The consideration of post-exercise impact on SCAT3 scores in athletes immediately following a head injury

Examine effects of high-intensity exercise and physical impacts during rugby match on self-report symptoms in The Sport Concussion Assessment Tool (SCAT3), and its ability to differentiate head-injured players from controls. Methods: Symptoms were assessed immediately following completion of a rugby match (median 60 minutes). Players removed from the match for assessment due to a head hit were classified as head injured. Controls completed match without head hit. Results: 209 players (67 female; 33 ± 13 years) participated with 80 experiencing a head injury. Symptom severity was significantly greater in head injured (26.2 ± 17.6) compared with controls (8.9 ± 11.5, P 16 symptom severity, misclassifying them as suspected concussion. There were no significant sex differences. Factor analysis produced four symptom clusters of which Headache was most discriminatory between the head injured (median = 1.7) and controls (median = 0.0). Conclusion: These findings demonstrate that exercise and contact during a game affect symptom assessment, increasing the likelihood of misclassifying players with suspected concussion. Factor characterization of symptoms associated with head injury using an exercised comparison group provides more useful discrimination. These results highlight the necessity for objective measures to diagnose concussions outside of symptom self-report

Human adaptations to multiday saturation on NASA NEEMO

Human adaptation to extreme environments has been explored for over a century to understand human psychology, integrated physiology, comparative pathologies, and exploratory potential. It has been demonstrated that these environments can provide multiple external stimuli and stressors, which are sufficient to disrupt internal homeostasis and induce adaptation processes. Multiday hyperbaric and/or saturated (HBS) environments represent the most understudied of environmental extremes due to inherent experimental, analytical, technical, temporal, and safety limitations. National Aeronautic Space Agency (NASA) Extreme Environment Mission Operation (NEEMO) is a space-flight analog mission conducted within Florida International University's Aquarius Undersea Research Laboratory (AURL), the only existing operational and habitable undersea saturated environment. To investigate human objective and subjective adaptations to multiday HBS, we evaluated aquanauts living at saturation for 9-10 days via NASA NEEMO 22 and 23, across psychologic, cardiac, respiratory, autonomic, thermic, hemodynamic, sleep, and body composition parameters. We found that aquanauts exposed to saturation over 9-10 days experienced intrapersonal physical and mental burden, sustained good mood and work satisfaction, decreased heart and respiratory rates, increased parasympathetic and reduced sympathetic modulation, lower cerebral blood flow velocity, intact cerebral autoregulation and maintenance of baroreflex functionality, as well as losses in systemic bodyweight and adipose tissue. Together, these findings illustrate novel insights into human adaptation across multiple body systems in response to multiday hyperbaric saturation

Cerebrovascular reactivity and cerebral autoregulation are improved in the supine posture compared to upright in healthy men and women.

Cerebrovascular reactivity and cerebral autoregulation are two major mechanisms that regulate cerebral blood flow. Both mechanisms are typically assessed in either supine or seated postures, but the effects of body position and sex differences remain unclear. This study examined the effects of body posture (supine vs. seated vs. standing) on cerebrovascular reactivity during hyper and hypocapnia and on cerebral autoregulation during spontaneous and slow-paced breathing in healthy men and women using transcranial Doppler ultrasonography of the middle cerebral artery. Results indicated significantly improved cerebrovascular reactivity in the supine compared with seated and standing postures (supine = 3.45±0.67, seated = 2.72±0.53, standing = 2.91±0.62%/mmHg, P<0.0167). Similarly, cerebral autoregulatory measures showed significant improvement in the supine posture during slow-paced breathing. Transfer function measures of gain significantly decreased and phase significantly increased in the supine posture compared with seated and standing postures (gain: supine = 1.98±0.56, seated = 2.37±0.53, standing = 2.36±0.71%/mmHg; phase: supine = 59.3±21.7, seated = 39.8±12.5, standing = 36.5±9.7°; all P<0.0167). In contrast, body posture had no effect on cerebral autoregulatory measures during spontaneous breathing. Men and women had similar cerebrovascular reactivity and similar cerebral autoregulation during both spontaneous and slow-paced breathing. These data highlight the importance of making comparisons within the same body position to ensure there is not a confounding effect of posture

Does treadmill walking affect neurovascular coupling during cognitive activation in healthy individuals?

Treadmill desks have become increasingly popular in the workplace to improve physical health. However, it is unknown whether treadmill walking affects neurovascular coupling, which is the increase in cerebral blood flow during cognitive tasks. Additionally, it is unknown whether the speed of treadmill walking affects neurovascular coupling or if there is a sex difference in the response. A total of 49 subjects (22 male, 27 female) walked on a treadmill at four different walking speeds (0.5 mph, 1.5 mph, 2.5 mph and 3.5 mph) in addition to a standing condition (0 mph). While standing or walking at each speed, participants also performed the Stroop color-word test. Continuous cerebral flow velocity in the right middle cerebral artery (MCAv), blood pressure, heart rate, and end-tidal CO2 were measured throughout testing. The percent increase in MCAv from the no tasking condition (standing or walking at each speed) to the Stroop tasking condition (Stroop + standing or walking at each speed) was analyzed to measure neurovascular coupling. Results showed a significant effect of walking speed (p=0.003) as well as a significant interaction between walking speed and sex (p=0.012) on the percent increase in MCAv during the Stroop tasking condition (0 mph: Men = 2.6 ± 5.8%, Women = 1.8 ± 3.7%; 0.5 mph: Men = 2.3 ± 4.2%, Women = 3.6 ± 5.2%; 1.5 mph: Men = 4.1 ± 6.2%, Women = 4.2 ± 4.9%; 2.5 mph: Men = 3.4 ± 7.4%, Women = 4.0 ± 4.3%; 3.5 mph: Men = −1.7 ± 7.8%, Women = 3.4 ± 7.0%). There was also a small, but significant effect of walking speed on the difference in end-tidal CO2 between the Stroop tasking condition and the no tasking condition within each speed (p=0.005; 0 mph: Men = 0.0 ± 1.1 mmHg, Women = −0.1 ± 1.4 mmHg; 0.5 mph: Men = −0.1 ± 0.8 mmHg, Women = 0.0 ± 0.7 mmHg; 1.5 mph: Men = 0.0 ± 1.3 mmHg, Women = 0.2 ± 0.9 mmHg; 2.5 mph: Men = 0.4 ± 1.7 mmHg, Women = 0.1 ± 0.9 mmHg; 3.5 mph: Men = −1.0 ± 2.0 mmHg, Women = −0.2 ± 1.1 mmHg). There was no interaction between speed and sex in end-tidal CO2. This data suggests that there is a small, but significant reduction in neurovascular coupling in men during the Stroop test at 3.5 mph, but this reduction may be partially explained by the reduction in end-tidal CO2. This study highlights that neurovascular coupling is preserved during treadmill walking across the slower walking speeds. However, neurovascular coupling at 3.5 mph needs to be further examined with controlled levels of end-tidal CO2 to support whether neurovascular coupling is reduced at this faster walking speed in men

Effect of sympathetic activation on middle cerebral artery diameter in a healthy man

The effects of the sympathetic nervous system on control of the cerebral blood flow in men and women remain unclear. Recent studies(1,2) the diameter of the middle cerebral artery changes in response to changes in arterial CO2, but it is unclear whether the diameter changes during increases in sympathetic neural outflow during lower body negative pressure (LBNP)