The influence of physical activity self-efficacy on the continuance use of AI learning tools among physical education students: a three-wave longitudinal study.

Acute hypoxic exposure is a substantial physiological challenge that can impair oxygen transport and reduce exercise capacity (). When hypoxia is combined with exhaustive exercise, this challenge may be further intensified, leading to metabolic disturbance, oxidative stress, inflammatory activation, and structural injury in multiple tissues, particularly skeletal and cardiac muscle (). These responses are closely linked to reduced exercise tolerance and fatigue development under hypoxic conditions (). Therefore, identifying safe and effective nutritional or bioactive interventions that improve tolerance to hypoxic exercise stress is of both physiological and practical relevance. Natural bioactive compounds have attracted increasing attention as potential nutritional strategies for stress adaptation and tissue protection (). Cycloastragenol, an active constituent derived from , has been reported to possess anti-inflammatory, antioxidative, and tissue-protective properties (). Existing evidence suggests that cycloastragenol may contribute to the regulation of redox homeostasis, attenuation of inflammatory responses, and protection against stress-related tissue injury (). However, its potential role as a bioactive nutritional candidate in hypoxia-related exhaustive exercise stress remains insufficiently understood. has long been used as a medicinal and food-related botanical material in traditional Chinese medicine (), where it is commonly associated with “Qi-tonifying,” stress adaptation, and fatigue-related conditions. Cycloastragenol is a tetracyclic triterpenoid sapogenin and an aglycone/metabolite related to astragaloside IV, one of the major saponins of (). Compared with whole Astragalus extracts (), cycloastragenol provides a chemically more defined intervention, which is advantageous for mechanistic interpretation and reproducibility. Therefore, cycloastragenol was selected in the present study as a representative Astragalus-derived bioactive constituent for evaluating protection against acute hypoxic exercise stress.