Low back pain suppresses preparatory and triggered upper-limb activation after sudden upper-limb loading.

Department of Neurosurgery, Kuopio University Hospital, Kuopio, Finland.
Spine (Impact Factor: 2.16). 04/2007; 32(5):E150-5. DOI: 10.1097/01.brs.0000256886.94791.94
Source: PubMed

ABSTRACT A cross-sectional comparative study between healthy controls and patients with chronic low back pain (LBP).
To assess the effect of chronic LBP on biceps brachii muscle activation during sudden upper-limb loading.
Chronic LBP is related to altered trunk muscle function. However, it is not known if these changes are also found in upper-limb function, indicating a general effect.
Surface electromyographic recordings were made from the biceps brachii bilaterally from 22 control subjects without chronic LBP and 29 patients with chronic LBP. Electromyography was recorded during expected and unexpected limb loading, with the activation pattern recorded for analysis at 150 milliseconds before loading, and 3 consecutive 50 milliseconds periods following loading. RESULTS.: Chronic LBP patients had decreased biceps brachii activation before expected perturbation (P = 0.035) and during the third 50-millisecond period (from 100 to 150 milliseconds) after unexpected perturbation (P = 0.010). During the first 2, 50-millisecond periods (from 0 to 100 milliseconds) after the perturbation, the activation was similar.
Chronic LBP did not affect reflex activation of biceps brachii muscles but decreased preparatory and triggered reactions. The finding indicates that back pain may disturb higher level information processing in motor control.

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    ABSTRACT: HintergrundZiel der Studie war die Untersuchung der posturalen Kontrolle während externer über die Füße eingeleiteter Störungen bei Patienten mit chronischem nichtspezifischem Rückenschmerz (CNRS). Zudem wurde der Einfluss der visuellen Information (Augen offen vs. Augen geschlossen) auf die posturale Kontrolle untersucht. Material und MethodenEs wurden 8Patienten mit CNRS (Alter: 40±12Jahre; Body Mass Index, BMI: 23±2kg/m2) ohne degenerative Bandscheibenerkrankung der Wirbelsäule (Befund der Magnetresonanztomografie) und 12gesunde Vergleichspersonen (Alter: 28±7Jahre; BMI: 21±3kg/m2) untersucht. Mittels Oberflächenelektromyografie (OEMG) wurde die posturale Kontrolle bei 5Rumpf- und 5Beinmuskeln sowie einem Beckenmuskel bei distalen lateralen Störungen analysiert. ErgebnisseGesunde (Mittelwert±Standardabweichung: 96,42±64,77µV) zeigten im Vergleich zu Patienten mit CNRS (56,29±39,63µV) eine signifikant (F=6,00; p<0,05) größere erste Maximalamplitude der muskulären Reflexantwort des M. gluteus medius während externer Störungen im aufrechten Stand. Beide Gruppen zeigten für ausgewählte Beinmuskeln ein signifikant größeres Integral der ersten Reflexantwort bei geschlossenen Augen im Vergleich zu offenen Augen. SchlussfolgerungPatienten mit CNRS zeigen eine veränderte reflektorische Antwort des M. gluteus medius, welche mit einer verminderten Beckenstabilisierung einhergehen könnte. BackgroundThe aim of this study was to examine postural control in patients with chronic non-specific low back pain (CNRS). Furthermore the influence of visual information (eyes open versus eyes closed) was analyzed. Material and methodsA total of 8patients with CNRS and 12healthy control subjects were examined. Surface electromyography (SEMG) recordings were made from 5trunk and 5lower limb muscles as well as one hip muscle during application of distal lateral perturbation. ResultsHealthy controls (mean±standard deviation: 96.42±64.77µV) showed a significantly higher maximum amplitude of the gluteus medius muscle in comparison to patients with CNRS (56.29±39.63µV). Furthermore activation of several lower limb muscles was found to be dependent on visual information. ConclusionPatients showed an altered reflex response of the gluteus medius muscle which could be associated with reduced hip stability. SchlüsselwörterRückenschmerz–Posturale Kontrolle–Visuelle Information–Beckenmuskulatur–Elektromyografie KeywordsLow back pain–Postural balance–Visual information–Hip muscle–Electromyography
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    BMC Musculoskeletal Disorders 09/2011; 12:211. · 1.88 Impact Factor
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