An athlete's absolute maximal oxygen consumption remained similar after gaining weight, while VO2 max decreased due to the weight gain.

“i think the other thing that was very compelling was he was tested again several months later um he'd put on two and a half kilos so his number came down into the 80s but his absolute level of maximal oxygen consumption had barely come down he went from something like 7.2 liters to 7.1 liters but the number came down from you know call it whatever it was 96 and change to 89 and change which was accounted for by the gain and weight which again is effectively like repeating the test and getting the same result”