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Updated: Feb 7, 2026

A Neuroscientific Approach to the Examination of Concussions in Student-Athletes
Published on: December 8, 2014
End-tidal carbon dioxide levels in patients with post-concussion syndrome during neurocognitive and physical tasks
Patrick Siedlecki1,2, Paolo Sanzo1,3, Carlos Zerpa1
1a School of Kinesiology , Lakehead University , Thunder Bay , ON , Canada.
Primary Objective:
Recent findings suggest breathing may negatively affect performance after concussion. The aim of the study was to examine group differences between individuals with and without post-concussion syndrome (PCS) in end-tidal carbon dioxide (ETCO2) and respiratory rate (RR) during neurocognitive and physical tasks.
Hypothesis:
Individuals in the PCS group will have elevated ETCO2 and lower RR compared to the control group.
Methods:
A quasi-experimental study was used in which a capnography unit collected ETCO2 and RR breathing data from 22 participants (control = 17; PCS = 5) during rest, the completion of the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) battery and while slow and fast walking. Four repeated measures mixed factorial ANOVAs, with an alpha level set at p ≤ 0.05, were used to examine group and task differences.
Results:
Both groups displayed similar breathing responses to cognitive and physical stress; however, PCS participants had significantly elevated ETCO2 throughout the study (during rest, the ImPACT and while walking) compared to the control. Conversely, no significant group differences were found in RR.
Conclusion:
Cerebral physiological alterations and deficits in the autonomic nervous system may cause abnormal ETCO2 in individuals after concussion. Future research evaluating breathing patterns in PCS may be warranted.
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