Multimechanistic actions of functional factors in enhancing physical strength and endurance: a scoping review of nutritional basis and natural extracts.

This article provides a scoping review of various types of functional factors and their mechanisms of action in enhancing physical strength and endurance, focusing on their roles in regulating the central nervous system, improving energy metabolism, reducing metabolite accumulation, enhancing antioxidant and anti-inflammatory capacity, regulating the endocrine system, and improving blood circulation. For functional factors supported by sufficient human evidence, stratified application can be made according to their primary effects. Those applicable to strength-type sports include creatine, HMB, vitamin D, L-arginine, L-citrulline, L-carnitine, curcumin, epicatechin, and golden root extract. Those applicable to endurance-type sports include beta-alanine, taurine, iron, caffeine, eleutheroside, anthocyanins, powdered Montmorency tart cherry, and beetroot concentrate. Those applicable to mixed-discipline sports include BCAAs, glutamine, whey protein, coenzyme Q10, and magnesium. Mechanisms that specifically enhance physical strength include increased blood flow delivery via the NO-sGC-cGMP pathway, attenuation of central nervous system fatigue through LAT1-mediated tryptophan competition, and maintenance of calcium homeostasis via the SERCA-RyR1-VDAC1-MCU axis. Endurance-specific enhancement is achieved primarily by promoting type IIa muscle fiber formation through the AMPK/SIRT1/PGC1-α and PKA-CREB-ERRγ signaling axes. Functional factors that simultaneously improve both outcomes act through reducing oxidative stress via the Nrf2-Keap1-ARE network, regulating energy metabolism via the PI3K/Akt/mTOR and AMPK pathways, suppressing NF-κB-mediated inflammation, and optimizing the gut-liver-muscle axis. In addition, this article points out research challenges such as individual differences and experimental design limitations and suggests that the long-term safety of personalized sports nutrition strategies and functional factors needs to be further explored in the future. The review provides a scientific theoretical basis for sports training and health management, as well as an important reference for the development of novel sports nutrition programs.