The classification of lower-limb disabilities is commonly based on the site of the spinal cord lesion or the amount of functional muscle. Another important variable in assessing wheelchair users is their ability to carry out the activities of daily living. The cardiorespiratory fitness of those with lower-limb disabilities is usually assessed with arm-ergometry and wheelchair tests, each of which has some advantages. Muscle strength and endurance are also important aspects of the disabled person's ability to function. Fitness is often poor in the disabled, and normal wheelchair use does not seem to prove an adequate training stimulus. Exercise with an arm ergometer and with pulleys and participation in vigorous wheelchair sports can improve physical condition. Participation in exercise programs should be based on the results of a fitness assessment and on the level of the spinal cord lesion in those with paraplegia. Progression in such programs should be gradual to ensure that the exerciser does not become discouraged and drop out of classes before fitness is increased. Data on wheelchair athletes suggest that, with persistence, many individuals in wheelchairs can adjust relatively well to their disabilities.