This review examined demographic and clinical characteristics of participants from exercise trials in 3 neurologic disability conditions (multiple sclerosis, spinal cord injury, and traumatic brain injury) and compared these data with population-based statistics. The authors included 75 published studies from 2006 to 2016: 53 studies for multiple sclerosis (n = 2,034), 14 for spinal cord injury (n = 302), and 8 for traumatic brain injury (n = 272). Pooled data resembled some heterogeneous aspects of population data sets. However, many characteristics were not reported; samples were small and predominantly White, and 48.1% of the people screened were excluded. Thus, findings from these studies may not be translatable across the range of people with these three conditions, which warrant efforts to target the inclusion of underrepresented subgroups in future exercise trials.