The mobility aids being studied are all standard types of mobility aids used by people with limited mobility (e.g., wheeled walker, manual wheelchair, power wheelchair/scooter). Analyses will proceed in a stepwise fashion. The first step will be to examine the primary study question relating device type to the dependent variable, with velocity being the primary outcome. The next step in the analysis will be to determine if there is an interaction between medical condition, mobility devices, and the dependent variable. Finally, exploratory analyses will be carried out to examine the relationship between baseline measures of physical function and mobility performance with each of the devices. Study related risks are minimal.