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PubMed1989

Effect of physical exercise on blood mononuclear cell subpopulations and in vitro proliferative responses.

The present study was designed to examine the effect of physical exercise on subsets and proliferative responses of blood mononuclear cells. Sixteen young, healthy volunteers underwent 60 min of bicycle exercise at 75% of maximal oxygen uptake (VO2max). After an interval of at least 1 week, six of the subjects underwent a 60-min back muscle training period at up to 30% of VO2max. Blood samples were collected before and during the last minutes of exercise, as well as 2 and 24 h later. Blood mononuclear cell (BMNC) subpopulations were determined and the proliferative responses after incubation with phytohaemagglutinin (PHA) or purified derivative of tuberculin (PPD), were quantified by [3H]thymidine incorporation. During bicycle exercise the relative blood concentration of T cells (CD3+ cells) declined, mainly due to a fall in T helper cells (CD4+ cells). The natural killer (NK) cell subset (CD16+ cells) increased during work, but reverted after; the monocytes (CD14+ cells) increased 2 h after work, whereas the B-cell subset (CD20+ cells) did not change. BMNC subsets were not significantly changed by back muscle exercise. The PHA-induced proliferative response decreased during bicycle exercise, whereas the PPD-induced response did not change. No significant changes occurred during back muscle exercise. Investigation of subgroups after incubation with [3H]thymidine showed that the proliferative response per CD4+ cell did not change in relation to exercise, but the contribution of the CD4+ subgroup to proliferation declined during bicycle exercise due to the decreased proportion of CD4+ cells. The suppression of the PHA response during bicycle exercise can be explained in part by a relative fall in CD4+ cells. The pool sizes of BMNC subfraction may be elicited by increased catecholamine and cortisol levels.

Adult↗
PubMed2001

A triaxial dynamometer to monitor lateral bending and axial rotation moments during static trunk extension efforts.

OBJECTIVE: The purpose of the study was to describe a new static triaxial dynamometer designed to monitor the lateral bending and axial rotation moments during trunk extension efforts. BACKGROUND: Most studies on back muscle function using electromyographic spectral analysis have not controlled moments produced about the three orthopaedic axes during trunk extension efforts. Criteria to control lateral bending and axial rotation moments during extension efforts have not been proposed in the literature. METHODS: Fourteen healthy subjects performed three trunk extension ramp contractions (0-100% of the maximal voluntary contraction). Triaxial L5/S1 moments at 20%, 40%, 60% and 80% of the maximal voluntary contraction in extension were extracted. RESULTS: During the extension efforts, the lateral bending and axial rotation moments at L5/S1 increased significantly across the force levels and reached 6.2 Nm (SD: 6.6) and 6.1 Nm (SD: 4.5), respectively, at 80% of the maximal voluntary contraction. Tolerance limits were proposed to control these associated efforts in the context of the electromyographic analysis of back muscles. Relevance. Simultaneous measurement of lateral bending and axial rotation moments at L5/S1 during extension efforts might help to explain and control load sharing between back muscles during extension efforts.

Adult↗
PubMed1993

Fat content of lumbar extensor muscles and low back disability: a radiographic and clinical comparison.

The fat content of the lumbar back extensor muscles was assessed from computed tomograms and correlated to self-reported disability in 39 consecutive chronic low back pain patients. The assessment for the quality of fat was done separately for the three lowest lumbar intervertebral levels. The Oswestry index was used to evaluate the low back disability. Analysis showed positive relationship between the fat content of the lumbar paraspinal muscles at lumbosacral level and self-reported disability in men. The relationship was weaker in women, and at higher lumbar levels it was not found in either sex.

Adipose Tissue↗
PubMed1989

Involvement of 5-HT2 receptors in the behaviours produced by intrathecal administration of selected 5-HT agonists and the TRH analogue (CG 3509) to rats.

1. The behavioural effects of the intrathecal injection of a thyrotrophin-releasing hormone (TRH) analogue L-orotyl-L-histidyl-prolineamide (CG 3509, 0.5 micrograms), the non-selective 5-HT1 and 5-HT2 receptor agonist 5-methoxy-N,N'-dimethyltryptamine (5-MeODMT, 2-100 micrograms) and the selective 5-HT2 receptor agonist 2,5-dimethoxy-alpha,4-dimethyl-benzene ethamine hydrochloride (DOM, 2-25 micrograms) were compared with the response of systemically administered 5-MeODMT (2 mg kg-1, i.p.) in rats, to establish whether the agonist-induced behaviours were mediated by bulbospinal 5-HT1 or 5-HT2 receptors. 2. Intrathecal injection of 5-MeODMT or DOM produced dose-related back muscle contractions (a previously undocumented behaviour) and wet-dog shakes which were both markedly attenuated by ritanserin pretreatment (1 mg kg-1, i.p.) indicating the involvement of 5-HT2 receptors. In contrast, reciprocal forepaw treading, flat body posture and Straub-tail were evoked by 5-MeODMT but not by DOM indicating that these behaviours were not produced by 5-HT2 receptor activation alone. However, as ritanserin pretreatment reduced the reciprocal forepaw treading induced by intrathecal 5-MeODMT, this behaviour may be facilitated by 5-HT2 receptor activation. 3. Intrathecal 5,7-dihydroxytryptamine (5,7-DHT, 2 x 150 micrograms) treatment decreased thoraco-lumbar spinal cord 5-HT (-95%) and potentiated the back muscle contractions produced by intrathecal DOM injection without altering the wet-dog shake behaviour. None of the components of the 5-HT syndrome produced by 5-MeODMT (2 mg kg-1, i.p.), with the exception of a small increase in wet-dog shakes, was significantly altered by intrathecal 5,7-DHT (which reduced thoraco-lumbar spinal cord 5-HT by 84%). Taken together these data suggest that the only 5-HT agonist-induced behaviour mediated by the activation of 5-HT2 receptors located postsynaptic to bulbospinal 5-hydroxytryptaminergic (5-HTergic) neurones was back muscle contractions. 4. The wet-dog shake and forepaw licking behaviors produced by intrathecal CG 3509 (0.5 micrograms) were attenuated when ritanserin was administered intrathecally 30 min before, but not when it was given at the same time as CG 3509 and neither behaviour was altered by intrathecal 5,7-DHT. This suggests that bulbospinal 5-HTergic neurones are not involved in the production of these TRH analogue-induced behaviours and that the 5-HT2 receptors which mediate these behaviours are not located in the spinal cord.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1982

Loads on the lumbar spine. Validation of a biomechanical analysis by measurements of intradiscal pressures and myoelectric signals.

UNLABELLED: We studied the validity of predictions of compressive loads on the lumbar spine and contraction forces in lumbar trunk muscles based on a biomechanical model. The predictions were validated by quantitative measurements of myoelectric activities at twelve locations on the trunk and of the pressure in the third lumbar disc. Twenty-five tasks were performed isometrically by four healthy volunteers. The model predicted that the tasks imposed mean compressive loads on the spine of as much as 2400 newtons and required contraction forces of the posterior muscles of the back of as much as 1800 newtons. Intradiscal pressures of as much as 1600 kilopascals were measured. The predicted and measured quantities were well correlated. It appears that the model adequately predicted the compressive loads on the lumbar spine and the tensions in the back muscles. CLINICAL RELEVANCE: Patients with low-back disorders limit their physical activities, which indicates that loading on the spine must be a factor in those disorders. This study shows that the loads imposed on the spine by physical activities need not be measured. They can easily be calculated. This will significantly accelerate biomechanics research on low-back disorders. The calculation techniques that we validated for predicting loads on the spine can be used to calculate the loads on any skeletal structure. Those loads are largely determined not by the externally applied loads, but by the moments of those applied loads and by the moments of the weights of the body segments that the structure must support.

Abdomen↗
PubMed1989

[Back exercises for patients with chronic low back pain].

The training therapy, which most back therapists consider an indispensable basic element in attempts to treat chronic low back pain, is reviewed, with an historical survey and description of the basic research in the field. Epidemiological studies show concurrence between chronic low back pain and reduced endurance of the back musculature and that the combination of a weak back and a back-straining occupation greatly increases the risk of low back trouble. On the basis of these studies, it is concluded that use of isometric back exercises in low dosage, which are central to the internationally acknowledged Swedish back school, only results in strengthening and increased endurance of the back muscles with difficulty. The author recommends introduction of intensive dynamic back extensor exercises which result in strength and endurance of the muscles. The back muscle training ought to be lifelong; thus, the exercises must be simple, learned over a longer period of time, so that the patients perceive the training as a natural and necessary part of everyday life.

Back Pain↗
PubMed1993

[Musculoskeletal symptoms and working postures in pear and apple orchard workers].

Musculoskeletal symptoms in pear and apple orchard workers were studied in relation to working postures, particularly arm elevation and head extension. The same forty-six female workers were examined three times; in May while thinning pears, in June while bagging pears, and in July while bagging apples. Musculoskeletal symptoms in the neck and shoulders were predominant in thinning and bagging pears when compared with bagging apples. When thinning pears, there was a significantly higher prevalence of complaints of stiffness and pain in the neck and shoulders, pain in the upper and lower back, muscle tenderness in the shoulders and forearm, and decreased back muscle power. When bagging pears, there was a significant difference in complaints of stiffness and pain in the neck and shoulders, muscle tenderness in the shoulders, and pain in motion of the neck joint. Pear tasks require more arm elevation and head extension than apple tasks. The working postures of arm elevation and head extension were considered to be a dominant causative factor in shoulder-neck disorders of the workers examined. The low back pain from thinning pears may be related with continuous backward bending of the back associated with the thinning work.

Agriculture↗
PubMed1981

Paralumbar muscle activity in chronic low back pain.

Muscle spasm is often considered to be a prominent feature operating in chronic low back spin syndrome (LBP). The present study compared levels of paralumbar muscle activity, determined by an electromyogram (EMG), for LBP patients and normal subjects during periods of rest and voluntary muscular contraction. The resting state EMG measure did not differ in the 2 groups. However, when attempting to relax the low back while contracting other muscle groups, LBP patients exhibited higher mean levels of low back muscle activity as compared to the non-pain group. These results would suggest that such "cocontraction relaxation" procedures may provide a viable behavioral technique for assessing and possibly treating functional backache thought to be symptomatic of muscle spasm. Previous studies employing feedback and progressive relaxation techniques have trained subjects to reduce muscle tension in the resting state. Results of the present study suggest that the acquisition of "resting level" relaxation may be of little benefit to patients who exhibit excessive muscular tension while performing daily tasks. Rather, to maximize the likelihood of beneficial results, training would be better directed at relaxation of the low back during activity of other muscle groups.

Adult↗
PubMed1992

Response of the trunk muscles to training assessed by magnetic resonance imaging and muscle strength.

A group of 12 sedentary medical students (1 man and 11 women aged 21-27 years) participated in a strength training programme for the trunk muscles lasting 18 weeks. The maximal isometric flexion and extension forces of the trunk muscles were measured before the training and at 18 weeks by dynamometer. The cross-sectional area of the back muscles, i.e. erector spinae, multifidus and psoas muscles, was measured from magnetic resonance images (spin echo sequence TR/TE 1500/80, slice thickness 10 mm) obtained at the L4-L5 disc level before the training, at 11 and 18 weeks. During training, no significant change in the body mass or body fat content was found. Muscle forces or muscle cross-sectional area were not related to body mass. There was a significant increase in both trunk muscle cross-sectional area (psoas muscle P < 0.001 and back muscles P < 0.01) and trunk muscle forces (flexion and extension forces P < 0.01) during the training but no direct association between the muscle cross-sectional area and strength of the flexors and extensors was detected before or after the training.

Adipose Tissue↗
PubMed2000

Trunk muscle activation and low back loading in lifting in the absence of load knowledge.

People who know the actual mass of an object to be lifted normally prepare themselves before attempting a lift to control the movement and to minimize low back loading. In this study, the trunk muscular reactions and low back torque were investigated in the situation in which the individual did not know the actual mass but only had some idea of the range within which the mass lay. Nine males lifted boxes weighing 6.5 or 16.5 kg under the condition in which they knew the actual mass before attempting a lift (the 'known' condition) and the condition in which they only had the information that the mass would be within the range of 6.5-16.5 kg (the 'unknown' condition). The ground reaction forces and body movements were measured in the trials and, from these, the L5/S1 torques were calculated. The activation of back and abdominal muscles was also measured. For the 6.5 kg weight, a higher (16%) back muscle activation in grasping the box and a higher (10%) peak L5/S1 torque in actual lifting were observed in the 'unknown' compared with the 'known' weight condition. For the 16.5 kg weight, the back muscle activation was lower (10%) during grasping, and higher (10%) during lifting in the 'unknown' compared with the 'known' weight condition. Knowledge of the load had no effect on the activation of the abdominal muscles. It was concluded that in the so-called 'unknown' conditions, the risks of low back injury were increased in comparison with the conditions where the actual weight was known in advance.

Abdominal Muscles↗
PubMed2005

The effect of early isolated lumbar extension exercise program for patients with herniated disc undergoing lumbar discectomy.

OBJECTIVE: To determine the effects of a postoperative early isolated lumbar extension muscle-strengthening program on pain, disability, return to work, and power of back muscle after operation for herniated lumbar disc. METHODS: Seventy-five patients were randomized into an exercise group (20 men, 15 women) and a control group (18 men, 22 women) to perform a prospective controlled trial of a lumbar extension exercise program in patients who underwent lumbar microdiscectomy or percutaneous endoscopic discectomy. Six weeks after surgery, patients in the exercise group undertook a 12-week lumbar extension exercise program. The assessment included measures of lumbar extensor power by the MedX (Ocala, FL) lumbar extension machine, muscle mass of multifidus and longissimus (L4-L5 cross-sectional area) by computed tomography. All patients completed the visual analog scale and the Oswestry disability index to assess pain and disability, respectively. Return to work data were also investigated. RESULTS: After the exercise program, significant improvements were observed in the exercise group versus the control group for lumbar extensor power (51.67% versus 17.55%, respectively; P < 0.05), the cross-sectional area of multifidus and longissimus muscle (29.23% versus 7.2%, respectively; P < 0.05), and the visual analog scale score (2.51 versus 4.30, respectively; P < 0.05). The percentages of returning to work within 4 months after surgery were significantly greater in the exercise group than in the control group (87% versus 24%, respectively). Although this was not statistically significant (P > 0.05), the Oswestry disability index scores in the exercise group were better than that in control group (24.6 versus 30.6, respectively). CONCLUSION: These results support the positive effects of the postoperative early lumbar extension muscle-strengthening program on pain, return to work, and strength of back muscles in patients after operation of herniated lumbar disc.

Adult↗
PubMed2001

Paraspinal muscle EMG fatigue testing with two methods in healthy volunteers. Reliability in the context of clinical applications.

OBJECTIVE: Comparison of the accuracy of surface electromyogram for back muscle endurance assessment with two different tests. DESIGN: Test-retest measurements in 16 healthy volunteers on two separate occasions for each test under controlled conditions. BACKGROUND: Back muscle endurance is considered important in low back pain rehabilitation. Reliability of paraspinal muscle endurance assessment is a pre-requisite for accurate and meaningful clinical applications of the technique. METHODS: All participants performed each test twice. A direct comparison was made between two popular fatigue testing methods, the modified Biering-Sørensen and a 60% maximum voluntary isometric contraction in the upright position during which time fatigue was assessed from the electromyogram spectral and amplitude analysis. RESULTS: Reproducibility of initial median frequency was excellent for both tests. Normalised median frequency slope values were more reliable with the 60% maximum voluntary contraction upright test. The clinical applicability of these measures in detecting significant differences after patient rehabilitation is recommended. Root mean square had very large between-day error for both tests.

Adult↗
PubMed2000

Minimal influence of facet joint anesthesia on isokinetic muscle performance in patients with chronic degenerative low back disorders.

STUDY DESIGN: Experimental design. OBJECTIVES: To examine the influence of pain reduction after facet joint injections on isokinetic back muscle performance. SUMMARY OF BACKGROUND DATA: Methods for evaluating the effect of facet joint injections vary. Recent studies base their results solely on the patient's subjective opinion and suggest a need for more objective, concrete, and reliable measurements. METHODS: Eighty-seven patients with a degenerative low back disorder (49 women and 38 men; mean age, 48 years; range, 22-79) who had facet joint injections as a part of preoperative evaluation participated. The mean duration of symptoms was 12.3 years (range, 1-45). The patients underwent isokinetic trunk flexor and extensor muscle strength testing at angular velocities of 60 deg/sec and 120 deg/sec. They performed two tests before the facet joint injections (to eliminate learning effect). All patients had bilateral facet joint injections at L5-S1. Those who did not report pain relief had additional injections at L4-L5. The flexion-extension test was repeated 15 minutes after each injection. Pain and fear were registered on visual analog scales. RESULTS: All 87 patients could perform the isokinetic tests. For extension at 60 deg/sec, a significant improvement was found between the two pretests (P < 0.05). Pain increased significantly from the first to the second pretest (P = 0.02), and a significant decrease in pain was found after the first injection (P = 0.0001). Fear decreased between each test, with a significant decrease after the first injection. No significant change was found for the muscle strength measurements after facet joint anesthesia. There were only weak correlations between decrease in pain and alteration in muscle performance, ranging from 0.06 to 0.37. CONCLUSION: Pain reduction after facet joint injections did not influence isokinetic muscle performance in patients with degenerative low back disorders.

Adult↗
PubMedDate not supplied

[Non-operative treatment of chronic low back pain: specific back muscular strength training versus improvement of physical fitness].

AIM: A systematic review was performed to evaluate the clinical effects of specific back muscle and non-specific physical fitness training in chronic low back pain. METHOD: A computer-aided Medline research (19861999) of randomised clinical trials concerning both rehabilitation concepts was conducted. A rating system was used to assess the methodological score of each study. The results were analysed and a final statement for evidence according to three main parameters (back pain, physical capacity, and patients comfort) was postulated. RESULTS: Twelve randomised clinical trials were identified. Nine studies were determined as high-quality trials. For chronic low back pain specific back muscle exercises as well as non-specific fitness training were able to improve the patients' conditions sufficiently. In comparison with passive treatment or no treatment there is strong evidence for pain and physical capacity in both groups, but only a positive influence for patient' comfort in fitness groups. Nevertheless, a confrontation of both concepts in two studies did not reveal any notable differences in all three parameters. CONCLUSION: Principally, a specific strength training for back rnuscles as well as a non-specific fitness training are comparably effective to rehabilitate chronic low back pain.

Combined Modality Therapy↗
PubMed2000

Spinal reflex attenuation associated with spinal manipulation.

STUDY DESIGN: This study evaluated the effect of lumbosacral spinal manipulation with thrust and spinal mobilization without thrust on the excitability of the alpha motoneuronal pool in human subjects without low back pain. OBJECTIVES: To investigate the effect of high velocity, low amplitude thrust, or mobilization without thrust on the excitability of the alpha motoneuron pool, and to elucidate potential mechanisms in which manual procedures may affect back muscle activity. SUMMARY OF BACKGROUND DATA: The physiologic mechanisms of spinal manipulation are largely unknown. It has been proposed that spinal manipulation may reduce back muscle electromyographic activity in patients with low back pain. Although positive outcomes of spinal manipulation intervention for low back pain have been reported in clinical trials, the mechanisms involved in the amelioration of symptoms are unknown. METHODS: In this study, 17 nonpatient human subjects were used to investigate the effect of spinal manipulation and mobilization on the amplitude of the tibial nerve Hoffmann reflex recorded from the gastrocnemius muscle. Reflexes were recorded before and after manual spinal procedures. RESULTS: Both spinal manipulation with thrust and mobilization without thrust significantly attenuated alpha motoneuronal activity, as measured by the amplitude of the gastrocnemius Hoffmann reflex. This suppression of motoneuronal activity was significant (P < 0.05) but transient, with a return to baseline values exhibited 30 seconds after intervention. CONCLUSIONS: Both spinal manipulation with thrust and mobilization without thrust procedures produce a profound but transient attenuation of alpha motoneuronal excitability. These findings substantiate the theory that manual spinal therapy procedures may lead to short-term inhibitory effects on the human motor system.

Adult↗
PubMedDate not supplied

Neuronal pathways from low-threshold muscle and cutaneous afferents innervating tail to trunk muscle motoneurons in the cat.

We studied neuronal pathways from low-threshold muscle (group I, II) and cutaneous afferents (group A(alpha)beta) innervating the tail to motoneurons innervating trunk muscles (m. iliocostalis lumborum and m. obliquus externus abdominus) in 18 spinalized cats. Stimulation of group I muscle afferents produced excitatory postsynaptic potentials or excitatory postsynaptic potentials followed by inhibitory postsynaptic potentials in all motoneurons innervating the m. iliocostalis lumborum which showed effects (32%), and predominantly inhibitory postsynaptic potentials in motoneurons innervating the m. obliquus externus abdominus (47%). Stimulation of group I+II afferents produced significant increases of the incidence of motoneurons showing postsynaptic potentials (the notoneurons innervating the m. iliocostalis lumborum, 87%; the motoneurons innervating the m. obliquus externus abdominus, 82%). The effects of low threshold cutaneous afferents were bilateral, predominantly producing inhibitory postsynaptic potentials in motoneurons innervating both muscles. These results suggest that neuronal pathways from muscle afferents to back muscle motoneurons mainly increase the stiffness of the trunk to maintain its stability, while those to abdominal muscles help to extend the dorsal column by decreasing their activities. The results also indicate that neuronal pathways from cutaneous afferents to trunk motoneurons functionallY disconnect the tail from the trunk.

Action Potentials↗
PubMed2002

Quantitative analysis of the effect of lumbar orthosis on trunk muscle strength and muscle activity in normal subjects.

We studied the effect of lumbar orthosis on trunk muscle strength and muscle activity during flexion-extension bending of the trunk in 31 male volunteers. Trunk muscle strength was measured with a kinetic measurement system. Peak torque was calculated by using the mean torque of five repetitions. Trunk muscle activity was measured with commercially available equipment that has portable EMG data-collection units. The maximum level of the EMG signal was evaluated by employing the analyzing part of the computer's measuring program. With the application of the lumbar orthosis, the strength of the abdominal muscle and the back muscle increased; conversely, the activities of both muscles were decreased significantly. This might imply that lumbar orthosis reduces the load of the trunk muscles during performance.

Adult↗
PubMed1996

An isoinertial predictor for maximal acceptable lifting weights of Chinese male subjects.

The practicality of using restrained as well as standard isoinertial strength tests in predicting the maximum acceptable weight of lift (MAWL) of Chinese male subjects was examined using a restrained strength test, which allows the subject to pull on the load in front of the body and to apply force in a functional free posture. Prediction models were constructed and evaluated under task conditions of two lifting ranges, two box sizes, and three lifting frequencies. The following measurements were taken for each subject in each test: (1) the body posture and joint angles, and (2) electromyographic activities of the arm muscles (biceps brachii), back muscles (erector spinae), and leg muscles (rectus femoris). Results indicate that the restrained knuckle height isoinertial strength (RK) was related significantly to the MAWL for all tasks, and the correlation coefficients ranged from 0.42 to 0.69. A step-wise multiple regression analysis based on data from the 22 subjects showed that RK, chest circumference, and thigh length accounted for 90 to 94% of the variance. A validation effort on a different sample (N = 10) showed that the MAWLs can be predicted within an absolute mean (SD) error of 0.84 (3.30) kg. Percentages of muscle activation levels indicated that, other than strength from the erector spinae, the strongest contribution to the RK value was that of biceps brachii strength. Since the strength of the body's upper extremity was also recruited, the weak upper extremity strength of Chinese subjects was better reflected. Evidence for the existence of a close match between MAWL and RK values, and the conditions of the existence, suggest that RK is good predictor for the MAWL.

Adult↗