Hey Dmitri, good for you! Like you, I'm 50+ and pay attention to VO2 max. It is OK to compare us to younger age groups. I do shorter triathlons (not Ironman) and I frequently finish ahead of other athletes who are 20 years younger than me. I don't care about bragging rights, but the VO2 max measure of fitness, relative to age, makes sense in my experience. Stay healthy and safe!