The amino acids arginine and ornithine have been shown to support healthy growth hormone production. Growth hormone is naturally released by the pituitary gland in response to sleep and exercise in order to help replenish tissues. It supports muscle protein synthesis, moderates the breakdown of muscle tissue and promotes fat utilization for energy. Arginine supports healthy growth hormone synthesis and is also utilized for protein synthesis. Ornithine alpha-ketoglutarate (OKG) has shown the potential to support healthy nitrogen balance, which is important for healthy muscle function. OKG also promotes healthy polyamine, arginine and glutamine levels, important metabolites involved in muscle health. One study suggested the potential for arginine and ornithine in combination to support healthy hormonal profiles in athletes. One small study involving 22 males suggested a possible role of arginine and ornithine in supporting lean muscle mass and strength when combined with a 5-week high-intensity strength training program. Taken one hour before physical activity or bedtime, arginine and OKG may support healthy growth hormone production.