Could this be used to increase athletic performance? Also, I'm wondering if there would be any negative effects from radically increasing the amount of oxygen

Could this be used to increase athletic performance? Also, I'm wondering if there would be any negative effects from radically increasing the amount of oxygen your blood can hold. On the other hand, it would be like a superpower. I can imagine competitive free-divers using this or a future version of this to do some really impressive diving!