Biomedical subjects

Christoph Anders

Publications and source records attributed to Christoph Anders.

5 recordsLinked to original sources

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↗

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

Back extensor muscle oxygenation and fatigability in healthy subjects and low back pain patients during dynamic back extension exertion.

The purpose of this study was to assess if chronic low back pain patients have impaired paraspinal muscle O2 turnover and endurance capacity as compared to healthy control subjects during dynamic exercise. Middle-aged healthy male subjects (n = 12, control) and male patients with chronic low back pain (n = 17, CLBP) participated in the study. L4–L5 level paraspinal muscle fatigue was objectively assessed during earlier validated 90 s dynamic back endurance test (spectral EMG, MPFslope). Also EMG amplitude (EMGamplitude) and initial MPF (MPFinitial) were assessed from the initial 5 s of the endurance contraction. Simultaneously near infrared spectroscopy (NIRS) was used for quantitative measurement of local L4–L5 paraspinal muscle O2 consumption. Subcutaneous tissue thickness (ATT) was measured from the EMG and NIRS recording sites. The results indicated that control and CLBP groups were compatible as regarding anthropometric variables, paraspinal muscle activation levels (EMGamplitude), initial MPF (MPFinitial) and ATT. When the ATT was used as a covariate in the ANOVA analysis, CLBP group did not show significantly greater paraspinal muscle fatigability (right MPFslope – 12.2 ± 10.7%/min, left right MPFslope – 12.6 ± 13.3%/min) or O2 consumption (right NIRSslope – 52.8 ± 79.6 μM/l/s) as compared to healthy controls (right MPFslope – 11.9 ± 7.6%/min, left MPFslope – 12.7 ± 8.6%/min, right NIRSslope – 53.7 ± 95.2 μM/l/s). As a conclusion, these CLBP male patients did not show any impaired rate of paraspinal muscle oxygen consumption or excessive paraspinal muscle fatigability during dynamic exercise as compared with healthy controls. Subcutaneous tissue thickness has a strong influence on the NIRS and EMG amplitude measurements and, if unchecked, it could result in the false interpretation of the results.

Journal Article↗

PubMed2004

Activation characteristics of shoulder muscles during maximal and submaximal efforts.

Determination of individual maximum voluntary contraction (MVC) force is used as the gold standard for normalising surface EMG (SEMG) data. Assuming a linear amplitude-force relationship, individual strain levels are defined according to percentage rates of the measured MVC levels. The purpose of the study was to investigate if the assumed force-strain relationship can be applied without qualification. Therefore, healthy volunteers (nine men, ten women) were investigated during isometric exercises of shoulder muscles at MVC and 50% levels. Tasks were performed at four different angular positions in frontal, sagittal and horizontal planes. In each plane, both possible force directions were investigated. SEMG was taken simultaneously from 13 muscles of the shoulder and upper arms from both sides of the body. At a force level of 50% MVC, SEMG amplitude levels were compared to the expected 50% level. Differences in muscular co-ordination patterns were also determined. During retroversion and horizontal flexion, amplitude levels significantly remained at levels below 50%. This was seen for all the muscles investigated, independent of relative contribution to force production. During horizontal extension and abduction, the main force-producing muscles showed amplitude levels that significantly exceeded the expected 50% level. Co-ordination patterns differed significantly between MVC and submaximal conditions for anteversion, retroversion and horizontal extension. Specifically, four shoulder muscles showed higher proportions at the 50% level compared to MVC. Therefore, certain percentage rates of MVC force levels exhibit quite different strain rates, as identified by SEMG. Depending on force direction, differences in co-ordination patterns exist between MVC and submaximal test conditions. Both findings have implications for therapeutic and training applications.

Adult↗

PubMed2004

Activation of shoulder muscles in healthy men and women under isometric conditions.

PURPOSE: Due to the low osseous lead of the shoulder joint a large portion of the shoulder muscles, in addition to executing movements, deals with stabilising tasks. This requires a permanent readjustment of the intermuscular co-ordination of all involved muscles. The aim of the study was to verify the existence of gender dependent differences in intramuscular co-ordination patterns of shoulder muscles. METHOD: Fifteen healthy men and nine healthy women, who executed 24 isometric exercises in sagittal, frontal and horizontal planes with a loading of 50% of their individual isometric maximum force, were investigated. In every plane, four angular positions were chosen and both opposite force directions were measured, respectively. SEMG was taken from 13 muscles of the shoulder and the upper arm. Due to inter-individual differences SEMG amplitudes were normalised. RESULTS: Gender specific differences of functional intermuscular co-ordination patterns could be proven systematically. Women showed less activation of muscles acting in the main force direction. In addition, those muscles less necessary for the actual force production were more activated in women than in men. CONCLUSIONS: Functionally comparable shoulder function showed a gender dependency in terms of functional intermuscular co-ordination.

Adult↗