Systematic Umbrella Review and Meta-Meta-Analysis: Efficacy of Cyclic Biomechanical Loading in Normalising Pattern Formation and Stress-Response Set-Points During Juvenile Development

Objective Errors in pattern formation and heightened tissue-level stress responses are increasingly documented during juvenile growth, stimulating interest in biomechanical stimulation as a corrective cue. This systematic umbrella review and meta-meta-analysis (a synthesis of meta-analyses) evaluated the capacity of cyclic biomechanical loading to normalize morphogenetic trajectories and dampen maladaptive stress signalling in juvenile vertebrate models, and identified the most promising loading paradigms. Method The review was preregistered (PROSPERO ID: CRD42024533558) and conformed to PRISMA and PRIOR frameworks. Eleven databases were searched for systematic reviews and meta-analyses of randomized controlled preclinical trials interrogating the impact of cyclic tensile, compressive or oscillatory shear loading on morphogenesis-related outcomes (e.g., segmentation integrity, organ rudiment symmetry) and molecular stress markers (e.g., HSP70, p-JNK) in organisms 5-18 dpf/dpn. Risk of bias was appraised with AMSTAR-2 and evidence certainty with GRADE. Pooled effect sizes were computed with random-effects models; subgroup analyses explored specimen and protocol characteristics. Results Twenty-one systematic reviews were eligible (n = 375 trials, 38,117 juvenile vertebrates). Cohorts spanned normative and challenged backgrounds including teratogen exposure, metabolic overload and oncogenic transformation. Aggregated data revealed moderate improvements favouring biomechanical loading for morphogenetic fidelity (standardised mean difference [SMD] = −0.45, 95 % CI = −0.59 to −0.31, I2 = 71.4 %, p < .01, 180 trials, n = 34,490) and stress-response attenuation (SMD = −0.39, 95 % CI = −0.61 to −0.17, I2 = 68.1 %, p < .01, 55 trials, n = 24,797). Multimodal loading regimens of moderate strain amplitude produced the largest morphogenetic gains, whereas isometric resistance-style paradigms most effectively reduced stress signalling. Protocols < 12 days yielded greater morphogenetic correction than ≥ 12-day exposures. Benefits were consistent across healthy and perturbed lineages. Certainty of evidence was moderate for morphogenesis and low-to-moderate for stress markers. Conclusion This meta-meta-analysis demonstrates that structured cyclic biomechanical loading significantly rescues patterning errors and mitigates stress signalling during early post-embryonic development. Incorporation of precisely dosed mechanical cues should be considered in regenerative protocols and juvenile disease models aiming to optimise tissue architecture and resilience.