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Table 3 ICC, SEM and MDC, CV values for within-day and between-days reliability of the ultrasound measurements at different testing positions

From: Reliability of ultrasound measurement of automatic activity of the abdominal muscle in participants with and without chronic low back pain

Position Muscle Without LBP With LBP
Within-day Between-days Within-day
(Between-trial) (Between-trial)
ICC SEM MDC CV% ICC SEM MDC CV% ICC SEM MDC CV%
P 1 TrA 0.92 0.19 0.52 5.4 0.90 0.21 0.58 5.8 0.91 0.25 0.69 6.9
IO 0.92 0.20 0.55 2.1 0.92 0.20 0.55 2.1 0.92 0.26 0.71 3
EO 0.90 0.23 0.63 3.9 0.88 0.26 0.71 4.5 0.89 0.34 0.93 5.7
RA 0.88 0.28 0.77 2.1 0.85 0.31 0.85 2.4 0.93 0.25 0.69 1.7
P 2 TrA 0.95 0.30 0.82 7.6 0.92 0.38 1.05 9.7 0.94 0.37 1.02 10.2
IO 0.93 0.40 1.10 4.5 0.93 0.40 1.10 4.2 0.93 0.39 1.07 4.8
EO 0.94 0.38 1.05 6.1 0.91 0.47 1.29 9 0.94 0.53 1.46 8.1
RA 0.93 0.52 1.43 3.9 0.93 0.52 1.43 3.9 0.94 0.56 1.54 3.6
P 3 TrA 0.90 0.34 0.93 7.7 0.86 0.40 1.10 9 0.90 0.39 1.07 10
IO 0.92 0.31 0.85 3.1 0.90 0.34 0.93 3.4 0.93 0.49 1.35 5.3
EO 0.92 0.29 0.80 4.6 0.89 0.33 0.91 5.3 0.92 0.56 1.54 8.3
RA 0.93 0.22 0.60 1.6 0.87 0.31 0.85 2.2 0.93 0.65 1.79 4
P 4 TrA 0.94 0.40 1.10 6.3 0.89 0.54 1.49 8.3 0.93 0.78 2.15 17.3
IO 0.94 0.41 1.13 3.2 0.94 0.41 1.13 3.2 0.92 1.27 3.50 12
EO 0.92 0.52 1.43 7 0.93 0.48 1.32 6.4 0.92 1.23 3.39 15
RA 0.94 0.55 1.51 3.3 0.90 0.71 1.96 4.3 0.94 0.93 2.57 5.3
  1. SD Standard deviation, ICC Intra-class correlation coefficient, SEM Standard error of measurement, MDC Minimal detectable change, CV Coefficient of variation, LBP Low back pain, TrA Transversus abdominis, IO Internal oblique, EO External oblique, RA Rectus abdominis, P 1 Supine lying, P 2 Sitting on chair with both feet on the ground, P 3 Sitting on gym ball with both feet on the ground, P 4 Sitting on gym ball lifting the left foot off the floor. All SEM and MDC values are in millimeter.