{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T11:33:02Z","timestamp":1780399982746,"version":"3.54.1"},"reference-count":47,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,10,14]],"date-time":"2025-10-14T00:00:00Z","timestamp":1760400000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Nutr."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Exercise-induced muscle fatigue is a major challenge for athletes. Our previous study indicated that <jats:italic>Levilactobacillus brevis<\/jats:italic> GKEX improved endurance and reduced fatigue in mice. This study aimed to further evaluate the effects of different preparations of <jats:italic>L. brevis<\/jats:italic> GKEX on exercise performance and fatigue resistance.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Eight-week-old male ICR mice were divided into six groups (<jats:italic>n<\/jats:italic> = 8): vehicle, BCAA, low-dose GKEX (0.0615 mg\/day), high-dose GKEX (0.615 mg\/day), heat-killed GKEX (0.615 mg\/day), and freeze-killed GKEX (0.615 mg\/day). Treatments lasted for four consecutive weeks. Exercise performance, fatigue-related biochemical markers, and gut microbiota composition were assessed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Compared with BCAA, <jats:italic>L. brevis<\/jats:italic> GKEX significantly improved aerobic performance, including forelimb grip strength and running-exhaustion time. It enhanced lactate clearance and glycogen storage in the liver and muscles while reducing lactate production and blood urea nitrogen levels after exercise. <jats:italic>L. brevis<\/jats:italic> GKEX supplementation also increased key short-chain fatty-acid\u2013producing bacteria in the intestines.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Oral administration of different doses of live and dead <jats:italic>L. brevis<\/jats:italic> GKEX promoted exercise performance and ameliorated fatigue, especially live GKEX. These findings suggest that <jats:italic>L. brevis<\/jats:italic> GKEX may serve as an ergogenic aid for athletes and support broader applications across various product forms.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fnut.2025.1625645","type":"journal-article","created":{"date-parts":[[2025,10,14]],"date-time":"2025-10-14T04:15:27Z","timestamp":1760415327000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":3,"title":["Effects of Levilactobacillus brevis GKEX supplementation on exercise performance and fatigue resistance in 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