BackgroundOlder adults with frailty are at an increased risk of adverse outcomes after surgery. Exercise before surgery (exercise prehabilitation) may reduce adverse events and improve recovery after surgery. However, adherence with exercise therapy is often low, especially in older populations. The purpose of this study was to qualitatively assess the barriers and facilitators to participating in exercise prehabilitation from the perspective of older people with frailty participating in the intervention arm of a randomized trial.MethodsThis was a research ethics approved, nested descriptive qualitative study within a randomized controlled trial of home-based exercise prehabilitation vs. standard care with older patients (≥ 60 years) having elective cancer surgery, and who were living with frailty (Clinical Frailty Scale ≥ 4). The intervention was a home-based prehabilitation program for at least 3 weeks before surgery that involved aerobic activity, strength and stretching, and nutritional advice. After completing the prehabilitation program, participants were asked to partake in a semi-structured interview informed by the Theoretical Domains Framework (TDF). Qualitative analysis was guided by the TDF.ResultsFifteen qualitative interviews were completed. Facilitators included: 1) the program being manageable and suitable to older adults with frailty, 2) adequate resources to support engagement, 3) support from others, 4) a sense of control, intrinsic value, noticing progress and improving health outcomes and 5) the program was enjoyable and facilitated by previous experience. Barriers included: 1) pre-existing conditions, fatigue and baseline fitness, 2) weather, and 3) guilt and frustration when unable to exercise. A need for individualization and variety was offered as a suggestion by participants and was therefore described as both a barrier and facilitator.ConclusionsHome-based exercise prehabilitation is feasible and acceptable to older people with frailty preparing for cancer surgery. Participants identified that a home-based program was manageable, easy to follow with helpful resources, included valuable support from the research team, and they reported self-perceived health benefits and a sense of control over their health. Future studies and implementation should consider increased personalization based on health and fitness, psychosocial support and modifications to aerobic exercises in response to adverse weather conditions.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12877-023-03990-3.