Biomedical subjects

Roland Grassme

Publications and source records attributed to Roland Grassme.

6 recordsLinked to original sources

PubMed2006

Treadmill locomotion in normal mice-Step related multi-channel EMG profiles of thigh muscles.

Mouse models are increasingly used in current research on motor disorders. In mice, the myoelectrical activation of thigh muscles during locomotion has not yet, however, been investigated in depth. Especially intramuscular coordination has hardly been clarified. Therefore, the aims of this study were to characterize myoelectrical activity in the vastus lateralis (VL) and the biceps femoris (BF) muscle of the healthy mouse for reference purposes. The VL and the BF muscles of 12 healthy mice performing a total of 1985 steps during treadmill locomotion were investigated with two subcutaneous arrays each incorporating four electrodes. Eight-channel EMG was recorded simultaneously with high-speed videography. The EMG curves of each step were rectified and smoothed by calculating root mean square (RMS) profiles and then time-normalized for comparisons within and between animals. The EMG-activity of both muscles increased during late swing phase. The VL activity rose steeply and peaked during mid-stance phase, while the biceps activity reached a plateau during early stance phase. With increasing gait velocity, stance time decreased. The increase in gait velocity was also associated with greater EMG amplitudes. The results suggest that the BF lifts the lower hind leg during swing phase and stabilizes the leg during stance, while the VL bears the weight of the body during the stance phase.

Journal Article↗

PubMed2006

Trunk muscle activation patterns during walking at different speeds.

Investigations of trunk muscle activation during gait are rare in the literature. As yet, the small body of literature on trunk muscle activation during gait does not include any systematic study on the influence of walking speed. Therefore, the aim of this study was to analyze trunk muscle activation patterns at different walking speeds. Fifteen healthy men were investigated during walking on a treadmill at speeds of 2, 3, 4, 5 and 6 km/h. Five trunk muscles were investigated using surface EMG (SEMG). Data were time normalized according to stride time and grand averaged SEMG curves were calculated. From these data stride characteristics were extracted: mean SEMG amplitude, minimum SEMG level and the variation coefficient (VC) over the stride period. With increasing walking speed, muscle activation patterns remained similar in terms of phase dependent activation during stride, but mean amplitudes increased generally. Phasic activation, indicated by VC, increased also, but remained almost unchanged for the back muscles (lumbar multifidus and erector spinae) between 4 and 6 km/h. During stride, minimum amplitude reached a minimum at 4 km/h for the back muscles, but for internal oblique muscle it decreased continuously from 2 to 6 km/h. Cumulative sidewise activation of all investigated muscles reached maximum amplitudes during the contralateral heel strike and propulsion phases. The observed changes argue for a speed dependent modulation of activation of trunk muscles within the investigated range of walking speeds prior to strictly maintaining certain activation characteristics for all walking speeds.

Abdominal Muscles↗

PubMed2006

Investigations of back muscle fatigue by simultaneous 31P MRS and surface EMG measurements.

Investigations of back muscle fatigue are important for understanding the role of muscle strain in the development of low back pain. The aim of this contribution is to review the two main techniques used for in vivo investigations of metabolic and electrophysiological changes, namely magnetic resonance phosphorous spectroscopy ((31)P MRS) and surface electromyography (SEMG), and to report some of our recent results on simultaneous measurements using these techniques during isometric back-muscle contraction in volunteers. Since it appears that electrophysiological and metabolic factors are simultaneously involved in the processes of fatigue and muscle recovery during load application, simultaneous acquisition of complete information is quite promising for obtaining new insights into the metabolic origin of electrophysiological changes or vice versa. Performing these measurements simultaneously, however, is more intricate owing to the occurrence of signal artifacts caused by mutual signal interferences of both techniques. Besides these mutual disturbances, further experimental difficulties are related to spatial limitations within the bore of clinical whole-body high-field magnetic resonance (MR) systems (1.5 T) and the sensitivity of MR measurements to motion-induced artifacts. Our own experimental results are presented, and problems that occur using both techniques simultaneously, as well as possibilities to resolve them, are discussed. The results shed light on the interrelation of electrophysiological and metabolic changes during fatigue of the back muscle while performing an exercise.

Adenosine Triphosphate↗

PubMed2005

Muscular activation patterns of healthy persons and low back pain patients performing a functional capacity evaluation test.

The results of most reported studies show differences between the muscular activity of low back pain patients and healthy subjects, but the focus has usually been on trunk muscles only, and they have not involved work-related tests or exercises. The reintegration of chronic low back pain patients to job market is a common problem. Therefore assessment systems like the functional capacity evaluation (FCE) according to Isernhagen [S.J. Isernhagen, Work Injury: Management and Prevention, Aspen Publishers Inc., Gaithersburg, MD, 1988] are often used tools to determine the physical abilities and deficits of long-time incapacitated persons. The aim of the present study was to compare the healthy persons and chronic low back pain patients in performing a FCE-test and to analyse their muscular activation and motion patterns. The results indicate differences in the activation patterns of the groups in the test task "floor to waist lift" common in many occupations.

Journal Article↗

PubMed2005

Trunk muscle co-ordination during gait: relationship between muscle function and acute low back pain.

Low back pain costs billions of Euros annually in all industrialized countries. Often radiological diagnosis fails to give evidence of the pathogenesis of low back pain. Although psychophysiological characteristics have an influence, it seems that insufficient muscular spinal stabilization may play the major role in the development of low back pain. Assessment of trunk muscle stabilization activity during everyday activities is rare. Therefore, in this study healthy persons were investigated during walking on a treadmill at a speed of 4 km/h. Women (n = 16) with no history of back pain were investigated before and after a static loading situation of the spine, i.e. while wearing a waistcoat. After this loading situation four women developed pain (pain subjects). Surface EMG (SEMG) was taken from five trunk muscles of both sides. Grand averaged amplitude curves over stride, amplitude normalized curves and variation between all included strides were calculated for all muscles and subjects, respectively. The normal range of all calculated parameters was defined within the span between the 5th and the 95th percentiles of all pain free subjects. Data were evaluated according to deviations from the normal range. Already before the load situation, pain subjects showed considerable deviations from the normal range, mainly of their abdominal muscles. There was no relationship between magnitude of deviation and pain intensity, but perceived exertion was highest in those subjects who showed the most symptoms in terms of number of muscles being identified as considerably deviating from the normal range. No specific "dysfunction pattern" could be identified, which argues for highly individual mechanisms instead of a single target muscle. The results suggest cumulative effects of different disturbance levels resulting in acute back pain. Since deviations could be identified already before the pain occurred, disturbed muscle function seems to be a risk factor for developing back pain. Further investigations aimed at clear identification of and, as a second step, correction of muscle function are necessary.

Journal Article↗

PubMed2005

A surface EMG multi-electrode technique for characterizing muscle activation patterns in mice during treadmill locomotion.

In mice a new method for 2x4-channel surface electromyography (EMG) recordings of the vastus lateralis and biceps femoris muscles during locomotion on a treadmill with varying speed is presented. The approach involves high-speed-videography (sampling interval 2.5 ms) in concert with the application of chronically implanted surface EMG multi-electrodes (EMG sampling rate 4000 Hz, frequency range 10-700 Hz). The recordings are started 2 days after surgery and finished 2 weeks after surgery. During the whole investigation period EMG recordings of both muscles have been possible. The monopolar EMG activities recorded by the electrode-arrays and the bipolar EMG signals derived from the monopolar activities permit an evaluation of the extent of myo-electrical activation in larger regions of both muscles and co-ordination between the flexor and extensor muscles. Bipolar EMG signals indicate propagation of activities along the muscle fibers and a slight effect of non-propagating signal components. Thus, the cross talk between these muscles is small and does not influence the evaluation of the EMG results. The resolution of the simultaneously recorded synchronized data allows a precise temporal correlation of kinematic and EMG parameters.

Action Potentials↗