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 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.

Occupational heat stress increases the risk of developing kidney injury (KI), which is due to the development of hyperthermia and/or hypohydration. It is speculated that this KI is caused by a relative mismatch in oxygen supply (i.e., reductions in renal perfusion) and demand (due to increased sodium reabsorption) in the renal tubules. That said, the modulatory role of hydration on renal vascular control during physical work in the heat is largely unknown. Recent observations indicate that ad lib drinking largely prevents hypohydration during simulated occupational heat stress. Thus, we tested the hypothesis that, compared to ad libitum drinking, fluid restriction induces a pro-vasoconstrictor state in the renal vasculature during physical work in the heat.On two occasions, six healthy adults (1 woman) completed 2 h of exercise in a wet bulb globe temperature of 30±0°C, conditions that are commonly experienced by U.S. outdoor workers. Exercise consisted of completing eight circuits involving treadmill walking (10 min) and rowing (5 min) at a workload eliciting an oxygen uptake of 1.2 L/min, the work intensity observed during agriculture work. In the drinking trial (Drink), subjects were provided 237 mL of sport drink every 15 min and drank ad libitum, which is compliant with workplace hydration recommendations. In the fluid restriction trial (NoDrink), no fluid was provided. Rectal temperature and body mass loss were recorded in each trial. Blood pressure and right renal segmental blood velocity (BV, Doppler ultrasound) was measured before, and following 60 and 120 min of exercise. Before and following exercise, a cold pressor test (CPT) was used to assess the renal vasoconstrictor response to sympathetic activation by immersing the subject’s foot in an agitated ice slurry for 2 min. Blood pressure and segmental BV were measured during each minute of the CPT. Segmental artery vascular resistance (VR) was calculated as mean arterial pressure divided by segmental BV. Data presented as mean ± SD.Average rectal temperature was not different between Drink (37.8±0.4°C) and NoDrink (37.9±0.4°C, p=0.517). Body mass loss was greater in NoDrink (3.1±0.7%) vs. Drink (1.8±0.8%, p=0.014). Segmental BV did not change differently between trials (interaction: p=0.651). Segmental VR did not differ between trials before (Drink: 2.7±0.6, NoDrink: 2.5±0.6 mmHg/cm/s) or after 60 (Drink: 2.8±0.7, NoDrink: 2.6±0.6 mmHg/cm/s) and 90 (Drink: 2.5±0.3, NoDrink: 2.3±0.8 mmHg/cm/s) min of exercise (interaction: p=0.988). Peak increases in segmental VR during the CPT did not differ between trials before (Drink: 0.5 ± 0.7, NoDrink: 0.9 ± 0.6 mmHg/cm/s) or after (Drink: 0.4 ± 0.7, NoDrink: 0.4 ± 0.6 mmHg/cm/s) exercise (interaction: p=0.405).These findings preliminarily indicate that fluid replacement does not modify renal vascular control during physical work in the heat. NCT: NCT05458843. Supported by: R01OH011528 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.