1st Endurance Optygen 90 caps is a stimulant-free adaptogen formula for athletes in endurance sports, such as marathons and triathlons. The formula was created with the help of clinical trials and advanced scientific research to make the best endurance-enhancing formula ever. It features two main adaptogens, which Tibetan Sherpas have used to help them climb Mount Everest. Research into these adaptogens has shown that they enhance oxygen utilization, which allows the body to adapt to higher levels of physical stress. These adaptogens also boost the anaerobic threshold and reduce lactic acid production.