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 (I = 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.