Study correlating physical ability at 60 compared to 80?

Sorry, took longer to edit than allowed. Let me explain further. (Graphs taken from Attia.)

The second graph (above) shows how VO2 declines with age for people of high (95% for age), average (50% for age) and low (5% for age) levels of fitness, as well as the VO2 needed to do various strenuous activities. Taken from Attia, the data is from a 2020 book by Ligouri from the ACSM.

The first table shows VO2 ranges (and METabolic eqivalentS which are multiples of 1=“at rest”) for men and women by age range and fitness of low (bottom 25%), below average (26-50%), above average (51-75%), high (75-97.6%) and elite (top 2.3%). The data is taken from the JAMA study below. Essentially, an eighty year old man in the top 2.3% of fitness has the same VO2 max as an unfit nineteen year old woman (in the bottom 25%). Basically, comparing a 60 year old man of fitness X% for age sixty, an eighty year old man would be roughly the same as fitness (X-25)% for age sixty (and X>25).

To reduce the drop in VO2 max which occurs with age, you want to do strenuous activities, particularly ones lasting longer than a minute. VO2 testing often uses activities from 3-8 minutes at a high (but not maximum) level of intensity, say a “perceived exertion” of 8/10 or so.