Intervention Response of Muscle Architecture and Composition Markers Assessed via Ultrasound Imaging: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Objectives

To evaluate the response of skeletal muscle architecture (fascicle length and pennation angle) and composition (echo intensity) markers assessed by ultrasonography to intervention in older adults.

Design

This is a subsection of a more comprehensive systematic review of clinical trials focusing on changes in muscle quality, registered in PROSPERO (registration number: CRD42022357116).

Setting and Participants

Randomized controlled trials evaluating the effectiveness of interventions lasting ≥8 weeks in adults aged ≥60 years on fascicle length, pennation angle, and echo intensity.

Methods

After the literature search, 6 peer reviewers and 1 decider conducted a 2-stage screening process, including studies that met the eligibility criteria. Random-effects modeling for Hedges’ g was applied to a meta-analysis of studies with sufficient data. The risk of bias in the included studies was assessed using version 2 of the Cochrane Risk-of-Bias tool for randomized trials.

Results

In total, 4832 studies were initially searched, and 28 trials involving 1101 participants were included. Six trials were analyzed for fascicle length, 8 for pennation angle, and 8 for echo intensity. The standardized mean differences with 95% CIs, where a positive direction indicates improvement due to treatment, were fascicle length, −0.04 (−0.27 to 0.19); pennation angle, 0.08 (−0.02 to 0.18); and echo intensity, 0.00 (−0.02 to 0.02). No heterogeneity was observed for the outcomes (I² = 0%). The Cochrane Risk-of-Bias tool showed that 78.6% of the trials had a high risk of bias.

Conclusions and Implications

Muscle architecture and composition markers assessed via ultrasound did not respond to the intervention. Further well-designed clinical trials are necessary to confirm the clinical validity of these markers.