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PubMedDate not supplied

Correlation of motor control in the supine position and assistive device used for ambulation in chronic incomplete spinal cord-injured persons.

Neurocontrol of movement after spinal cord injury (SCI) is often spared, but few studies have investigated the chronic incomplete SCI patient. Multichannel surface electromyography (SEMG) can describe characteristics of neurocontrol during a series of volitional and reflex events. The relationship of these neurocontrol characteristics to clinical function is incompletely described. This study, retrospectively, evaluated the relationship between neurocontrol patterns evoked by lower limb movement in the supine position and the assistive device used for ambulation in chronic, incomplete SCI persons. The records of 15 neurologically healthy (9 male, 6 female) and 36 incomplete SCI persons (27 male, 9 female) (C2-T10) were used. SEMG was recorded from both quadriceps, adductors, hamstrings, anterior tibialis and triceps surae muscles and displayed on a stripchart for analysis. SEMG patterns of activity recorded in the supine position during volitional, unilateral, multijoint (hip and knee flexion and extension) movement attempts were characterized, divided into seven groups and compared with the subjects' self-selected ambulation device (independent, cane, crutches, walker or nonambulatory). The neurocontrol patterns recorded in the supine position correlated well with the SCI subjects ambulatory assistive device. Marked decreases in motor unit output and/or loss of motor organization were found in the nonambulatory group. Coactivation of proximal muscles, poor timing of muscle activity and radiation of activity into contralateral muscles were also noted in subjects who required a walker or crutches. To a lesser degree, abnormal motor patterns were also noted in subjects who ambulated with a cane or independently.

Adult↗

PubMed2004

Back muscle fatigue during intermittent prone back extension exercise.

UNLABELLED: The purpose of this study was to estimate the level of muscular activation and muscle fatigue of the low back muscles during the performance of an intermittent prone back extension (PBE) exercise. Forty-one healthy students (24 males and 17 females) lying prone on a bench with the legs fixed performed two maximal voluntary contractions (MVC) in extension, a maximum of 100 repetitions of an intermittent PBE exercise immediately followed by a final MVC in extension. In addition, 12 subjects (11 males and one female) repeated the PBE exercise but with the addition of a 45-N weight on the back. The PBE exercise consisted of a task broken into four 1-s segments, while lying prone on a bench (10 degrees below horizontal): (1) raising the trunk to a horizontal position; (2) holding the trunk in the static phase (10 degrees above horizontal); (3) returning to the original position; and (4) resting on the bench. Electromyography (EMG) was used to measure the level of muscle activity (erector spinae (ES), gluteus maximus (GM), hamstrings (HA)) relative to the maximum voluntary EMG (MVE). RESULTS: Most of the subjects (34 out of 41) completed the 100 repetitions without excessive muscle fatigue according to the post-exercise MVC values. The intermittent PBE increased fatigue in the lumbar and hip extensor muscles in terms of: (1) a decrease in the MVC; (2) an increase in the level of muscle activation; and (3) a decline of the median frequency (MF). There was no gender difference in all EMG measurements. The level of muscle activation in the hip extensors (GM and HA) was associated with task failure (number of repetitions <100) for some subjects and the addition of a weight of 45 N had more impact on HA than ES. In conclusion, the PBE exercise as performed in the present study (including rest intervals), although not very strenuous for our healthy subjects, seems an adequate exercise to measure and train the aerobic capacity of the back muscles. However, to train specifically the back muscles, the exercise must be adjusted to avoid task failure due to possible hip extensor fatigue.

Adult↗

PubMed2003

Kinematic and electromyographic analysis of the push movement in tai chi.

BACKGROUND: Tai chi is a form of exercise derived from the martial art folk traditions of China. The force used in tai chi includes different principles of mechanical advantage. No studies on the kinematic features of tai chi exercise have been published. OBJECTIVE: To analyse the kinematics and electromyographic characteristics of tai chi. METHODS: An experienced tai chi master was asked to perform a sequence of basic movements: ward off, roll back, press, and push. The movements were videotaped and digitised using a motion analysis system. Electromyographic activities of the lumbar erector spinae, rectus femoris, medial hamstrings, and medial head of gastrocnemius were recorded by surface electrodes. The push movement data were analysed. RESULTS: The medial hamstrings and medial head of gastrocnemius muscle groups maintained low activity, with higher electromyographic values in the lumbar erector spinae and substantially higher ones in the rectus femoris during the push movement. Both concentric and eccentric contractions occurred in muscles of the lower limbs, with eccentric contraction occurring mainly in the anti-gravity muscles such as the rectus femoris and the medial head of gastrocnemius. The forward and backward shifts in centre of gravity (CG) were mainly accomplished by increasing and decreasing respectively the joint angles of the bilateral lower limbs rather than by adopting a forward or backward postural lean. The path of the CG in the anteroposterior and mediolateral component was unique, and the sway or deviation from the path was small. The master maintained an upright posture and maintained a low CG (hips, knees, and ankles bent) while travelling slowly and steadily from one position to another. CONCLUSION: The eccentric muscle contraction of the lower limbs in the push movement of tai chi may help to strengthen the muscles.

Electromyography↗

PubMed1997

Improved body composition after 8 wk of electrically stimulated leg cycling in tetraplegic patients.

The practical aspects of utilizing electrically stimulated leg cycling (ESLC) to counteract alterations in body composition were investigated in five tetraplegic subjects with long-standing complete spinal cord injuries (C5-C7). After a 2-wk adaptation period, the subjects performed seven ESLC sessions per week for 8 wk. No adverse reactions were noted in response to the ESLC program. The ESLC sessions were accompanied by higher lactate concentrations compared with arm exercise. Heart rate and blood pressure response revealed clear, but not serious, signs of autonomic dysreflexia in the beginning of the ESLC sessions. Body temperature increased moderately during the ESLC sessions. Peak oxygen uptake (Vo2) during an ESLC session increased by 70% (P < 0.05) after 8 wk of training. Body composition, evaluated by dual-energy X-ray absorptiometry (DEXA), demonstrated an increase in lean body mass (LBM) from 66.2 +/- 2.6 to 68.2 +/- 2.1% (P < 0.05), with a concomitant decrease in whole body fat (BF) content from 29.7 +/- 2.6 to 27.8 +/- 2.1% (P < 0.05) after training. The cross-sectional area of quadriceps, hamstrings, gluteus maximus, and gluteus medius muscles, measured by computer tomographic scans, increased from 267 +/- 27 to 324 +/- 27 cm2 (P < 0.05) after the training. In conclusion, daily ESLC sessions during a 2-mo period resulted in increased LBM, decreased BF content, and increased muscular endurance in tetraplegic subjects without any noticeable adverse effects.

Absorptiometry, Photon↗

PubMed1987

Evaluation of gait with multichannel electrical stimulation.

Short, intensive multichannel electrical stimulation therapy was evaluated in 14 hemiplegics after stroke or head injury. The stimulation of the peroneal nerve, soleus, quadriceps, hamstring, gluteus maximus, and triceps brachii muscles with individually preprogrammed sequences was applied by surface electrodes at the beginning of gait rehabilitation. The patients started walking with the support of a therapist, gradually increased the walking distance and all reached independent ambulation with a crutch after an average of 14 stimulation sessions. A portable microprocessor six-channel stimulator/stride analyzer enabled the collection of gait parameters and recording of statistical mean values of stride time, gait symmetry, right and left stance times, and their standard deviations. Without additional equipment, several hundred stimulated strides were measured during each stimulation session.

Adolescent↗

PubMed2001

Use of ultrasonographic guidance in interventional musculoskeletal procedures: a review from a single institution.

We have evaluated the utility of ultrasonographic guidance for intervention in the musculoskeletal system. All interventional musculoskeletal procedures using ultrasonographic guidance performed at our institution from July 1998 through November 1999 were reviewed. Examinations were performed using either a linear or curved phased array transducer, based on depth and local geometry. The choice of needle was likewise optimized for specific anatomic conditions. One hundred ninety-five procedures were performed on 167 patients from July 1998 through November 1999. Thirty-one procedures had magnetic resonance correlation within 6 months beforehand. Excluding large-joint aspirations and injections, we found that 180 of the procedures were more readily performed using ultrasonography than any other imaging modality. These included therapeutic injections into tendon sheaths (biceps, flexor digitorum longus, posterior tibial, and iliopsoas), Morton's neuromas, plantar fascia, wrist ganglia, and tarsal tunnel cysts; peritendinous hamstring injections; and synovial cyst and muscle biopsies. In all cases, the target of interest was identified easily with ultrasonography, and needle position was documented readily. Also in all cases, aspiration or medication delivery to the site of interest was observed during real time and was documented on postprocedure images of the area. No significant complications (e.g., bleeding, infection, and neurovascular compromise) were encountered during or immediately after any procedure. Ultrasonography is a readily available imaging modality useful for guiding interventional procedures in the musculoskeletal system. The ability to document exact needle placement in real time confirms accurate placement of therapeutic injections, fluid aspiration, and soft tissue biopsies.

Adolescent↗

PubMed1998

An electromyographic investigation of 4 elastic-tubing closed kinetic chain exercises after anterior cruciate ligament reconstruction.

OBJECTIVE: To determine the electromyographic (EMG) activity of the vastus medialis oblique (VMO), vastus lateralis (VL), semitendinosus and semimembranosus (ST), and biceps femoris (BF) muscles during 4 elastic-tubing closed kinetic chain exercises in postoperative patients with anterior cruciate ligament (ACL)-reconstructed knees. DESIGN AND SETTING: A 4 x 4 repeated-measures analysis of variance design guided this study. Independent variables were type of exercise and muscle; the dependent variable was EMG activity. SUBJECTS: Fifteen patients, 5 to 24 weeks after ACL reconstruction. MEASUREMENTS: Subjects performed 4 exercises (front pull, back pull, crossover, reverse crossover) with elastic tubing attached to the foot of the uninjured leg. Time-and amplitude- normalized EMG activity was recorded from the VMO, VL, ST, and BF muscles of the injured leg. The hamstrings: quadriceps ratio was calculated. RESULTS: The normalized VMO, VL, and BF EMG activity ranged from 25% to 50% of maximum voluntary isometric contraction for the 4 exercises. The ST ranged from 12% on the back pull to 58% on the front pull. The hamstrings: quadriceps ratios were 137% (front pull), 115% (crossover), 70% (back pull), and 60% (reverse crossover). CONCLUSIONS: We suggest that clinicians use these exercises during early ACL rehabilitation since they incorporate early weightbearing with hamstring and quadriceps coactivation.

Journal Article↗

PubMed1984

Hip joint load and muscular activation during rising exercises.

The load on the hip joint and activation of the gluteus maximus, hamstrings, adductor magnus and rectus femoris muscles during rising exercises including different adaptive adjustments were investigated in nine healthy subjects. The joint load was calculated from forces recorded with a force-measuring platform and pictures on cine-film. Levels of muscular activity were recorded with rectified, low-pass filtered, time-averaged and normalized EMGs. The loading moment about the hip joint was about 45 Nm during the initial part of the rising exercise, decreasing with smaller hip angle. Increase of the backward inclination of the trunk increased the load moment, which was maintained at about the same level during the rising exercise. Two adaptive adjustments lowered the joint load: foot position further backward and reduced resistance from the device. Foot position further forward increased the joint load. The levels of muscular activity in the hip extensors were low to medium and were slightly increased by posterior foot position and increased resistance from the device. Increased backward trunk inclination increased the activity in the final part of the rising exercise.

Adult↗

PubMed1997

Differences in patellar tracking and knee kinematics among three different total knee designs.

Patellar complications are the primary reason for reoperation of the current condylar type designs. The aim of this study was to compare patellar tracking of various knee implant designs: Genesis II NexGen, and the P.F.C. Sigma Modular Knee System regarding trochlear groove center curvature. Nine unembalmed whole cadaveric lower extremities were used. The quadriceps and hamstrings were dissected into their individual muscles and loads were applied onto the muscles proximally based on the cross sectional area of the muscles. The three-dimensional kinematics of the patellofemoral and tibiofemoral joint of the intact knee were measured using a 3Space tracking system. Three implants (one from each company) were implanted onto the same cadaveric knee in random order consecutively. This was done to ensure consistency of the soft tissue constraints in influencing the amount of patellar tracking. Patellar rotation, patellar tilting, patellar lateral shift and patellar displacement in relation to groove center were measured. There was no significant difference between the intact knee and the various implants regarding patellar rotation and lateral shift. However, all three prosthetic designs showed a significant degree of lateral tilting when compared with the intact knee. At 60 degrees knee flexion, the normal patella was tilted laterally to 0.44 degree +/- 2.15 degrees as compared with the Genesis II patella at 4.75 degrees +/- 4.81 degrees, the NexGen patella at 4.85 degrees +/- 4.81 degrees, and the P.F.C. Sigma patella at 4.89 degrees +/- 3.79 degrees lateral tilt. There was no difference between the intact knee compared with the resurfaced patella in patellar displacement in relation to the groove center. This study suggests the relatively similar kinematic behavior between the implant designs as compared with the intact knees. However, additional modification of implant geometry may be required to help decrease the amount of patellar tilt.

Arthroplasty, Replacement, Knee↗

PubMed1993

A kinematic and electromyographic analysis of the development of sitting posture in infants.

This study was designed to describe the development of posture control in sitting in response to a natural perturbation. Seven normal infants 2 to 5 months of age were tested at two stages of independent sitting development. Trunk support was removed from infants while sitting erect and the postural responses were videotaped and EMG recorded from the upper trunk extensors, lumbar paraspinals, gluteus maximus, rectus femoris, hamstrings, and abdominals. Kinematic variables (trunk displacement, trunk velocity, trunk curvature) and an EMG variable (pattern of muscle activation) were analyzed with computer programs. Between Stages 1 and 2 of sitting development, anterior trunk displacement and velocity decreased significantly, although the trunk extension curve did not change significantly. Infants had variable muscle responses during Stage 1; however, during Stage 2 EMG analysis revealed less variability and the emergence of postural synergies. Overall, lumbar paraspinals, hamstrings, and quadriceps were the muscles most frequently active during the postural response. Each subject had a preferred synergy, with the most common synergies being a lumbar paraspinal-hamstring synergy and a lumbar paraspinal-quadriceps synergy. These data provide evidence that trunk displacement and trunk velocity decrease in infants develop independent sitting posture, and these variables may be used to measure improvement in sitting control. We suggest that the control of sitting posture is related to the emergence and preferred use of the paraspinal-hamstring and paraspinal-quadriceps synergies.

Age Factors↗

PubMed1998

Development of postural responses during standing in healthy children and children with spastic diplegia.

Studies on the development of balance control show a clear developmental progression of the emergence of organized muscle response patterns, with tonic background muscle activity decreasing and phasic bursts of activity emerging in all three agonist muscles in a synergic group (gastrocnemius-hamstrings-trunk extensors or tibialis anterior-quadriceps-abdominals) just prior to the onset of independent stance. The rudimentary ability to adapt postural responses to changing task conditions is present in children as young as 1 year of age. Older children with spastic diplegia have muscle activation patterns typically seen in normal children who are at the pull-to-stand stage of development, including poorly organized (proximal activated before distal muscles) responses with a high degree of antagonist co-activation. When normal children were asked to stand in a crouched posture like the CP children, the additional constraint caused muscle response patterns to resemble those of CP children, suggesting that differences in balance control in CP children are due to both CNS deficits and biomechanical changes in postural alignment.

Child↗

PubMed2002

Muscle reflexes during gait elicited by electrical stimulation of the posterior cruciate ligament in humans.

We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh and calf muscle during gait. The study group comprised eight young men without any history of injury to the knee joints. Multistranded teflon-insulated stainless steel wires were inserted into the PCL guided by sonography and in four subjects also into the fat pad of the knee. The PCL was electrically stimulated during gait on a treadmill at heel strike and 100 ms after heel strike. Electromyographic signals were recorded with bipolar surface electrodes placed over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 Hz; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing muscle activity in both the quadriceps and the hamstrings. The latency of the inhibition ranged between 78 and 148 ms in the quadriceps, between 88 and 110 ms in the hamstrings and between 189 and 258 ms in m. gastrocnemius. Stimulation of the fat pad of the knee did not influence the thigh and calf muscle motoneuron pool as evidenced by electromyography. The response elicited from the stimulation of the PCL was not limited to a specific muscle group but depended on ongoing muscle contraction, which suggests that the mechanoreceptors in the PCL are involved in the control of all muscles acting on the knee joint during gait.

Adult↗

PubMed2002

Self-release of ski-binding.

We investigated whether twenty-five male and female downhill skiers of different ages (11 - 63 years) and skiing skills were able to self-release their ski binding by an inward twist of the foot and leg. We also studied possible correlations between thigh muscle torques and the ability to release the binding. All subjects used the same ski and binding, Marker Titanum M48, individually set according to weight, height, skiing skill, age, and boot sole length. Prior to the test we used a special torque wrench, the Vermont Release Calibrator, to verify that the settings of the binding corresponded to the appropriate torque (Nm) to produce a release. Isokinetic concentric and eccentric quadriceps and hamstring torques were measured. EMG was used to study which muscles are engaged in this self-test. Nineteen skiers were able to release the binding, while four children and the two muscularly weakest skiers were not. The medial hamstrings produced the highest degree of muscle activity during the inward twist release of the binding. There was a highly significant correlation between thigh muscle torques and the ability to release the binding.

Adolescent↗

PubMed1999

Physical performance in individuals with late effects of polio.

The aim of this study was to evaluate physical performance in individuals with late effects of polio; specifically, to evaluate the effects of reduced muscle strength in the lower limbs. Thirty-two individuals seen at the polio clinic at Sahlgrenska University Hospital, Göteborg, Sweden, participated in the study. Each subject performed a bicycle exercise test in which peak oxygen uptake and anaerobic threshold were determined. Muscle strength in the quadriceps and the hamstrings were measured on an isokinetic dynamometer. Reductions in peak workload, peak oxygen uptake and predicted heart rate were seen. The anaerobic threshold was within or slightly lower than normal limits in relation to predicted maximal oxygen uptake, indicating that the cardio-respiratory system was not limiting performance. The muscle testing demonstrated a significantly lower ability to perform muscle actions compared with individuals from a reference group, and strong correlations were found between muscle strength peak VO2 and peak workload, respectively. Adjusted peripheral muscle endurance training might improve the work capacity in those individuals with weak leg muscles and low oxygen uptake, while individuals with relatively good muscle strength would improve their aerobic fitness in a general fitness program.

Adult↗

PubMed2005

Sagittal tibial translation during exercises in the anterior cruciate ligament-deficient knee.

The aim of this study was to describe and compare the sagittal tibial translation and electromyographic activity of muscles v. medialis and lateralis, gastrocnemius and hamstrings, during common rehabilitation exercises, in patients with anterior cruciate ligament (ACL) deficiency and non-injured controls. Sagittal tibial translation was registered with the CA-4000 electrogoniometer, in 12 patients and 17 controls, during Lachman test (static translation) and five exercises (dynamic translation). The exercises were grouped according to muscle work and joint compression (active extension, heel raises, cycling, one-legged squat and chair squat). The non-weight-bearing exercise with isolated muscle work (active extension) produced a large amount of tibial translation. During weight bearing, the total anterior-posterior tibial motion was halved compared to the non-weight-bearing exercises, but tibia was anterior positioned. Heel raising resulted in equal translation as the one-legged squat and chair squat, whereas cycling produced the smallest amount of tibial translation. The subjects utilized different amounts of their individual joint play (static translation) during the exercises, which may explain why there are no correlation between static translation and the patients functional outcome. These results enhance understanding on tibial translation during activity and gives indications on which exercises can be used early after ACL injury and reconstruction.

Adolescent↗

PubMed1979

Correlation between muscle shortening and derangement of the hip joint in children with spastic cerebral palsy.

From clinical studies on hip derangement and measurement of muscle shortening around the hip joint in 244 patients with spastic cerebral palsy, we found that the incidence of subluxation was 17.0% and that of dislocation was 8.2%; there was no dislocation in ambulatory spastics and the incidence of hip derangement was high in non-ambulatory patients; significant shortening of the adductors was closely correlated with hip derangement; the combination of damaged flexors, hamstrings and adductors led to hip derangement; surgical intervention in the adductors, the flexors (particularly the iliopsoas muscle) and the hamstrings should be considered in the treatment of advanced hip derangement in patients with cerebral palsy.

Adolescent↗

PubMed2006

Kinesiological surface electromyography in normal children: range of normal activity and pattern analysis.

To document the range of activity and patterns of normal surface kinesiological electromyography in normal children, 87 children ranging from age 3 to 18 years who were developing normally were evaluated at free walking speed. Analysis was performed on 6307 gait cycles from 11 different muscles with custom software. We devised an algorithm to do a computer-based KEMG curve pattern analysis to sort out curves that did not match the physiologic muscle activity pattern, We also devised a combined preset amplitude and statistics-based criteria to satisfactorily determine the onset/cessation of KEMG activity. The measurements of timing and duration of activity, body height and weight, body mass index, cadence, stride length, and age were obtained for statistical analysis. From the pattern recognition, the medial and lateral hamstrings, gluteus maximus and medius, and gastrocnemius muscles had the highest percentage of clinically relevant curves. In most muscle groups, The KEMG curves had an average background activity of about 11-15% of maximum amplitude. The surface KEMG curves from normal subjects have 12.7% cycles that did not match their physiologic activity pattern. The timing and duration of KEMG activity was poorly or only fairly correlated with age, body height, body weight, and body mass index. The ensemble average of the linear envelope KEMG curves of each muscle could be applied as a normal database in a clinical gait analysis laboratory focusing on pediatric patients.

Adolescent↗

PubMed2001

Initial evidence for the mixing and soft assembly of the ankle, suspensory, and hip muscle patterns.

The onset latencies of automatic muscle responses to backward translations of the support surface in standing subjects were assessed to test two longstanding hypotheses: that (1) the ankle, hip, and suspensory muscle patterns represent discrete synergies; and (2) the suspensory pattern cannot be mixed with the ankle and the hip patterns (based on theoretical modeling). Muscle responses were recorded at the leg (medial gastrocnemius and tibialis anterior), thigh (hamstring and quadriceps), lower trunk (paraspinals and abdominals), and the upper trapezius muscles. A principal factor analysis with orthogonal varimax rotation was conducted to describe the variation among the muscle onset latencies by means of the smallest possible set of newly defined variables, or factors. Muscles that were correlated with each other were grouped into a factor. The analysis produced three factors with eigenvalues > or =1, which accounted for 81% of the total variance. Based on the first muscle response in each factor, the muscle patterns resembled the hip, ankle, and suspensory synergies. Muscle responses within a synergy were activated before the completion of the muscle responses in the other synergies, indicating that the synergies, though mixed, are triggered separately. This is consistent with the hypothesis that the ankle, hip, and suspensory patterns represent discrete synergies. On the other hand, the results do not support the hypothesis that the three patterns cannot be combined.

Adult↗