A Smartphone Application to Evaluate Energy Expenditure and Duration of Activities for Overweight and Obese People

There is a growing interest in evaluating physical activity and energy expenditure (EE) to provide feedback to the user. The use of mass-market sensors such as accelerometers offers a promising solution for the general public due to the growing smartphone market over the last decade.

Two previous studies allowed to propose a function named PredEE, which has been tested on normal-weighted volunteers.

This EE estimation function has been tested and improved with data collected from 43 overweight volunteers equipped with smartphones and two or three research sensors (Fitmate, Armband and Actiheart in controlled conditions, and Armband and Actiheart in free-living conditions). Research sensors' data serves as reference during the evaluation and improvement of the proposed function.

This EE estimation function using the smartphone technology is dedicated to light- and moderate-intensity activities, and the investigators believe it can be a new way to help people controlling their daily physical activity level.

Inclusion criteria

• men and women
• age: 18-60 years
• BMI between 28 and 42 kg/m²
• subject considered as healthy after clinical examination and medical questionnaire
• no pregnant women
• subject with normal rest electrocardiogram (validated by a cardiologist)
• certificate of non-indication against the practice of exercise stress testing delivered by a physician
• subject with normal blood pressure (<140/90 mm Hg) with or without medical treatment
• subject with no foot pad problem
• subject giving his/her written informed consent
• subject willing to comply with study procedures
• affiliated to National Health Insurance

Exclusion criteria

• respiratory failure or cardiovascular problem
• non-indication against the practice of exercise stress testing
• known cardiac decompensation or myocardial infarction
• surgery made less than 6 months before the study beginning
• pregnant women and nursing mother
• current infectious pathology
• abnormal electrocardiogram
• not affiliated to national health insurance people
• under legal guardianship
• refusal to sign informed consent
• refusal to be registered on the national volunteers data file
• currently participating or who having got 4500€ in this year before to have participated in another clinical trial