The aim of this study was to validate functions for estimating energy expenditure in free-living conditions. This method was based on accelerometry data acquired from a smartphone worn in a trouser pocket. The developed functions have been compared to the estimations provided by two research devices named Armband and Actiheart.

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.

Thus, the proposed EE estimation function has been created using accelerometry data collected from 10 volunteers equipped with a smartphone and two research sensors (Armband and Actiheart) used to estimate EE during several controlled activities. The research sensors' data serves as reference during the creation and evaluation of the proposed function.

It has been evaluated with data of 6 other volunteers in free-living conditions in the previous eMouve project.

eMouve2 consists in acquiring more data from 24 new volunteers in order to validate the function in free-living conditions.

This EE estimation function using the smartphone technology is dedicated to light- and moderate-intensity activities, and we 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 18.5 and 25 kg/m²
• subject considered as healthy after clinical examination and medical questionnaire
• women of childbearing age: use of a contraceptive method
• subject with normal rest electrocardiogram (validated by a cardiologist)
• 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
• 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