Leonidas earned a dual PhD degree in environmental (integrative) physiology from the University of Thessaly and the University of Copenhagen. He has participated in several international funded projects where he had the opportunity to conduct research across many countries around the globe, leading to the development of national and international legislations. He has also collaborated with armed forces in Europe, as well as other reputable organizations, including the World Health Organization and the International Labour Organization, on projects aiming to enhance human health and wellbeing.