Testing Interventions for Mobility through Exercise (TIME): Study protocol for a randomized trial comparing a novel, brief home-based exercise program and a standard home-based group exercise for older adults with mobility disability.

One in four older adults report difficulty walking, greatly increasing the risk of future disability and death. Though exercise improves mobility, too few older adults do it. While studies show that brief exercise sessions provide most of the benefit of longer sessions and that older adults note that "time" is a critical barrier to being active, what remains unknown is whether briefer RT sessions can improve mobility as well as, or better than, longer traditional sessions, possibly due to greater adherence.