Sport-related concussion alters cerebral hemodynamic activity during controlled respiration


Sport-related concussion (SRC) is known to disrupt neuro-hemodynamic activity, cardiac function, and blood pressure (BP) autoregulation. This study aims to observe changes in cerebrovascular and cardiovascular responses during controlled respiration after sustaining an SRC. University varsity athletes (n=81) completed a pre-season physiological assessment and were followed up within five days of sustaining an SRC. During pre-season and follow-up assessments, participants' continuous beat-to-beat BP was collected by finger photoplethysmography and right prefrontal cortex oxygenation was collected using near-infrared spectroscopy (NIRS). Participants completed 5 minutes of seated rest and 5 minutes of a 6-breaths-per-minute controlled breathing protocol (5s-inhale and 5s-exhale; 0.10 Hz). Wavelet transformation was applied to the NIRS and BP signals, separating them into respiratory (0.10 to 0.6 Hz) and cardiac (0.6 to 2 Hz) frequency intervals. Physiological signals were assessed for quality before inclusion. Of the 81 participants, 74 had a usable BP signal, 43 had usable NIRS signals, and 28 had both usable BP and NIRS signals. Wavelet amplitudes and coherence were assessed. There was a significant (ptextless0.05) decrease in oxygenated hemoglobin amplitude from 0.062 to 0.054 Hz and hemoglobin difference amplitude from 0.059 to 0.051 Hz, both at the respiratory (0.10-0.6 Hz) frequency interval, from pre-season to acute SRC, respectively. Therefore, during controlled respiration, there was a reduction in intensity at the respiratory band, suggesting a protective, reduced respiratory contribution to cerebral hemodynamic activity following acute SRC.

Journal of Neurophysiology