Exercise to Improve Sleep in Heart Failure

PROCEDURES. Walking Exercise Intervention. An individualized program of walking exercise is prescribed (walking up to 5 times a week for up to 30 minutes each session). The protocol for this walking intervention is based on exercise programs adapted from 12 research protocols for patients with NYHA Class II-III heart failure, one cardiac rehabilitation protocol in use for approximately 20 years; and the AHCPR Clinical Practice Guidelines for activity prescriptions for heart failure patients. The walking exercise prescription is based on a modified Naughton treadmill test and a 6-minute walk test, both conducted as part of eligibility screening and used as pretest measures. The target exercise heart rate range is calculated from the peak heart rate (measured on treadmill at the peak of oxygen utilization) minus the resting heart rate, multiplied by 40% to 60%, plus the resting heart rate. Weekly for 6 weeks, and then every other week for 10 weeks, the research nurse makes visits to initiate, monitor, and advance an individualized program of walking exercise. POPULATION. Our target population was persons diagnosed with heart failure (HF). Pretest and posttest measures include an exercise tolerance test; two nights of somnographic sleep and oxygen saturation recordings; one 24-hour recording of heart rate variability; and subjective reports of quality of life. One-way analyses of variances (ANOVA) will be used to test for control-treatment group differences in cardiac function (Aim 1) and sleep (Aim 2). Interaction will be examined in a two-way ANOVA of group (HF subjects with frequent vs. few apnea-hypopnea episodes walking vs.control) and time (before and after condition) to determine whether HF subjects with frequent apnea-hypopnea episodes who exercise have better outcomes than HF subjects with few apnea-hypopnea episodes who exercise, or the control group (Aim 3).