Multicenter Exploratory Study of Accelerometry in Dilated Cardiomyopathy

Inclusion Criteria: 1. Males and females, 18-75 years of age 2. Diagnosis of dilated cardiomyopathy * (Unexplained left ventricular enlargement (left ventricular end diastolic dimension (LVEDD) \>95th percentile for gender and height by echo or MRI) * (Left ventricular ejection fraction (LVEF) less than 50%) 3. CPET within 14 days prior to baseline visit with no intervening change in therapy 4. Echocardiogram or cardiac MRI within 1 year prior to baseline 5. Able to walk \>100ft without limitation 6. More than 30 minutes of exercise per week for at least 3 months prior to study enrollment, and plan to continue exercising for the next two weeks (duration of study). 7. Ability to provide informed consent and willingness to complete the study (including weekly phone follow-up) Exclusion Criteria: 1. Heart failure hospitalization within four weeks prior to enrollment 2. Non-cardiac limitation of activity 4\. Prior exercise-induced syncope or exercise-induced sudden death 5. Primary exercise mode is swimming or stationary biking 6. Participation in competitive or high intensity exercise against medical advice 7. Implantable Cardiverter Defibrillator (ICD) placement in the 2 months prior to enrollment 8. Plan for surgery, device implantation, or significant change in clinical management during the two weeks of the study