First Endurance Optygen HP - First Endurance Optygen HP, the next-generation of Optygen. This revolutionary formula is the result of human clinical trials and the latest scientific research on increasing endurance and performance. New features include Beta-Alanine as well the most potent Rhodiola available. The two main adaptogens in OPTYGENHP were first used by Tibetan Sherpas to help them climb Mt. Everest.