RELATIONSHIP BETWEEN ORTHOSTATIC STRESS RESPONSE AND ACUTE MOUNTAIN SICKNESS SUSCEPTIBILITY AT HIGH ALTITUDE: A PILOT STUDY

The purpose of this study was to determine whether there is a difference in hemodynamic responses to head-up tilt (HUT) in subjects who do, and do not, experience acute mountain sickness (AMS) during exposure to hypobaric hypoxia. Secondarily, we aimed to determine if those hemodynamic variables altered during HUT correlated with AMS severity. Fifteen participants completed three testing sessions: 1) VO2max test to determine workload at 50% VO2max for hypoxia exposure; 2) HUT test consisting of supine rest for 20 min followed by 70° upright tilting for ≤ 40 min; and 3) six hours of hypobaric hypoxic exposure simulating 4572 m where participants performed two, 30 min cycling bouts and rested when not exercising. During HUT, continuous blood pressure monitoring was used to assess systolic and diastolic blood pressure (SBP & DBP), mean arterial pressure (MAP), variability in SBP, DBP, and MAP, and heart rate. AMS scores were determined before and after six hours of hypoxic exposure. Statistical analysis included mixed effects ANOVA to determine changes between supine rest and end of HUT and between selected AMS positive (AMS+) and AMS negative (AMS-) groups. Correlations by linear regression determined associations between HUT hemodynamic responses and AMS scores. Statistical significance was set to p \u3c 0.05. Those with higher AMS scores tended to have a greater magnitude of change in SBP, DBP, and MAP variability during the HUT test (r = 0.65, 0.64, & 0.60, respectively). Increased blood pressure variability (BPV) indicated a disruption in blood pressure regulation, suggesting that AMS+ individuals may have a disruption in their blood pressure regulation. This increases their susceptibility which could be observed during a postural change prior to hypoxic exposure. In conclusion, BPV during HUT may be a promising predictive variable for AMS but further research is needed. In the future, researchers should consider using sea-level living participants and a range of simulated elevations to determine the predictability of AMS-susceptibility by BPV

Estimated age of first exposure to American football and outcome from concussion

To examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion. Participants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football. In unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed ( = 0.031, = 0.012) at 24-48 hours following injury and lower (better) BSI-18 Somatization subscores ( = 0.014, = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores. Earlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion

Estimated age of first exposure to American football and outcome from concussion

ObjectiveTo examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion.MethodsParticipants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football.ResultsIn unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed (R 2 = 0.031, p = 0.012) at 24-48 hours following injury and lower (better) BSI-18 Somatization subscores (R 2 = 0.014, p = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores.ConclusionEarlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion