Nutraceutical Periodization for eXercise (NPX): Matching Bioactives to Training Load, Recovery Demand, and Adaptation Windows

Nutraceuticals are evaluated as though efficacy were a stable ingredient property, although net value may vary with exercise stimulus, exposure schedule, recovery pressure, athlete state, and prioritized outcome. This structured narrative review integrates exercise-adaptation biology, pe-riodized sports nutrition, training-load and recovery models, precision nutrition, and human evi-dence for sport-relevant interventions. Searches of PubMed/MEDLINE, Web of Science, and Scopus were updated through August 2026 and supplemented by citation tracking. General efficacy was separated from direct evidence of timing, context, or state modification. Nutraceutical Periodiza-tion for eXercise (NPX) is an allocation layer applied only after safety, legality, product quality, and plausible efficacy are established. It defines four non-sequential functional win-dows—performance exploitation, adaptation-permissive signaling, restoration, and resili-ence—and separates intervention strategy, training context, athlete state, and outcome hierarchy. Four falsifiable propositions test context modification, temporal allocation, bottleneck/state de-pendence, and whole-policy utility. Despite limited direct evidence for most allocation rules, NPX converts compound-specific efficacy into prospectively testable decisions. Targeted allocation may improve athlete-centered outcomes or preserve them with fewer exposures, lower burden, or less harm than standardized evidence-based use. Prospective interaction and policy trials are needed to establish the value and boundaries of these rules.