Heart Failure (HF) is a significant healthcare concern in the US, with a 120% rise in mortality rates over 15 years costing the country an estimated $37.2 billion in 2009. Veterans are currently impacted at a rate of 5.2%, and cost an average of $14,959/individual/year for those utilizing the VA's Healthcare services. Research has shown that exercise training (ET) improves aerobic capacity, endothelial dysfunction, quality of life, and the ability to tolerate activity within the overall HF population. Animal models have emerged to explain some of the underlying mechanisms for the pathologic expression of symptoms and the links to ET. A translational link has not yet been explored between the animal models and human symptom expression.
The long-term goal of this research program is to develop an exercise training (ET) program that effectively decreases fluid shift variability in HF patients, while being safely implemented in the home environment and remotely monitored by a healthcare provider within a nurse-lead HF Clinic. The purpose of the proposed research project was to determine if ET alters fluid status of patients with HF as compared to those under standard treatment of care. The central hypothesis was that a combined weight-bearing aerobic and resistance ET protocol will reduce (stabilize) 24-hour weight and bioelectrical impedance patterns of variability, as evaluated via mixed-effects regression modeling, greater than any other form of ET protocol.
Design: Using established experimental design techniques implemented in an innovative manner, a between-group design was used within the experimental arm employing a single subject, multiple-baseline design. The use of such technique allowed for the subjects to act as their own controls, while also allowing for statistical group comparisons.
Subjects and Setting: 98 subjects meeting inclusion/exclusion criteria were screened from the VA HF Clinic, outpatient VA cardiology clinic, and VA primary care clinics in the Columbia, South Carolina area VA medical center and clinics. Of the 98 subjects, 15 were female. 21 subjects meet both inclusion and exclusion criteria, 16 subjects were enrolled with 13 subjects completing the full protocol. All subjects were male as all females failed the screening phase. Subjects were randomized to the exercise or usual care groups.
Procedures: The exercise protocol lasted 12 weeks, with subjects being randomized to order of ET. Weight-bearing aerobic ET was walking on a treadmill; non-weight-bearing aerobic ET was stationary bicycling; and resistance ET was a combination of lower body, core and upper body ET. Fluid stability is the concept of day-to-day variability of movement of intra-cellular fluid to extra-cellular space. Fluid stability was assessed using 24-hour weight and bioelectrical impedance and quantified statistically.
Data Analysis: Statistical analysis utilized a longitudinal mixed-effects regression model, modeling variability over time for the subjects individually, as well as within groups. Additionally, main effects (time and group) and interaction effects (time by group) was assessed.
The study is in data analysis mode. Findings will be coming shortly.
By examining the varying exercise protocols, clinicians and researchers gain a greater understanding of how best to utilize exercise as an agent in the medical management of heart failure within the management of fluid shifts in Veterans with advanced heart failure. Additionally, new statistical methods for evaluating weight variability assessed have far reaching future implementation.
External Links for this Project
Grant Number: I01HX000308-01
None at this time.