Speeding-up by Slowing-Down1 July 2011
Middle-aged and elderly people exercising during(Underscores mine.) So the caption is claiming that the population is aging quickly and may age even more quickly if aging is slowed.Respect for the Aged Dayin Tokyo in 2005. Japan's population is aging particularly quickly. The ratio of people younger than 20 compared to those older than 65 is shifting, from 9.3 in 1950 to a predicted 0.59 in 2025. If scientists succeed at slowing aging, this trend may well accelerate.
Now, what's really happening in that caption is that the verb
age is being used in two related but very different senses. In
aging particularly quickly, the sense is one of increase in average chronological age; in
slowing aging, the sense is one of become decrepit. The underlying thought is entirely reasonable; the expression is inept, because it moves from one meaning to the other (and then implicitly back to the first) without signally that it is doing so except in the sense that the passage is otherwise absurd; best not to make the reader sort-out such things.
I don't know who wrote that caption. The author of the piece in which it is embedded actually notes
the word aging refers to different thingsexactly to explain how confusions of these meanings results in practice in logically invalid arguments.