Back muscle contraction patterns of patients with low back pain before and after rehabilitation treatment: an electromyographic evaluation

[Application progress of surface electromyography and surface electromygraphic biofeedback in low back pain]

Objective

To summarize the application progress of surface electromyography (sEMG) and surface electromygraphic biofeedback (sEMGBF) in low back pain (LBP).

Methods

The related literature about the application of sEMG and sEMGBF in diagnosis and therapy of LBP was summarized and analyzed.

Results

As a auxiliary diagnostic technique, lumbar muscle fatigue, lumbar muscle activity disorder, flexion-relaxation phenomenon, and asymmetry of the paravertebral muscle electromygraphic activity were found in patients with LBP by sEMG. For treatment, sEMG combined with sEMGBF technology to form sEMGBF training. sEMGBF training include sEMGBF training and sEMGBF stretching exercise. sEMGBF training can improve lumbar muscle activity disorder, recover muscle function, and relieve back pain.

Conclusion

sEMG can monitor the electromyographic signal and sEMGBF biofeedback information can relax or strengthen the muscle. It is very meaningful for diagnosis and therapy of LBP.

Flexion-relaxation ratio in sitting: application in low back pain rehabilitation

STUDY DESIGN

A multiple-comparative study between normal and low back pain (LBP) patients before and after rehabilitation.

OBJECTIVE

To examine whether there is a change in flexion-relaxation phenomenon in sitting in LBP patient following a rehabilitation treatment.

SUMMARY OF BACKGROUND DATA

There is an association between LBP and seated spine posture. Previous study has reported an absence of flexion-relaxation phenomenon in LBP patients during sitting. However, it is unknown whether there is a difference in flexion-relaxation phenomenon in sitting in LBP patients before and after rehabilitation treatment.

METHODS

A total of 20 normal subjects and 25 chronic LBP patients who underwent a 12 weeks rehabilitation program were recruited. Surface electromyography recordings during upright sitting and flexed sitting were taken from the paraspinal muscles (L3) bilaterally from the normal subjects, and in the LBP patients before and after the rehabilitation treatment. The main outcome measures for patients include the visual analogue scale, Oswestry disability index, subjective tolerance for sitting, standing and walking, trunk muscle endurance, lifting capacity, and range of trunk motion in the sagittal plane. Flexion-relaxation phenomenon in sitting, expressed as a ratio between the average surface electromyography activity during upright and flexed sitting, was compared between normal and patients; and in LBP patients before and after rehabilitation.

RESULTS

Flexion-relaxation ratio in sitting in normal subjects (Left: 6.83 +/- 3.79; Right: 3.45 +/- 2.2) presented a significantly higher (Left: P < 0.001; Right: P < 0.05) value than LBP patients (Left: 3.04 +/- 2.36; Right: 2.02 +/- 1.49). An increase in flexion-relaxation ratio in sitting was observed in LBP patients after rehabilitation (Left: 4.69 +/- 3.94, P < 0.05; Right: 3.58 +/- 2.97, P < 0.001), together with a significant improvement (P < 0.05) in subjective tolerance in sitting and standing, abdominal and back muscle endurance, lifting capacity, and range of motion. There were no significant changes in disability and pain scores, and subjective tolerance in walking.

CONCLUSION

Flexion-relaxation ratio in sitting has demonstrated its ability to discriminate LBP patients from normal subjects, and to identify changes in pattern of muscular activity during postural control after rehabilitation.

Visualization of lumbar muscle contraction synergy using surface electromyography (sEMG) streaming topography

Because of the difficulty in analysis and interpretation of surface electromyography (sEMG), the specific muscle contraction synergy associated with low back pain continues to be debated. Streaming topography is a novel method of continuously visualizing the distribution of sEMG signals during dynamic motion to provide a more comprehensive examination and subsequent insight into the synergy of muscle recruitment pattern. The purpose of this study was to assess the feasibility of streaming topography as a diagnostic tool. Ten healthy subjects were recruited to establish the normal pattern of lumbar muscle activity. An array of surface EMG electrodes was applied to the low back region and recorded during forward bending. The root mean square (RMS) of the sEMG signals were calculated as a function of both position and time to produce streaming topographical videos of the muscle activity in the lumbar region. In addition, a preliminary clinical study was carried out with 3 LBP patients. In normal subjects, RMS streaming topography was consistent, reproducible, and reliable. In clinical observation, the RMS streaming topography of LBP patients was obviously different from that of normal subjects. Some of LBP patients showed an asymmetric distribution during symmetric action. Streaming topography provides a dynamic analysis of lumbar muscle activities and illustrates the synergy of muscle contractions, which may be useful to improve physiotherapy management of LBP.

Muscular activation patterns of healthy persons and low back pain patients performing a functional capacity evaluation test

The results of most reported studies show differences between the muscular activity of low back pain patients and healthy subjects, but the focus has usually been on trunk muscles only, and they have not involved work-related tests or exercises. The reintegration of chronic low back pain patients to job market is a common problem. Therefore assessment systems like the functional capacity evaluation (FCE) according to Isernhagen [S.J. Isernhagen, Work Injury: Management and Prevention, Aspen Publishers Inc., Gaithersburg, MD, 1988] are often used tools to determine the physical abilities and deficits of long-time incapacitated persons. The aim of the present study was to compare the healthy persons and chronic low back pain patients in performing a FCE-test and to analyse their muscular activation and motion patterns. The results indicate differences in the activation patterns of the groups in the test task "floor to waist lift" common in many occupations.

A Meta-Analytic Review of Surface Electromyography Among Persons With Low Back Pain and Normal, Healthy Controls

Significant differences in surface electromyography (SEMG) have been reported between persons with low back pain (LBP) and normal, healthy controls. This manuscript presents a systematic meta-analytic review of studies examining SEMG differences between these groups. Forty-four articles were identified using MEDLINE and a review of reference lists in articles. For static SEMG, the largest effect size was observed for SEMG while standing, with subjects having LBP demonstrating higher SEMG. The effect size for flexion/relaxation measures was found to be very high (d = -1.71). Studies examining SEMG during isometric exercise or muscle recovery following exercise produced inconsistent findings. Sensitivity and specificity of SEMG for dynamic SEMG measures averaged 88.8% and 81.3%. Most classification schemes were statistically determined and utilized a combination of measures. Only one published study prospectively validated a classification scheme. SEMG measures of flexion-relaxation appear to distinguish LBP subjects from controls with good accuracy, and the sensitivity and specificity of SEMG can be increased by using multiple measures. Further research is needed to determine the combination of measures that are cost-effective, reliable, valid and discriminate with a high degree of accuracy between healthy persons and those with LBP.

PERSPECTIVE

SEMG is a simple and noninvasive measure of muscle activity. SEMG measures hold promise as an objective marker of LBP.

Erector Spinae and Quadratus Lumborum Muscle Endurance Tests and Supine Leg-Length Alignment Asymmetry: An Observational Study

OBJECTIVE

To determine if there is an association between supine leg-length alignment (LLA) asymmetry and the endurance of the erector spinae (ES) and quadratus lumborum (QL) muscles.

METHODS

Forty-seven subjects (21 women; average age, 36 years old) were tested for ES endurance using the Biering-Sorensen (B-S) test, and 69 (31 women; average age, 34.5 years) were tested for QL endurance. Subjects were examined for supine LLA and tested for ES and QL muscle endurance. The muscle endurance times were compared against those who did and did not demonstrate LLA asymmetry and the side of the "short leg."

RESULTS

In the B-S test, volunteers with LLA asymmetry (n = 27) had a mean endurance time of 89.7 seconds (SD, 43.3), and the no-LLA asymmetry group (n = 20) had a mean endurance time of 161.5 seconds (SD, 57.1), a significant difference (P < .001). In the QL test, after correction for the effects of sex and exercise, those with a right "short leg" (n = 22) had a right QL endurance time of 25.9 seconds (SE, 4.2) and a left QL endurance time of 34.7 seconds (SE, 4.3). The right QL endurance time was significantly different from those subjects with balanced legs (P = .001). Those with a left "short leg" (n = 20) had a left QL endurance time of 28.6 seconds (SE, 4.7) and a right QL endurance time of 38.1 seconds (SE, 4.5). Both QL endurance times were significantly different from those with balanced leg-length (P = .002 and .016, respectively).

CONCLUSION

This study suggests that, using the B-S test, the group of volunteers who demonstrated a commonly used sign of subluxation/joint dysfunction, supine LLA asymmetry, had a decreased endurance times over those who did not. The QL endurance tests showed that the QL muscle ipsilateral to the supine short leg had significantly decreased endurance times over the same-side QL fatigue times in the no leg-length asymmetry group.

Muscle activation imbalance and low-back injury in varsity athletes

There are conflicting findings in the literature regarding erector spinae activation imbalance in people with low-back pain (LBP). Some studies have found asymmetric recruitment between muscle pairs in people with LBP, whilst other studies have not; some reported people with LBP recruit more lumbar muscles whilst other have reported greater thoracic activity. Using 242 varsity athletes, EMG activity of thoracic and lumbar erector spinae pairs was recorded during an isometric trunk extension. Activation imbalance among muscle pairs and levels was compared between athletes with and without a history of low-back injury (HxLBI). There were no group differences in the imbalance between sides, but the HxLBI group had greater activation imbalance between lumbar and thoracic levels than the No HxLBI group. Activation imbalance between levels was similar for individuals with No HxLBI and those who sustained first time injury suggesting that imbalance does not cause LBI. There was no difference between the athletes with single and multiple episode LBI, nor between short and long symptom duration suggesting that the presence of imbalance is not an impairment. Interestingly, activation imbalance occurred in both directions, meaning more thoracic activity for some, and more lumbar activity for others, which might be a functional adaptation related to pathology.

Pain-Related Fear, Lumbar Flexion, and Dynamic EMG Among Persons With Chronic Musculoskeletal Low Back Pain

OBJECTIVES

The purpose of this study was to examine the relationship between pain-related fear, lumbar flexion, and dynamic EMG activity among persons with chronic musculoskeletal low back pain. It was hypothesized that pain-related fear would be significantly related to decreased lumbar flexion and specific patterns of EMG activity during flexion and extension.

STUDY DESIGN

Data was obtained from subjects who, on a single day, completed self-report measures of pain and pain-related fear, and were interviewed to determine demographic and pain information. Subjects then underwent a dynamic EMG evaluation for which they were asked to stand, then bend forward as far as possible, stay fully flexed, and return to standing. Lumbar EMG and angle of flexion were recorded during this time. A flexion-relaxation ratio (FRR) was computed by comparing maximal EMG while flexing to the average EMG in full flexion.

SUBJECTS

Seventy-six persons with chronic musculoskeletal low back pain.

RESULTS

Zero-order correlations indicated that pain-related fear was significantly related to reduced lumber flexion (r = -0.55), maximum EMG during flexion (r = -0.38) and extension (r = -0.51), and the FRR (r = -0.40). When controlling for pain and demographic factors, pain-related fear continued to be related to reduced lumbar flexion. Using a path-analytic model to examine whether angle of flexion mediated the relationship between fear and EMG activity, the models examining maximal EMG during flexion and extension supported the notion that pain-related fear influences these measures indirectly through its association with decreased range of motion. Conversely, pain-related fear was independently related to higher average EMG in full flexion, while angle of flexion was not significantly related. Pain-related fear was directly related to a smaller FRR, as well as indirectly through angle of flexion.

CONCLUSIONS

Pain-related fear is significantly associated with reduced lumbar flexion, greater EMG in full flexion, and a smaller FRR. The relationship between pain-related fear and EMG during flexion and extension appears to be mediated by reduced lumbar flexion. These results suggest that pain-related fear is directly associated with musculoskeletal abnormalities observed among persons with chronic low back pain, as well as indirectly through limited lumbar flexion. These musculoskeletal abnormalities as well as limited movement may be involved in the development and maintenance of chronic low back pain. In addition, changes in musculoskeletal functioning and flexion associated with pain-related fear may warrant greater attention as part of treatment.

Spine loading in patients with low back pain during asymmetric lifting exertions

BACKGROUND CONTEXT

Recurrent low back pain (LBP) is a common and costly problem that might be related to increased spine loads in those with LBP. However, we know little about how the spine is loaded when those with LBP perform lifting exertions.

PURPOSE

Document spine loading patterns of patients with LBP performing symmetric and asymmetric lifting exertions compared with asymptomatic individuals performing the same tasks.

STUDY DESIGN

Spine loadings during lifting exertions that varied in asymmetric origin as well as horizontal and vertical distance from the spine were compared between asymptomatic subjects and patients with LBP.

METHODS

Sixty-two patients with LBP and 61 asymptomatic individuals performed a variety of lifting exertions that varied in lift origin horizontal and vertical position (region), lift asymmetry position and weight lifted. An electromyography-assisted model was used to evaluate spine loading in each subject during the lifting exertions. Differences in spine loading between the LBP and asymptomatic subjects were noted as a function of the experimental variables.

RESULTS

Patients with LBP experienced greater spine compression and shear forces when performing lifting tasks compared with asymptomatic individuals. The least taxing conditions resulted in some of the greatest differences between LBP and asymptomatic individuals.

CONCLUSIONS

Greater levels of antagonistic muscle coactivation resulted in increases in spine loading for patients with LBP. Specific lifting conditions that tend to exacerbate loading can be identified by means of physical workplace requirements. These findings may impact acceptable return-to-work conditions for those with LBP.