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- Crommert, Martin Eriksson, et al.
(författare)
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Trunk muscle reactions to sudden unexpected and expected perturbations in the absence of upright postural demand
- 2009
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Ingår i: Experimental Brain Research. - : Springer. - 0014-4819 .- 1432-1106. ; 196:3, s. 385-392
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to increase the understanding of the multifunctional role of the trunk muscles in spine control, particularly transversus abdominis (TrA). In 11 healthy males, intramuscular fine-wire electromyography (EMG) was obtained bilaterally from TrA, obliquus externus (OE), rectus abdominis (RA) and erector spinae (ES). The subjects lay on their right side on a horizontal swivel-table with immobilized pelvis and lower limbs and the trunk strapped to a movable platform. Unexpected or expected release of loads attached to the table by steel cables produced a perturbation inducing either trunk flexion or extension. The timing and the amplitude of activation of TrA were independent of direction of induced trunk movement. Furthermore, timing of TrA activation was simultaneous to or later than that of the more superficial abdominal muscles. Expectation of the perturbation caused a general shortening of onset latencies. The results indicate a direction independent function of TrA in lumbar spine control. Balancing the trunk vertically appears to add specific demands, since the recruitment of TrA in relation to the other abdominal muscles differed from earlier experiments in standing.
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| 2. |
- Eriksson Crommert, A. E. Martin, et al.
(författare)
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Trunk muscle coordination in reaction to load-release in a position without vertical postural demand
- 2008
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 185:3, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the coordination between the innermost muscle layer of the ventro-lateral abdominal wall, the transversus abdominis (TrA), and other trunk muscles, in reaction to a load-release without the postural demand of keeping the trunk upright. Eleven healthy male volunteers participated. Intramuscular fine-wire electromyography (EMG) was obtained bilaterally from the TrA, rectus abdominis (RA), obliquus externus (OE) and erector spinae (ES) muscles. The subjects lay on their right side on a horizontal swivel-table with immobilized pelvis and lower limbs and with the trunk strapped to a movable platform allowing for trunk flexion and extension. Subjects maintained trunk flexion or extension at different force levels against a static resistance, which was suddenly released. They were instructed to resume the start position as fast as possible. EMG signals were analysed with respect to amplitude and timing of muscle activation. Following released static flexion, TrA increased its activity in synergy with ES. Also in released static extension, TrA increased its activity, but now in synergy with RA and OE. The direction-independent activation of TrA indicates a role of this muscle in controlling inter-segmental movements of the lumbar spine. This function was not accompanied by an early activation of TrA as has been shown previously for trunk perturbations in standing, i.e. a situation with an additional demand of maintaining the trunk posture upright against gravity.
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