6-Minute Walk Test: Exploring Factors Influencing Perceived Intensity in Older Patients Undergoing Cardiac Rehabilitation—A Qualitative Study

Background/Objectives: In cardiac rehabilitation, the 6-minute walk test (6-MWT) is a standard assessment of initial evaluation. It measures walking distance as a surrogate of submaximal physical performance. Thereby, a subjective rating of perceived exertion, assessed by the Borg Scale, plays an important role. It has been observed that patients with coronary heart disease often rate themselves lower than the person supervising the test. Since this discrepancy might lead to inadequate exercise prescription, this study aims to explore reasons for low self-rating. Methods: In a qualitative study, influencing factors for low self-rating were collected from patients using interviews and questionnaires and from a focus group of physiotherapists. The evaluation was based on the grounded theory. Results: Self-image after retirement emerged as the central factor, as it shaped patients’ behavior during the 6-MWT and their subsequent self-assessment. Additionally, five different categories of causal conditions were detected from ten patients and five therapists: fears, physical limitations, test instruction, testing conditions, and therapists’ expectations. Conclusions: Patients with coronary heart disease had poor self-perception of exercise intensity and limited understanding of the meaning of the Borg Scale and the 6-MWT. Physiotherapists should place greater emphasis on patients’ perceived exertion to be able to effectively tailor exercise prescription and, therefore, improve attainment of cardiac rehabilitation goals and long-term adherence.