It seemed like a pretty good hypothesis (and still might be) - giving testosterone to frail elderly men with limitations in mobility could help them regain a little of what they had in youth, namely stronger bones and muscles.
However, a study to look at this question in 209 men age 65 and older was halted when 23 men in the group receiving testosterone gel experienced serious cardiac problems (one died from a heart attack). Only five men receiving the placebo gel with no testosterone in it had cardiac problems.
In addition, the men receiving testosterone had more respiratory and skin problems during the study. However, the testosterone group "had significantly greater improvements in leg-press and chest-press strength and in stair climbing while carrying a load."
I don't think this means that testosterone therapy is inherently dangerous to all older men. Instead, it seems like some screening procedures could identify people for whom this therapy would be appropriate, once the link between testosterone therapy and cardiac problems is made.
