This document describes all data sources and variables in the study.
Processed data are archived at: https://doi.org/10.5281/zenodo.15315735
All primary analyses read from a single file: data/acttrust_validation_full.csv
Raw data are stored in raw_data/ and were processed by proprietary device software before export. All subsequent processing and analysis is performed in open-source R.
| Source | Folder | Description | Format |
|---|---|---|---|
| ActTrust® actigraphy | raw_data/ACTTRUST/ |
Raw exports from ActTrust® devices (Condor Instruments, São Paulo, Brazil). Worn on the dominant hip and non-dominant wrist simultaneously. Records activity in PIM (Proportional Integration Mode) — a measure of the integral of acceleration above a threshold — sampled at 25 Hz, band-pass filtered 0.5–2.7 Hz, and exported at 1-s epochs via Act Studio software. One file per participant per placement. | Proprietary .txt |
| ActiGraph® GT3X+ actigraphy | raw_data/Gt3x/ |
Raw exports from ActiGraph® GT3X+ devices (ActiGraph Corporation, Pensacola FL). Worn on the dominant hip and non-dominant wrist simultaneously. Records activity as vector magnitude (VM) counts — the Euclidean norm of triaxial acceleration — sampled at 30 Hz, band-pass filtered 0.25–2.5 Hz, and exported at 1-s epochs via ActiLife v6.13.4. One file per participant per placement. | .gt3x / .csv |
| Indirect calorimetry | raw_data/ERGO/ |
Breath-by-breath oxygen uptake (VO₂) measured by a Quark CPET metabolic cart (Cosmed®, Rome, Italy) during each treadmill condition. METs are computed as individual VO₂ / 3.5 mL O₂/kg/min. Values represent the mean from the central 4 minutes of each condition to exclude transition effects. | Proprietary Cosmed export |
Note on count magnitude differences: ActTrust® PIM counts are systematically higher in absolute value than ActiGraph® GT3X+ vector magnitude counts due to differences in filtering, integration method, and hardware sensitivity. The two devices must not be compared directly in absolute terms — use device-specific regression equations and cut-points from this study.
One row per participant × treadmill condition. Activity counts and METs are averaged over the central 4 minutes of each condition.
| Column | Type | Units | Description |
|---|---|---|---|
ID |
character | — | Unique participant identifier |
Conditions |
character | — | Treadmill condition. Values: Rest, 3 km/h, 5 km/h, 7 km/h, 9 km/h, Sit-Stands. Sit-Stands is excluded from all primary analyses. |
Sex |
numeric (raw) / character (recoded) | — | 1 = Female, 2 = Male in the CSV. Recoded to Female / Male on load via dplyr::recode(). |
BMI |
numeric | kg/m² | Body mass index |
| Column | Type | Units | Description |
|---|---|---|---|
METs |
numeric | METs | Metabolic equivalent of task from indirect calorimetry. Calculated as individual VO₂ / 3.5 mL O₂/kg/min. Values are the mean over the central 4 minutes of each condition. 1 MET ≈ 3.5 mL O₂/kg/min at rest. |
Four device × placement combinations stored as separate columns. Both are averaged over the central 4 minutes of each condition.
| Column | Type | Units | Description |
|---|---|---|---|
GT3X+ (hip) |
numeric | counts/min | ActiGraph® GT3X+ on dominant hip. Reference level in all regression models. Vector magnitude counts; 30 Hz; band-pass 0.25–2.5 Hz; 1-s epochs; exported from ActiLife v6.13.4. |
GT3X+ (wrist) |
numeric | counts/min | ActiGraph® GT3X+ on non-dominant wrist. Same hardware and processing as hip placement. |
ACTT (hip) |
numeric | counts/min | ActTrust® on dominant hip. PIM mode; 25 Hz; band-pass 0.5–2.7 Hz; 1-s epochs; exported from Act Studio. |
ACTT (wrist) |
numeric | counts/min | ActTrust® on non-dominant wrist. Same hardware and processing as hip placement. |
Supplementary participant-level data. See Zenodo archive for full description.
These variables do not exist in the CSV but are computed in index.qmd.
| Variable | Created by | Description |
|---|---|---|
act |
pivot_longer() |
Device × placement label after reshaping to long format. Factor with reference level GT3X+ (hip). Values: GT3X+ (hip), GT3X+ (wrist), ACTT (hip), ACTT (wrist). |
act_value |
pivot_longer() |
Activity count value corresponding to the act device × placement column. |
fit_MET |
`lm() | > fitted() |
actual_class |
cut(METs, ...) |
Observed PA intensity class from measured METs. Breaks: [0,3), [3,6), [6,9), [9,∞). |
predicted_class |
calc_met_class(fit_MET) |
Predicted PA intensity class from model-fitted METs, using the same breaks as actual_class. |
mean_val |
Bland-Altman section | Mean of fit_MET and METs — the x-axis of Bland-Altman plots. |
diff_val |
Bland-Altman section | Difference fit_MET − METs — the y-axis of Bland-Altman plots. |
| Class label | MET range | Intensity |
|---|---|---|
[0,3) |
0 ≤ METs < 3 | Light |
[3,6) |
3 ≤ METs < 6 | Moderate |
[6,9) |
6 ≤ METs < 9 | Vigorous |
[9,inf) |
METs ≥ 9 | Very Vigorous |
Summary statistics reported in Table 1 of the manuscript. Individual-level anthropometric data beyond ID, BMI, and Sex are not present as columns in the CSV but are available in the Zenodo archive.
| Characteristic | Male (n = 34) | Female (n = 22) |
|---|---|---|
| Age (years) | 28.3 ± 4.6 | 26.8 ± 5.0 |
| Height (cm) | 172 ± 6.2 | 160 ± 7.3 |
| Weight (kg) | 78.2 ± 11.9 | 59.9 ± 9.4 |
| BMI (kg/m²) | 23.1 ± 1.6 | 26.7 ± 2.5 |