![](bg5.png)
Figure 9: Mean RR interval as a function of task in (black
bars) trial 1 and (grey bars) trial 2 across all teams.
4 CONCLUSIONS
Participants wore Charles River Analytics/Plux
sensors and standard sensors (Biopac) while
completing well-validated cognitive tasks, physical
tasks, and combinations of cognitive and physical
tasks. This allowed us to assess the accuracy of
Charles River Analytics/Plux sensors (by comparing
them to Biopac data). The evaluation of this sensor
suite included 21 teams of three students completing
physical and cognitive challenges. Various
physiological measures were collected from each
participant.
The correlations in RR interval between the
fNIRS device, Armband device, and Biopac sensor
are small, but positive, indicating that the sensors are
picking up on similar information, but there is weak
correspondence.
The physical and cognitive tasks had very
different effects on heart rate. As expected, the ECG
signal was much more variable during the completion
of the physical tasks, including movement between
stations of the experiment. Occasionally, a sensor
might be sufficiently jostled, particularly in the rope
jumping task, or it might fall off. In those situations,
the signal became very noisy, which made the QRS
complex difficult to resolve. The consequence was
that the peak-picking algorithm might skip relevant
peaks in the signal and estimate an inflated RR
interval (e.g. RR interval>2 sec).
ACKNOWLEDGEMENTS
This material is based upon work supported by the
United States Army Medical Research and Materiel
Command under Contract No. W81XWH-14-C-
0018. Any opinions, findings and conclusions or
recommendations expressed in this material are those
of the author(s) and do not necessarily reflect the
views of the United States Army Medical Research
and Materiel Command. In the conduct of research
where humans are the participants, the investigators
adhered to the policies regarding the protection of
human participants as prescribed by Code of Federal
Regulations (CFR) Title 45, Volume 1, Part 46; Title
32, Chapter 1, Part 219; and Title 21, Chapter 1, Part
50 (Protection of Human Participants).
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