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PubMed1991

Reproducibility of nine tests to measure spinal mobility and trunk muscle strength.

The reproducibility of nine back function tests suitable for use in the occupational health service was determined in 30 male employees. The correlation of three tests made with a tape measure--forward bending, modified Schober, and side bending--was high in both intra- and inter-observer comparisons (r = 0.82-0.96). Immediate repetition of the testing procedure improved the performance in the forward and side bending tests. The reproducibility was also good for the tests of dynamic (K = 0.57-0.78) and endurance (r = 0.90-0.96) strength of the abdominal muscles and quite good for the test of endurance strength of the back muscles (r = 0.74-0.80). The differences between the examiners must be taken into account in the modified Schober test, and in testing the flexibility of the hip flexors and hamstrings and the endurance strength of the back muscles.

Adult↗
PubMed2005

Nonlinear analysis of electromyography time series as a diagnostic tool for low back pain.

BACKGROUND: A number of studies have evaluated lumbar spinal muscle fatigue using the electromyography (EMG) signal. However, back muscle fatigue studies do not consistently report endurance levels for patients with or without low back pain (LBP). In this case report, we investigated a nonlinear analysis of EMG time series that characterizes their complexity. MATERIAL/METHODS: A 37-year-old male with chronic LBP and an age- and gender-matched volunteer were compared. The endurance of the erector spinae muscle was determined using a modified version of the isometric Sorensen fatigue test. Nonlinear time series analysis techniques reveal the presence of long-range, power-law correlations. After checking that the signal was stationary, the original time series of 60,000 entries was reduced to 6000 entries by averaging over 10 consecutive entries. RESULTS: There was a difference between the entropy time dependence exhibited by entropy time dependence exhibited by the healthy subject and the LBP subject. The entropy associated with the LBP subject saturates at very short-times--two orders of magnitude shorter than for the healthy subject. CONCLUSIONS: The characterization of the nonlinear time series in this case study provides a consistent measure of back muscle activities. It is important to understand the potential limitations before undertaking an EMG analysis in the field of ergonomics or biomechanics. Further studies are needed to investigate the characteristics of back muscles.

Adult↗
PubMedDate not supplied

Evaluation of superior rectus muscle attachment following hang-back recession in rabbit eyes.

PURPOSE: The hang-back suture technique has been advocated to decrease the risk of scleral perforation during strabismus surgery. In this study, we evaluated the muscle insertion site in rabbits 4 weeks after a hang-back recession was performed. METHODS: Twenty-five eyes of 13 rabbits underwent hang-back recessions of between 5 and 8 mm of the superior rectus muscle. Four weeks later, the attachment sites were examined. RESULTS: Four weeks following the surgery, 14 muscles (n=25, 56%) were anteriorly displaced. In the 5 mm recession group, one muscle was anteriorly displaced (n=7, 14.3%). In the 6 mm recession group, 50% of the muscles recessed were displaced anteriorly (n=8). The 7 mm hang-back recession group demonstrated forward displacement in five muscles operated (n=6, 83%) and in the 8 mm recession group, all four muscles (100%) were anteriorly displaced. The magnitude of displacement was positively correlated to the amount of the hang-back recession performed (Pearson correlation p<0.001). CONCLUSIONS: Anterior displacement of muscles using the hang-back technique in the rabbit eye is unacceptably high and occurred in 56% of the cases. A positive, statistically significant correlation exists between the amount of recession performed and the number of muscles displaced from their new insertion. Therefore, when performing large recessions using the hang-back technique displacement should be anticipated.

Animals↗
PubMed1996

Mechanical behaviour of hamstring muscles in low-back pain patients and control subjects.

The purpose of this study was to measure and compare the passive elastic moment, the stiffness and the damping coefficient of the hip joint, as functions of the hip and knee joint angles in men with and without low-back pain. Two conventional tests, the straight-leg-raising test and the trunk forward flexion, were also performed and compared between these subjects. The passive elastic moment was measured using an isokinetic device in the passive mode. This device raised the lower limb from the horizontal position to the straight-leg-raising angle at a slow and constant angular velocity. A custom-made splint connected with the lever arm of the isokinetic device maintained the knee in extension and the ankle in the neutral position. The damping coefficient of the hip joint was measured for 0, 15, 45, 60, 75 and 90% of straight leg raising angle of each subject, using the suspension method based on small oscillation theory. To ensure that muscles were inactive during the passive hip moment tests, muscle activity was monitored with surface EMG. The stiffness was computed as the ratio of the change in passive elastic moment to the change in the hip angle. The passive elastic moment, the stiffness and the normalized trunk flexion were significantly different between the two groups respectively. There was, however, no difference between the two groups in the results of straight-leg-raise and damping coefficient of the hip. The passive elastic moment was a nonlinear function of the hip flexion angle and showed large intersubject differences, especially as the joint limit was approached. The damping coefficient was a polynomial function of the hip flexion angle. The measured variables were analysed using a discriminant function and it was shown that the two groups were clearly discriminable in a meaningful manner.

Journal Article↗
PubMed1987

Normal trunk muscle strength and endurance in women and the effect of exercises and electrical stimulation. Part 2: Comparative analysis of electrical stimulation and exercises to increase trunk muscle strength and endurance.

Several studies have shown positive correlations between muscle strength, flexibility, and the frequency of low-back pain. Weak trunk musculature and decreased endurance have thereby come to be identified as significant risk factors in the development of occupational back problems. Because it is widely accepted that exercise plays an important role in the conservative treatment and prevention of low-back pain, the goals of most rehabilitative programs involves improving the strength and endurance of the low-back pain patient. Whereas electrical stimulation has been shown to increase the muscle strength of the lower extremities, this effect has not been demonstrated for the trunk muscles. Part 2 is a prospective controlled study designed to document and to compare objectively the effects of electrical stimulation and exercise on trunk muscle strength. A total of 117 healthy women were divided randomly into four groups. Two groups received electrical stimulation with different electrical parameters, one group received exercises, and one group acted as a control group. The results showed that low-frequency electrical stimulation and exercises significantly (P less than .05) increased isokinetic back-muscle strength compared to the control and medium-high-frequency electrical stimulation groups. Both types of electrical stimulation, however, significantly increased (P less than .05) the endurance in the back muscles compared with the control and the exercise groups. This study showed that electrical stimulation may be a valuable treatment in the early care of low-back pain patients in maintaining and increasing strength and endurance of back muscles when a more active exercise program is too painful to perform.

Adolescent↗
PubMed2004

Trunk muscle strength, cross-sectional area, and density in patients with chronic low back pain randomized to lumbar fusion or cognitive intervention and exercises.

STUDY DESIGN: A randomized study. OBJECTIVES: To compare muscle strength, cross-sectional area, and density of the back muscles in two categories of patients with chronic low back pain, randomized to either lumbar fusion or cognitive intervention and exercises. SUMMARY OF BACKGROUND DATA: In two clinical trials, patients with chronic low back pain plus disc degeneration and postlaminectomy syndrome, respectively, were randomized to either lumbar fusion or cognitive intervention and exercises. We have previously reported that results for the primary outcome were similar at the 1-year follow-up examination. METHODS: As the treatment alternatives and test procedures were identical, the two trials were merged into one. A total of 124 patients 25 to 60 years of age were included. Muscle strength, measured by isokinetic test device and by the Biering-Sørensen Test, was measured in 112 patients, and the cross-sectional area and density of the back muscles were measured in 61 patients at the inclusion and at the 1-year follow-up examination. RESULTS: The exercise group performed significantly better in muscle strength than did the lumbar fusion group, with the mean difference at 184 Nm (95% confidence interval, 64-303 Nm; P = 0.003) and for the Biering-Sørensen Test 21 seconds (95% confidence interval, 6-36 seconds; P = 0.006). The density at L3-L4 decreased in the lumbar fusion group but remained unchanged in the exercise group. The mean difference was 5.3 HU (95% confidence interval, 1.1-9.5 HU; P = 0.01). The cross-sectional area was unchanged in both groups. CONCLUSIONS: Patients with chronic low back pain who followed cognitive intervention and exercise programs improved significantly in muscle strength compared with patients who underwent lumbar fusion. In the lumbar fusion group, density decreased significantly at L3-L4 compared with the exercise group.

Adult↗
PubMed2005

Influences of trunk muscles on lumbar lordosis and sacral angle.

BACKGROUND: The strength of abdominal muscle and back extensors or their balances are commonly mentioned as major indicators of potential low back pain (LBP). Former studies on anthropometrics in terms of trunk muscle strength seemed to lack precision in methodology. Furthermore, the extension-flexion ratio, which is a good parameter of trunk muscle balance, was not as much studied as simple maximum torques in this area of study. OBJECTIVES: To investigate relationship between trunk muscle strength and lumbar lordosis, sacral angle in patients who did not show significant abnormal findings on their simple lateral radiograph. METHODS: Thirty-one subjects were participated and their mean age was 35. Lumbar simple lateral radiograph was taken and lordotic angle was obtained by altered Cobb's method. Sacral angle was also examined on the same film. The relationship between these angles and muscle strength (isometric maximum torques and ratios of them) was investigated by the correlation analysis. RESULTS: None of the isometric maximum torques was related to sacral angle or lordotic angle. However, the ratio of extension to flexion was significantly related to the lordotic angle (Pearson's correlation coefficient=0.491, p<0.01). Other ratios were not related to any of the angles. CONCLUSIONS: An imbalance in trunk muscle strength can influence significantly lordotic curve of lumbar spine and might be one risk factor for potential low back pain.

Abdominal Muscles↗
PubMed2000

Abdominal insufflation does not cause hematogenous spread of colon cancer.

BACKGROUND AND PURPOSE: Previous investigators have suggested that port-site recurrences are possibly a result of abdominal insufflation, forcing viable cancer cells into the circulation to metastasize and thrive in areas of trauma. Using a syngeneic animal cancer model, we tested the hypothesis that pneumoperitoneum increases the incidence of wound metastasis by a blood-borne mechanism. METHODS: Male BD IX rats (N = 150) were injected intraperitoneally with 2 x 10(5) viable syngeneic 1,2-dimethylhydralazine-induced colon cancer cells (DHD-K12). Animals were divided into three groups: A (abdominal insufflation with 3-cm incision on the back into muscle remote from the peritoneum); B (3-cm back incision alone); and C (control group with 3-cm midline abdominal incision). Three weeks after surgery, the animals were euthanized and autopsied. RESULTS: In the two groups with back wounds, the incidence of cancer growth at the incision was zero, as demonstrated grossly and by histologic sample (A: 0/47, B: 0/43). In contrast, the autopsied control group had a 42% incidence of metastasis to the wound (25/59). There seemed to be no difference in the distribution of intra-abdominal disease between those rats that underwent insufflation and those that did not. CONCLUSION: It is unlikely that pneumoperitoneum promotes hematogenous wound implantation of free intraperitoneal cancer cells.

Animals↗
PubMed1993

Leisure time physical activity in the young. Correlation with low-back pain, spinal mobility and trunk muscle strength in 15-year-old school children.

From a population of 1503 school children, 38 15-year-old children reporting recurrent or continuous low-back pain (LBP) and 38 asymptomatic controls (34 boys and 42 girls) matched for age, sex and school class, were compared with respect to spinal mobility and trunk muscle strength. The subjects were interviewed on leisure time physical activity preceding the measurements. Of the subjects with recurrent or continuous LBP and of those completely without LBP experience 73.7% vs 42.1% reported that they pursued some physical activity two days a week or less (P = 0.006). Further, decreased spinal mobility, diminished endurance strength of the back muscles and diminished dynamic strength of the abdominal muscles were found in the group with a low frequency of activity. Mobility in children pursuing physical activity two days a week or less was decreased in lumbar extension measured by flexicurve, in forward bending, in side bending and in straight leg raising. Our results indicate that a very low frequency of physical activity in the young might be the risk factor for LBP. Pursuing sports as a leisure time activity is not harmful; on the contrary it has positive effects on spinal mobility and trunk muscle strength.

Abdominal Muscles↗
PubMed2004

Activation of lumbar paraspinal and abdominal muscles during therapeutic exercises in chronic low back pain patients.

OBJECTIVES: To assess the activities of paraspinal and abdominal muscles during therapeutic exercises for the treatment of patients with nonspecific chronic low back pain (CLBP), and to study the effects of active physical rehabilitation on these activities. DESIGN: A cross-sectional study comparing muscle activities during 18 stabilization exercises, and a prospective follow-up of patients with CLBP during rehabilitation. SETTING: Rehabilitation clinic in university hospital in Finland. PARTICIPANTS: Nine volunteers (5 men, 4 women) aged 27 to 58 years. INTERVENTION: Three months of active outpatient rehabilitation (4 to 6 times in a rehabilitation clinic, supplemented with self-motivated exercise at home) supervised by a physiotherapist. MAIN OUTCOME MEASURES: Surface electromyography was recorded bilaterally from L5 level paraspinal, rectus abdominis, and obliquus externus abdominis muscles. The recorded signal was averaged and normalized to the maximal electromyographic amplitude obtained during the maximal voluntary contraction. The measurements were taken before and after the exercise treatment period. RESULTS: CLBP patients showed variable trunk muscle activity patterns during the different therapeutic exercises, similar to those that we reported earlier in healthy subjects. The maximal trunk isometric extension (pre, 147.3+/-75.9Nm; post, 170.1+/-72.3Nm) and flexion (pre, 72.0+/-37.9Nm; post, 93.5+/-42.5Nm) torques did not show a significant changes during the exercise period. However, trunk rotation-flexion torque (pre, 52.9+/-26.5Nm; post, 82.4+/-65.8Nm) increased significantly (35.8%) after the exercise period (P<.05). The corresponding maximal electromyographic amplitudes of back and abdominal muscles remained unchanged. Disability, as assessed by visual analog scale and Oswestry Disability Index, did not change. CONCLUSIONS: The CLBP patients performed therapeutic exercises with similar abdominal and back extensor muscle activities in the same way as the healthy subjects in our earlier studies. In this study, active physical rehabilitation had no effect on the abdominal and back muscle activities or on pain and functional disability indices.

Abdominal Muscles↗
PubMed1983

Intraabdominal pressure and trunk muscle activity during lifting--effect of abdominal muscle training in healthy subjects.

Isometric training of the abdominal muscles is recommended as a preventive measure against low back complaints in the hope that the increased strength of the abdominal muscles should result in an increased intraabdominal pressure when lifting. There is, however, neither experimental nor clinical proof of this hypothesis. Twenty healthy young men went through intense isometric training of the abdominal muscles for five weeks. Before and after training the subjects were put through a standardized test programme, measuring the strength of abdominal and back muscles, and a series of lifts, 10, 25, and 40 kg, leg lifts and back lifts. The intraabdominal pressure (IAP), and the EMG activity of the oblique abdominal muscles, and of the erector spinae muscle were recorded. It was found that: The strength of the trunk flexors increased markedly after training. The activity of the oblique abdominal muscles when lifting decreased after training, i.e. motor unit recruitment was not improved. The IAP at lifting was not affected by training. The activity of the oblique abdominal muscles was of no decisive importance to the IAP. The strength of the back muscles increased, but the activity of the back muscles at lifts was not affected by training. In back lifts there was no detectable activity of the back muscles during the beginning of the lifting and during a great part of the lowering. In back lifts the maximum activity of the abdominal muscles appeared long before the peak of the IAP which may be of importance with regard to the pathogenesis of inguinal hernia. Further investigation is needed, both to study the effect of training on patients with back complaints, and to study the factors determining the IAP.

Abdomen↗
PubMed1997

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Abdominal Muscles↗