PubMed · 4254793
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G A Lawrence. 1971. External abdominal hernia.. https://pubmed.ncbi.nlm.nih.gov/4254793/
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STUDY DESIGN: Postural changes and trunk muscle activities were examined in patients with motion-induced intermittent low back pain (MILBP) and healthy controls. OBJECTIVES: To assess the ability to maintain an upright standing position. SUMMARY OF BACKGROUND DATA: Since MILBP is not observed at rest, its pathophysiology is complicated to investigate. METHODS.: Postural changes were measured with a 3-dimensional motion analyzer, and muscle activities with a surface electromyography while 10 female patients at an average age of 76 years (MILBP group) and 10 healthy controls at an average age of 74 years (Control Group) were standing upright and loaded with 10-kg weights. RESULTS: In the Control Group, no significant forward bending motion occurred. In the MILBP group, there was a temporal increase in forward bending at various speeds and at various time phases. In the MILBP group but not in the Control Group, the rate of changes in median power frequency of erector spinae muscle declined significantly as compared with that in the Control Group (P < 0.05). CONCLUSIONS: These results indicated that fatigue of the back muscles occurred in MILBP patients and could be a pain generator in low back pain.
We present a new critical illness VR rehabilitation device (X-VR-D) that enables diversified self-training and is applicable early in the rehabilitation of severely injured or ill patients. The X-VR-D consists of a VR program delivering a virtual scene on a flat screen and simultaneously processing commands to a moving chair mounted on a motion system. Sitting in the moving chair and exposed to a virtual reality environment the device evokes anticipatory and reactive muscle contractions in trunk and extremities for postural control. In this study we tested the device in 10 healthy subjects to evaluate whether the enforced perturbations indeed evoke sufficient and reproducible EMG muscle activations. We found that particular fast roll and pitch movements evoke adequate trunk and leg muscle activity. Higher angular velocities and higher angles of inclination elicited broader EMG bursts and larger amplitudes. The muscle activation pattern was highly consistent between different subjects and although we found some habituation of EMG responses in consecutive training sessions, the general pattern was maintained and was predictable for specific movements. The habituation was characterized by more efficient muscle contractions and better muscle relaxation during the rest positions of the device. Furthermore we found that the addition of a virtual environment to the training session evoked more preparatory and anticipatory muscle activation than sessions without a virtual environment. We conclude that the X-VR-D is safe and effective to elicit consistent and reproducible muscle activity in trunk and leg muscles in healthy subjects and thus can be used as a training method.
Rehabilitative ultrasound imaging (RUSI) is considered a valid method to measure muscle activation in key spinal muscles in asymptomatic subjects. Research measuring muscle activation with RUSI in painful subjects is limited. The aim of this study was to determine if changes in muscle activation from experimentally induced pain can be measured by RUSI. Six male subjects performed tasks known to activate the transverse abdominis (TrA) and lumbar multifidus (LM) while RUSI measurements of muscle thickness were obtained during control and hypertonic saline conditions. The abdominal draw-in maneuver was used to volitionally activate the TrA and a series of upper extremity lifting tasks were used to automatically activate the LM. Pain was induced by injecting 5% hypertonic saline into the longissimus muscle adjacent to the LM at the L4 level. The percent change in muscle thickness from rest to contraction represented muscle activation. Activation was significantly less (p<0.01) during the painful condition on 4 of the 5 tasks performed for the LM and on the task performed for the TrA. These results indicate that RUSI can be used to measure pain-related changes in deep trunk muscle activation. Future research should include a larger sample size and women.