Army Policy Research Articles

Cold Habituation Does Not Alter Thermal Responses or Manual Dexterity During Prolonged Cold Air Exposure

Background: Habituation is a pattern of cold acclimatization characterized by attenuated cold defense responses, including a reduction in peripheral vasoconstriction and subsequent increase in skin temperature (TSk) as well as a decrease in shivering thermogenesis. Habituation is achieved through repeated reductions in TSk, rather than deep body core temperature (TC), via exposure to prolonged cold air or brief cold-water immersion. Due to improvements in TSk, enhanced manual dexterity and peripheral cold injury risk reduction are purported benefits of cold habituation. Warfighters frequently operate in cold climates and experience decrements in manual dexterity and strength. These functional losses can negatively impact mission critical tasks and training exercises; however, the effectiveness of cold habituation as a potential countermeasure to alleviate the deleterious effects of prolonged cold exposure on peripheral temperatures, thermal comfort, and hand function is unclear. Purpose: To evaluate the influence of eight consecutive cold air exposures on the thermal (TC and TSk), perceptual (thermal comfort and sensation), and functional (manual dexterity and strength) responses to cold air. We hypothesized that TSk would be higher and perceptual responses and manual dexterity improved, following repeated cold exposure. Methods: Eight young adults (6 M/1 F/1 FTM; 21 ± 2 years; %BF 24.5 ± 7.0) underwent a 2-h cold air exposure (8 °C, ~50% RH) on 8 consecutive days wearing minimal clothing. On Day 0 (baseline exposure ~1 week prior) and Days 1 and 8 of repeated exposure, TC was recorded continuously via a telemetry pill used as a rectal suppository. Extremity (Thand and Tfinger) and mean weighted TSk (MWTSk) from 8 skin sites were recorded continuously. Thermal comfort (TC) and thermal sensation (TS) were recorded at 20 min intervals. Expired gases were collected at 20 min intervals and used to calculate metabolic heat production (MHP). Manual dexterity was assessed using the Purdue Pegboard and Minnesota Manual Dexterity Test (MMDT), and hand strength were measured before and at the end of cold exposure. Results: TC changed across time ( p < 0.05) but did not differ between days ( p > 0.05). MWTSk, Thand, and Tfinger decreased across time ( p < 0.05) but also did not differ between days ( p > 0.05). Mean and minimum whole-body TS and TC were not different between days ( p > 0.05). MHP increased across time ( p < 0.05) but did not differ between days ( p > 0.05). Purdue Pegboard, MMDT task performance, and hand strength did not differ between days ( p > 0.05). Conclusion: Eight consecutive days of cold air exposure does not augment extremity skin temperature, thermal comfort, or manual performance during prolonged cold conditions. Supported by U.S. Army Medical Research and Development Command, Military Operational Medicine Research Program; author views not offcial US Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 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.

Increase in Plasma S100B Concentration Is Associated With Decrements in Spatial Processing During Acute High-Altitude Exposure

Vasogenic edema consequent to blood-brain barrier (BBB) permeability may contribute to cognitive performance decrements during acute exposure to high altitude. S100B is a putative marker of BBB permeability, but S100B responses to high altitude are poorly characterized and the relation to cognitive performance is unknown. To test the hypothesis that S100B increases upon ascent to high altitude and that increase is associated with changes in cognitive performance, 41 healthy Soldiers (mean±SD; age=26±5yr) were tested at their baseline residence (SL, 331m), transported to Taos, NM (2845m), then immediately hiked (n=21) or were driven (n=20) to a high-altitude (HA, 3600m) facility. Plasma S100B was measured at 06:00 throughout the study; twice at SL and again after the first night at HA (16h exposure). The automated neuropsychological assessment metric (ANAM) was administered four times at SL and once at HA to assess sustained attention, working memory, spatial processing, computation, executive function, and reaction time. ANAM performance was assessed using throughput scores, a metric considering both response speed and accuracy. The last SL morning assessment and the HA morning assessment (19h exposure) were used to generate ΔANAM scores. Correlations between ΔS100B and ΔANAM scores were significant for 1 of 9 modules, simultaneous spatial processing (SPD; r=-0.401; p=0.009). S100B increased (5.3%, p=0.02) from SL to HA while SPD scores decreased (8.2%, p=0.05). Using the reliable change index (RCI) to dichotomize individuals into those demonstrating a decrease in performance that exceeded measurement error and day-to-day variability (responders; RCI <-1.64; n=7) and those who did not (non-responders; RCI >-1.64; n=34) revealed that responders experienced a greater increase (+12.3%, p=0.01) in S100B from SL to HA relative to non-responders (+3.4%, p=0.14) Findings suggest that acute exposure to 3600m may increase BBB permeability, as indicated from plasma S100B concentrations, and the increased BBB permeability may be mechanistically associated with spatial processing decrements. Funding: USAMRDC, PRMRP. Authors’ views not offcial U.S. Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 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.

Imparied insulin sensitivity in the early hours following either active or passive ascent to 3600m is associated with acute mountain sickness susceptibility

Reduced insulin sensitivity (a higher glucose level for the same insulin concentration) at baseline residence (BLR) has been associated with increased susceptibility to acute mountain sickness. (AMS) at high altitude (HA). The objective of this study was to determine whether fasting blood glucose (GLU), lactate (LAC) and insulin (INS) were impacted during an active versus passive ascent to 3600m in AMS-susceptible and AMS-resistant individuals. We hypothesized that insulin sensitivity would be reduced at BLR in the AMS-susceptible cohort based on previous research. To test this hypothesis, 78 active-duty Soldiers were tested at baseline residence (BLR), transported to Taos, New Mexico (2,845m), then hiked (n=39) or were driven (n=39) to 3600m, and stayed for four days. AMS-C was assessed using the Environmental Symptoms Questionnaire (ESQ) at HA twice on day 1, five times on days 2 and 3 and once on day 4. If AMS-C was ≥0.7 at any timepoint, individuals were categorized as AMS-susceptible (AMS+, n=33); others categorized as resistant (AMS−, n=45). Fasting rested blood GLU and LAC responses collected at 06:00 were measured using a blood gas analyzer and serum INS responses were measured using an ELISA assay at BLR, HA2 (14-h post-ascent), HA3 (38-h post ascent), and HA4 (62-h post ascent). An additional sample for blood GLU and LAC was collected on HA1 at 18:00 (2-h post ascent). As expected, the active compared to passive ascent group demonstrated an increase (p<0.05) in GLU (113.6±14.3 vs. 101.9±15.1) and LAC (2.56±0.93 vs. 1.73±0.78) on HA1 most likely due to sympathetic stimulation following active ascent. However, differences in fasting GLU and LAC between ascent groups did not persist on HA2 through HA4. There were also no ascent group differences INS in any of the conditions. Fasting GLU levels on HA2 were higher in the AMS+ vs. AMS− cohorts (99.8±9.8 vs 95.3±7.9 mg/dl; p<0.05) but fasting INS levels on HA2 did not differ between cohorts (9.8±5.4 vs.7.1±3.4 mIU/ml; p>0.05) indicating impaired insulin sensitivity in those susceptible to AMS early in the HA exposure. There were no differences, however, in GLU and INS levels between AMS+ vs. AMS− cohorts on BLR, HA3 or HA4. Fasting LAC also demonstrated no differences in any of the conditions in the active vs. passive ascent groups or AMS+ vs. AMS− cohorts. In conclusion, the increase in blood GLU and LAC at HA1 following active compared to passive ascent was expected. Contrary to our hypothesis, however, a reduction in insulin sensitivity was not found in AMS-susceptible individuals at BLR but was found at 14-h post ascent to 3600m and quickly resolved thereafter. The inability to effectively utilize glucose as an O2-effcient fuel in the early hours of HA exposure may contribute to AMS symptoms. USAMRDC. Authors’ views not offcial U.S. Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 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.

Elevated sympathoadrenal response following active ascent to 3,600m is not associated with acute mountain sickness

Previous reports have suggested an increase in plasma epinephrine (EPI) and either an increase, no change or decrease in norepinephrine (NE) following acute (< 4 h) exposure to high altitude (HA). In addition, previous research has demonstrated an exercise-induced increase in EPI and NE during exercise initiated following arrival at HA. Last, some but not others have reported an association between increased sympathoadrenal activity and acute mountain sickness (AMS). We hypothesized that elevated sympathoadrenal activity induced from active ascent on foot to 3,600m may contribute to the development of AMS. Thirty-seven Soldiers (mean ± SD; 6 women; age=25.5±4.9 years) were tested at their baseline residence (BLR; Fort Bliss, TX, 1,190m), transported to Taos, NM (2,845m), then hiked (n=18) or were driven (n=19) to the HA data collection site where they resided for four days (68hrs). AMS Cerebral Factor Score (AMS-C) was determined using the Environmental Symptoms Questionnaire (ESQ-III) recorded twice at HA on day 1 (HA1), five times on days 2 (HA2) and 3 (HA3) and once on day 4 (HA4). If AMS-C was ≥0.7 on any measurement occasion, individuals were categorized as AMS-susceptible (AMS+, n=11) others were AMS-resistant (AMS─, n=26). Plasma EPI (pg/ml) and NE (pg/ml) were measured from venous blood draws at 06:00 at BLR, a non-fasted blood draw at 18:00 following ascent on HA1, and subsequent fasted blood samples at 06:00 on each morning at HA (HA2, HA3, HA4). AMS-susceptibility was not associated with the EPI or NE response in any condition so both cohorts were combined. The EPI response to active vs. passive ascent was similar with an increase (p<0.05) from BLR (28.0±26.8) to HA1 (47.5±40.3) followed by a subsequent decrease (p<0.05) from HA1 to HA2 (28.0±18.6) through HA4 (25.4±16.9). NE, however, increased (p<0.05) only in the active ascent group from BLR (413±216) to HA1 (729±281) and remained stable from HA1 through HA4 (644±192). The passive ascent group demonstrated no change in NE from BLR (327±126) to HA1 (413±181) through HA4 (466±144). NE levels were similar (p>0.05) in the active vs passive ascent group at BLR but higher (p<0.05) in the active ascenders on HA1 through HA4. In conclusion, contrary to our hypothesis, the sympathoadrenal response to HA was not impacted by AMS susceptibility but active ascent induced a greater NE response following ascent and throughout the duration of the HA stay. USAMRDC. Authors’ views not offcial U.S. Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 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.

Pro- and Anti-Inflammatory Responses Following Active and Passive Ascent to 3600 m

Lowlanders who develop acute mountain sickness (AMS) following rapid ascent to high altitude (HA) demonstrate increased levels of both pro-inflammatory (tumor necrosis factor α (TNFα), Interleukin (IL)- 1β, IL-6, IL-8, and IL-17α) and anti-inflammatory biomarkers (IL-10 and IL-1 receptor agonist; IL-1ra). Whether ascending by self-locomotion (i.e., active ascent) modulates these pro- and anti-inflammatory cytokine responses at HA is unknown. We hypothesized a greater pro-inflammatory response in the AMS-susceptible group following active ascent. To test this hypothesis, 78 healthy Soldiers (mean±SD; age, 26±5yr) were tested at baseline residence (BLR), transported to Taos, NM (2845m), then hiked (n=39) or were driven (n=39) to HA (3600m), and stayed for 4 days. AMS-Cerebral factor score (AMS-C) was assessed using the Environmental Symptoms Questionnaire (ESQ) at HA twice on day 1 (HA1). If AMS-C was ≥0.7 at either assessment, individuals were categorized as AMS-susceptible (AMS+; n=24); others were AMS-resistant (AMS−; n=54). Fasting blood samples were taken at 06:00 at BLR, HA2, HA3 and HA4 and analyzed to determine cytokine (TNFα, IL-1β, IL-6, IL-8, IL-10, IL-17α, and IL-1ra) responses following the initial hypoxic insult. Blood values (pg/mL) were log-transformed and adjusted for plasma volume changes from BLR to HA. The active group expended a greater ( p<0.05) amount of energy (745±435 kcal) than the passive group (55±10 kcal) during ascent. There were no differences in biomarkers between ascent groups, so data were combined. In the AMS-susceptible group, IL-17α increased ( p<0.05) from BLR to HA2 (63.3±8.8 to 73.1±8.8, p=0.002) and remained increased at HA3 (70.1±8.8) and HA4 (73.1±8.8). In the AMS-resistant group, IL-17α did not change from BLR to any of the days at HA. Independent of AMS susceptibility, the anti-inflammatory marker IL-1ra increased from BLR to HA2 (63.5±11.4 to 89.9±11.4, p=0.013) and then fell back down to BLR values on HA3 (70.4±11.4, p=0.560) and HA4 (71.8±11.4, p=0.537). When all days were combined, TNFα (+15%, p=0.036), IL-6 (+50%, p=0.042), and IL-10 (+36%, p=0.040) were increased in the AMS-susceptible compared to the AMS-resistant group. IL-1β and IL-8 did not change ( p>0.05) from BLR to any time point at HA in either group. In conclusion, both a robust pro- (TNFα, IL-6, IL-17α) and anti-inflammatory (IL-10) response occurred at HA in those susceptible to AMS most likely due to inflammation following the initial hypoxic insult followed quickly by an anti-inflammatory response. However, ascent strategy on HA1 had no impact on pro- or anti-inflammatory cytokines on days 2-4 at HA. Authors’ views not offcial U.S. Army or DoD policy. Funding: USAMRDC. This is the full abstract presented at the American Physiology Summit 2024 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.

Pioglitazone does not affect exogenous glucose oxidation or metabolic clearance rate during steady-state aerobic exercise at high altitude

Background: Hypoxia-induced insulin insensitivity decreases exogenous glucose oxidation and metabolic clearance rate (MCR, proxy for peripheral glucose uptake) in native lowlanders exercising during the initial hours of high-altitude (HA) exposure compared sea level. These data suggest that administering an insulin sensitizing drug before HA exposure may increase exogenous glucose oxidation rate by stimulating peripheral glucose uptake. Objective: To compare the effects of pioglitazone (PIO) and placebo (PLA) on exogenous glucose oxidation and MCR during steady-state aerobic exercise at HA. We hypothesized that exogenous glucose oxidation and MCR would be higher with PIO than PLA. Methods: Using a randomized, crossover design, native lowlanders (n = 7 males, mean ± SD, age: 23 ± 6 y, body mass: 84 ± 11 kg) consumed 145 g (1.8 g/min) of glucose while performing 80-min of metabolically-matched (1.43 ± 0.16 VȮ2 L/min) treadmill exercise at HA (460 mmHg) after being administered PIO (15 mg) or PLA (microcrystalline cellulose pill) daily for five days. Substrate oxidation and glucose turnover were determined using indirect calorimetry, oral 13C-glucose and [6,6-2H2]-glucose primed, continuous infusions. Results: Exogenous glucose oxidation rate was not different between PIO (0.31 ± 0.03 g/min) and PLA (0.32 ± 0.09 g/min). Total carbohydrate oxidation with PIO (1.65 ± 0.22 g/min) was the same as PLA (1.68 ± 0.32 g/min). There were no treatment effects on glucose rate of appearance (PIO: 2.46 ± 0.27, PLA: 2.43 ± 0.27 mg/kg/min) disappearance (PIO: 2.19 ± 0.17, PLA: 2.20 ± 0.22 mg/kg/min), and MCR (PIO: 1.63 ± 0.37, PLA: 1.73 ± 0.40 mL/kg/min). Conclusion: These data do not support our hypothesis that exogenous glucose oxidation during exercise at HA can be restored through the short-term administration of PIO. Findings from this study may suggest that hypoxia-induced insulin resistance may be a symptom and not the primary etiology of dysregulated glucose metabolism during acute HA exposure. Supported by MOMRP; authors’ views not offcial US Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 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.

Warfare under scrutiny: British public perspectives of soldiers, and tactical behaviours in operation HERRICK

ABSTRACT The importance of civil society to the military is well documented in UK Defence and Army policy, doctrine, and concepts. Civilian and military analyses commonly focus on the policy dimensions of the relationship whereby British civil society is deemed important for the legitimacy of campaigns. This research paper draws together less-common references from across the literature about a more direct impact that societal perspectives can have on deployed land operations and extends them through new archival research. It uses the military’s experience in Helmand to propose a model of “societal operational influence.” In this model tactical behaviours across the conceptual, physical, and moral components of Task Force Helmand’s fighting power altered in response to the military’s interpretation of public opinion about soldiers, which arguably resulted in changes to its culture.

Interpreting Empire: English, U.S. Advisors, and Interpreters in the Korean War

Abstract The Korean Military Advisory Group (kmag) – a relatively small unit of U.S. Army officers – developed, advised, and exerted influence over the Republic of Korea (rok) Army from its inception in 1946 through the signing of the Korean War armistice in July 1953. kmag advisors served down to the battalion level, working alongside South Korean counterparts in rok Army units, causing language to be a crucial battlefield that animated American anxieties and negative racial assumptions. In a moment when few, if any, American military officers had Korean language proficiency, South Koreans with English-language capability became essential to the U.S. foreign policy project in South Korea. South Korean interpreters, too, amplified racialized concerns about the trustworthiness of rok soldiers. This article places American understandings of language in kmag affairs into critical focus, highlighting the cultural assumptions that came to effect material change in U.S. Army policy towards the rok Army before and during the Korean War. It shows how language was a means of U.S. penetration into the fabric of Korean state and society, but also a target of imaginations that disturbed the U.S. military because of its consistent reminder of how language could resist American suggestion.

Changes In Leukocyte Distribution And T-cell Reactivity During Initial Military Training

PURPOSE: Physiological stressors present during initial military training (IMT) may increase risk of illness and infection by suppressing immune function. This study aimed to improve insight into those relationships by characterizing changes in markers of innate and adaptive immune function during IMT. METHODS: Sixty U.S. Army infantry recruits (97% male) provided fasted blood and saliva samples at the beginning (PRE; week 0) and end (POST; week 22) of IMT. Peripheral leukocyte distribution was measured by flow cytometry, and T-cell and innate cell reactivity were measured by mitogen (anti-CD3/CD28 or lipopolysaccharide (LPS))-stimulated cytokine profiles in 48-hr whole blood culture. Latent reactivation of Epstein-Barr virus (EBV), varicella-zoster virus (VZV), and herpes simplex virus 1 (HSV1) was measured in saliva by qPCR. RESULTS: Lymphocyte percentage increased (+28%) while granulocytes (-15%) and monocytes (-13%) decreased PRE to POST (all P < 0.01). This lymphocytosis was driven by an increase in natural killer cells (+19%), and accompanied by decreases in B-cells (-9%) and T-cells (-5%; all P < 0.01). Within T-cell subsets, terminally differentiated CD4+ (+22%) and CD8+ (+30%) cells increased while those of effector memory CD4+ cells (-11%), effector memory CD8+ cells (-54%) and central memory CD8+ cells (-15%) decreased (all P ≤ 0.02). T-cell production of most measured cytokines following anti-CD3/CD28 stimulation increased from PRE to POST (P < 0.05). Conversely, stimulation with LPS resulted in reduced production of most measured cytokines (P < 0.05). Prevalence of EBV reactivation was higher POST (n=30) relative to PRE (n=19; P = 0.01), but neither VZV nor HSV1 reactivation was observed at either time point. CONCLUSION: Lymphocytosis, maturation of CD4+/CD8+ T-cell subsets, and heightened T-cell reactivity at POST collectively suggests an appropriate immune response to pathogen challenges during IMT. Though EBV reactivation was increased at POST, no evidence of VZV or HSV1 reactivation, which are more common during severe stress, was observed. Findings suggest that EBV reactivation during IMT was likely appropriately controlled in recruits and that immune-competence was relatively uncompromised at the end of IMT. Supported by USAMRDC. Authors’ views not official DoD or Army policy

Ventilatory And Cardiovascular Acclimatization Remains Unchanged Following Active Versus Passive Ascent To 3600 m

PURPOSE: Sympathetic stimulation, induced by intense endurance exercise, may alter the process of ventilatory and cardiovascular acclimatization. The purpose of this study was to examine the magnitude and time course of ventilatory and cardiovascular acclimatization following active and passive ascent to 3600 m. METHODS: Forty-one healthy unacclimatized Soldiers (n = 41, mean ± SD; age = 26 ± 5 yr; body weight = 83.5 ± 11.6 kg; VO2max = 47.9 ± 5.5 ml · kg−1 · min−1) were tested at sea level (SL) in Ft. Leonard Wood, MO, flown to Taos Ski Valley, NM (2845 m) where they arrived around 1400 m, and then either hiked (n = 21; 5.0 km, 15.5% mean grade) or were driven (n = 20; 30-min drive) to a high altitude (HA) ski patrol facility located at 3600 m. Energy expenditure during ascent was measured with an ankle accelerometer. Portable real-time capnography was used to measure end-tidal carbon dioxide partial pressure (PETCO2) after 10 min of sitting at SL, after 19 h (HA2), 43 h (HA3), and 67 h (HA4) at HA. Mean arterial blood pressure (MAP), heart rate (HR), and pulse arterial oxygen saturation (SpO2) were measured at the same time (~0900) as PETCO2 RESULTS: The active group expended a greater (P < 0.05) amount of energy (745 ± 435 kcal) than the passive group (55 ± 10 kcal) during ascent. There were no differences between groups in terms of ventilatory and cardiovascular acclimatization so data were combined. Resting PETCO2 (mmHg) decreased (P < 0.05) from SL (37.5 ± 3.35) to HA2 (33.5 ± 3.71), remained stable from HA2 to HA3 (33.8 ± 3.73) and decreased further (P < 0.05) from HA3 to HA4 (30.8 ± 4.9). Resting MAP and HR, respectively, increased (P < 0.05) from SL (89.9 ± 6.9 mmHg; 65.7 ± 9.8 bpm) to HA2 (100.0 ± 7.2 mmHg; 78.7 ± 10.1 bpm), MAP decreased (P < 0.05) but HR remained unchanged from HA2 to HA3 (96.9 ± 7.1 mmHg; 78.5 ± 15.4 bpm), and both stayed consistent from HA3 to HA4 (98.1 ± 7.1 mmHg; 80.1 ± 12.9 bpm). Resting SpO2 (%) decreased (P < 0.05) from SL (97.6 ± 1.3) to HA2 (88.7 ± 3.1), increased (P < 0.05) from HA2 to HA3 (89.7 ± 2.9), and remained unchanged from HA3 to HA4 (89.1 ± 3.2). CONCLUSION: Ventilatory and cardiovascular acclimatization occurred at HA but sympathetic stimulation and increased metabolic rate due to the active ascent did not change the magnitude or time course of either of these processes. Authors’ views not official U.S. Army or DoD policy. Funding: USAMRDC

Dynamic Relationship Between Heart Rate And Core Temperature During Exercise-heat Stress And Iced Sheet Cooling

Athletes, military personnel, and others who perform physical work in the heat are at risk for exertional heat illness due to the combined presence of high ambient temperature and elevated metabolic heat production. Cooling with iced sheets is an immediate treatment used by the military and others to rapidly decrease body temperature in a field setting. Physiologically, increases in core temperature (Tc) and heart rate (HR) contribute to the cardiovascular strain associated with exercising in the heat. This increased HR is linked to the combination of metabolic (exercise) and thermal (environmental) requirements for systemic blood flow (i.e. cardiac output). Mechanisms include both autonomic neural and local influences of temperature on the heart. PURPOSE: To quantify the dynamic response of HR to changes in Tc during exercise in the heat and subsequent iced sheet cooling. We hypothesized that for a given Tc, HR would be higher during increases in Tc compared to during decreases in Tc. METHODS: Nine healthy (n = 8 males) volunteers (age 25 ± 6 y, ht 176.9 ± 9.7 cm, wt 86.6 ± 15.9 kg, body surface area 2.03 ± 0.2 m2) participated in a exercise-heat stress protocol consisting of up to 180 minutes of treadmill walking (3.5 mi·hr-1, 5% grade, in 40 °C, 30% RH). Volunteers then lay supine and underwent iced-sheet cooling (ISC) (bed sheets placed in 5-gallon ice buckets with 2/3 ice, 1/3 cool water; rotated out with pre-soaked sheets every 3 min) until Tc decreased to ≤38.0 °C. Individual changes in HR during both exercise and cooling were compared at Tc = 38.2 and 38.6 °C using 2-way analysis of variance. RESULTS: HR was significantly higher for a given Tc when Tc was increasing during exercise compared to when it was decreasing during cooling. For example, during exercise, HR was 150 ± 13 bpm at Tc = 38.2 °C and 157 ± 9 bpm at Tc = 38.6 °C, while during cooling, HR was 96 ± 10 bpm at Tc = 38.2 °C and 104 ± 14 bpm at Tc = 38.6 °C (both p < 0.01). CONCLUSION: These data confirm the efficacy of iced-sheet cooling for decreasing cardiovascular strain associated with heat-related events. The fact that cooling resulted in lower HR for a given Tc suggests that exercise associated autonomic reflexes predominated over direct effects of temperature on sinus node control of HR. Supported by USAMRDC; author views not official US Army or DoD policy.

Active Ascent Does Not Alter Cognitive Performance Compared To Passive Ascent To 3600 m

PURPOSE: Cognitive performance is known to decrease following acute exposure to high altitude (HA) but it is unknown whether active ascent affects that response. The purpose of this study was to examine changes in cognitive performance following active and passive ascent to 3600 m. METHODS: Forty-one healthy unacclimatized Soldiers (n = 41, mean ± SD; age = 26 ± 5 yr; body weight = 83.5 ± 11.6 kg; VO2max = 47.9 ± 5.5 ml · kg−1 · min−1) were tested at sea level (SL) in Ft. Leonard Wood, MO, flown to Taos Ski Valley, NM (2845 m) where they arrived around 1400 and then either hiked (n = 21; 5.0 km, 15.5% mean grade) or were driven (n = 20; 30-min drive) to a HA ski patrol facility located at 3600 m where they resided for the next 4 days. Energy expenditure during ascent was measured using an ankle accelerometer (Actical, Respironics, Inc.). Six cognitive modules (simple reaction time (SRT), match to sample (M2S), mathematical processing (MTH), procedural reaction time (PRO), simultaneous spatial processing (SPD) and simple reaction time 2 (SR2)) were administered using the Automated Neuropsychological Assessment Metrics in the morning (~0900) four times at SL, and following ~19 h at HA (HA2), and ~ 43 h at HA (HA3). All cognitive modules demonstrated no difference between the third (am) and fourth (pm) administrations at SL so the 3rd administration was used for the baseline record. RESULTS: The active group expended a greater (P < 0.05) amount of energy (745 ± 435 kcal) than the passive group (55 ± 10 kcal) during ascent. There were no differences in cognitive performance between groups so data were combined. The SRT decreased (P < 0.05) from SL (203 ± 28) to HA2 (192 ± 34) and increased (P < 0.05) from HA2 to HA3 (204 ± 29). PRO decreased (P < 0.05) from SL (97.5 ± 13.7) to HA2 (91.2 ± 14.9) and increased (P < 0.05) from HA2 to HA3 (96.1 ± 11.3). The SRT2 decreased (P < 0.05) from SL (195 ± 29) to HA2 (179 ± 46) and remained unchanged from HA2 to HA3 (188 ± 34). There were no changes in M2S, MTH, and SPD from SL to HA2 or HA3. CONCLUSION: Active compared to passive ascent did not impact cognitive performance at HA but reaction time whether simple, procedural, or repeated decreased on HA2. Both SRT and PRO recovered on HA3 but SR2, a measure of cognitive fatigue, did not recover. Authors’ views not official U.S. Army or DoD policy. Funding: USAMRDC

Foreign Policy of the Ukrainian State Based on the Diary of Pavlo Skoropadskyi

The struggle of the Ukrainian people for independence during the war of national liberation of 1917-1921 is an important period in the history of Ukraine and is relevant today. One of the most prominent figures of this period is P. Skoropadskyi, who made many important political decisions during his rule. The then Ukrainian State pursued an active foreign policy, the investigation of which is relevant for historians, for the purpose of a broad and objective study of this period, and for diplomats who, based on the experience of the past, determine the current geopolitical course of Ukraine. The purpose of the study is an in-depth analysis of the foreign policy of the Ukrainian State, based on the memoirs of P. Skoropadskyi. When writing the paper, the following methods were used: analysis, comparison, specification and generalisation of information. Based on the findings of the study, the following conclusions were drawn: the foreign policy of the then Ukraine and the Hetman's government was determined by the terms of the Treaty of Brest-Litovsk; most of all, the Ukrainian State cooperated with Germany, which had an impact on the course of internal political processes. The study discussed in detail the activities of the Germans in the context of the creation of the Ukrainian army and land policy. The issue of whether this cooperation can be considered an occupation was also considered. In addition, Ukraine's international relations with such states and regions as Romania, Bolshevik Russia, Crimea, and Kuban were considered. In the course of the study, in addition to the actual material, the opinions and plans of P. Skoropadskyi's foreign policy activities were considered. The paper outlines the ideas of Hetman and creates the basis for further research on the history of external relations of this period. This study also touched upon an important topic that few researchers had previously considered, namely the problem of relations between Hetman's government and the Entente

Associations of Low-Inflammatory Dietary Patterns With Psychological Health and Wellbeing During Weight Loss in Military Family Dependents

ObjectivesEmerging evidence suggests that anti-inflammatory dietary patterns may improve depression, stress, and quality of life. Similar benefits are observed during weight loss interventions; however, the effect of combining these dietary patterns with weight loss is not clear. We evaluated the association between dietary inflammation and measures of psychological health in female military dependents with overweight and obesity during a behavioral weight loss intervention. MethodsParticipants (n = 120) received a 6-month intervention recommending dietary patterns with an anti-inflammatory profile. An energy-adjusted dietary inflammatory index (DII) score was calculated from 28 food components collected using 3 interviewer-administered multiple-pass 24-hour recalls at each study time point. A negative score indicates a lower-inflammatory dietary pattern, and a positive score indicates a pro-inflammatory pattern. Self-reported symptoms of depression, stress, general health, vitality, and psychological quality of life were measured by validated questionnaires. Multivariable linear mixed models were used to assess the association between 6-month changes in DII and each outcome and were adjusted for age, ethnicity, military rank of spouse, body weight, and physical activity. ResultsOn average, females were 42.2 ± 11.8 years old with a body mass index of 34.9 ± 6.4 kg/m2. The average DII score was 0.07 (range: –4.3, 3.0) at baseline. Six-month improvements in DII scores (i.e., for a 1-unit reduction) were associated with fewer self-reported symptoms of depression (β: –0.87; 95% confidence interval: –1.43, –0.31; P = 0.003) and stress (–0.85; –1.44, –0.26; P = 0.005), as well as higher general health (0.57; 0.23, 0.91; P = 0.001), vitality (0.45; 0.12, 0.77; P = 0.008), and psychological quality of life (0.33; 0.11, 0.55; P = 0.004). No significant associations between weight loss or physical activity and any outcome were observed in these models that included the DII. ConclusionsAnti-inflammatory dietary patterns are associated with beneficial effects on a range of psychological health and wellbeing measures independent of weight loss. Funding SourcesJean Mayer USDA Human Nutrition Research Center on Aging Doctoral Scholarship; Department of Defense (DoD) grant W81XWH-14–2-0005 (SBR). Author views do not reflect official DoD or Army policy.

Inter-individual Variability in Gut Microbiota Composition Is Associated With Changes in the Fecal Metabolome of Individuals Consuming a Military Ration Diet

ObjectivesThe fecal metabolome provides a functional readout of interactions between host, diet and the gut microbiota that may help identify gut microbiota-derived compounds associated with health outcomes. This study aimed to determine associations between inter-individual variability in gut microbiota composition, diet-induced changes in the fecal metabolome and gastrointestinal symptoms in adults consuming a diet consisting solely of military rations. MethodsSecondary analysis of a randomized-controlled trial in which 54 healthy adults (32 ± 14 yr, BMI 26 ± 3 kg/m2) were randomly assigned to consume their usual diet (Control) or a provided diet of Meal, Ready-to-Eat military rations (MRE) for 3wk. Fecal microbiota composition was measured by 16S rRNA sequencing and the fecal metabolome by untargeted UPLC-MS/MS at baseline and post-intervention. Self-reported gastrointestinal symptoms were measured weekly using the Irritable Bowel Severity Scoring System (IBSSS). ResultsPrincipal coordinates analysis of baseline gut microbiota composition separated MRE participants into two clusters determined primarily by ratio of Bacteroides to Prevotella (HIGH (n = 17) or LOW (n = 10)). Random Forest classification of changes in the fecal metabolome within Control, HIGH, and LOW produced error rates of 7%, 18% and 100%, respectively, suggesting a more discriminant metabolome response in HIGH than LOW. Between-group differences in 153 metabolites were detected by ANOVA (FDR <0.20). Among those, 39 identified and 20 unidentified metabolites demonstrated an association with the gut microbiota (HIGH vs. LOW, P < 0.05). Compounds within xenobiotic, peptide/amino acid, and lipid metabolism pathways comprised 29 of the microbiota-associated metabolites. Changes in microbiota-associated metabolites were not correlated with changes in IBSSS scores. ConclusionsChanges in the fecal metabolome of individuals consuming a short-term military ration diet are associated with inter-individual variability in gut microbiota composition, but changes in microbiota-associated fecal metabolites do not appear to impact gastrointestinal symptoms. Funding SourcesMilitary Operational Medicine Research Program. DisclaimerAuthors’ views do not reflect official DoD or Army policy.

High And Standard Free-form EAA Intake Equally Stimulate Muscle Protein Synthesis During Moderate Energy Deficit

BACKGROUND: Muscle protein synthesis (MPS) is regulated by essential amino acid (EAA) intake, postprandial extracellular EAA concentrations, and exercise. During energy balance, consuming approximately 0.10-0.14 g EAA/kg/meal (0.25-0.30 g protein/kg/meal) optimally stimulates MPS after exercise. However, EAA requirements are increased during energy deficit, and whether consuming EAA beyond 0.10-0.14 g/kg/meal further stimulates MPS during energy deficit is unknown. PURPOSE: Determine the effects of standard and high EAA intake on resting and post-resistance exercise MPS during moderate energy deficit. METHODS: Nineteen males (mean±SD; age: 22.9±5y; BMI: 25.4±2.7kg/m2) completed a randomized, double-blind crossover study consisting of two, 5d periods of controlled energy deficit (30±4%), separated by a 14d washout. At the end of each energy deficit period, MPS was determined at rest (postabsorptive and postprandial) and post-resistance exercise (postprandial) using a unilateral resistance exercise model and primed, constant 2H5-phenylalanine infusions. Drinks providing standard (0.10g/kg/meal, 7.87±0.87g) and high (0.30g/kg/meal, 23.5±2.54g) EAA amounts were consumed post-exercise. Circulating EAA concentrations were measured throughout each infusion. RESULTS: Postabsorptive MPS at rest was not different (p=0.71) between standard (0.047±0.3%/h) and high (0.045±0.02%/h). In the postprandial state, and independent of EAA, MPS at rest (standard, 0.055±0.01%/h; high, 0.061±0.02%/h) and post-exercise (standard, 0.055±0.01%/h; high, 0.065±0.02%/h) was greater than postabsorptive MPS at rest (fed state main effect, p=0.019 and p=0.005). Postprandial MPS at rest and post-exercise did not differ (p=1.0). EAA concentrations were greater in high (peak: 2915±569μmol/L; AUC: 228485±54783μmol/L/240min) than standard (peak: 1843±497μmol/L; AUC: 75727±32254μmol/L/240min; both, p=0.001). CONCLUSION: Despite greater increases in extracellular EAA concentrations for high versus standard EAA intakes and the mechanical stimulus exerted by exercise, the stimulatory effect of varying doses of free-form EAA on MPS are equivalent during moderate energy deficit. Supported by USAMRDC; authors’ views not official U.S. Army or DoD policy.

Mood State Is Related To Acute Mountain Sickness At Both 3000m And 4050m Altitude

PURPOSE: The purpose of this study was to further explicate the relationship between changes in mood states, assessed using the Automated Neuropsychological Assessment Metrics Mood Scale (ANAM-MS), and severity of acute mountain sickness (AMS) without the confounding factors of acetazolamide, climbing rate and environmental conditions. METHODS: Nineteen healthy lowlanders (16 men, 3 women; mean±SE; 22 ±1yr, 76.6 ±3.1 kg, 173.2 ±2.1cm, 46.0 ±1.2 ml · kg−1 · min−1) were randomly exposed to either 3000m (526mmHg) or 4050m (460mmHg) in a hypobaric chamber for 20h. Seven mood states (anger, anxiety, happiness, fatigue, depression, restlessness, and vigor) were assessed using the ANAM-MS; a series of 42 questions answered on a 0-6 Likert Scale. AMS severity was assessed using the AMC-Cerebral Factor Score (AMS-C) of the Environmental Symptoms Questionnaire. Both tests were administered on 8 occasions at sea level (SL), and after 2h and 20h at each altitude (HA2 and HA20). The SL baseline scores for ANAM-MS and AMS-C were calculated as the mean of the 7th (morning) and 8th (afternoon) assessments. RESULTS: There were no differences between altitude groups in mood at SL, HA2 or HA20 so data were combined. There was differences between altitude groups in AMS-C score so data was analyzed separately. No mood state changed significantly from SL to HA2. However, fatigue and restlessness increased (P<0.05) from SL (0.57 ±0.13; 0.07 ±0.03) to HA20 (1.41 ±0.32; 0.52 ±0.20), respectively. In addition, vigor decreased (P<0.05) from SL (1.97 ±0.30) to HA20 (0.88 ±0.21). Happiness, anxiety, depression and anger did not change over time. AMS-C was elevated (P<0.05) at 4050m (1.82 ±0.27) compared to 3000m (0.22 ±0.29) at HA20. Restlessness (r=0.66; P=0.037) and anxiety (r=0.65; P=0.044) correlated with AMS-C at HA20 in the 4050m group. Fatigue (r=0.77; P<0.016) and anger (r=0.95; P=0.0001) correlated with AMS-C at HA20 in the 3000m group. CONCLUSION: ANAM-MS ratings of fatigue, restlessness and decreased vigor emerge as low as 3000m due to hypobaric hypoxia alone. Mood disturbances were related to AMS severity; subjects with the highest ratings of fatigue and anger at 3000m, and restlessness and anxiety at 4050m possessed the highest AMS-C scores in their respective groups. Authors’ views not official U.S. Army or DoD policy. Funding: USAMRDC

Impact Of Heat Acclimation On Steady-State Exercise And Time-Trial Performance In Hypobaric Hypoxia (3500m)

Heat acclimation (HA) has been reported to improve endurance exercise performance in normobaric hypoxia. However, the impact of prior HA on exercise performance in hypobaric hypoxia (HH) is unclear. PURPOSE: To determine whether HA alters steady-state (SS) exercise responses and time-trial (TT) cycle performance during a 30 hour exposure to HH. METHODS: Thirteen sea level (SL) resident men (mean ± SD; age: 21 ± 3 years; height: 173 ± 8 cm; weight: 75 ± 12 kg; SL cycle ergometer VO2peak: 43 ± 5 ml·kg-1·min-1) participated in two 30 hour HH exposures in a hypobaric chamber (496mmHg or ~3500m, 20°C, 20% RH). The HH exposures were separated by a 14 day washout period during which volunteers completed an 8-day exercise-HA protocol (2 hours of treadmill walking: 5km·h-1, 2% grade; 40°C, 40% RH). During each HH exposure, volunteers completed 30 min of SS exercise followed by a 15 min cycle TT at ~2 and 24 hours of exposure. SS exercise consisted of cycling at ~50% SL VO2peak while gas exchange (oxygen consumption (VO2), minute ventilation (VE), end tidal partial pressure of oxygen (PETO2)), and oxygen saturation (SpO2) were recorded. For the TT, volunteers completed as much work (kJ) as possible in 15 min, with heart rate (HR), SpO2, and Rating of Perceived Exertion (RPE, Borg Scale) recorded at the end of exercise. A two way repeated measures ANOVA was used to compare the effects of condition (Pre HA and Post HA) and time (~2 and 24 hours). RESULTS: There were no condition x time interaction effects among the SS or TT variables. For main effect of condition, from Pre HA vs. Post HA, SS VO2 tended to be lower (1.63 ± 0.00 L·min-1 vs. 1.60 ± 0.01 L·min-1; p = 0.05), PETO2 was higher (75.7 ± 1.0 mmHg vs. 76.8 ± 0.7 mmHg; p < 0.01), and VE and SpO2 did not differ (p > 0.05 for both). For the TT, there was no main effect of HA on total work completed (106.8 ± 23.0 kJ vs. 103.8 ± 21.3 kJ), HR (159 ± 13 bpm vs. 158 ± 13 bpm), SpO2 (83 ± 3% vs. 83 ± 3%), or RPE (17 ± 2 vs. 17 ± 2) (p > 0.05, for all). CONCLUSIONS: Our results suggest that although HA may augment some aspects of ventilation during low-intensity SS exercise, exercise performance measured by a 15 min cycle TT in HH is not affected by HA. Supported by USAMRDC; author views not official US Army or DoD policy

Inter-individual Variability In Rate Of Heat Acclimation Using A Standard, Fixed Intensity Protocol

In combination with increases in core temperature (Tc) during acute exercise in the heat, progressive increases in heart rate (HR) contribute to increased cardiovascular strain as compared to the same exercise performed in cooler conditions. It is well-established that heat acclimation (HA), defined by both thermal and cardiovascular adaptations (lower Tc and HR), is achieved within ~7 to 10 days of repeated exercise for 60-120 min or more in the heat. More recent research indicates that HA can be achieved in <7 days, also referred to as short-term heat acclimation (STHA). PURPOSE: To quantify the occurrence and magnitude of STHA in a group of young healthy males participating in a standard, 8-day military HA protocol. We hypothesized that some but not all volunteers would achieve STHA. METHODS: Thirteen healthy male volunteers (age 21 ± 3 yrs, ht: 173 ± 8 cm, wt: 75.1 ± 12.2 kg) participated in an 8 day exercise-heat acclimation protocol (120 minutes of treadmill walking: 3.1 mi·hr-1, 2% grade, in 40°C, 40% RH). Tc and HR were recorded every 5 minutes. Pre-and post-exercise nude body-weight (corrected for urine output) were used to calculate total body sweat rate (SR). Individual and group mean (ANOVA) changes in final Tc, HR, and SR were compared across Days 1, 5, and 8 of HA. The criteria for achievement of HA were ΔTc during exercise ≤ 0.9 °C and ΔHR ≤ 33 bpm, which were based on average values attained at Day 8. RESULTS: Group mean Tc (Day 1: 38.1 ± 0.34 vs. Day 5: 37.9 ± 0.3 vs. Day 8: 37.8 ± 0.3°C) and HR (Day 1: 134 ± 17 vs. Day 5: 122 ± 13 vs. Day 8: 121 ± 13 bpm) were significantly decreased by Day 5 (p<0.05) and did not decrease further by Day 8 (p>0.05). Using our criteria for achieving HA, 31% (4/13) of the volunteers achieved HA on Day 5. SR was not different across time points (Day 1: 860 ± 148 vs. Day 5: 908 ± 210 vs. Day 8: 873 ± 203 ml·hr-1; p>0.05). CONCLUSIONS: These data suggest that during a standard fixed-intensity heat acclimation protocol, about one third of the volunteers will achieve STHA with no further change in Tc or HR responses beyond Day 5. Future research should evaluate the mechanisms contributing to the variability of achieving STHA. Supported by USAMRDC; author views not official US Army or DoD policy.

Is Normobaric Hypoxia Effective For Sustaining Previously Acquired Altitude Acclimatization-induced Improvements In Mood State?

PURPOSE: Mood state has been shown to improve with high altitude (HA) acclimatization to 4300 m. The purpose of this study was to determine if these acclimatization effects on mood state persist during reintroduction to 4300 m altitude (RA) after 12 days at sea level (SL) and whether or not normobaric hypoxia (NH) treatment is an effective countermeasure to prevent de-acclimatization. METHODS: Seventeen SL residents (age= 22 ± 6 yr, weight= 75.2 ± 13.3 kg; mean ± SD) completed in the following order: 1) 4 days of baseline SL testing; 2) 12 days of HA acclimatization at 4300 m; 3) 12 days at SL post-HA acclimatization where each received either NH (n=9, FiO2=0.122) or Sham treatment (n=8; FiO2=0.207); and 4) 24-hour reintroduction to 4300 m altitude (RA) in a hypobaric chamber (460 Torr). Mood state was assessed using the Automated Neuropsychological Assessment Metrics Mood Scale (ANAM-MS), which includes the measurement of 7 mood dimensions: vigor, restlessness, depression, anger, fatigue, anxiety and happiness. The test was administered in the afternoon (~2-3pm) on 5 occasions at SL, once after 2h at HA (HA1), 20h at HA (HA2), 11 days at HA exposure (HA11), and following 4 h of RA (RA4). RESULTS: As there were no group differences between NH and Sham mood test scores at any of the time points, data were combined. Fatigue increased (P<0.05) from SL (0.44 ± 0.58) to HA1 (1.16 ± 1.17) and HA2 (1.93 ± 1.26) and then decreased (P<0.05) from HA2 to HA11 (0.67 ± 0.78) and remained low at RA4 (0.58 ± 0.72). Vigor decreased (P<0.05) from SL (2.80 ± 1.42) to HA1 (1.54 ± 1.19) and HA2 (1.33 ± 1.31), and then remained unchanged (P>0.05) from HA2 to HA11 (1.46 ± 1.58), and this effect persisted at RA4 (1.33 ± 1.05). Anxiety increased (P<0.05) from SL (0.17 ± 0.31) to HA1 (0.49 ± 0.97), decreased (P<0.05) from HA1 to HA2 (0.07 ± 0.17), remained unchanged from HA2 to HA11 (0.19 ± 0.60), and remained low at RA4 (0.14 ± 0.30). All other mood states remained unchanged from SL to HA and then RA. CONCLUSION: These results suggest that HA-induced improvements in mood state are retained during RA after 12 days at SL whether or not NH treatment is utilized. Authors’ view not official US Army or DOD policy. Funding USAMRDC.