Table 3.
The INTERLIVE checklist to be considered for the validation protocol of wearable to estimate maximal oxygen consumption (VO2max)
| Target population assessment |
| Age |
| Children (< 12 years) |
| Adolescents (12–18 years) |
| Adults (18–65 years) |
| Older adults (> 65 years) |
| Sex (equal sample of males and females) |
|
Sample size Calculated based on previously published or pilot study data OR If previous data is not available, sample of convenience (n ≥ 45 participants) |
| Reference standard |
| The gold standard is a maximal exercise test in laboratory conditions with indirect calorimetry |
| Any brand of metabolic cart is accepted and should be calibrated following manufacturer’s instructions |
| Index device assessment |
|
Consumer wearables placed according to manufacturer’s instructions to be tested in ecological locations Hear rate can be measured with both chest strap or PPG, and it should be reported which of them was used |
| Testing protocols and conditions |
| Reference standard |
| To consider at least 2 maximal-effort criteria during the incremental test |
| A verification phase after the maximal test is recommended to corroborate the VO2max |
| Any type of exercise testing is accepted (e.g., walking, running, or biking) as long as it adapts to the type of activity in which the consumer wearable is intended to be validated |
| Control the standardized conditions before the maximal exercise test |
| Consumer wearable |
| Follow the manufacturer’s instructions for the VO2max estimation protocol |
| Provide all the setup information required by the devices |
| If exercise mode is available, choose the one that best reflects the activity to be performed |
| Ensure an optimal GPS connection when this data is used |
| Processing |
| Reference standard |
| If VO2max is averaged within a time window, it is recommended to use a 15- to 30-s window |
| If a breath-by-breath average is used, a 15-breath running average is recommended |
| Confirm that the maximum-effort criteria were met when interpreting the VO2max values |
| Time interval between evaluations |
| In those wearables using resting conditions, no time interval is needed |
| In exercise conditions, an interval between 24 and 48 h is recommended |
| Statistical analysis |
| Bland–Altman with limits of agreement |
| Least products regression of the differences against the means |
| MAPE |
See the Table 2 for more detailed information about each item
INTERLIVE Towards Intelligent Health and Well-Being Network of Physical Activity Assessment, MAPE mean absolute percentage error, PPG photoplethysmography