The purpose of this individual National Research Service Award (NRSA) application is to provide research training for a nurse to become an independent investigator focusing on how exercise therapy, defined as routine exercise lasting at least 8 weeks, in the heart failure (HF) patient population impacts the parallel processes of physiologic and symptom changes and influences HF patients' outcomes. In addition to supporting scholarly coursework, acquiring methodological and statistical skills, and learning to conduct ethically sound research with vulnerable populations, this NRSA training grant will also support research to explain the heterogeneous response to exercise therapy in the HF patient population. From a clinical perspective, there is huge potential for exercise therapy to be better integrated into patient care plans and be reimbursed by Medicare. Further understanding of who benefits most is first needed. I hypothesize that there are common and distinct responses to exercise therapy in the HF patient population that can be identified, predicted, and quantified in association with health outcomes. I will investigate this hypothesis empirically using a subgroup of patients from the Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) dataset. I have received special permission to use the dataset, including biomarker, symptom and outcome data from the principal investigators of the study: Dr. Christopher O'Connor and Dr. David Whellan. My research training will be guided by my sponsor and co- sponsor who are two internationally known HF scientists, Dr. Barbara Riegel, a well-known HF nurse expert and leader, and Dr. Kenneth Margulies, a highly acclaimed HF transplant specialist. This project will also receive significant input from Dr. Christopher Lee, a nurse scientist, advanced methodologist and consultant on this project. The long-term impact of this research training is important because exercise training is a self-management behavior strongly encouraged but under-used in the HF patient population. This research is closely assigned with the priorities of the National Institute of Nursing Research, which specify the need to investigate multiple determinants of health and the impact they have on patients' ability to self-manage their disease, manage their symptoms and improve their health-related quality of life. This work will lead to knowledge of whom to target with specific tailored exercise interventions. The specific research and methodological approach proposed in this application has wide applicability to many stakeholders, including professionals, caregivers and patients with HF. PUBLIC HEALTH RELEVANCE: The focus of my pre-doctoral training is on becoming an independent nurse investigator. The research component of this fellowship focuses on characterizing the heterogeneous physiologic and symptom responses to exercise therapy in HF patients using growth mixture modeling. Although exercise therapy is known to be safe in the HF patient population, it is not routinely incorporated into patients' treatment plans because the symptom-biology mechanisms are not well characterized or understood. Although many clinicians advocate referral to Cardiac Rehabilitation, Medicare does not reimburse it. The proposed research will dissect the heterogeneous responses to exercise therapy (by characterizing them in terms of distinct trajectories) and identify select subpopulations of HF patients who demonstrate favorable responses. The longer-term implication is to be able to provide the scientific evidence to support advocating for Medicare reimbursement for HF patients who will benefit most from exercise therapy.