Chapter 4. European guidelines for the management of chronic nonspecific low back pain.
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Chronic Disease↗
Biomedical subjects
O Airaksinen
Publications and source records attributed to O Airaksinen.
Changes in knee extension and flexion force, EMG and functional capacity during strength training in older females with fibromyalgia and healthy controls.
OBJECTIVE: To investigate the effects of strength training on neuromuscular functions in elderly females with fibromyalgia (FM). METHODS: Thirteen females with fibromyalgia [group FMt; mean age (s.d.) 60.2 (2.5) years] and 11 healthy controls [group HCt; 64.2 (2.7) yr] carried out supervised strength training twice a week for 21 weeks. Thirteen FM patients [group FMc; 59.1 (3.5) yr] served as non-training controls. Maximal isometric force and electromyographic (EMG) activity of the right quadriceps femoris in knee extension and flexion actions, maximal 10-m walking speed, and 10-step stair-climbing time were measured. Tender points were assessed by palpation, subjectively perceived symptoms with a visual analogue scale, and the self-reported physical function capacity by Health Assessment Questionnaire (HAQ). RESULTS: The mean (s.d.) increases in maximal extension force during the training period in groups FMt and in HCt were 32 (33)% (P < 0.001) and 24 (12)% (P < 0.001) respectively and those of flexion were 13 (20)% (P < 0.05) and 24 (17)% (P < 0.01). Explosive force of the extensors increased in both FMt and in HCt. The integrated EMGs of the vastus lateralis and medialis muscles increased in both FMt and HCt. Muscle forces and EMGs in group FMc remained at the basal level. Walking speed, stair-climbing time and the HAQ index improved in group FMt. The changes in the number of tender points and in perceived symptoms were in favour of the training group FMt. CONCLUSIONS: The data support the hypothesis that elderly female FM patients have normal neuromuscular function. Supervised strength training also suits elderly FM patients, has positive effects on perceived symptoms and improves functional capacity without complications.
Aged↗
Segmental lumbar spine instability at flexion-extension radiography can be predicted by conventional radiography.
AIM: To identify plain radiographic findings that predict segmental lumbar spine instability as shown by functional flexion-extension radiography. MATERIALS AND METHODS: Plain radiographs and flexion-extension radiographs of 215 patients with clinically suspected lumbar spine instability were analysed. Instability was classified into anterior or posterior sliding instability. The registered plain radiographic findings were traction spur, spondylarthrosis, arthrosis of facet joints, disc degeneration, retrolisthesis, degenerative spondylolisthesis, spondylolytic spondylolisthesis and vacuum phenomena. Factors reaching statistical significance in univariate analyses (P < 0.05) were included in stepwise multiple logistic regression analysis. RESULTS: Degenerative spondylolisthesis (P = 0.004 at L3-4 level and P = 0.017 at L4-5 level in univariate analysis and odds ratio 16.92 at L4-5 level in multiple logistic regression analyses) and spondylolytic spondylolisthesis (P = 0.003 at L5-S1 level in univariate analyses) were the strongest independent determinants of anterior sliding instability. Retrolisthesis (odds ratio 10.97), traction spur (odds ratio 4.45) and spondylarthrosis (odds ratio 3.20) at L3-4 level were statistically significant determinants of posterior sliding instability in multivariate analysis. CONCLUSION: Sliding instability is strongly associated with various plain radiographic findings. In mechanical back pain, functional flexion-extension radiographs should be limited to situations when symptoms are not explained by findings of plain radiographs and/or when they are likely to alter therapy.
Adolescent↗
Disc herniation-related back pain impairs feed-forward control of paraspinal muscles.
STUDY DESIGN: A comparative study of lumbar paraspinal muscle reflexes during sudden upper limb loading in healthy control subjects and patients with sciatica. OBJECTIVES: To assess reflex activation of paraspinal muscles during sudden upper limb loading. SUMMARY OF BACKGROUND DATA: Sudden upper limb loading and upper limb voluntary movements cause reflex activation of trunk muscles. A short latency response of approximately 50 msec of lumbar muscles has been observed before, but the reflexes have not been studied in patients with sciatica. METHODS: The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG from 20 patients selected for an operation as a result of disc herniation-related chronic low back pain and 15 back-healthy controls. Pain, disability, and depression scores were recorded. RESULTS: Short latency response of paraspinal muscles for unexpected upper limb loading was similar in healthy controls and patients with sciatica in supported standing. During normal standing anticipation shortened the lumbar reflex latency in healthy controls but not among the patients. CONCLUSIONS: The results provide evidence for impaired feed-forward control of lumbar muscles in patients with sciatica.
Adult↗
Back and abdominal muscle function during stabilization exercises.
OBJECTIVES: To assess the paraspinal and abdominal muscle activities during different therapeutic exercises and to study how load increment produced by varying limb movements and trunk positions could affect these muscle activities. DESIGN: A cross-sectional study comparing muscle activities between men and women. SETTING: Rehabilitation clinic in university hospital. PARTICIPANTS: Twenty-four healthy volunteers (14 women, 10 men) aged 21 to 39 years. INTERVENTIONS: Subjects performed 16 different therapeutic exercises commonly used to treat low back pain. MAIN OUTCOME MEASURES: Surface electromyography was recorded from the paraspinal (T9, L5) and abdominal (rectus abdominis, obliquus externus) muscles during these exercises. Average electromyographic amplitudes obtained during the exercises were normalized to the amplitude in maximal voluntary contraction (% MVC) to produce interindividually comparable muscle activity assessments. RESULTS: Mean average normalized electromyographic amplitudes (% MVC) of the exercises were below 50% MVC. At L5 level, the multifidus muscle activities were significantly higher (p <.05) in women than in men, whereas no significant difference was found at T9 level. Similarly, rectus abdominis and obliquus externus activities were significantly higher (p <.001, p <.05) in women than in men. Load increment in hands or unbalanced trunk and limb movements produced higher paraspinal and abdominal muscle activities (p <.05). CONCLUSIONS: Simple therapeutic exercises are effective in activating both abdominal and paraspinal muscles. By changing limb and trunk positions or unbalancing trunk movements, it is possible to increase trunk muscle activities. Women were better able to activate their stabilizing trunk muscles than men; but it is also possible that men, having a much higher degree of strength on maximal contraction, only need to activate a smaller amount of that maximum to perform a similar activity.
Abdominal Muscles↗
Monitoring of muscle fatigue during isokinetic exercise.
The aim of this study was to evaluate and clarify the usefulness of different spectral characteristics of myoelectrical activity in the follow-up of development of muscle fatigue. Vastus lateralis (part of quadriceps) muscle loaded in a simple isokinetic exertion test was used as a model. Twelve, well trained athletes served as study subjective to minimize the inter-individual variations. They went through one-minute test with isokinetic device at the range of 90 degrees extension and flexion at the level of their maximal force. The myoelectrical signals were registered from middle of the vastus lateralis muscle by a computerized fast Fourier transform analyzing system based on 80286 and 80287 microprocessors and using surface electrodes. Mean power frequency (MPF) was 65.6 (SE=Standard Error, 1.6) Hz, median frequency (MF) 55.8 Hz and zero crossing rate (ZCR) 92.5 (SE 1.5) during first performance. All these parameters decreased apparently linearly and significantly from the beginning of the test (P<0.001). The decrease rate of ZCR was fastest and MF slowest. The area of power spectrum (PSA) was 1753 (SE 320) units during first performance, and it increased markedly with slightly accelerating rate during the test. In conclusion, for the evaluation of the muscular performance during the development of fatigue it is beneficial to monitor simultaneously MPF, MF and ZCR.
Adult↗
Back and hip extensor activities during trunk flexion/extension: effects of low back pain and rehabilitation.
OBJECTIVE: To compare lumbar paraspinal, gluteus maximus, and biceps femoris muscle function during sagittal trunk flexion and extension in patients with chronic low back pain and healthy control subjects, and to assess the influence of rehabilitation in the back pain patients. DESIGN: A cross-sectional study comparing chronic low back pain patients and healthy controls, and a prospective follow-up in back pain patients during rehabilitation. SETTING: Physical medicine and rehabilitation clinic. SUBJECTS: Nineteen women with chronic low back pain, and 19 women without pain (controls). INTERVENTION: Five-week active outpatient rehabilitation (1 hour three times a week) guided by a physiotherapist, followed by 5-week self-motivated exercise at home. OUTCOME MEASURES: Subjects performed sagittal trunk flexion and extension while surface electromyogram was bilaterally recorded of paraspinal (L1-L2 level), gluteus maximus, and biceps femoris muscles. The muscle activity was assessed from the average electromyogram and the relative muscle activation onsets and their duration were calculated. RESULTS: During early flexion, lumbar paraspinal and biceps femoris were activated simultaneously before gluteus maximus. At the end of flexion and during extension all investigated muscles were activated and relaxed in order. Lumbar paraspinal and biceps femoris muscles were activated in a similar order in low back pain patients and healthy controls during flexion and extension. However, the duration of gluteus maximus activity was shorter in the back pain patients than in controls during the trunk flexion (p<.05), and it ended earlier during extension. Active rehabilitation did not change the muscle activities of lumbar paraspinal and biceps femoris in the back pain patients, but in the measurements after rehabilitation the onset of gluteus maximus activity occurred later in flexion and earlier in extension. CONCLUSIONS: The activity of the gluteus maximus muscle during the flexion-extension cycle was reduced in patients with chronic low back pain. The gluteal muscles should be taken into consideration in the rehabilitation of these patients.
Adult↗
Computed tomography findings 4 years after surgical management of lumbar spinal stenosis. No correlation with clinical outcome.
STUDY DESIGN: A prospective, cross-sectional study of the correlation between postoperative computed tomography findings and patients' clinical outcomes approximately 4 years after laminectomy for lumbar spinal stenosis. OBJECTIVES: To evaluate clinical and radiologic characteristics and their relation to each other. SUMMARY OF BACKGROUND DATA: The goal of surgical management for lumbar spinal stenosis is to decompress the stenotic area determined in radiologic examinations to relieve pressure on the neurovascular structures. However, the success of this decompression very rarely has been confirmed by postoperative radiologic imaging or compared with clinical outcome. METHODS: Postoperative computed tomography was performed on 191 patients. The findings were classified as "no stenosis," "central stenosis," "lateral stenosis," or "central-lateral stenosis." Postoperative instability of the lumbar spine was investigated by functional radiography. Clinical status was assessed by clinical examination. Subjective disability was assessing using the Oswestry questionnaire, and severity of pain using the visual analog scale. Walking capacity was evaluated by the tread-mill test. RESULTS: Radiologic studies revealed postoperative stenosis in 123 patients (64%). Small differences between the computed tomography groups were shown for the Oswestry score, but not for walking distance. Clinical signs, severity of pain, and radiologic instability were very similar for all computed tomography groups. CONCLUSIONS: Postoperative radiologic stenosis was very common in patients operated on for lumbar spinal stenosis, but this did not correlate with clinical outcome. The clinician must be cautious when reconciling clinical symptoms and signs with postoperative computed tomography findings in patients operated on for lumbar spinal stenosis.
Disability Evaluation↗
Long-term clinical and magnetic resonance imaging follow-up assessment of patients with lumbar spinal stenosis after laminectomy.
STUDY DESIGN: A cross-sectional retrospective study to observe the correlation between postoperation findings shown on magnetic resonance imaging and clinical observations of 56 patients 10 years after laminectomy for lumbar spinal stenosis. OBJECTIVE: To evaluate the relation between postoperation findings on magnetic resonance imaging and surgical outcome in patients surgically treated for lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: Surgical management of lumbar spinal stenosis is based on the compression seen in radiologic imaging of neurovascular structures in the vertebral canal, but the success of surgical decompression and its correlation with clinical observations very seldom have been monitored by postoperation radiologic imaging. METHODS: In this study, 56 patients surgically treated for lumbar spinal stenosis were re-examined clinically by use of the Oswestry disability questionnaire. Their walking capacity was evaluated by the treadmill test. Severity of pain before and after the treadmill test was investigated using a visual analog scale. Patients' perception of improvement measured as the change in their condition during the preceding 5 years was elicited by a questionnaire. On the basis of the stenotic findings on magnetic resonance imaging, the patients were classified into no stenosis (NoSten, n = 15) and stenosis (Sten, n = 41) groups, and a summative degenerative scale also was constructed with the findings categorized as follows: disc degeneration, disc herniation, facet joint arthrosis, and degenerative spondylolisthesis. RESULTS: Whereas the patients' perception of improvement correlated very strongly with the Oswestry score and walking capacity, there was no statistical difference between the NoSten and Sten groups in the Oswestry score, walking capacity, perception of improvement, or severity of pain. The effect of the summative degenerative scale on the patients' walking capacity was 13 times greater than the effect of the minimum area of the dural sac. CONCLUSIONS: Patients' perception of improvement had a much stronger correlation with long-term surgical outcome than structural findings seen on postoperation magnetic resonance imaging. Moreover, degenerative findings had a greater effect on patients' walking capacity than stenotic findings.
Female↗
The degree of decompressive relief and its relation to clinical outcome in patients undergoing surgery for lumbar spinal stenosis.
STUDY DESIGN: A cross-sectional, clinical study to evaluate surgical decompression of the stenotic area monitored by computed tomographic scan and its relation to clinical variables in patients operated on for lumbar spinal stenosis. OBJECTIVE: To study in patients with lumbar spinal stenosis the influence of the degree of compressive relief on the patients' clinical outcome. SUMMARY OF BACKGROUND DATA: The goal of surgical treatment in lumbar spinal stenosis is to decompress the stenotic area. Although the decompression should be adequate, there are no clear guidelines to determine the extent of necessary decompression. In fact, there is clinical evidence that there is a discrepancy between the surgical outcome in the patient with lumbar spinal stenosis and postoperative radiologic findings. METHODS: In 92 patients with lumbar spinal stenosis who had had no prior back surgery, preoperative and postoperative computed tomographic scans were obtained to determine the degree of decompression. The postoperative scan findings were classified according to the degree of decompression into a no-stenosis group (n = 35), an adjacent-stenosis group (n = 27), and a residual-stenosis group (n = 30). The postoperative instability of the lumbar spine was investigated by functional radiography. The subjective disability of the patients was assessed using the Oswestry score and the severity of pain using the visual analog scale. Walking capacity was evaluated by a treadmill test. The patients' estimations of the results of surgery were classified into groups of satisfied patients and dissatisfied patients. RESULTS: The mean Oswestry score in all 92 patients was 27.1, and mean walking capacity was 630 m. In the satisfied patients, the Oswestry score was 18.8 and in the dissatisfied patients, 34.9 (P < 0.0000). Walking capacity was 690 m and 594 m, respectively. There were 30 patients with postoperative spinal instability, but it had no influence on surgical outcome. There were no differences in the Oswestry score, walking capacity, and patients' satisfaction among the postoperative CT groups. In the linear regression analysis, the satisfied patient corresponded significantly with the Oswestry score. CONCLUSIONS: The satisfaction of the patients with the results of surgery was more important in surgical outcome than the degree of decompression detected on computed tomographic scan.
Cross-Sectional Studies↗
The efficacy of active rehabilitation in chronic low back pain. Effect on pain intensity, self-experienced disability, and lumbar fatigability.
STUDY DESIGN: A randomized study comparing the results of active rehabilitation and passive control treatment in patients with chronic low back pain with follow-up at 6 months and 1 year. OBJECTIVES: To study the efficacy of active rehabilitation on pain, self-experienced disability, and lumbar fatigability. SUMMARY OF BACKGROUND DATA: Exercises in an outpatient setting are widely used for the treatment of chronic low back pain. The efficacy of the active rehabilitation approach has been documented in randomized control studies, but these studies have seldom been focused on lumbar fatigability, which is now recognized as a frequent problem among patients with chronic low back pain. METHODS: Fifty-nine middle-aged patients (37 men and 22 women) with nonspecific chronic low back pain were randomly assigned to 12 weeks' active rehabilitation or to a passive control treatment (massage, thermal therapy). Pain and disability index, low back pain intensity (visual analog scale, 100 mm), and the objectively assessed lumbar muscle fatigability (spectral electromyogram, mean power frequency slope [MPFSLOPE]) in a new 90-second submaximal isoinertial back endurance test were recorded before and after the interventions and at 6-month and 1-year follow-up visits. RESULTS: Results of repeated measures multivariate analysis of variance indicated that back pain intensity (visual analog scale) and functional disability (pain and disability index score) decreased, and lumbar endurance (MPFSLOPE) improved significantly more (P < 0.05) in the active rehabilitation group than in the passive control treatment group, when measured at a 1-year follow-up examination. The group difference in visual analog scale and pain and disability index changes became even more significant at the end of 1 year. The change in lumbar endurance was significantly greater in the active rehabilitation group than in the passive control treatment group at the 6-month follow-up, but not at the 1-year follow-up. CONCLUSIONS: The active progressive treatment program was more successful in reducing pain and self-experienced disability and also in improving lumbar endurance than was the passive control treatment. However, the group difference in lumbar endurance tended to diminish at the 1-year follow-up.
Adult↗
Back and hip extensor muscle function during therapeutic exercises.
BACKGROUND: Therapeutic exercises are widely used in the treatment of low back problems. Clinical knowledge about targeting the load in these exercises, however, is insufficient. This study assessed the L2 and L5 level paraspinal and gluteus maximus muscle activities in different therapeutic exercises. Intramuscular and surface electromyography (EMG) measurements were obtained to study whether surface EMG measurements can be used in the assessment of multifidus muscle function. METHODS: Eleven healthy subjects (5 men, 6 women) 21 to 38 years of age volunteered for the study. The subjects performed 18 different therapeutic exercises. During the exercises paraspinal EMG was recorded using fine wire and surface electrodes. The normalized peak and average muscle EMG activities (percentage of amplitude in maximal voluntary contraction [MVC]) during each task were determined. RESULTS: The correlations between the average intramuscular and surface activities of the normalized EMG (% of MVC) at the L2 and L5 levels were .928 and .950, respectively. The peak and average EMG amplitudes of the exercises were below 50% and 25% of MVC, respectively. At the L5 level, the multifidus peak and average EMG amplitudes (% MVC) were higher in women than in men, whereas no significant difference was found at the L2 level. In women, the normalized multifidus EMG amplitude was higher at the L5 level than at the L2 level, whereas no significant difference was found in men. In both sexes, the normalized EMG amplitude was higher in the multifidus than in the longissimus muscle. CONCLUSION: Surface EMG measurements may be used in the assessment of multifidus muscle function. Simple therapeutic exercises are effective in activating the lumbar paraspinal muscles.
Adult↗
[Physical examination of the patient with back pain at the physician's office].
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Back Pain↗
[Conservative treatment of back pain].
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Acute Disease↗
Fentanyl decreases beta-CIT binding to the dopamine transporter.
Evidence from animal studies suggest that centrally acting opiates increase synaptic dopamine (DA) concentration. However, the interaction between mu-opioid receptors and the DA system is unclear. We report here an effect of fentanyl on striatal [123I]beta-CIT binding to the DA transporter in a patient and in rats. A female patient underwent [123I]beta-CIT single-photon emission tomography (SPET) study after intrathecal injection of fentanyl for her back pain. After a 2-week drug-free period, the SPET study was repeated. In the experimental study, male Wistar rats were treated with fentanyl either acutely (50 micrograms/kg, i.p.) before imaging study or subacutely for 4 days (10 micrograms/kg, twice a day, i.p.). Brain planar imaging was performed at 3.5 hours after an intravenous injection of [123I]beta-CIT with gamma camera with a pinhole collimator. In a female patient, [123I]beta-CIT binding in the basal ganglia was decreased by 37% during fentanyl as compared to the binding after 2-week drug-free period. Similarly in rats, acute fentanyl treatment decreased [123I]beta-CIT binding to the striatum by 30% as compared to that of with the control rats. After subacute administration of fentanyl, no significant difference was observed compared to the control group. According to the present data, fentanyl decreases [123I]beta-CIT binding in the basal ganglia both in human and rats, suggesting that opiates possibly directly affect DA reuptake.
Adult↗
Comparative immunohistochemical study of group II (synovial-type) and group IV (cytosolic) phospholipases A2 in disc prolapse tissue.
Phospholipase A2 (PLA2) has been suggested to be present in herniated disc tissue and it could possibly be involved in sciatica/ discogenic back pain mechanisms. In the present study the occurrence of two different phospholipase A2 enzymes, (1) low molecular weight (14 kDa) group II synovial-type (sPLA2) and (2) high molecular weight (85 kDa) group IV cytosolic (cPLA2), were compared. Fifty-three disc prolapses obtained at disc operations were analyzed by immunohistochemistry, using anti-human monoclonal antibodies to sPLA2 and cPLA2, respectively. Only cell-associated (disc cells, hyaline cartilage chondrocytes) sPLA2 and cPLA2 immunoreactivity could be observed. The results showed that sPLA2 was more common (25/53, 47%) than cPLA2 (13/53, 25%). sPLA2 and cPLA2 were simultaneously present in 13 of 53 samples (25%). However, both PLA2 enzymes were predominantly present in hyaline cartilage cells (sPLA2: 16/53, cPLA2: 5/53), being less commonly observed in disc cells (sPLA2: 6/53, cPLA2: 3/53). In addition, three samples for sPLA2 and two samples for cPLA2 exhibited immunoreactivity in cartilage and disc cells simultaneously. sPLA2 was observed in no other locations, but in 3 of 53 samples cPLA2 was observed more diffusely in areas of granulation tissue, possibly in macrophages. No gender- or age-related dependence for either type of PLA2 enzyme immunoreactivity could be observed. Neither did their occurrence relate to clinical data such as straight leg raising or neurological deficit. The results do not support a major role for either of the two disc-cell-associated PLA2s in disc pathophysiology. For both enzymes, the major pool appears to reside in cartilage tissue cells, presumably in dislodged end-plate fragments. Disc cells are apparently unlikely candidates for major PLA2 storage.
Adult↗
Back and hip extensor fatigability in chronic low back pain patients and controls.
OBJECTIVE: To compare the lumbar paraspinal and gluteus maximus muscle fatigability between chronic low back pain patients and healthy controls by using electromyographic (EMG) spectral analysis during a maximal isometric endurance task. DESIGN: A cross-sectional comparative study between chronic low back pain patients and healthy control subjects. SETTING: Physical medicine and rehabilitation clinic in Finland. SUBJECTS: Twenty women with nonspecific chronic low back pain (longer than 3 months) and 15 healthy controls. INTERVENTION: Subjects performed maximal voluntary isometric back extensions (MVC) at 30 degrees forward flexion in a specially designed measurement unit. A 50% MVC load was used in isometric endurance test. OUTCOME MEASURES: Low back pain intensity was assessed by using the visual analogue scale and functional disability by the Oswestry disability index. Time to endurance was measured. Bipolar surface EMG recordings were made over the lumbar paraspinal muscles (L3-L4, L5-S1) and over the gluteus maximus muscles. Average EMG (aEMG%), and initial spectral median frequency (MFinit) and change over time (MFslope) were computed. RESULTS: Pain intensity and functional disability were higher and MVC and time to endurance were lower in the chronic low back pain group (p < .05). Similar muscle activity levels (aEMG%) and MFinit indicated similar muscle loading in both groups at the beginning of the endurance test. EMG spectral decreases (MFslope) indicated that lumbar paraspinal muscle fatigability was similar in both groups. In the chronic low back pain group, the gluteus maximus fatigued faster than in the control group (greater MFslope, p < .05). However, the shorter endurance time indicated greater fatigability in the chronic low back pain group in general (p < .05). CONCLUSIONS: The chronic low back pain patients were weaker and fatigued faster than the healthy controls. The EMG fatigue analysis results suggest that the gluteus maximus muscles are more fatigable in chronic low back pain patients than in healthy control subjects during a sustained back extension endurance test.
Adult↗
Age, sex, and body mass index as determinants of back and hip extensor fatigue in the isometric Sørensen back endurance test.
OBJECTIVE: To study the ability of a widely used isometric back endurance test to measure lumbar back erector muscle fatigue and to assess the influence of age, sex, and body mass index (BMI) on back and hip extensor muscle fatigability (EMG spectral indices). DESIGN: Cross-sectional study of men and women without back problems. SETTING: Occupational health center and rehabilitation clinic in Finland. SUBJECTS: Experiment 1 consisted of 233 consecutive occupational health center customers (133 women, 100 men) without back problems. Experiment 2 consisted of 20 healthy women. INTERVENTION: Subjects performed the isometric Sørensen back endurance test up to 240sec in experiment 1 and to the limit of endurance in experiment 2. OUTCOME MEASURES: Raw surface EMG was recorded bilaterally over the belly of lumbar erector spinae muscles at L1-L2 and L4-L5 levels in experiment 1, and bilaterally over the medial paraspinal muscles at L1-L2, L3-L4, and L5-S1 levels and over the major hip extensor muscles (gluteus maximus and biceps femoris) in experiment 2. In both experiments, time to endurance was recorded (in experiment 1 up to 240sec). The EMG spectral median frequency (MF) decrease over time was used for the assessment of back and hip extensor fatigability. RESULTS: In experiment 1, the rate of change in paraspinal MF was greater in men than in women, indicating greater paraspinal fatigability in men. Multiple regression analysis indicated that the rate of MF decrease (fatigue) during the test was dependent on age and BMI in both sexes and that the effects of age and BMI were more pronounced in women than in men. Correlation analysis revealed that the rate of paraspinal muscle MF decrease was associated with endurance time and BMI in women and with endurance time and age in men. In experiment 2, the paraspinal muscles, as well as the hip extensor muscles, biceps femoris, and gluteus maximus, showed clear decreases in MF during the isometric endurance test in women. MF decrease was highly related to endurance time and BMI in women. CONCLUSIONS: Lumbar paraspinal muscle fatigability during the Sørensen test is influenced by subject characteristics. Further, the hip extensor muscles also significantly fatigue, indicating load sharing between back and hip extensor muscles during the test. According to these results, the validity of this widely used back endurance test in specifically measuring lumbar paraspinal muscle endurance is questionable, as is the direct comparison of test results between women and men.
Aging↗