A dose response analysis of exercise prescription variables for lateral abdominal muscle thickness and activation: A systematic review.

BACKGROUND: Various exercise programs are used to treat lateral abdominal muscle (LAM) impairments in people with low back pain. Factors comprising these programs include exercise type, session time, frequency, and program duration. However, specific clinical guidance about optimal exercise prescription is lacking. OBJECTIVES: To perform a dose-response analysis on exercise prescription variables for LAM thickness and activation as measured by ultrasound imaging. DESIGN: Systematic review METHOD: Databases were searched from their inception for studies examining the association between exercise interventions and LAM thickness/activation measured by ultrasound imaging in healthy individuals. Risk of bias was assessed using the Joanna Brigg's Institute critical appraisal tools. For each muscle, subgroup analyses were performed to determine the dose response of exercise prescription variables for LAM thickness and activation. Where there was insufficient data for subgroup analyses, data was narratively synthesised. RESULTS: Fourteen studies comprising 395 participants were included. Statistical and narrative synthesis revealed specific local abdominal exercises, programs from four weeks duration, three sessions per week and sessions of ≥30 min were associated with greatest improvements to LAM thickness. Only the variables exercise type, program duration and session frequency showed a significant between groups difference for the subgroup analysis. The main limitation was inability to perform subgroup analyses for all variables across all muscles measured at rest and during contraction, due to non-reporting of data. CONCLUSION: This review provides preliminary guidance to practitioners on how the LAM respond to different exercise dosages. Future research should trial these findings.

The reliability of rehabilitative ultrasound to measure lateral abdominal muscle thickness: A systematic review and meta-analysis.

BACKGROUND: Variations in rehabilitative ultrasound imaging (RUSI) protocols may alter lateral abdominal muscle (LAM) thickness measurements. A standardised protocol is required for clinicians to accurately compare LAM thickness changes. OBJECTIVE: In healthy and lower back pain (LBP) populations, to assess the 1) overall reliability of RUSI to diagnose LAM thickness via meta-analysis, 2) reliability of ultrasound variables to diagnose LAM thickness via systematic review, and 3) propose a RUSI protocol for the LAM using variables associated with excellent reliability (intraclass correlation coefficient [ICC] >0.9). DESIGN: Systematic review and meta-analysis. METHOD: Databases were searched from January 2000 for studies reporting the reliability of RUSI on the LAM at rest. Title, abstract and full-text screening were performed. Reference lists of reviews and included full-text articles were scanned for further articles. Study characteristic, ultrasound procedure and reliability data were extracted, and article quality assessed. Data was synthesised using meta-analysis to determine the overall reliability for RUSI in different subgroups; calculation of the mean ICCs and standard error of measurements of protocol variables; and narrative synthesis of protocols to contrast those of differing reliability. RESULTS: Twenty-seven articles, involving 884 participants were included. Reliability ranged from good-to-excellent (ICC 0.859-0.958) in all subgroups. Protocols ranged in subject selection and position, examiner experience, transducer position with the comprehensiveness of protocol description the main limitation of the reviewed literature. Based on the findings an ultrasound protocol was proposed. CONCLUSIONS: RUSI variables for the LAM at rest show moderate-to-excellent reliability; future research should explore reliability following the proposed protocol.