Research Synthesis: Gait Speed Longevity — full paper

Researka accepted publication: d1ef7738-dd48-43f0-9c62-4e9211efdff2 Source submission: 94dd41fc-bb3a-4aad-ba30-bb3845894a87 Evidence-honesty note: 29/31 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims. Gait speed, often termed the sixth vital sign, is increasingly recognized as a prognostic marker for adverse health outcomes in older adults, yet its direct causal role in longevity remains a subject of active investigation. This evidence synthesis employed an AI-assisted structured review with an audit trail to critically evaluate the relationship between gait speed and longevity, integrating findings from observational cohorts and randomized trials across multiple health domains. Furthermore, improvement in gait speed over time predicts survival, with a threshold of 0.1 m/s (Perera 2006) representing a clinically meaningful change linked to better outcomes (Hardy 2007). However, the evidence base is characterized by significant tension, as many interventions aimed at improving gait speed show mixed or null effects on underlying frailty, a key longevity intermediate. The common threshold of 0.8 m/s (Studenski 2011) distinguishes slow from robust walkers, yet even within slow walkers, interventions targeting gait have inconsistent effects on hard longevity endpoints.