Trunk Muscle Activation During Abdominal Hollowing In CLBP
Trunk Muscle Activation During Abdominal Hollowing In CLBP
Using magnitude based inferences, for the left IO:RA ratio the control group would be at least 75% more likely to have a substantially greater ratio in the supine (cervical neutral position), ATNR left and right, cervical rotation to the right and cervical extension positions (d = -0.54, -0.52, -0.77, -0.51 and -0.54 respectively; all "moderate") than the CLBP group. Similarly on the contralateral side it was at least 75% more likely that the control group would have a greater right IO:RA ratio than the CLBP group in the supine (cervical neutral) and ATNR left positions (d = -0.58 and -0.91, respectively "moderate" and "large"). A greater IO:RA ratio represents relatively less RA EMG activity (Figure 2).
(Enlarge Image)
Figure 2.
Figures plot standardized effect size differences between control and chronic lower back pain groups when comparing a) left internal obliques to left external obliques, b) right internal obliques to right external obliques, c) left internal obliques to left rectus abdominus, and d) right internal obliques to right rectus abdominus. Each graph represents a muscle group with plots representing the magnitude of difference between ratios between muscle groups between the two groups in the different postures. Positive values indicate the chronic lower back pain group had higher normalized values. Error bars indicate 95% confidence limits of the mean difference between groups. The shaded area of the graph indicates the region in which the difference between groups is trivial (i.e. between -0.20 and 0.20 standardized effect sizes). Asterisks (*) indicate conditions with >75% likelihood that the difference exceeds the smallest worthwhile difference.
Analysis of confidence limits and effect sizes illustrated <75% likelihood of a clinical difference between the two groups in any position for the IO or EO sites (Figure 3). There were however, likely clinical differences between groups for the RA. For the left RA it was likely that the CLBP group would have greater activation than the control in the supine (cervical neutral) (d = 0.97, "large"), ATNR left (d = 0.80, "large") and right (d = 0.97, "large"), cervical rotation to the right (d = 0.70, "moderate") and flexion (d = 0.77, "moderate") positions (Figure 3). For the right RA it was likely that the CLBP group would have greater activation than the control in the supine (cervical neutral) (d = 0.87, "large") and cervical flexion position (d = 0.59, "moderate") (Figure 3).
(Enlarge Image)
Figure 3.
Graphs plot standardized effect size differences between control and chronic lower back pain groups for a) left internal obliques, b) right internal obliques, c) left rectus abdominus, d) right rectus abdominus, e) left external obliques, f) right external obliques. Each graph represents a muscle group with plots representing the magnitude of difference between the two groups in the different postures. Positive values indicate the chronic lower back pain group had higher normalized values. Error bars indicate 95% confidence limits of the mean difference between groups. The shaded area of the graph indicates the region in which the difference between groups is trivial (i.e. between -0.20 and 0.20 standardized effect sizes). Asterisks (*) indicate conditions with >75% likelihood that the difference exceeds the smallest worthwhile difference.
Statistical significance can be inferred from the 95% confidence limits. If 95% confidence limits cross the zero, the mean must have a p > 0.05, because the lower limit is less than zero while the upper limit is greater than zero. If, however, the 95% confidence limits in the figures are both on the same side of the zero, the mean has a p < 0.05 (Figures 2 and 3).
Results
Between Group Differences for IO:RA Ratio
Using magnitude based inferences, for the left IO:RA ratio the control group would be at least 75% more likely to have a substantially greater ratio in the supine (cervical neutral position), ATNR left and right, cervical rotation to the right and cervical extension positions (d = -0.54, -0.52, -0.77, -0.51 and -0.54 respectively; all "moderate") than the CLBP group. Similarly on the contralateral side it was at least 75% more likely that the control group would have a greater right IO:RA ratio than the CLBP group in the supine (cervical neutral) and ATNR left positions (d = -0.58 and -0.91, respectively "moderate" and "large"). A greater IO:RA ratio represents relatively less RA EMG activity (Figure 2).
(Enlarge Image)
Figure 2.
Figures plot standardized effect size differences between control and chronic lower back pain groups when comparing a) left internal obliques to left external obliques, b) right internal obliques to right external obliques, c) left internal obliques to left rectus abdominus, and d) right internal obliques to right rectus abdominus. Each graph represents a muscle group with plots representing the magnitude of difference between ratios between muscle groups between the two groups in the different postures. Positive values indicate the chronic lower back pain group had higher normalized values. Error bars indicate 95% confidence limits of the mean difference between groups. The shaded area of the graph indicates the region in which the difference between groups is trivial (i.e. between -0.20 and 0.20 standardized effect sizes). Asterisks (*) indicate conditions with >75% likelihood that the difference exceeds the smallest worthwhile difference.
Between Group Differences for Normalized Site Specific Activation Levels
Analysis of confidence limits and effect sizes illustrated <75% likelihood of a clinical difference between the two groups in any position for the IO or EO sites (Figure 3). There were however, likely clinical differences between groups for the RA. For the left RA it was likely that the CLBP group would have greater activation than the control in the supine (cervical neutral) (d = 0.97, "large"), ATNR left (d = 0.80, "large") and right (d = 0.97, "large"), cervical rotation to the right (d = 0.70, "moderate") and flexion (d = 0.77, "moderate") positions (Figure 3). For the right RA it was likely that the CLBP group would have greater activation than the control in the supine (cervical neutral) (d = 0.87, "large") and cervical flexion position (d = 0.59, "moderate") (Figure 3).
(Enlarge Image)
Figure 3.
Graphs plot standardized effect size differences between control and chronic lower back pain groups for a) left internal obliques, b) right internal obliques, c) left rectus abdominus, d) right rectus abdominus, e) left external obliques, f) right external obliques. Each graph represents a muscle group with plots representing the magnitude of difference between the two groups in the different postures. Positive values indicate the chronic lower back pain group had higher normalized values. Error bars indicate 95% confidence limits of the mean difference between groups. The shaded area of the graph indicates the region in which the difference between groups is trivial (i.e. between -0.20 and 0.20 standardized effect sizes). Asterisks (*) indicate conditions with >75% likelihood that the difference exceeds the smallest worthwhile difference.
Statistical significance can be inferred from the 95% confidence limits. If 95% confidence limits cross the zero, the mean must have a p > 0.05, because the lower limit is less than zero while the upper limit is greater than zero. If, however, the 95% confidence limits in the figures are both on the same side of the zero, the mean has a p < 0.05 (Figures 2 and 3).
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