As cited in any biology book, humans require oxygen for functioning properly. Using non-experimental-based results, and plain logic, an air with higher concentration of O2 gives any human a better performance. When mountain climbers climb mountains, they slowly require more oxygen. If they don't get it, their capabilities go down. If any person living in a high city goes to the sea, he/she could run faster, higher or anything similar because a slight rise of the quantity of oxygen. This only tells me that pure oxygen could have a 'boost' on animals, incluiding humans. But this link here jumps objecting. http://www.medicalnewstoday.com/releases/72299.php So I wanted to ask a scientific community about it. Whaddya think, or know? And yes, I'm aware that, in a scenario that there is not a single problem, I'd have a hard time getting back into an average 21% ox'd air.