Low back pain suppresses preparatory and triggered upper-limb activation after sudden upper-limb loading.
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: The emphasis in treating back pain has changed over the last century; moving from resting the patient ‘allowing tissues to heal’, towards encouraging movement and activity as early as possible. This has been mirrored by a shift from so-called passive treatments which were done to a patient (e.g. ultrasound and traction) to active ones where the patient is encouraged to play a role in their own recovery. Rehabilitation is a popular treatment option increasingly utilised by all major professions involved with musculoskeletal injury. Guidelines exist from several international bodies providing statements on rehabilitation and yet the evidence for its effectiveness appears week. There does not appear to be much advantage for patients with a first episode of short duration back pain in doing any specific back exercises. Where the pain is longer lasting or reoccurring it is likely that exercise can play a useful role in reducing pain and disability. However, the form that this exercise should take and the best way for it to be provided it is much less clear. This is in part because of the way evidence has been collated and also the rigid way that some guideline groups have set about producing their statements.Clinical Chiropractic 01/2008; 11(4):199-204.
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ABSTRACT: It has been reported that altered neuromuscular control of the trunk is associated with lower back pain. In this context reflex delays of the trunk muscles have often been assessed but the reliability of the tests has not been well established. The aim of this study was to test the reliability of measuring reflex delays of the trunk muscles after two types of postural perturbations. 24 Healthy subjects participated in the intra-session study and 13 of them repeated the test protocol within 1-3 weeks, to determine inter-session reliability. Postural reflex delays to unexpected loading and unloading of the arms were assessed in a standing unrestrained position. Each subject performed 40 trials of each test in order to evaluate muscle responses of 5 trunk muscles using surface electromyography. Overall reliability increased with higher number of the averaged trials. Good intra-session (ICC3,1>0.75) and moderate (ICC3,1>0.60) inter-session reliability were reached in most of the monitored trunk muscles. Within the performed number of trials we did not observe any significant systematic intra- or inter-session bias effect. Averaging a higher number of consecutive trials would be recommended in future research and clinical practice.Journal of biomechanics. 06/2014;