The primary objective of this study is to identify and evaluate the range of values provided by accelerometers during a variety of typical daily lifestyle activities for heart failure patients, and to relate these to the measured intensity of performing each activity in the heart failure population.

The precise measurement of physical activity is now possible with advances in wearable technology, namely accelerometers. This is useful in order to properly evaluate interventions such as cardiac rehabilitation that aim to increase physical activity. One of the challenges with accelerometry is the need for raw data to be translated into meaningful behavioural units. This is addressed through a calibration study, where accelerometry data is related to oxygen consumption and cut points are derived where activity is considered light, moderate or vigorous intensity. However, calibration studies have only been done in young and healthy adults, not in the elderly or those with chronic disease such as heart failure where movements are slower and exercise capacity is reduced. This means there is a risk of underestimating the true level of physical activity in this population. Therefore the aim of this study is to run a calibration study with 18-30 heart failure patients.

Adults (aged 18 years and older) diagnosed with heart failure, with stable symptoms that are willing and able to give informed consent will be eligible for the study. Patients with contraindications to physical activity will be excluded from the study. Patients will be identified from the Royal Devon & Exeter NHS Foundation Trust and the study will be conducted in the sports science laboratory at St Luke's Campus, University of Exeter. Each patient will be required to attend a single study visit that should last approximately 3 hours in total. During the visit patients will be required to complete a number of physical activity tasks (such as lying, sitting and walking) whilst wearing various accelerometers and gas analysis equipment.

Inclusion Criteria:

• Patient willing and able to give written informed consent to participate in study
• Adult (aged ≥18 years)
• Patients with confirmed diagnosis of heart failure
• Stable symptoms of heart failure

Exclusion Criteria:

• Patients with contraindications to exercise testing or physical activity
• Patients who are in a long term care establishment or who are unwilling or unable to travel to research site
• Patients who are unable to understand the study information.
• Patients judged to be unable to participate in the study for any other reason (e.g. diagnosis of dementia, psychiatric disorder, life-threatening comorbidity).