Over 260,000 Americans are living with a traumatic spinal cord injury (SCI). Medical advances have increased the longevity of individuals living with SCI into middle age and beyond. The majority of these individuals are living with an incomplete SCI (NSCISC, 2012), and the proportion of incomplete injuries is rising (DeVivo, 2012). There is little research that specifically examines the changes in physical function experienced by individuals aging with a traumatic incomplete SCI. The purpose of this qualitative descriptive study was to describe the changes in physical function experienced by participants with a traumatic incomplete SCI aging through middle age. Data were collected through moderately structured individual interviews (N=17), in either a face-to-face (n=6) or an email (n=11) format. The seventeen participants ranged in age from 35 to 65 years, with a 16 to 36 year duration of injury. Participants described changes in various body systems and recalled the timing of those changes as they transitioned through their middle years. Qualitative content analysis revealed that participants described primarily gradual changes including decreased muscle strength, decreased endurance, weight gain, and wear and tear changes. When asked to identify sources of information about physical changes, participants predominantly emphasized their lack of knowledge about anticipated changes. Further content analysis revealed three themes related to this transition. Participants likened their experience to travelling through uncharted territory. They described strategies for living in uncharted territory that help them to prevent or manage changes in physical function, with sub-themes of being vigilant in their self-assessment and self-management practices, investing time in figuring out what changes they experienced and why those changes happened, and staying positive. They also described the importance of recognizing the impact of changes. These findings provide a foundation for understanding this age-related transition, and identify the need for further research to support effective self-management strategies and efficient mechanisms for disseminating this knowledge to people with SCI, their caregivers and families. In acute and chronic patient care settings, nurses are well-positioned to be a valuable support and information source for individuals living with an incomplete SCI.