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At least 109 records · Page 6Linked to original sources

PubMed1985

Painful muscle spasm reversed by magnesium sulphate. A case report.

A 25-year-old paraplegic man who had sustained a T3/T4 vertebral compression fracture 3 years previously presented with severe, painful spasm of the left hamstring muscle group of 2 hours' duration. This spasm produced extreme knee flexion of a degree which held the left foot posterior to the right buttock. An intravenous injection of 2 g magnesium sulphate produced immediate relief. Possible mechanisms of action of magnesium are discussed.

Adult↗

PubMed1990

[Referral pattern, diagnoses and occurrence of short muscles in children and adolescents in an orthopedic specialist practice].

The patterns of referral for 600 consecutive children and adolescents under the age of 17 years were analysed and the symptoms were compared with the diagnoses. 40% were referred because of foot problems, 20% had mobility problems and 20% had pain in the back or extremities. Out of the 240 patients with foot problems, these could be confirmed in 44%. 30% had merely short muscles and 7% had, in addition, spasticity. 70% out of the 110 patients referred on account of flat foot had too short achilles tendons. 50% out of the 600 patients referred had short achilles tendons and/or hamstring muscles. In 20%, the short muscles alone could explain the symptoms experienced by the patients. Short heel tendons are found with broad fore-feet, cavus and valgus feet, loose subtaloid joints, heel exostoses, pain in the heel and in the calf. Short hamstrings result in a shuffling gait, high-riding patellae with periodic pain, pain on the posterior aspect of the thigh and a straight transition in the thoraco-lumbar region with subsequent Scheuermann's disease. The length of the muscles should, therefore, be investigated. If they are too short, they should be stretched for one minute every twelfth hour to obtain optimal elasticity and length.

Achilles Tendon↗

PubMed1987

Force-time measurements of knee muscle functions of subjects with multiple sclerosis.

The purpose of this study was to determine whether the time-rate of muscle tension development, the muscle tension-maintaining capacity, and the reciprocal inhibition time of muscles in subjects with multiple sclerosis were significantly different from those of healthy subjects. An isokinetic dynamometer was used to evaluate the quadriceps femoris and hamstring muscles of 15 Experimental Group subjects with multiple sclerosis and 17 healthy Control Group subjects. The muscles were tested isometrically at 45 degrees of knee flexion and isokinetically at speeds of 30 degrees/sec and 90 degrees/sec. The subjects with multiple sclerosis demonstrated a significant (p less than .001) slowing of the time-rate of muscle tension development and a significant (p less than .005) decrease in muscle tension-maintaining capacity when compared with healthy subjects. The difference in the reciprocal inhibition time of muscles of the Experimental and Control Groups was not significant. When the reciprocal inhibition time of muscles was expressed as a percentage of the total torque curve, however, a significant prolongation (p less than .001) was observed in the subjects with multiple sclerosis.

Adolescent↗

PubMedDate not supplied

Dynamic EMG analysis of anterior cruciate deficient legs with and without bracing during cutting.

The purpose of this research was to determine if bracing altered muscle firing amplitude, duration, or timing, creating improved dynamic stability. We hypothesized that a derotational knee brace improved the stability of an ACL deficient knee by augmenting limb proprioception, causing hamstring muscles to increase in activity and/or to contract earlier during a side-step cut. Ten subjects with documented unilateral isolated ACL deficient knees and five normal controls participated. A strap dominant brace (Lenox Hill, Lenox Hill Brace, Inc., Long Island City, NY) and a shell dominant brace (CTi, Innovation Sports, Irvine, CA) were selected for study. Using footswitches and dynamic EMG, we tested each subject during performance of a side-step cutting maneuver. Subjects completed 15 trials: 5 without bracing, 5 with the strap dominant brace, and 5 with the shell dominant brace. Normals cut 10 times each on their dominant limb. In swing phase, subjects had 38% more and 32% higher lateral hamstring EMG activity than normals; in stance phase, subjects had less quadriceps and gastrocnemius activity but more medial hamstring activity. When braced during stance phase, the ACL deficient legs demonstrated a further reduction of 18% in quadriceps total activity and 14% in peak activity compared to the unbraced situation. The hamstrings showed a concomitant decrease of 18% in total activity. No timing differences were noted between the braced and unbraced conditions during swing or stance phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1985

Thigh muscle activity during maximum-height jumps by cats.

Cats were trained to jump from a force plate and touch a cotton ball suspended as high as 1.6 m. Force-plate reaction forces and double-joint hamstring muscle activity observed early in propulsion varied from one maximal jump to another. This variability is consistent with theory (31, 32, 42); that is, different coordination strategies can be implemented prior to the heels losing contact with the force plate (heel-off). Single-joint hip extensor and double-joint posterior thigh (hip extensor-knee flexor) muscles were coactivated prior to heel-off. This coactivation is probably partially responsible for the observed backward rotation of the trunk. Forepaws, observed to contact the force plate prior to heel-off, probably assist the hindlimbs in generating trunk rotation. Both single-joint knee extensor and hip extensor muscles exhibited greatest activation between heel-off and body lift-off. Single-joint flexor muscles were inactive throughout propulsion. Double-joint posterior thigh muscles were deactivated at heel-off and remained inactivated until lift-off. These observations agree with the theoretical notion that muscles should be either fully activated, inactivated, or switched from one extreme to the other (i.e., bang-bang control) between heel-off and body lift-off (31, 32, 42, 44). All seven muscles studied shortened while activated. Using computations based on muscle geometry, fiber architecture, and joint angle trajectories, I propose that sarcomeres shorten along the flat and ascending regions of the force-length curve. De- and inactivation of double-joint posterior thigh muscles between heel-off and lift-off coincided with muscle stretch. The reason for inactivation of these muscles is that the negative work that would have been generated had these muscles stayed activated would have hindered propulsion. Contractions preceded by active stretch were not observed. Enhancement of positive work by previous storage of energy in elastic musculotendinous structures is thus not used by cat thigh musculature in jumps starting from the squat. Adductor femoris, semimembranosus anterior, and biceps femoris anterior muscles were activated synergistically as one group yet differently from the synergistic activation of gracilis, semitendinosus, and biceps femoris posterior muscles. The separation of these muscles into two groups based on their activation patterns during jumping is compatible with the classification of these muscles into hip extensor and knee flexor muscle groups, respectively, based on their reflex patterns (37), spinal cord reflex connectivity (18, 30), and firing patterns during locomotion (20).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1985

Mechanics of the knee. A study of joint and muscle load with clinical applications.

The load moment of force about the knee joint during machine milking and when lifting a 12.8 kg box was quantified using a computerized static sagittal plane body model. Surface electromyography of quadriceps and hamstrings muscles was normalized and expressed as a percentage of an isometric maximum voluntary test contraction. Working with straight knees and the trunk flexed forwards induced extending knee load moments of maximum 55 Nm. Lifting the box with flexed knees gave flexing moments of 50 Nm at the beginning of the lift, irrespective of whether the burden was between or in front of the feet. During machine milking, a level difference between operator and cow of 0.70 m - 1.0 m significantly lowered the knee extending moments. To quantify the force magnitudes acting in the tibio-femoral and patello-femoral joints, a local biomechanical model of the knee was developed using a combination of cadaver knee dissections and lateral knee radiographs of healthy subjects. The moment arm of the knee extensor was significantly shorter for women than for men, which resulted in higher knee joint forces in women if the same moment was produced. A diagram for quantifying patellar forces was worked out. The force magnitudes given by the knee joint biomechanical model correlated well with experimentally forces measured by others. During the parallel squat in powerlifting, the maximum flexing knee load moment was estimated to 335-550 Nm when carrying a 382.5 kg burden and the in vivo force of a complete quadriceps tendon-muscle rupture to between 10,900 and 18,300 N. During isokinetic knee extension, the tibio-femoral compressive force reached peak magnitudes of 9 times body weight and the anteroposterior shear force was close to 1 body weight at knee angles straighter than 60 degrees, indicating that high forces stress the anterior cruciate ligament. A proximal resistance pad position decreased the shear force considerably, and this position is recommended in early rehabilitation after anterior cruciate ligament repairs or reconstructions. The methods presented quantify muscle activity, sagittal knee joint moments and forces, enabling assessments to be made of different work postures, training exercises and joint derangements.

Adult↗

PubMed1990

Differential responses to proprioceptive neuromuscular facilitation (PNF) stretch techniques.

The purpose of this study was to investigate the effects of sustained stretch and two common proprioceptive neuromuscular facilitation (PNF) stretch techniques on hamstring muscle activation and knee extension range of motion (ROM) in different athletic populations. Three stretch techniques: stretch-relax (SR), contract-relax (CR), and agonist contract-relax (ACR) were applied to 10 endurance athletes (EN), 10 high intensity athletes (HI), and 10 control subjects (C). The results revealed that ACR produced 89-110% greater hamstring EMG activity (P less than 0.05) and 9-13% more knee joint ROM than CR and SR, respectively. This same pattern was evident for the individual subject groups. Comparisons of mean data among the three subject groups revealed that the EN athletes generated 58-113% more hamstring EMG activity (P less than 0.05) than the HI and C groups, respectively, across all stretch conditions, whereas the EN group attained significantly less ROM than the HI and C groups for CR and ACR conditions. It was postulated that high intensity-short term activity training necessitates less hamstring resistance to knee extension than long term endurance training. The findings suggest that decreases in muscle activity may not be strongly related to increases in joint range of motion and that factors other than muscle relaxation are important in achieving increased ROM. Also, the differential effects of various stretch techniques between dissimilar athletic populations should be considered if stretch-induced injury is to be avoided.

Adult↗

PubMed1988

Ankle muscle activity during gait in children with cerebral palsy and equinovarus deformity.

Temporal electromyographic (EMG) characteristics of lower limb muscles during gait of spastic hemiplegic and diplegic children with cerebral palsy are described. All subjects were referred for presurgical evaluation of equinovarus deformity. The data indicated both similar and discriminating phasic EMG characteristics between groups of patients. All children displayed premature triceps surae activity beginning in swing phase of gait and continuing through stance. Tibialis posterior, normally active during stance, was also active during swing phase of gait. However, some patients displayed cocontraction of triceps surae and tibialis anterior during stance, together with hamstring muscle activity within normal limits. The remainder of the patients displayed a prolonged duration of hamstring activity. How this gait analysis contributed to presurgical decisions for equinovarus gait is discussed and compared with data from postsurgical gait analysis.

Ankle↗

PubMed1986

Serial isokinetic evaluations used for a patient with scapuloperoneal muscular dystrophy. A case report.

This article reports the reversal of an atypical rapid decline in muscle strength experienced by a patient with scapuloperoneal muscular dystrophy by modulating his excessive daily physical activity. This process was aided by our monitoring the strength of the quadriceps femoris and hamstring muscles using an isokinetic dynamometer. Serial torque values for muscle strength were compared as the total daily physical activity was decreased systematically. The torque values for thigh muscle strength increased as the subject's total work load was decreased. A complete management program for neuromuscular patients should include specified amounts of daily physical activity, rest, and therapeutic exercise.

Adult↗

PubMed1992

Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex.

The onset latency and discharge amplitude of preprogrammed postural responses were evaluated in order to determine if the structure of synergistic activation could be altered by ligamentous laxity at the knee joint. Twelve subjects with unilateral and one subject with bilateral anterior cruciate ligament (ACL) insufficiency were tested while standing on a moveable platform. External balance perturbations (6 cm anterior or posterior horizontal displacements of the platform) were presented at velocities ranging from 15 to 35 cm/s. Perturbations were presented under the following experimental conditions: unilateral and bilateral stance, knees fully straight or flexed, and with ankle motion restricted or free. These stance, knee position, and ankle motion conditions were introduced to alter the stress transmitted to the knee joint during movement of the support surface. The automatic postural response was recorded from the tibialis anterior (T), quadriceps (Q), and medial hamstrings muscles (H) bilaterally. The normal response to an externally induced backward sway involved the automatic activation of T and Q at latencies of 80 ms and 90 ms respectively. Activation of the hamstrings in the non-injured extremity was not coupled with the postural response. Hamstrings are not typically involved in the correction posterior sway because H activation would tend to pull the center of mass further backwards. However, when the response in the ACL-deficient extremity was compared to the non-injured limb: (1) the automatic postural response in the ACL-deficient extremity was restructured to include hamstrings activation (100 ms latency), (2) H activation time was faster and less variable in the ACL-deficient limb, and (3) the ratio of H/Q discharge amplitude integrated over 100 ms and 200 ms from the onset of EMG activation showed a dominance of hamstring activity during unilateral stance on the lax limb. In addition, H/Q ratios integrated over 200 ms showed dominant hamstring activity in the ACL-deficient limb during bilateral stance. (4) Cross-limb comparisons showed greater normalized IEMG amplitudes for T, H, and Q during unilateral stance on the lax limb. These results suggest that a capsular-hamstring reflex is integrated into the existing structure of a preprogrammed postural synergy in order to compensate for ligamentous laxity. Furthermore, the generalized increase of response gain observed during perturbations of unilateral stance on the lax limb indicates that joint afference can modulate central programming to control localized joint hypermobility. A concept of postural control is discussed with respect to the capsular reflex, joint loading and displacement of the center of gravity.

Adolescent↗

PubMed1987

Non-surgical management of overuse knee injuries in runners.

Seventy-three injured runners (45 men, 28 women) who presented with 83 running-induced overuse knee injuries were managed conservatively. The regimens utilized focused on quadriceps and hamstring muscle retraining and the control of functional overpronation. Patello-femoral pain syndrome (42 cases) was by far the most common problem. The next most common problems were iliotibial band friction syndrome (10), patellar tendonitis (9) and popliteal tendonitis (5). The most frequent etiological factor was a sudden increase in training mileage. Following the initial visit and at regular intervals throughout the recovery phase, quadriceps and hamstring capacities were determined on a Cybex II isokinetic unit at 60 degrees/second and 180 degrees/second. Significant differences (p less than 0.01) in Cybex scores were observed between strong and weak extremities in males and females for both muscle groups at both velocities. The mean Cybex scores and the differences with muscle groups between strong and weak legs for the subjects were similar to those reported for healthy non-athletes. The treatment protocol followed four basic principles: control of pain; rebuilding of muscle strength and endurance; improvement of bio-mechanical efficiency and gradual reintroduction of training. No significant changes in the differences between strong and weak leg Cybex scores occurred between the initial and final evaluations, except in the male group when the hamstrings were evaluated at 60 degrees/second (p less than 0.01). In the 82 cases managed non-surgically, 1 poor, 8 fair, 36 good and 37 excellent results were obtained. The authors believe that the significance of disturbance in quadriceps and hamstring function to the etiology of overuse knee injuries may be increased in runners who over-pronate.

Adolescent↗

PubMed1991

Serum creatine kinase activity and its changes after a muscle biopsy.

The significance of the absolute elevations of serum creatine kinase (CK) levels after intense exercise and injuries was studied by measuring CK activities from seven healthy active males during a 2-week period, with a muscle biopsy taken between the first and second week. Most of the subjects (three lifters and two runners) carried on their normal exercise activities, while two lifters stopped training during the 2 weeks. The weight of the biopsy, number of fibres, percentage of fibre types, and cross-sectional areas of the muscle fibres were measured. The CK levels of the non-active subjects and runners remained consistently low during the control week, whereas those of the lifters were usually 500% greater than those of the other two groups, and fluctuated with the intensity of their workouts. A muscle biopsy, having a mean weight of 71.3 mg and containing 1800 fibres, increased the CK values by approximately 100 units litre-1 (U l-1) in most of the subjects. One runner injured his right hamstring muscles 2 days prior to the biopsy, and his CK values rose from 50 to 4400 U l-1. The increases in CK after the biopsy were not related to fibre type, activity, weight of the biopsy, or number or size of fibres removed. These results indicate that: (1) CK values are consistently lower in normal subjects and runners than in lifters. (2) Weight training results in chronic elevations of CK. (3) Compared to a muscle biopsy, muscular injury dramatically increases CK levels. (4) Elevation of serum CK is observed as early as 1 h after an intense weight-lifting session.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy, Needle↗

PubMed1985

Isokinetic measurements of muscle strength in hysterical paresis.

The torque during isokinetic knee extensions and flexions was determined in repeated tests at 3 speeds of angular rotation in 25 patients with pareses considered to be hysterical after relevant examinations and follow-up. The torque records were combined with surface EMG from the quadriceps and the hamstring muscles in some patients. Besides the weakness, 3 signs were observed that are not usually seen in patients with pareses due to verified peripheral or central lesions. These signs were: Enlarged variability of torque in repeated tests of the same movement (larger than 20% of maximum torque in 22 patients). Higher torque in fast movements than in slow movements (8 patients). Force production in knee flexion less than that expected from the weight of leg and lever arm due to restraining activation of the quadriceps muscle (12 patients). The restraint was present although there was no spasticity. The signs reflect inconsistent and contradictory motor performance that is not compatible with a genuine paresis. Thus, they aid the identification of weakness of functional origin.

Adult↗

PubMed1981

Topical anesthesia: H-reflex recovery changes by desensitization of the skin.

The H-reflex recovery curve of the soleus muscle was studied in 53 normal subjects before and after the application of topical anesthesia (20% benzocaine) to various skin areas and dermatomes of the lower limb. Skin areas were those overlying the calf, tibialis anterior, quadriceps and hamstrings muscles, and the dermatomes were L2, L3, L4, L5, S1, S2. In 42 subjects the H-reflex initial recovery decreased by 10-80 msec with a mean of 20 +/- 17 msec 30 min after application of topical anesthesia. Also, the test reflex (the second sequential H-reflex) had a faster recovery with less inhibition than that before anesthesia. It was also noticed that the longer the inhibition period before anesthesia, the greater the decrease in recovery time. These observations had no correlation with the skin area or dermatome desensitized by the anesthesia. furthermore, these observations were not noted when a placebo was sprayed on the skin. The results from this study indicate that input from cutaneous afferents may have an important inhibitory effect on the alpha-motoneurons of the soleus muscle. This effect is possibly more profound on the large phasic motoneurons. These results are discussed in relation to clinical interpretations of the H-reflex recovery curves.

Adolescent↗

PubMed1983

Reflex responses of human thigh muscles to non-noxious sural stimulation during stepping.

An investigation of reflex responses of leg muscles to sural stimulation during stepping was performed on human subjects. Non-noxious electrical stimulation applied during the swing phase or the latter half of the stance phase produced a mixed increase and decrease of EMG activity in the hamstring muscles. No response or very weak response was observed when the same stimulus was applied during either quiet standing or various levels of constant voluntary effort at varying hip and knee joint angles.

Adult↗

PubMed1990

Electromyographic analysis of postural adjustments in two methods of balance testing.

The primary purpose of this study was to compare postural responses during two methods of balance testing: 1) a platform perturbation test (PP), with destabilizing forces of uniform magnitude given at the base of support, and 2) a postural stress test (PST), with destabilizing forces of increasing magnitude given at the waist. A secondary purpose was to examine the relationship between balance strategy scores and the patterns of muscle responses as determined by electromyographic analysis on the PST. Postural responses to backward sway of 17 healthy subjects, aged 60 to 79 years (means = 69.0, s = 5.3), were characterized bilaterally by EMG recording of the tibialis anterior, quadriceps femoris, gastrocnemius, and hamstring muscles. We examined three measures of bilateral postural responses: 1) latency to first muscle response (FR) among the four lower extremity muscle groups, 2) tibialis anterior muscle latency (TA), and 3) patterns of muscle responses. Our results demonstrated significantly shorter (p less than .001) TAs and FRs (in milliseconds) on the PST than on the PP (PST TA: = means = 80.3, s = 12.4; PP TA: = means = 142.6, s = 13.4; PST FR: means = 75.9, s = 10.4; PP FR: = means = 140.4, s = 13.6). The ankle strategy was the most frequently used pattern of muscle response during both the PP and the PST, but it occurred less frequently on the PST than on the PP (PP = 72.5%, PST = 50.9%) (p less than .05). No consistent relationship was observed between the balance strategy scores as determined by videotape analysis of the PST and the patterns of muscle responses as determined by EMG analysis.

Aged↗

PubMed1992

A clinical trial of strengthening and aerobic exercise to improve gait and balance in elderly male nursing home residents.

The purpose of this study was to determine whether a moderate to high intensity strengthening and aerobic exercise program can improve the strength, exercise capacity, gait and balance of deconditioned male nursing home residents. Ambulatory subjects who scored 30 or less on the modified Tinetti gait and balance assessment scale, who demonstrated less than 80% of age-matched lower extremity strength on isokinetic muscle testing and who gave informed consent were enrolled. Subjects were randomized to either an exercise (n = 8) or a control (n = 6) group. All participants underwent an exercise test to determine maximal oxygen uptake (VO2max) and received quantitative gait and balance measurements. The subjects assigned to the exercise group than completed a 12-wk program of weight training for the lower extremities and stationary cycling. Both the exercise and control groups were then retested. Ten outcome variables were assessed: Tinetti mobility scores, VO2max, isokinetic-tested lower extremity strength and endurance, stride length, gait velocity, stance time, gait duration, cadence and balance. The exercise group, after completion of the program, demonstrated significant improvements in Tinetti mobility scores (P < 0.05), combined right and left quadricep muscle strength (P < 0.01), right and left lower extremity muscular endurance (P < 0.01), left stride length and gait velocity (P < 0.05), although other outcome variables changed insignificantly. The control group revealed no changes of significance with the exception of improvement of the combined right and left hamstring muscle strength (P < 0.05). Nevertheless, for those outcome variables that had improved significantly in the exercise group, the changes amounted to only a 5 to 10% increase over the baseline measurements. These findings showed that an appropriately designed high intensity exercise program can result in significant although limited improvements for clinical mobility scores, strength, muscular endurance and certain gait parameters.

Aged↗

PubMed1989

A sequential study of the peripheral nervous system involvement in experimental Chagas' disease.

To search for the sequential compromise of the spinal cord, nerves, and skeletal muscle in mice chronically infected with Trypanosoma cruzi, animals were subjected to electromyographic investigation, end-plate recordings, and histological studies at 7, 15, 37, 60, 90, 120, 180, 270, and 360 days postinfection. Electromyographic studies showed signs of motor unit remodeling as early as 15 days postinfection, when diminished duration and amplitude of motor unit potentials pointing to a primary muscle involvement were found. Thereafter, certain features of denervation, reinnervation, and primary muscle involvement were often found to coexist. Low miniature end-plate potentials with normal frequency and acetylcholine quantum content were found in end-plate recordings made at the phrenic-diaphragm in vitro. Double end-plate potentials were observed in most of the tested muscle fibers from day 90 postinfection. All these features suggest post-synaptic damage of the end-plate and the presence of reinnervation after day 90 postinfection. Histological studies disclosed inflammatory infiltrates consisting of lymphocytes and macrophages, with vasculitis as the main lesion in the hamstring muscles; intracellular parasites were seen in 25% of the cases. Neuropathic features, as expressed by type fiber grouping and grouped muscle fiber atrophy, were found. On nerve examination epineural, perineural, and endoneural vasculitis were seen. Digestion chambers and myelin ovoids (axonal degeneration) were observed. In teased fiber preparations, segmental internodal and paranodal demyelination and remyelination were found. The lumbar inflammatory spinal cord failed to show grey or white matter infiltrates. However, spinal roots and dorsal root ganglia were densely affected by inflammatory cells.

Animals↗