EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

Abstract

Abstract.4bnormal patterns of trunk muscle activity could aKect the biomechanics of spinal movements and result in back pain. The present study aimed to examine electromyographic (EMG) activity of abdominal and back muscles as well as triaxial torque output during isometric axial rotation at different exertion levels in back pain patients and matched controls. Twelve back pain patients and 12 matched controls performed isometric right and left axial rotation at 100%, 70%, 50%) and 30% maximum voluntary contractions in a standing position. Surface EMG activity of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results showed that there was a trend ( P = 0.08) of higher flexion coupling torque during left axial rotation exertion in back pain patients. Higher activity for external oblique and lower activity for multifidus was shown during left axial rotation exertion in back pain group when compared to the control group. In right axial rotation, back pain patients exhibited lesser activity of rectus abdominis at higher levels of exertion when compared with matched controls. These findings demonstrated that decreased activation of one muscle may be compensated by overactivity in other muscles. The reduced levels of activity of the multifidus muscle during axial rotation exertion in back pain patients may indicate that spinal stability could be compromised. Future studies should consider these alternations in recruitment patterns in terms of spinal stability and internal loading. The findings also indicate the importance of training for coordination besides the strengthening of trunk muscles during rehabilitation process.

Core Stabilization Exercise Improves Pain Intensity, Functional Disability and Trunk Muscle Activity of Patients with Clinical Lumbar Instability:a Pilot Randomized Controlled Study

“…For sub-MVIC testing of back muscles, each subject performed a double knee raise of 5 cm from the floor in the prone lying position with 90° of knee flexion, three times with five-second holds, and the RMS values of LM and ICLT muscles were simultaneously recorded. Two minutes rest was given between the tests to avoid muscle fatigue 23) . The normalized RMS data of the middle three seconds of the five-second testing period were analyzed and the average values of the three tests were used as reference values of sub-MVIC normalization for each muscle 24) .…”

“…The ADIM was performed three times with 10-second holds, and a one minute rest period between the tests was given to avoid muscle fatigue 23,25) . To generate ADIM, each subject gently drew in the lower anterior abdominal wall below the navel level with no movement of the spine and pelvis, and a small pillow was placed under the ankles in the four-point kneeling position 10) .…”

Activation of Abdominal Muscles during Abdominal Hollowing in Four Different Positions

“…The maximal reading from either sitting or crook lying, whichever was the greatest, was used for each subject. When measuring MVC, each contraction was maintained for 5 seconds, followed by a rest of 2 minutes, in order to prevent muscle fatigue 23) . After measuring the MVC of each subject, one of the four different positions was randomly selected for the experiment.…”

Prospective study of the relationship between musculoskeletal and psychological complaints and electromyographic activity during isometric muscular contractions in a working population

“…In some of the recent literature, reduced muscular activity related to experimentally induced muscular pain or disabling clinical pain has been documented during different types of muscular work with different contraction levels (25)(26)(27)(28)(29). Findings of reduced muscular activity with pain were the basis for the pain-adaptation hypothesis of Lund and his co-workers (12).…”