ACTT Validation Study
From Movement to METs: Validating the ActTrust® actigraphy device
About
This repository contains all data and analysis code for a controlled laboratory validation of the ActTrust® actigraphy device (Condor Instruments, São Paulo, Brazil). The study compares ActTrust® activity counts to those from the ActiGraph® GT3X+ accelerometer, and relates both to metabolic equivalents (METs) measured by indirect calorimetry during a treadmill protocol in healthy young adults.
The entire analysis is implemented as a single Quarto notebook (index.qmd) that renders a self-contained HTML report with all figures, tables, and statistical outputs inline — making every step fully auditable and reproducible.
Batista ES, Basilio Gomes SR, Morais Ferreira AB, França LGSF, Fontenele Araújo J, Mortatti AL, Leocadio-Miguel MA. From Movement to METs: A Validation of ActTrust® for Energy Expenditure Estimation and Physical Activity Classification in Young Adults. bioRxiv 2025. doi:10.1101/2025.05.16.654458
Study Design
56 healthy young adults (34 men, 22 women; aged 18–35) completed a controlled treadmill protocol in a single laboratory session. Participants simultaneously wore four devices — two ActiGraph® GT3X+ and two ActTrust® units at hip and wrist — while oxygen uptake was measured breath-by-breath by indirect calorimetry (Quark CPET, Cosmed®).
| Condition | Speed | Description |
|---|---|---|
| Rest | — | Seated, no movement |
| Walking | 3 km/h | Slow walk |
| Walking | 5 km/h | Brisk walk |
| Walking/Running | 7 km/h | Fast walk / slow run |
| Running | 9 km/h | Running |
Each condition lasted 10 minutes, separated by 5-minute rest periods. Activity counts and METs were averaged over the central 4 minutes of each condition to exclude transition effects.
Key Contributions
- First published cut-points for physical activity intensity classification using ActTrust® devices at hip and wrist placement
- General linear model for estimating energy expenditure (METs) from ActTrust® counts, with device × placement interaction terms
- Balanced accuracies above 0.77 for all intensity ranges, exceeding 0.90 for light and moderate activity
- Bland-Altman analysis of predicted vs measured METs per device × placement
- Sex-stratified supplementary analysis addressing body composition differences
Derived Cut-points
Physical activity intensity cut-points derived by inverting the regression model at MET thresholds of 3, 6, and 9 (counts/min):
| Device (Placement) | Light < 3 METs | Moderate 3–6 METs | Vigorous 6–9 METs |
|---|---|---|---|
| ActTrust® hip | < 5057 | 5057–23339 | 23339–46410 |
| ActTrust® wrist | < 3761 | 3761–22368 | 22368–47203 |
| GT3X+ hip | < 1132 | 1132–4853 | 4853–9468 |
| GT3X+ wrist | < 1698 | 1698–9503 | 9503–19787 |
Reproducibility
The analysis can be reproduced in two ways:
RStudio — open ACTT_validation_study.Rproj and render index.qmd.
Docker — docker-compose up builds the full R environment and renders the notebook automatically.
Data are archived on Zenodo: doi:10.5281/zenodo.15315735