Introduction There is a need for rapid and objective assessment tools to identify people at risk of impaired cognitive function during hypoxia. Purpose To test the hypotheses that performance on gamified cognitive tests examining the cognitive domains of executive function (Gridshot), working memory (Capacity) and spatial tracking (Multitracker) will be reduced during normobaric exposure to moderate normobaric hypoxia. Methods Following three consecutive days of practice, twenty-one healthy adults (27 ± 5 y, 9 females) completed five 1-min rounds of the tablet-based games Gridshot, Capacity, and Multitracker (Statespace Labs, Inc.) at Baseline and 60 and 90 min after exposure to 14.0 ± 0.2% (hypoxia) and 20.6 ± 0.3% (normoxia) oxygen. Both conditions were completed on the same day and were administered in a single-blind, block randomized manner. Arterial oxyhemoglobin saturation was estimated via forehead pulse oximetry (SpO2). Data were analyzed using ANCOVA with a covariate of Baseline. Results Compared to normoxia (98 ± 1%), SpO2 was lower (p < 0.001) at 60 (91 ± 3%) and 90 (91 ± 2%) min of hypoxia. No condition x time interaction effects were identified for any gamified cognitive tests (p ≥ 0.32). A main effect of condition was identified for Capacity (p = 0.05) and Multitracker (p = 0.04), but not Gridshot (p = 0.33). Post hoc analyses of the composite scores for both Capacity (p = 0.11) and Multitracker (p = 0.73) demonstrated no difference between conditions. Conclusion Performance on gamified cognitive tests was not consistently affected by acute normobaric moderate hypoxic exposure.

INTRODUCTION The acute effect of hypoxia on cognition is dependent on the magnitude and duration of the hypoxia, and the assessed cognitive domain. For example, there is little effect of ~1 h exposure to a fraction of inspired oxygen (FiO2) of ~14% on simple cognitive tasks that measure reaction time. However, complex or novel cognitive tasks can be hindered under the same conditions. These possible cognitive alterations are recognized by the use of supplemental oxygen when flying in unpressurized aircraft for >1 h at altitudes >3048 m. Notably, people often cannot recognize their own hypoxia‐induced symptoms. Thus, there is a need to develop objective assessment tools to consistently identify potential detrimental cognitive effects of moderate hypoxia. One potential solution is the use of gamified cognitive assessments, whereby electronic games can provide metrics of changes in cognitive functioning. However, the effect of moderate hypoxia on gamified cognitive performance has never been explored. PURPOSE Test the hypothesis that moderate normobaric hypoxia decreases gamified cross‐domain cognitive performance. METHODS Following three consecutive days of practice, twenty‐one healthy adults (27 ± 5 y, 9 females) completed five 1 min rounds of the tablet‐based game Gridshot (Statespace Labs, Inc.) at Baseline and 60 and 90 min after exposure to a chamber with an FiO2 = 14.0 ± 0.2% (hypoxia) and FiO2 = 20.6 ± 0.3% (normoxia). Both conditions were completed on the same day and were administered in a single‐blind, block randomized manner. Gridshot is a novel first‐person shooter style assessment in which a participant’s performance is measured as hits (#), misses (#), hit rate (%), hits per second (#/s), shots per second (#/s), median time to hit (s), and shot precision (i.e., the variability of shot locations relative to the center of targets). Arterial oxyhemoglobin saturation was estimated via forehead pulse oximetry (SpO2). Data were analyzed using ANCOVA with a covariate of Baseline and are presented as adjusted means (95% confidence intervals). RESULTS Compared to normoxia (98 ± 1%), SpO2 was lower (p < 0.001) at 60 (91 ± 3%) and 90 (90 ± 3%) min of hypoxia. A main effect of time was identified for average hits (p = 0.039) and hits per second (p = 0.039), such that, independent of condition, average hits [114 (112, 116) vs. 116 (114, 118)] and hits per second [1.89 (1.86, 1.94) vs. 1.93 (1.89, 1.97)] increased from 60 to 90 min. However, no effect of condition or a condition x time interaction was identified for either average hits (p ≥ 0.255) or hits per second (p ≥ 0.255). There were no condition, time, or condition x time interaction effects identified for average misses (p ≥ 0.138), hit rate (p ≥ 0.057), shots per second (p ≥ 0.247), median time to hit (p ≥ 0.220), and shot precision (p ≥ 0.145). CONCLUSION These preliminary findings indicate that, compared to normoxia, 90 min of moderate hypoxia does not elicit measurable alterations in metrics of a first‐person shooter stylistic cross‐domain cognitive ass...

INTRODUCTION The effect of acute hypoxia on cognition is a function of the magnitude and duration of hypoxia and the assessed cognitive domain. For example, there is little effect of acute exposure to a fraction of inspired oxygen (FiO2) of 11‐14% on simple cognitive tasks. However, performance on more complex tasks, such as those involving aspects of executive function, can be hindered under the same conditions. These possible cognitive changes underlie the use of supplemental oxygen when flying in unpressurized aircraft for >1 h at altitudes >3048 m. People often cannot recognize their own symptoms of hypoxia. Thus, there is a need for tools that can identify detrimental cognitive effects of hypoxia. One potential solution is gamified cognitive assessments, where electronic games can provide targeted metrics of cognitive function, such as working memory and selective attention. However, whether gamified assessments of executive function are sensitive to moderate hypoxia is unknown. PURPOSE Test the hypothesis that moderate normobaric hypoxia decreases gamified working memory and selective attention performance. METHODS Following three consecutive days of practice, twenty‐one healthy adults (27 ± 5 y, 9 females) completed five 1 min rounds of the tablet‐based games Capacity and Multitracker (Statespace Labs, Inc.) at Baseline and 60 and 90 min after exposure to a chamber with an FiO2 = 14.0 ± 0.2% (hypoxia) and FiO2 = 20.6 ± 0.3% (normoxia). Both conditions were completed on the same day and were administered in a single‐blind, block randomized manner. Capacity (a visuospatial working memory game) and Multitracker (a multiple object tracking and selective attention game) in which participant performance is measured as median time to hit (s), correct trials (#), incorrect trials (#), proportion of correct trials (%), and mean difficulty (#). Arterial oxyhemoglobin saturation was estimated via forehead pulse oximetry (SpO2). Data were analyzed using ANCOVA with a covariate of Baseline and are presented as adjusted means (95% confidence intervals). RESULTS Compared to normoxia (98 ± 1%), SpO2was lower (p < 0.001) at 60 (91 ± 3%) and 90 (90 ± 3%) min of hypoxia. For Capacity, there were no condition, time, or interaction effects for the median time to hit (p ≥ 0.268), correct trials (p ≥ 0.310), incorrect trials (p ≥ 0.258), proportion of correction trials (p ≥ 0.272), and mean difficulty (p ≥ 0.761). For Multitracker, a main effect of condition was identified for mean difficulty (p = 0.008), such that, independent of time, the mean difficulty achieved was higher in normoxia [249 (235, 264) vs. 244 (233, 254)]. A main effect of time was identified for correct trials, such that, independent of condition, the number of correct trials increased from 60 [28.5 (27.6, 29.3)] to 90 [28.7 (28.0, 29.4)] min. There were no condition, time, or interaction effects for the median time to hit (p ≥ 0.584), incorrect trials (p ≥ 0.248), and proportion of correction trials (p ≥ 0.162). CONCLUSION These preliminary findings indicate ...

INTRODUCTION: Indigenous diving populations like the Bajau have extraordinary breath-hold abilities, which includes tolerating arterial partial pressures that are low in oxygen and high in carbon dioxide. While these populations have genetic adaptations that improve their hypoxemic and hypercapnic tolerances, other populations can improve these tolerances through training adaptations that allow for increases in oxygen carrying and pH buffering capacities. For example, two weeks of residence at altitude stimulates increases in hemoglobin mass (Hbmass) via erythropoiesis, while completing apnea training daily for 14 days elevates reticulocyte count. However, it is unclear whether relatively brief (<4 h) daily exposures to moderate hypoxia and maximal apneas, such as may occur with diving, meaningfully stimulates erythropoiesis in people without breath hold diving experience or ancestry. PURPOSE: Test the hypothesis that 14 d of moderate hypoxia for 3 h/d and 10 maximal apneas/d augments circulating Hbmass and reticulocyte count. METHODS: Eighteen healthy adults (27±6 y; 11 women) completed 14 days of training within a 16-day period. Training days consisted of 10 maximal apneas and 3 h of exposure to normobaric hypoxia (FiO2=0.14). Average apnea duration was recorded and presented as mean ± SD. On Days 1, 7, and 14 subjects completed a carbon monoxide rebreathe procedure pre and post training to estimate Hbmass (n=11) and provided a venous sample of blood for reticulocyte count (n=14) pre and post training. Repeated measures linear mixed models were used to assess change in Hbmass and reticulocytes from Day 1. These data are presented as mean difference (diff.) from Day 1 and 95% confidence intervals. RESULTS: Average apnea duration increased from Day 1 (69±29 s) to Day 7 (83±30 s, p<0.01) and to Day 14 (90±29 s, p<0.01), but there was no change from Day 7 to Day 14 (p=0.26). There was no interaction (p=0.79) or main effects of Day (p=0.54) or pre/post training (p=0.94) on Hbmass. Specifically, pre training Hbmass did not differ from Day 1 on Day 7 (mean diff. 23 (–131, 178) g, p=0.91) or Day 14 (mean diff. 5 (–154, 164) g, p=0.99) and post training Hbmass did not differ Day 1 on Day 7 (mean diff. 29 (–152, 210) g, p=0.90) or Day 14 (mean diff. 5 (–154, 164) g, p=0.99). An interaction effect (p=0.02) for reticulocyte count, showed a mean increase from pre to post training on Day 14 (mean diff. 9 (3, 15) #·μL-1, p<0.01). However, there was no change in reticulocyte count between Days (p=0.53). Pre training Day 1 reticulocyte count did not differ from Day 7 (mean diff. -3 (–9, 4) #·μL-1, p=0.48) or Day 14 (mean diff. -2 (–9, 6) #·μL-1, p=0.79). CONCLUSION: Fourteen days of brief daily exposures to moderate hypoxia and maximal apnea training did not augment circulating Hbmass or reticulocytes. Supported by Office of Naval Research award N00014-20-1-2593. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

This study tested the hypotheses that (1) spleen volume increases during head out water immersion (HOWI) and returns to pre HOWI values post diuresis, and (2) the magnitude of apneas induced spleen contraction increases when pre apneas spleen volume is elevated. Spleen volume was measured pre- and post- a set of five apneas in twelve healthy adults (28 ± 5 y, 3 females) before, during (at 30 and 150 min) and 20 min following temperate temperature (36 ± 1°C) HOWI. At each timepoint, spleen length, width, and thickness were measured via ultrasound and spleen volume was calculated using the Pilström equation. Compared to pre HOWI (276±88 ml), spleen volume was elevated at 30 (353±94 ml, p<0.01) and 150 (322±87 ml, p<0.01) min of HOWI, but returned to pre HOWI volume at post HOWI (281±90 ml, p = 0.58). Spleen volume decreased from pre to post apnea bouts at each timepoint (p < 0.01). The magnitude of reduction in spleen volume from pre to post apneas was elevated at 30 minutes of HOWI (-69±24 mL) compared to pre HOWI (-52±20 mL, p = 0.04) but did not differ from pre HOWI at 150 min HOWI (-54±16 mL, p = 0.99) and post HOWI (-50±18 mL, p = 0.87). Thus, spleen volume is increased throughout 180 minutes of HOWI, and while apneas induced spleen contraction is augmented after 30 minutes of HOWI, the magnitude of spleen contraction is unaffected by HOWI thereafter.