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H C Scholle

Publications and source records attributed to H C Scholle.

At least 19 recordsLinked to original sources
PubMed2005

Back muscle activation pattern and spectrum in defined load situations.

For the prevention and rehabilitation of low back pain the understanding muscle function in the low back region is essential. Important aspects of function include the muscle activation patterns and muscle fatigue. In the low back region m. erector spinae plays a critical role. The different parts of this muscle complex differ considerably in function. Following the concept of Bergmark [A. Bergmark, Stability of the lumbar spine, Acta Orthop. Scand. 60 (1989) 1-54] trunk muscles can be divided in two subsystems, the global-mobilizing-system and the local-stabilizing-system. At present the multifidus muscles are assigned to the local whereas the longissimus and iliocostalis muscles are assigned to the global system. From results of the four parts of our investigation, it can be shown that essential information about muscle function can be obtained by spectral and intra- as well as inter-muscular surface EMG parameters. Obtained data demonstrated functional transitions between the local and global system of trunk muscles for the multifidus muscle.

Journal Article↗
PubMed2004

Simultaneous surface electromyography (SEMG) and 31P-MR spectroscopy measurements of the lumbar back muscle during isometric exercise.

The aim of this study was to demonstrate the feasibility of simultaneous surface electromyography (SEMG) and 31P-MR spectroscopy (31P-MRS) measurements on the back muscle of volunteers during the performance of an isometric exercise. Six volunteers (three male, three female) performed a modified Biering-Sörensen test inside a 1.5 T MR scanner while simultaneously recording SEMG signals. A surface coil was used for 31P-MRS with a CSI sequence. Spectra were collected with a voxel resolution of 40 mm x 40 mm x 100 mm and a temporal resolution of 30 s during periods of rest, sustained muscle contraction and recovery. The duration of muscle contraction was 150 s. SEMG analysis yielded a decrease of the mean SEMG frequency of approximately 20%. The SEMG amplitudes were constant or increased up to approximately 150% during exercise. 31P-MRS showed a maximum decrease of the phosphocreatine (PCr) amplitude down to approximately 32% of its initial value. Simultaneously, a doubling of the inorganic phosphate (Pi) signal was observed. The present study demonstrates that simultaneous SEMG and 31P-MRS measurements of the back muscle are feasible during isometric exercises.

Adult↗
PubMed2001

Spatiotemporal surface EMG characteristics from rat triceps brachii muscle during treadmill locomotion indicate selective recruitment of functionally distinct muscle regions.

Multichannel surface EMG recordings of a multiheaded skeletal muscle during cyclic locomotion combined with cineradiography were analysed in a chronic experiment. The resulting detailed two-dimensional activation pattern from the long and lateral triceps brachii heads of the rat during treadmill locomotion were combined with gait characteristics and fibre typing of the muscle. Shortly before ground contact of the forelimb, maximum muscle activity was found in the proximal part of the long head of the muscle. During the stance phase maximum activity was observed in the proximal part of the lateral head. The frequency dependent behaviour of cross-covariance functions over both muscle heads confirmed this selective shift in activation. In the lateral triceps brachii head of the investigated rats, exclusively type II fibres were found. In the long head the frequency of type I fibres was the highest in the deep muscle layers, proximally more than distally, whereas type II fibres were dominant in more superficial muscle layers. A combination of physiological and histological findings supports an anticipating mechanism whereby fine-tuning of the vertical foot down manoeuvre is mainly achieved by the (type I fibre dominated) proximal deep compartment of the biarticular long triceps brachii head and force generation is predominantly executed by the monoarticular lateral triceps brachii head.

Animals↗
PubMed2000

Surface EMG-recordings using a miniaturised matrix electrode: a new technique for small animals.

A new method for multichannel surface-EMG measurements in small animals is presented. The underlying scientific aim is the characterisation of the spreading and the co-ordination of skeletal muscle activation between different muscles or muscle parts, depending on various motor tasks. The myoelectrical signals were recorded monopolarly by a 16-channel matrix electrode on the muscle surface directly under the skin on the fascia of the investigated muscle, without damaging the muscle. Surface-EMG's were recorded for at least 5 days after surgery without electrical interferences. During defined motor tasks, the projection of the myoelectrical activation of the different parts of the M. triceps brachii of rats (Rattus norvegicus), pikas (Ochotona rufescens) and cuis (Galea musteloides) or the M. anconeus of toads (Bufo marinus) on the muscle surface was mapped. The locomotion of the investigated animals was monitored by a three-dimensional kinematic analysis (video and/or high-speed cineradiography). There was no perceptible influence from application of EMG matrix electrode. The miniaturised matrix electrode seemed practicable in gaining insight into changes in myoelectrical activation patterns (EMG mapping). This allows a characterisation of the intramuscular co-ordination processes corresponding to the actual morphofunctional state of the investigated animals.

Anesthesia↗
PubMed2000

Surface EMG mapping of the human trapezius muscle: the topography of monopolar and bipolar surface EMG amplitude and spectrum parameters at varied forces and in fatigue.

OBJECTIVES: To investigate the factors affecting the topography of trapezius muscle EMG, multichannel recordings were made at different forces of isometric shoulder elevation and during fatiguing exercise. METHODS: Twenty-eight channels of monopolar EMG were recorded from an array of 4 x 7 electrodes placed on the upper trapezius muscle. From the monopolar EMG and the bipolar derivations the root mean square (RMS(monopolar), RMS(bipolar)) and power spectrum median frequency (MF(monopolar), MF(bipolar)) were calculated. RESULTS: The maximum RMS(monopolar) was located above the middle part of the trapezius muscle, where a minimum was found for RMS(bipolar). The cranial-caudal RMS distribution shifted upwards when the force was increased from 50 to 100% MVC and during fatigue. MF(bipolar) showed a peak above the endplate region, where the MF(monopolar) was low. During fatigue the normalized MF slope was independent of the cranial-caudal electrode position, but MF(monopolar) decreased most strongly at positions above the endplate region, where MF(bipolar) decreased less. CONCLUSIONS: While the changes in MF reflected metabolic properties and volume conduction phenomena in the muscle, changes in RMS reflected a compensation for the fatigue processes within the muscle. The RMS changes in fatigue can be explained by the direction of the fibres involved in shoulder elevation.

Adult↗
PubMed1999

Surface EMG of shoulder and back muscles and posture analysis in secretaries typing at visual display units.

OBJECTIVE: A study was carried out to investigate temporal changes of activation of shoulder and back muscles in workers at visual display units by means of surface EMG. Moreover, postural parameters were recorded to distinguish fatigue-related from posture-related changes of the myoelectrical activity. METHODS: Nine healthy female office workers typed texts spoken from tape during three 1-h-long sessions. After the first and again after the second hour there was a break of 15 min. Sixteen-channel surface EMG was bipolarly recorded from the erector spinae, trapezius, deltoid and sternocleidomastoid muscles. Root mean square (RMS) and power spectrum median frequency of the EMG were calculated. Sitting posture was assessed using an eight-channel movement analysis system with ultrasound markers. The position of the seventh cervical spinous process and the left and the right acromion were analysed synchronously with the EMG characteristics using regression analysis. RESULTS: The normalised RMS of the left and right trapezius muscle increased, while the median frequency did not change. The increase of the normalised RMS was significantly lower when the linear influence of posture was excluded. On average, the distance between C7 and the left and right acromion decreased within each working an hour. C7 became lower on average by 5.5 mm within an hour, whereas the acromions became lower by only 1.7 mm (left) and 3.3 mm (right). CONCLUSION: The increase in trapezius muscle activity was partly related to a lifting of the shoulders to compensate a slight slumping of the back. Another part of the EMG activity increase has to be attributed to fatigue, to attention-related activity or to the combination of both. Therefore, training of the back muscles and a varied organisation of work might have a preventive effect with respect to musculoskeletal complaints in VDU workers.

Adult↗
PubMed1998

Force regulation is deficient in patients with parietal lesions: a system-analytic approach.

By means of a quantitative system-analytic investigation strategy, the postural motor control of the fingers was evaluated, to characterise the possible deficit of force regulation in patients with parietal lesions. In spite of a normal response to short torque pulses, the parietal-lesion patients had difficulties in returning to the preload level after the application of an additional step torque load to fingers II-IV of their left or right hands. The control offset (measured 500 ms after step torque application) was significantly larger in the patient group. This deficit in the investigated patients with parietal lesions to compensate for step torque loads was not due to a paresis, but rather resulted from a disturbance in the generation of a sufficient counterforce against the applied step torque within an adequate time window and motor pattern. This distinct force-regulation deficit was found in patients with left- and right-sided parietal lesions.

Adult↗
PubMed1997

[EMG surface polygraphy of the pelvic floor--description of functional changes after radical prostatectomy].

Urinary stress incontinence after radical prostatectomy could be cured by physiotherapy in a high percentage. The authors developed an investigation procedure for description of myoelectrical activity of pelvic floor with surface electrodes. 10 patients were studied 1 day before, 10 days and 6 months after radical prostatectomy. Significant changes of amplitude and frequency characteristics could not be found in rest and during the stationary intervals of maximal contraction. But after the operation in all patients changed the activation pattern within the interval of increasing muscle contraction. The mean and median frequency decreased significantly (Friedman-test, p < 0.001). This was interpreted as a problem of intramuscular coordination. After physiotherapy urinary incontinence was cured or improved. The typical activation pattern of dyscoordination was not more evident after 6 months.

Aged↗
PubMed1995

[Muscle incoordination phenomena after surgical management of proximal rupture of the biceps tendon].

A significant atrophy of the biceps brachii muscle without decreasing maximal force during flexion in the elbow joint was shown at least 1.5 years after surgical refixation in 6 patients with a tendon-rupture of the long head of the right biceps. A decreased myoelectrical activity was found in the caput longum region of the muscle. The decrease correlates with an increase of spectral myoelectrical power in the region of caput breve or brachioradialis muscle. In addition compensatory recruitment processes can be supposed because of changed spectral myoelectrical power in the low-frequency bands. Changes of the morphological structure of the muscle were only found in 1 patient by sonography.

Arm Injuries↗
PubMed1994

A topographical analysis of spectral electromyographic data of the human masseter muscle under different functional conditions in healthy subjects.

In 20 healthy subjects, 16-channel surface electromyograms (EMG) were recorded with the mandible in its postural position, during compensation for forces applied from ipsilateral, contralateral and frontal positions, and during force-constant biting on a unilaterally placed force transducer. After artefact elimination, EMG power spectra were calculated on the basis of the original EMG curves via fast Fourier transformation. Using spectral EMG characteristics, EMG maps were computed by means of an interpolation algorithm and an imaging procedure. Spectral EMG maps were demonstrated for all the test conditions. Significant differences of myoelectrical activity were verified between the 16 electrode positions. Moreover, the levels and/or the topographical distributions of spectral EMG powers differed significantly between the test conditions. During biting as well as with contralaterally and frontally applied forces, the highest EMG activity was found in the inferior third of the masseter and the lowest in the superior third. With ipsilaterally applied forces, the topographical distribution of the total EMG power was completely changed. The power maximum was frequently demonstrated in the superior, especially the posterosuperior, third of the muscle, the minimum in the inferior third. In the postural position of the mandible, EMG activity decreased from the anterior to the posterior regions of the masseter. If the bite force or the horizontally applied forces were enhanced, EMG activity increased significantly but the EMG map structures were only changed in some details. The topographical distribution of myoelectrical activity demonstrated by EMG maps characterizes the intramuscular activation patterns of distinct masseter functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Quantitative topographic characterization of the myoelectric activity distribution of the masseter muscle: mapping of spectral EMG parameters].

A new method for quantitative characterization of myoelectrical masseter activity distribution by mapping of spectral EMG-parameters is described. The surface electromyograms of M. masseter were monopolarly recorded (16 channels). On the basis of registered EMG intervals (512 ms) the spectral EMG power of several frequency bands was calculated (Fast Fourier Transformation). The spectral EMG parameters between the 16 electrode positions were estimated by linear interpolation (4-nearest neighbours algorithm). Afterwards the spectral EMG parameters were fitted in a grey-tone or colour scale with 10 intervals. The so obtained EMG activity maps ("EMG-Maps") permit a quantitative-topographic characterization of myoelectrical masseter activity during different functional load procedures. The frequency range which is to consider in masseter surface-EMG investigations encloses frequencies between 15 and 500 Hz. The topography of EMG activation pattern of M. masseter is only described in a comprehensive manner when the electrode array consists of 16 electrodes and more. During defined motor tasks like clenching with controlled forces the reproducibility of EMG-Maps which respect to the topography of EMG activity pattern is very high. The absolute values of spectral EMG power as well as power changes of selected band ranges during clenching correlate to the extent of chewing forces.

Adult↗
PubMed1992

[Mapping spectral EMG parameters of the masseter muscle in normal probands under defined loads].

In 20 healthy volunteers 16-channel surface electromyograms were monopolarly recorded from the right and left masseter muscle during defined functional conditions (force-constant bite, right and left hand side, 196, 333, 530 N chewing force, during a compensation of a load directed from a frontal or a lateral position to the mandible (20, 49, 69 N), during rest position of the mandible). The EMG curves were quantified by the calculation of spectral EMG-parameters (FFT). With respect to the muscle a topographic oriented representation of the myoelectrical activity was realised by a mapping of spectral EMG-parameters. The monopolarly recorded EMG activities significantly differed between the 16 electrode positions (topographic EMG distribution pattern). During the several examination conditions of the masseter muscle different topographic distribution pattern of the myoelectrical activity were found. Moreover, the total EMG power between the muscle functions differed too. The level of the load influenced the spectral EMG power as well as, partly, the topographic EMG distribution pattern.

Adult↗
PubMed1992

[Control of isometric muscle contraction in muscle hypotonia of central origin: EMG mapping analysis].

Electromyographic and mechanographic investigations in patients with muscular hypotonia, which is, for instance, a side-effect after stereotactic treatment of tremor syndromes, permit the presumption that in this sensomotor open-loop situation the decreased muscular resistance to stretching during isometric contraction (initial stiffness) is caused by changes of muscular innervation pattern. Probably, the innervation pattern during tonic activity is changed by a shift of a more tonic motoneurone behaviour to motoneurone activities with predominantly phasic characteristics. In 17 controls and 4 patients with muscular hypotonia caused by stereotactic lesions of VIM area (treatment of tremor syndromes) the EMG of right and left side forearm flexors (especially the activity of the M. biceps brachii) was investigated by a sophisticated, topographically oriented 16-channel-surface-EMG-technique ("EMG-Mapping") during slight isometric contraction. EMG-Maps of forearm flexors (especially of M. biceps brachii) in patients with centrally evoked muscular hypotonia demonstrate that in these open-loop conditions the motor control is changed. For this the reason could be a shift of the activated motor units from a predominantly static to a more phasic functional behaviour. The latest results on muscular activation processes in cats support this presumption.

Adult↗
PubMed1991

[Quantification of artefacts in surface EMG by validating the lower frequency limit in clinico-physiologic studies].

The surface-EMG becomes more and more important because computer assisted analysing systems can be applied. The occurrence of artefacts makes it very difficult to compare several recorded EMG channels with each other. In this study a frequency related quantification of movement artefacts and ECG-related influences on the EMG is carried out to select a suitable lower cut-off frequency for surface-EMG investigations. In 764 monopolar surface-EMG-recordings of the neck and back muscles the solely artefact-caused part of EMG-segments was analysed and quantified by means of modelling methods.

Adult↗
PubMed1991

[Methodologic studies in dynamic EMG mapping based on the Hilbert transformation].

On the basis of Discrete Hilbert Transformation spectral parameters for dynamic EMG analysis can be introduced. Within analysis intervals which are used in the same manner as in spectral analysis, the momentary power of EMG frequency bands can be computed as time series of the same interval duration. A close connection exists between momentary power and the current phenomenology of power spectral analysis because the momentary power of a defined frequency band can be seen as the exact dynamic equivalent of the corresponding mean power value deduced from the power spectrum. A multichannel EMG recording (greater than or equal to 16 channels) makes the representation of the topographical distribution of the spectral parameter by a coloured map possible. Additionally, the momentary power can be used to calculate map sequences. In this way, changes of EMG activity can be quantified by map sequences of an arbitrary time resolution. By calculation of momentary frequency via DHT an artefact detection scheme for ECG interference can be suggested. A completion of this methodology can be carried out by applications of adaptive filtration procedures. Using this concept of EMG processing, a new and common methodical basis of EMG power spectral analysis can be introduced.

Brain Mapping↗
PubMed1990

[EEG and evoked potential mapping].

By spectral EEG-mapping and EP-mapping, especially the topologic dimension of electrical brain activity can be evaluated for clinical use. On the other hand, this method allows the highest solution from all functional imaging procedures within the time dimension of brain activity. On the other hand, the ability of topological solution is limited. But the latter is probably better than hitherto assumed and surprisingly well at least regarding neonates. However, several methodological prerequisites described here must be fulfilled. From the pathophysiological point of view, the limits must be considered besides the diagnostic possibilities. Meanwhile, spectral EEG-mapping and EP-mapping are diagnostically used in all main fields of traditional EEG-analysis, like seizures and in the preadiagnostics of tumors a.o. Also in the diagnostics of cerebrovascular disease including transient ischemic attacks, the EEG-mapping and/or EP-mapping are useful within the total diagnostics. There is a similar situation in the diagnostics of degenerative brain disorders. But the significance of frequently described changes inpsychoses, partly also neuroses and other functional disorders is not clear. Altogether, this non-invasive, economically most favourable method for the functional imaging procedures in brain diagnostics is promising to extent the routine diagnostics also to a more precise manner.

Brain↗
PubMed1990

Electrophysiological characterization of central sensory and motor pathway function in patients with moderate hemiparesis. I. Methodical approach.

The central sensory and motor pathway function in healthy persons and patients with several neurological disorders was selectively characterized by evaluation of latencies of short (R1) and long (R2) latency EMG responses as well as simultaneously recorded somatosensory potentials (N19, N26) evoked by electrical stimulation of N.medianus and N.peroneus. On the basis of these latencies the peripheral and central sensory/motor conduction times were calculated. By using this investigation procedure a selective quantification of central pathway functions is possible.

Adolescent↗