Brain Oxygenation in Post-concussion Combat Sport Athletes

Purpose: Investigate the feasibility of a non-invasive method to evaluate the physical and cognitive repercussions of long-lasting post-concussion effects in professional combat sports athletes. To help athletes return to professional combat, there is a need for unbiased objective tools and techniques used as a prognostic method of recovery after Sport Related Concussion (SRC).Methods: Six mild Traumatic Brain Injury (mTBI) athletes, age 20 divided by 43 yr (1 female, 5 males) and 7 not concussed (NC) participants (amateur), age 24 divided by 38 yr (3 females, 4 males), were tested Inspired/expired gas concentration, Cerebral changes in oxygenated hemoglobin (Delta[HbO(2)]) and deoxygenated hemoglobin (Delta[HHb]) were measured using near infrared spectroscopy (NIRS) with a 3-step protocol: rest before maximal oxygen uptake (VO(2)max) test, hypercapnia, and recovery after VO(2)max test. The brain oxygenation and respiratory parameters of both sample sets were calculated using a non-parametric test (Mann-Whitney U test). Aerobic fitness outcome was quantified through mean average using the Bruce test. Participants performed Fitt's test using a laptop and analysis of medio-lateral and anterior-posterior range of oscillation was carried out via a force platform Romberg test.Results: mTBI group showed statistically significant differences in saturated hemoglobin Delta[HbO(2)] (p < 0.001) during rest and recovery phase after maximal incremental exercise, in medio-lateral sway eyes open (p = 0.008, NC 25.35 +/- 4.11 mm and mTBI 17.65 +/- 4.79 mm). VO(2)max revealed no significant differences between the two groups: NC 47.47 +/- 4.91 mTBI 49.58 +/- 5.19 ml/kg/min(-1). The 2 groups didn't differ for maximum power output (NC 220 +/- 34, mTBI 255 +/- 50 W). End-tidal fractional concentration of O-2 (FetO(2) NC15.20 +/- 0.41, mTBI 16.09 +/- 0.68) throughout hypercapnia, saturated blood hemoglobin (Delta[HbO(2)]) revealed significant differences with the mTBI group. No differences emerged from Fitt's test.Conclusions: It emerges that NIRS is able to reveal differences in long time outcomes of mTBI. The medio-lateral variations cannot be considered as a marker of long-term damage in athletes specifically trained for balance.