Methods A 2-center, randomized, single-blind, controlled trial was conducted in which participants were assigned to an aerobic exercise program, a resistance exercise program, or an attention control group. Of the 439 community-dwelling persons aged 60 years or older with knee osteoarthritis originally recruited, the 250 participants initially free of ADL disability were used for this study. Incident ADL disability, defined as developing difficulty in transferring from a bed to a chair, eating, dressing, using the toilet, or bathing, was assessed quarterly during 18 months of follow-up.