Series review and commentary on sports nutrition (part 2): α-ketoglutarate

α-ketoglutarate （AKG），an intermediate of the tricarboxylic acid （TCA） cycle， serves as a key substrate for energy production from carbohydrate， lipid， and amino acid metabolites via the TCA cycle. It functions as a myokine secreted by skeletal muscle in response to exercise， regulating physiological processes including energy metabolism， hypoxia adaptation， inflammatory responses， and antioxidant functions. Current randomized controlled trials （RCT） indicate that supplementation with L-arginine alpha-ketoglutarate （AAKG）， an amino acid salt derivative of AKG， enhances upper-body muscle strength， power， and anaerobic work capacity in athletic populations. However， due to limited study numbers， small sample sizes， and relatively low evidence quality， the validity of these findings remains constrained. Regulatory frameworks currently classify AKG as nutritional ingredients only in the European Union. To support the potential inclusion of AKG or AAKG as nutritional ingredients in China， high-quality， single-factor controlled RCT remain imperative.