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 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.