different strategies for trunk co-activation during exercise.