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The relative timing of trunk muscle activation is retained in response to unanticipated postural-perturbations during acute low back pain.

Boudreau S, Farina D, Kongstad L, Buus D, Redder J, Sverrisdóttir E, Falla D - Exp Brain Res (2011)

Bottom Line: In each condition, participants stood on a moveable platform during which 32 randomized postural perturbations (8 repetitions of 4 perturbation types: 8 cm anterior slides, 8 cm posterior slides, 10° anterior tilts, and 10° posterior tilts) with varying inter-perturbation time intervals were performed over a period of 4-5 min.During the acute LBP condition: (1) the onset time of the ES and EO was delayed for the forward and backward sliding perturbations (P < 0.05); (2) EMG amplitude was reduced bilaterally for all perturbations (P < 0.05); (3) the order of activation and interval between the onset times of the ES and EO were unaltered and (4) ES, but not EO, activity was adjusted to account for the directional differences between the perturbations.This study revealed that re-establishment of posture and balance was a result of the individuals' ability to rapidly modulate ES with respect to EO activity and that the bi-directional postural responses, although shifted in time and amplitude, retained temporal features in the presence of acute LBP.

View Article: PubMed Central - PubMed

Affiliation: Center for Sensory-Motor Interaction, Department of Health Science and Technology Faculty of Medicine, Aalborg University, Aalborg, Denmark.

ABSTRACT
The purpose of this study was to assess the activation of the erector spinae (ES) and external oblique (EO) in response to unanticipated, bi-directional postural perturbations before and after the induction of acute low back pain (LBP) in healthy individuals. An experimental session consisted of a baseline, control, and an acute LBP condition. For the control and acute LBP condition, isotonic or hypertonic saline (HS), respectively, was injected into the right ES muscle. In each condition, participants stood on a moveable platform during which 32 randomized postural perturbations (8 repetitions of 4 perturbation types: 8 cm anterior slides, 8 cm posterior slides, 10° anterior tilts, and 10° posterior tilts) with varying inter-perturbation time intervals were performed over a period of 4-5 min. Bilateral surface electromyography (EMG) was recorded from the ES and EO in addition to subjective pain records. During the acute LBP condition: (1) the onset time of the ES and EO was delayed for the forward and backward sliding perturbations (P < 0.05); (2) EMG amplitude was reduced bilaterally for all perturbations (P < 0.05); (3) the order of activation and interval between the onset times of the ES and EO were unaltered and (4) ES, but not EO, activity was adjusted to account for the directional differences between the perturbations. This study revealed that re-establishment of posture and balance was a result of the individuals' ability to rapidly modulate ES with respect to EO activity and that the bi-directional postural responses, although shifted in time and amplitude, retained temporal features in the presence of acute LBP.

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Mean of the left and right EMG amplitude (a, b) and onset (c, d) of the erector spinae (ES) and external oblique (EO) for each perturbation type (PS posterior slide, AS anterior slide, PT posterior tilt, AT anterior tilt) for the mean of the baseline and control condition (a, b) and the acute low back pain (LBP) condition (c, d). Figures illustrate that balance was maintained from the adjustment of ES amplitude and onset latency for all perturbations type, in comparison with the relatively consistent behaviour of the EO for each perturbation type
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Fig6: Mean of the left and right EMG amplitude (a, b) and onset (c, d) of the erector spinae (ES) and external oblique (EO) for each perturbation type (PS posterior slide, AS anterior slide, PT posterior tilt, AT anterior tilt) for the mean of the baseline and control condition (a, b) and the acute low back pain (LBP) condition (c, d). Figures illustrate that balance was maintained from the adjustment of ES amplitude and onset latency for all perturbations type, in comparison with the relatively consistent behaviour of the EO for each perturbation type

Mentions: For the purpose of clarity and given the finding of no differences between the left and right EMG activity for the ES or EO, the left and right EMG activity data were pooled. Accounting for the main effect of condition on the activity of the EO and ES, namely a delay in onset time and/or a decrease in amplitude, further analyses revealed no differences between the amplitude (ANOVA, F = 0.8, P = 0.494) or onset time (ANOVA, F = 5.8, P = 0.275) of the EO between the four perturbation types. In contrast, each of the four perturbation types produced marked differences in the amplitude (ANOVA, F = 8.9, P = 0.0003) and/or onset time (ANOVA, F = 8.9, P = 0.0003) of the ES. These findings are summarized in Table 1 and the main effects of acute LBP on these predefined muscle activity patterns are expressed in Fig. 6a–d).Table 1


The relative timing of trunk muscle activation is retained in response to unanticipated postural-perturbations during acute low back pain.

Boudreau S, Farina D, Kongstad L, Buus D, Redder J, Sverrisdóttir E, Falla D - Exp Brain Res (2011)

Mean of the left and right EMG amplitude (a, b) and onset (c, d) of the erector spinae (ES) and external oblique (EO) for each perturbation type (PS posterior slide, AS anterior slide, PT posterior tilt, AT anterior tilt) for the mean of the baseline and control condition (a, b) and the acute low back pain (LBP) condition (c, d). Figures illustrate that balance was maintained from the adjustment of ES amplitude and onset latency for all perturbations type, in comparison with the relatively consistent behaviour of the EO for each perturbation type
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3066398&req=5

Fig6: Mean of the left and right EMG amplitude (a, b) and onset (c, d) of the erector spinae (ES) and external oblique (EO) for each perturbation type (PS posterior slide, AS anterior slide, PT posterior tilt, AT anterior tilt) for the mean of the baseline and control condition (a, b) and the acute low back pain (LBP) condition (c, d). Figures illustrate that balance was maintained from the adjustment of ES amplitude and onset latency for all perturbations type, in comparison with the relatively consistent behaviour of the EO for each perturbation type
Mentions: For the purpose of clarity and given the finding of no differences between the left and right EMG activity for the ES or EO, the left and right EMG activity data were pooled. Accounting for the main effect of condition on the activity of the EO and ES, namely a delay in onset time and/or a decrease in amplitude, further analyses revealed no differences between the amplitude (ANOVA, F = 0.8, P = 0.494) or onset time (ANOVA, F = 5.8, P = 0.275) of the EO between the four perturbation types. In contrast, each of the four perturbation types produced marked differences in the amplitude (ANOVA, F = 8.9, P = 0.0003) and/or onset time (ANOVA, F = 8.9, P = 0.0003) of the ES. These findings are summarized in Table 1 and the main effects of acute LBP on these predefined muscle activity patterns are expressed in Fig. 6a–d).Table 1

Bottom Line: In each condition, participants stood on a moveable platform during which 32 randomized postural perturbations (8 repetitions of 4 perturbation types: 8 cm anterior slides, 8 cm posterior slides, 10° anterior tilts, and 10° posterior tilts) with varying inter-perturbation time intervals were performed over a period of 4-5 min.During the acute LBP condition: (1) the onset time of the ES and EO was delayed for the forward and backward sliding perturbations (P < 0.05); (2) EMG amplitude was reduced bilaterally for all perturbations (P < 0.05); (3) the order of activation and interval between the onset times of the ES and EO were unaltered and (4) ES, but not EO, activity was adjusted to account for the directional differences between the perturbations.This study revealed that re-establishment of posture and balance was a result of the individuals' ability to rapidly modulate ES with respect to EO activity and that the bi-directional postural responses, although shifted in time and amplitude, retained temporal features in the presence of acute LBP.

View Article: PubMed Central - PubMed

Affiliation: Center for Sensory-Motor Interaction, Department of Health Science and Technology Faculty of Medicine, Aalborg University, Aalborg, Denmark.

ABSTRACT
The purpose of this study was to assess the activation of the erector spinae (ES) and external oblique (EO) in response to unanticipated, bi-directional postural perturbations before and after the induction of acute low back pain (LBP) in healthy individuals. An experimental session consisted of a baseline, control, and an acute LBP condition. For the control and acute LBP condition, isotonic or hypertonic saline (HS), respectively, was injected into the right ES muscle. In each condition, participants stood on a moveable platform during which 32 randomized postural perturbations (8 repetitions of 4 perturbation types: 8 cm anterior slides, 8 cm posterior slides, 10° anterior tilts, and 10° posterior tilts) with varying inter-perturbation time intervals were performed over a period of 4-5 min. Bilateral surface electromyography (EMG) was recorded from the ES and EO in addition to subjective pain records. During the acute LBP condition: (1) the onset time of the ES and EO was delayed for the forward and backward sliding perturbations (P < 0.05); (2) EMG amplitude was reduced bilaterally for all perturbations (P < 0.05); (3) the order of activation and interval between the onset times of the ES and EO were unaltered and (4) ES, but not EO, activity was adjusted to account for the directional differences between the perturbations. This study revealed that re-establishment of posture and balance was a result of the individuals' ability to rapidly modulate ES with respect to EO activity and that the bi-directional postural responses, although shifted in time and amplitude, retained temporal features in the presence of acute LBP.

Show MeSH
Related in: MedlinePlus