Quantitative Assessment of the Use of Ultrasound Feedback during Abdominal Drawing-in Maneuver
Date Issued
2008
Date
2008
Author(s)
Jhu, Jhong-Lin
Abstract
Background: Visual feedback has been reported to enhance the contraction of the deep muscles, such as the transversus abdominis (TrA), the multifidus, and the pelvic floor muscles. While exploring the effect of using ultrasound images as feedback for deep muscle training, most of the studies used visual determination to detect whether the performance of the abdominal muscles is improved or not. Lack of quantitative and reliable measurements were known to assess the performance of the deep abdominal muscles.urposes: The purposes of this study were 1) to establish a quantitative and reliable measurement of ultrasound parameters, and 2) to examine the performance of abdominal muscle contraction using ultrasound feedback for both asymptomatic adults and subjects with recurrent low back pain at the pre-training, initial phase of training, final phase of training, post-training, and four days of retention. ethods: In the first part of the study, the intra-image intra-rater and between-day intra-rater reliability designs were employed to explore the variability of measurement between measurements and between days. Eighteen participants in this study were university age students. The mean (±SD) age of the subjects was 22.6±2.5 years. The real-time ultrasound imaging was viewed in this study in B mode with a 12 to 5 MHz linear-array transducer. We measured thickness both at rest (Thr) and during maximal contraction (Thm) of the transversus abdominis (TrA) and obliquus internuus (OI) as well as lateral movement of the anterior abdominal fascia of TrA (△x) both at rest and during maximal contraction. Reliabilities were calculated using intra-class correlation coefficient (ICC), and within-subject coefficient of variance (CVw) to explore the variability of measurement. For the second part of the study, 15 subjects with recurrent low back pain (LBP), aged ranged from 20 to 35 years old, and 15 of age-matched subjects without LBP participated. The ultrasound images of each trial of training (20 trials) and testing (three trials at the pre-training, initial phase of training, final phase of training, post-training, and retention) were recorded. The outcome measures were the same as those in the first part of the study. Changes of variables in the two groups (subjects with and without recurrent LBP) during pre-training, post-training and retention were assessed using analyses of variance (ANOVA) with repeated measures. esults: In the study about intra-image intra-rater reliability, the ICC values of Thr and Thm of TrA and OI were all above 0.75, indicating excellent reliability. The CVw of all ultrasound parameters were less than 10%, indicating small variability within subjects. Similar results were found for between-day intra-rater reliability except that the CVw value of Δx on right side was above 10%. For patients with recurrent low back pain, improvement of △x, normalized thickness of TrA, and the preferential activation ratio was noted from pre-training to the initial phase of training (p =0.001, 0.009, 0.003 respectively) and such effect could be lasted for four days. However, no significant changes in training performance were found for asymptomatic subjects.onclusions: In the first part of this study, after controlling the possible errors during measurement, by clear instruction of the task, monitor preciseness of the movement, and using an internal marker to adjust the movement of the ultrasound transducer during contraction, measurement of thickness of OI and TrA and Δx were reliable both at rest and during maximum contraction. For the second part of this study, using real-time ultrasound feedback to teach abdominal muscle contraction and quantitatively measuring the outcome of ultrasound parameters, patients with recurrent low back pain demonstrated better abdominal muscle control after several practices, and such control could be maintained at the same level of performance up to 4 days. Optimal mode of ultrasound feedback remained to be determined for patients with recurrent low back pain.
Subjects
Transversus abdominis
Specific stabilization exercise
Ultrasound feedback
Low back pain
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