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PubMed1997

An epidemiological study of diagnostic and therapeutic strategies in office practice patients with subacute or chronic pain in the thoracic or low back. Comparison of practices in primary care and rheumatology settings.

UNLABELLED: There is a paucity of epidemiological data on diagnostic and therapeutic practices in office practice patients with subacute or chronic pain in the thoracic or low back. STUDY OBJECTIVE: to describe diagnostic and therapeutic strategies used in such patients. PATIENTS AND METHODS: descriptive, prospective, two-month epidemiological study in 50 general practitioners and 50 rheumatologists. Each physician was asked to provide data on the demographics, clinical features, history of spinal disease, investigations, prior treatments and treatments prescribed on D0 and D30 in two patients with low back pain and two with thoracic back pain, of one to 12 months' duration. RESULTS: A total of 352 patients were included. In the 217 patients with low back pain, including 107 women and 110 men, duration of the pain was 4.3 +/- 0.2 months and mean age was 49.6 +/- 1 years; 67% of these patients were economically active and 22% were retired; 59% were recruited by rheumatologists. In the thoracic back pain group, there were 135 patients, including 82 women (61%) and 53 men, with a mean duration of pain of 3.8 +/- 0.3 months and a mean age of 47.7 +/- 1.4 years; 60% were economically active and 22% were retired; 49% were recruited by rheumatologists. A history of conservatively-treated low or thoracic back pain was reported for 95.4% of patients in the low back pain group and 94% in the thoracic back pain group. Of the patients with low back pain, 6.3% had had spinal surgery. Investigations were as follows: roentgenograms in 85% of low back pain and 75% of thoracic back pain patients, computed tomography in 11% and 5.8%, magnetic resonance imaging in 2% and 1% and laboratory tests in 14% and 20%. Ninety-one per cent of low back pain and 84% of thoracic back pain patients were already under therapy on D0. Ninety-six per cent of patients overall were given a prescription at the end of the D0 visit, for a nonsteroidal antiinflammatory drug or an analgesic in 80% of low back pain and 63% of thoracic back pain patients, for muscle relaxants in 62% and 69%, for drugs aimed at preventing gastric side effects in 19% and 9.5%, for myotonic agents in 10% and 8% and for sedatives in 5% and 11%. A local steroid injection was given to 20% of low back pain patients. Twenty-four per cent of low back pain and 14% of thoracic back pain patients missed days of work (mean, 11 +/- 1.7 days and 13 +/- 4.6 days, respectively). Physical therapy was prescribed to 36% of low back pain and 27% of thoracic back pain patients and a lumbar support belt to 17% of low back pain patients. On D30, the pain had abated in 86% of low back pain and 89% of thoracic back pain patients and complete freedom from pain was reported by 28% and 32% of patients in these two groups, respectively. Treatments prescribed on D30 were physical therapy (43% and 31%), analgesics (40% and 36%) muscle relaxants (25% and 30%), and nonsteroidal antiinflammatory drugs (23% and 12%). Conclusion. This preliminary study provides data on common practices in subacute and chronic low back and back pain and may prove useful for health care cost estimations.

Acute Disease↗
PubMed1974

Effect of denervation on the adaptation of sarcomere number and muscle extensibility to the functional length of the muscle.

1. The effects of denervation on the response of the cat soleus muscle to immobilization at different lengths by plaster casts has been investigated for a period of 4 weeks.2. The passive length-tension properties of the denervated immobilized muscles were not significantly different from those of non-denervated muscles. Muscles immobilized in the shortened position showed a marked decrease in extensibility whether they were denervated or not. In all the other cases the length-tension curves were not significantly differetn from those of normal muscles.3. The denervated soleus muscle immobilized in the lengthened position was found to produce 25% more sarcomeres in series, whilst those immobilized in the shortened position lost 35%. This adaptation was essentially the same as in muscles that had been immobilized but not denervated.4. Denervation was found to have no effect on the recovery of muscles that had been subjected to 4 weeks immobilization in the shortened position. In these muscles the sarcomere increased back to the normal level within 4 weeks after removal of the plaster cast.5. The adjustment of sarcomere number to the functional length of the muscles does not therefore seem to be directly under neuronal control. It appears to be a myogenic response to the amount of passive tension the muscle is subjected to.

Animals↗
PubMed2002

Relations of Body Mass Index, body fat, and power of various muscles to sport injuries.

The aim of the present study was to estimate associations of Body Mass Index, body fat, and muscle power on sport injuries. In injured and noninjured athletes during a sport season of four months, the differences in Body Mass Index, the percent body fat, and back, leg, and right- and left-hand muscle strength were examined. The subjects were 329 men and 127 women attending classes in the departments of Physical Training and Sport of Atatürk University (Erzurum, Erzincan, and Ağri in Turkey). Body Mass Index was higher in injured athletes than in noninjured ones, but there was no difference in percent body fat between injured and noninjured athletes. The back and leg muscle power were higher for noninjured athletes than for injured ones. The right- and left-hand power was higher for injured athletes in some sports. Because the back and leg muscles function in control of equilibrium, the power of these muscles may be important for control related to avoidance of sport injuries.

Adipose Tissue↗
PubMed2005

Short latency stretch reflex in human lumbar paraspinal muscles.

The aim of the study was to measure stretch reflex latencies of the lumbar paraspinal muscles. An electromechanical tapping system was constructed enabling an accurate estimation of short latencies by utilizing a new technique combining results for different tapping durations. Latency parameters (onset, peak and zero-crossing of EMG signal) were obtained for the paraspinal muscles at the L3/L4 level for 10 male subjects. Detection of EMG onset, which was determined by a threshold criterion (2.5 S.D. of pre-activity), yielded 7.4+/-1.4 ms corresponding to a physiological short latency onset of 6.5 ms, which is considerably shorter than previously reported. However, it is shown to be consistent with the expected latency value for a monosynaptic stretch reflex for the paraspinal muscles of the low back.

Adult↗
PubMed1987

The role of prerotation of the trunk in axial twisting efforts.

The myoelectric activity of selected trunk muscles was recorded during the development of controlled isometric axial torques. Muscle activity was measured bilaterally over the erector spinae, the rectus abdominus, the oblique external and the oblique internal abdominal muscles at the L3 level. Subjects first applied graded isometric torque efforts over a 10 second ramp up to maximum voluntary contraction with the trunk in neutral rotation. They then repeated the effort with the trunk twisted to the left and right. The largest electromyographic activities were found in the agonistic oblique muscles, but considerable antagonistic activity was present also. While the activity of the internal oblique and rectus were bilaterally similar in symmetric standing a difference occurred between the two sides when the trunk was twisted to the right or left. Axial prerotation of the trunk by 30 degrees in the direction of torque development marginally decreased the maximal developed torque, whereas prerotation in the opposite direction increased the developed torque.

Abdominal Muscles↗
PubMed2005

Evolutionary aspects and muscular properties of the trunk--implications for human low back pain.

Considerations about back pain, its aetiology, pathogenesis and therapy often argue that low back pain is the "price" that humanity has to pay for the upright body posture and the bipedal mode of locomotion. In fact, there are only few species that have evolved an obligate bipedal locomotion (e.g. kangaroos). Surprisingly, there are only minor morphological adaptations in humans clearly connected to the upright body posture (e.g. the habitual lumbar lordosis). The overall organization of the body axis has been evolved in quadrupedal animals and was more or less unchanged suitable for the human bipedal mode of locomotion. Up to now, the assumed uniqueness of human's trunk does not explain the frequency of back problems. Because of minor macroscopic differences between humans and other mammals, and even primates, we started to take a closer look at the paravertebral musculature. A three-dimensional investigation of muscle's fibre type distribution was undertaken on laboratory rats. Serial sections from the caudal thoracic and lumbar regions of the back were analysed, and the fibre type distribution pattern in all paravertebral muscles was described. Comparisons to other species imply more general characters of the fibre type distribution in mammals. Established concepts of human back muscle function were exposed to be valid for quadruped mammals as well. Muscle properties predicted by a biomechanical model based on human's anatomy (Wagner et al., this issue) were confirmed by results of the current study on a small mammal. Therefore, we propose only minor differences from the observed pattern in human back muscles.

Journal Article↗
PubMed2007

Critical illness VR rehabilitation device (X-VR-D): evaluation of the potential use for early clinical rehabilitation.

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.

Abdominal Muscles↗
PubMed2003

Growth and cellular differentiation: a physico-biochemical conundrum? The example of the hand.

Currently, the predominant hypothesis explains cellular differentiation as an essentially genetic intracellular process. The goal of this paper is to suggest that cell growth and differentiation may be, simply, the result of physical and chemical constraints. Bone growth occurs at the level of cartilage conjunction (growth plate) in a zone of lesser constrain. It appears that this growth also induces muscle, tendon, nerve and skin elongation. This cartilage growth by itself seems to explain the elongation of the hand. Growth stops at puberty likely because of feed-back from an increasing muscle load. The ossification (that is differentiation of cartilage into bone) appears to result from the shear stress induced. The study of bone age, obtained by X-ray picture of the hand, shows that ossification of epiphyses is very precise both in time and space. Computer modelization suggests that this ossification occurs where shear stress is greatest. The cartilage which does not ossify (joint, nose, larynx, ear, bronchus, etc.) is not exposed to high shear. Shear stress induces the secretion of extracellular matrix and a change of the biochemical environment of the cell. Precipitation of calcium phosphate, as in ossification, seems related to the alkalosis induced by shear stress. To speak in more general terms, loss of cellular differentiation, as occurs with cancer, can result from a change in the physical-chemical environments.

Alkalosis↗
PubMed2006

Laboratory evaluation of belt usage with apple buckets.

BACKGROUND: Migrant and seasonal orchard harvest workers experience musculoskeletal strain caused by carrying heavy loads and holding awkward postures. An ergonomic hip belt designed to redistribute weight from the upper back, neck, and shoulders to the hips was evaluated. METHODS: A comparison of muscle exertion (using electromyography [EMG]) of four key back and shoulder muscles and shoulder surface pressure (using a surface pressure sensor [PS]) was made among 10 laboratory volunteers under intervention and control conditions, in two postures (standing erect [0 degrees ]) and flexed [45 degrees ]). RESULTS: All but one measure showed a significant reduction in the flexed posture with the intervention. Two of eight measures showed a significant reduction in the erect posture. Correlations with shoulder discomfort were found for deep shoulder EMG (r=0.71, P=0.021) and shoulder surface pressure (r=0.58, P=0.082). CONCLUSIONS: The hip belt intervention produces significant reductions in muscle activity while in a posture commonly assumed during orchard work.

Adult↗
PubMed2004

Back pain and disability after lumbar laminectomy: is there a relationship to muscle retraction?

OBJECTIVE: Preliminary studies have suggested that prolonged retraction of the paraspinal muscle during spinal surgery may produce ischemic damage. We report the continuous measurement of intramuscular pressure (IMP) during decompressive lumbar laminectomy and its relationship to subsequent back pain and disability. METHODS: Twenty patients undergoing two-level decompressive lumbar laminectomy for lumbar canal stenosis were recruited. Back pain and disability were assessed by use of the Visual Analog Score (VAS), Oswestry Disability Index (ODI), and Short-Form 36 (SF-36) Health Survey. During surgery, IMP was recorded continuously from the multifidus muscle by use of a pressure transducer. The intramuscular perfusion pressure (IPP) was estimated as the difference between the patient's mean arterial pressure and IMP. RESULTS: Two muscle retractors were used: the Norfolk and Norwich (n = 10) and the McCulloch (n = 10). The mean duration of deep muscle retraction was 62.7 +/- 8 minutes (range, 19-133 min). On application of deep muscle retraction, there was a rapid and sustained increase in IMP (P < 0.001), and overall, the calculated mean IPP approached 0 mm Hg or less during this period (P < 0.001). On release of deep muscle retraction, there was a rapid decrease in IMP to preoperative levels. The IPP was greater with the Norfolk and Norwich than the McCulloch retractor (P < 0.001). Compared with preoperative values, there was a decrease in ODI (P < 0.001) and VAS for back pain (P < 0.001) at discharge and 4 to 6 weeks and 6 months after surgery. In addition, there was a decrease in SF-36 scores at 6 months compared with preoperative values (P < 0.001). Total duration of muscle retraction greater than 60 minutes was associated with worse VAS scores for back pain and ODI and SF-36 scores for disability at 6 months after surgery (P < 0.05). There was no relationship between the VAS, ODI, and SF-36 scores and other parameters measured, including the mean IPP, retractor type, operating surgeon, and wound length. CONCLUSION: The McCulloch retractor generates a higher IMP than the Norfolk and Norwich retractor. However, postoperative improvement in VAS, ODI, and SF-36 scores in these patients was associated with a shorter duration of muscle retraction and not the degree of IMP or IPP generated. In this respect, periodic relaxation of the paraspinal muscle retractors during surgery to allow muscle perfusion may help to reduce postoperative back pain and disability.

Adult↗
PubMed2001

Oscillatory interaction between human motor cortex and trunk muscles during isometric contraction.

We investigated oscillatory interaction between magnetoencephalographic signals of the human motor cortex and surface electromyogram from the paraspinal (PS) and abdominal (ABD) muscles. The results were compared with data obtained during contraction of the first dorsal interosseus (FDI) and tibialis anterior (TA) muscles. Significant coherence at 15-35 Hz was observed for both PS and ABD muscles in all subjects but the coherence was weak compared with that for FDI and TA. The cortical sources for both the PS and the ABD coherences were located in the motor cortex between the source areas for the FDI and TA coherences, thereby agreeing with the classical trunk area of the motor homunculus previously determined by invasive studies. The sources were strictly contralateral for PS but bilateral for ABD contractions. Our results indicate that during isometric contractions descending motor commands are modulated by cortical oscillations for both limb and trunk muscles, although the modulation is weaker and may be bilateral for trunk muscles.

Abdominal Muscles↗
PubMed2003

Botulinum toxin type A therapy in chronic pain disorders.

This self-directed learning module highlights that the underlying problem in many types of muscle pain disorders is a distortion of critical structures that causes functional deficits and pain. An objective of treatment is to reverse this distortion, enabling repair of damaged tissues and strengthening of weakened muscles. Administering botulinum toxin type A (BTX-A; Botox) to reduce muscle tone and overactivity warrants consideration as part of an overall treatment approach that includes physical therapy to help restore normal muscle length and biomechanical balance to improve the prospect of ensuring long-term relief from associated pain. This article specifically focuses on pertinent review articles, results of controlled and open-trial data, and case reports to assess the role of BTX-A treatment in chronic pain disorders. OVERALL LEARNING OBJECTIVE: To review the clinical trial data of the safety and efficacy of BTX-A for the treatment of chronic pain syndromes associated with muscle disorders.

Anti-Dyskinesia Agents↗
PubMed2005

The mechanics of jumping versus steady hopping in yellow-footed rock wallabies.

The goal of our study was to explore the mechanical power requirements associated with jumping in yellow-footed rock wallabies and to determine how these requirements are achieved relative to steady-speed hopping mechanics. Whole body power output and limb mechanics were measured in yellow-footed rock wallabies during steady-speed hopping and moving jumps up to a landing ledge 1.0 m high (approximately 3 times the animals' hip height). High-speed video recordings and ground reaction force measurements from a runway-mounted force platform were used to calculate whole body power output and to construct a limb stiffness model to determine whole limb mechanics. The combined mass of the hind limb extensor muscles was used to estimate muscle mass-specific power output. Previous work suggested that a musculoskeletal design that favors elastic energy recovery, like that found in tammar wallabies and kangaroos, may impose constraints on mechanical power generation. Yet rock wallabies regularly make large jumps while maneuvering through their environment. As jumping often requires high power, we hypothesized that yellow-footed rock wallabies would be able to generate substantial amounts of mechanical power. This was confirmed, as we found net extensor muscle power outputs averaged 155 W kg(-1) during steady hopping and 495 W kg(-1) during jumping. The highest net power measured reached nearly 640 W kg(-1). As these values exceed the maximum power-producing capability of vertebrate skeletal muscle, we suggest that back, trunk and tail musculature likely play a substantial role in contributing power during jumping. Inclusion of this musculature yields a maximum power output estimate of 452 W kg(-1) muscle. Similar to human high-jumpers, rock wallabies use a moderate approach speed and relatively shallow leg angle of attack (45-55 degrees) during jumps. Additionally, initial leg stiffness increases nearly twofold from steady hopping to jumping, facilitating the transfer of horizontal kinetic energy into vertical kinetic energy. Time of contact is maintained during jumping by a substantial extension of the leg, which keeps the foot in contact with the ground.

Analysis of Variance↗
PubMed1996

Occupational back belt use: a literature review.

1. Back belts are thought to act by decreasing spinal loading, decreasing vertebral compression, and increasing intra-abdominal pressure by limiting twisting and upper body gross motions. 2. They appear to have little effect on most back injury risk factors, but may have a limited effect on improving muscle strength and supporting the back during lifting and twisting activities. 3. The use of back belts as a psychological support requires further investigation. 4. Based on insufficient objective scientific data, NIOSH recommended against back belt use by healthy people.

Back Pain↗
PubMed1996

Distributed moment histogram: a neurophysiology based method of agonist and antagonist trunk muscle activity prediction.

A neurocortical-based technique of muscle recruitment is presented to solve the muscle indeterminacy problem for lumbar torso modeling. Cortical recordings from behaving primates have established motor cortex cells that respond to a wide range of task directions, but are tuned to a preferred direction. A characteristic activity pattern of these neurons seems to be associated with effort direction. It was hypothesized that a model which recruits muscles based on a similar distribution would predict antagonistic muscle activity with greater realism than a widely referenced optimization formulation. The predictions of the Distributed Moment Histogram (DMH) method were evaluated under common speed (< 30 degrees s-1) sagittal plane lifting conditions using five subjects. The predicted forces showed high correspondence with agonist and antagonist myoelectric patterns. The mean coefficient of determination for the erector spinae was r2 = 0.91, and 0.41 for the latissimus. For the antagonistic muscles, the rectus abdominus was found to be electrically silent (< 3% MVC) and no activity was predicted by the method. The external oblique muscle was observed to be minimally active (< 16% MVC), and the DMH method predicted its mostly constant activity with a mean standard error of 1.6% MVC. The realistic antagonistic predictions supported the hypothesis and justify this cortical based technique as an alternative for muscle tension estimation in biomechanical torso modeling. A primary advantage of this method is its computational simplicity and direct physiologic analog.

Abdominal Muscles↗
PubMed1995

Concentric and eccentric strength of trunk muscles: influence of test postures on strength and characteristics of patients with chronic low-back pain.

The purpose of this study was to determine the influence of test postures on trunk muscle strength, and to clarify the difference between concentric and eccentric strength of healthy subjects and patients with chronic low-back pain (CLBP). Volunteered and controlled trials took place at a university hospital, which is a referral center and is also open to the general community. The patients were selected from the outpatient care in the university hospital. Fifty healthy subjects (25 men and 25 women; average age 25.7 years, ranging from 23 to 34 years) and 48 patients with CLBP (26 men and 22 women; average age 33.5 years, ranging from 26 to 39 years) volunteered for this study. The main outcome measures were flexor and extensor peak torque/body weight, and flexor/extensor peak torque ratio during concentric and eccentric contractions; Eccentric/concentric peak torque ratio in flexor and extensor. Trunk-muscle strength was significantly greater in the sitting posture when measured with the subjects' feet against the floor (p < .05). Some patients complained of a slight low-back pain during testing, although the pain was not aggravated in any patients. In both concentric and eccentric contraction modes, the patients with CLBP had greater flexor/extensor ratios than the healthy subjects (p < .01). This implies that extensors are more affected in these patients. However, a great imbalance between concentric and eccentric strength of the patients was found, not only in extensors, but also in flexors (p < .01). The current study shows that one should consider the test posture carefully when measuring trunk-muscle strength.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗