How long can we expect to remain active and how acive can we remain? How fast will our capacity diminish with age?

I just read a blog post that takes a shot at working out:

A lot of people (boomers?) seem to be convinced that if they lift one more weight or run one more mile, they will never get old. Even if you don’t succumb to cosmetic surgery or spend too much money on expensive anti-aging creams that don’t work, there comes a day, I think, when it’s too much effort any longer to keep up the pretense.

Fear of aging and death are obviously not the only reasons we lift weights or run, but I'm not deluding myself that this will go on forever -- how long can we remain active and how active can we remain? How fast will our capacity diminish with age?

There is no comprehensive answer to these questions, but there are hints and anecdotes. For example, we can estimate the optimistic upper limit by profiling outstanding people of various ages. We can also analyze speed records and other performance measures as Alan Jones and his colleagues have done for running. And, although it may not be politically correct, we can look at the affect of drugs and supplements like testosterone -- do they slow our losses? Are they safe?

I will look at each of these -- unusually fit people, data analysis and drugs and supplements -- in future posts.

One in eight people 65 and older exercise "vigorously" at least five days a week

According to a US Department of Health and Human Services report on the
Health Behaviors of Adults: United States, 2002–04 13.8% of people 65 and older exercise vigorously at least five days a week. A breakdown of the data shows that men are more likely to engage in frequent vigorous exercise than women and young people are more likely than old:

Age	Men	Women	Both
18-24	21.6	12	16.8
25-44	14.7	10.9	12.8
45–64	12.3	9.6	10.9
65-74	10.2	7.5	8.7
>=75	7.9	3.3	5.1

The authors of the 85-page report present other interesting data. For example, they found that the rate of vigorous exercise rises with income and education (which are correlated with age). They also observed differences based on race, region of the country, marital status and whether the respondent is from a metropolitan area, central city or smaller town.

The study defines a "vigorous" activity as one lasting at least 10 minutes and causing heavy sweating or large increases in breathing or heart rate.