Authors:Yasuki Sekiguchi et al. Abstract: Background: It is unclear whether energy intake can impact the incidence of upper respiratory symptoms (URS). The purpose of this study was to examine if there are differences in energy intake between symptomatic (SYM) and asymptomatic (ASYM) groups of URS in Ironman-triathletes. Methods: Thirty-three subjects competing in the Lake Placid Ironman-triathlon (mean±SD; age,37±8y; height,178±8cm; mass,76.3±10.4kg; body fat,10.8±3.8%) were randomized into either the control (CON) or intervention (INT). INT consumed 4-commercial recovery drinks, two immediately post-race and two 3-hours post-race. Calorie and macronutrient intake were recorded pre-, during, and post-race. Subjects completed the Wisconsin URS Survey to assess URS over the next two weeks. Two analyses were done by comparing results between CON and INT, and when subjects were classified as either asymptomatic (ASYM=20) or symptomatic (SYM=13). Results: There were no differences in energy intake (p>0.05) and URS (INT,32±38; CON,16±23; p=0.155). However, on the race day, SYM (9,044±2,598kcal) consumed less energy intake than ASYM (10,991±2497kcal) (p=0.044). Also, SYM consumed less energy the day before the race (p=0.031) and post-race (p=0.008). ASYM consumed greater carbohydrate the day before the race (p=0.032), fat the day of the race (p=0.006), carbohydrate post-race (p=0.08) and fat post-race (p=0.002). Conclusions: Overall energy intake was similar between CON and INT. However, when subjects were differentiated by URS, SYM consumed less calories the day before and day of the race versus ASYM. PubDate: Wed, 21 Sep 2022 05:21:04 PDT
Authors:Andrew T. Garrett et al. Abstract: Introduction: It is important to determine the accuracy of measurements relative to potential treatment effects, with time intervals between tests. Purpose: The aim of this study was to assess the error of measurement for blood parameters, physiological, and performance measures after the decay of short-term heat acclimation. Methods: Ten trained males (Mean±SD: age 28±7 y; body mass 74.6±4.4 kg; 4.26±0.37 L.min-1; peak power output (PPO) 329±42 W) completed an exercising heat stress test (HST) at baseline, 2nd day after acclimation and then during decay at 1, 2, 3 and 5-6 wks. CoV (95% CI), SE (95% CI) and Pearsons (r) were used for analysis of blood volume (blood, plasma, red cell volume, mean hemoglogin mass); plasma (aldosterone, arginine vasopressin [AVP], total protein, albumin, sodium); physiological (rectal temperature, cardiac frequency) and performance (exercise performance capacity, PPO). Results: The CoV (95% CI), SE (95% CI) and r with a 1-wk interval for blood volume was 2.3% (1.6 to 4.3; 1.9 [1.3 to 3.4 mL.Kg-1]; r=0.93; n=10). After 2-wk and 5-6 wks this had increased to 4.9% (3.4 to 9.3; 3.8 [2.6 to 7.0 mL.Kg-1]; r=0.76; n=9) and 5.5% (3.6 to 12.8; 4.5 [2.9 to 10.0 mL.Kg-1]; r=0.65; n=7) respectively. Conclusions: Blood volume and physiological measures demonstrated the least error one week apart but increased thereafter. Plasma concentrations and performance markers had the greatest error with repeat measures after one week. Therefore, for greater reliability and low measurement error measures should be taken no more than one week a part in repeated experimentation. PubDate: Mon, 09 May 2022 06:41:47 PDT
Authors:Andrew T. Garrett et al. Abstract: Purpose: Effectiveness of short-term heat acclimation (STHA), over 5-days (permissive dehydration), on intermittent heat stress test (HST) with males. Methods: Ten, moderately-trained, males (mean [SD]; age 25.6 [8.9] y; stature 180.7 [5.6] cm; body mass 83.2 [10.8] kg; and 45.3 [6.5] mL.kg-1.min-1) participated. The HST was 9 x 5min (45-min) of intermittent exercise based on professional soccer players. One week apart, HST1 vs HST (11.0°C; 50%RH), as a reliability trial and HST3 in 31.0°C; 50%RH were completed. Then 90 min dehydration, STHA (no fluid intake), for 5 consecutive days (39.5oC; 60%RH), using controlled-hyperthermia (~rectal temperature [Tre] 38.5oC). The HST4 within one week after STHA. Blood plasma constituents: percent plasma volume (%PV), aldosterone, total protein, albumin, electrolytes, cortisol and HSP70. Data analysis reported as mean differences with 95% confidence intervals (95%CI) and Cohen’s d effect size. Results: Post STHA, there was a decrease of -0.20 Tre at 45-min in the HST (95%CI -0.40 to -0.05°C; P=0.03; d =-0.56); mean skin temperature (-0.80; -1.30 to -0.30°C; P=0.007; d =-1.46) and mean body temperature (-0.30; -0.50 to -0.10°C, P=0.01; d =-0.75). Cardiac frequency reduced (-3: -5 to -1 b.min-1; P=0.01; d =-0.20) and %PV increased (7.3: 0.9 to 13.7%; P=0.03; d=0.59). Mean Peak Power (MPO) increased (Pd =0.63). Conclusions: Short-term heat acclimation (5-days) with dehydration, using controlled-hyperthermia technique, is effective for physiological adaptations during intermittent exercise in the heat, with moderately trained males. PubDate: Mon, 09 May 2022 06:41:41 PDT
Authors:Douglas Jones et al. Abstract: Purpose: Cold environments may deteriorate psychomotor performance due to slowing of neuronal signals, distractions caused by pain and discomfort, and a loss of manual dexterity. The extent to which core temperature (Tc) influences psychomotor performance in the cold has not been established. Therefore, psychomotor performance and Tc were assessed during a cold weather military training exercise to evaluate this relationship.Methods: Thirty-six military personnel (age: 26 ± 4 yr, ht: 175 ± 8 cm, wt: 79.1 ± 11.1 kg) participating in cold weather training volunteered for this study. Participants completed a 10-min immersion in cold (1°C) water, followed by 60 min of rewarming. Physiological, perceptual, and psychomotor assessments were made throughout the training. For analysis, participants were divided into groups based on their lowest achieved core temperature (< 35.0°C = HYP; 35.0-36.0°C = CS-M;> 36.0°C = CS-S). Psychomotor performance was then compared among the groups to determine the influence of Tc on performance.Results: Although cold water immersion deteriorated performance, no differences were observed among the three groups at any time point during the training for simple reaction time (HYP: 298 ± 49 ms; CS-M: 313 ± 55 ms; CS-S: 326 ± 53ms; p = 0.677).Conclusion: Findings suggest that cold water immersion deteriorates psychomotor performance which, even in the presence of mild hypothermia, is not directly influenced by Tc. Additional observations reveal large variations in Tc among a homogenous group in response to cold water immersion. PubDate: Mon, 24 Jan 2022 07:21:55 PST
Authors:D. Christopher Kayes et al. Abstract: Examples from aviation and aerospace illustrate the potential consequences that emerge when organizations replace learning from experience with technology, a process referred to as a cognitive offloading strategy (COS). Examples include the Air France Flight 447 crash involving an Airbus 330-203 and the Lion Air Flight 610 crash involving a Boeing 737 Max. From the perspective of human performance in extreme environments, COS represents an underexplored source of organizational vulnerability which presents a particular challenge for learning in organizations. Decrements in learning result from COS because COS creates gaps in procedural knowledge and deprives operators of opportunities to learn in the face of event-induced stress. Due to the inevitability of COS in extreme environments, recommendations for building resilience include offering training scenarios that support the development of a positive stress response, facilitating the ability to learn in the face of uncertainty, and supporting highly engaged experiential learning to build procedural (and often tacit) knowledge of operations. PubDate: Mon, 24 Jan 2022 07:21:47 PST
Authors:Inga Popovaite et al. Abstract: Most research on mixed-gender teams in space analog environments focuses on individual-level variation and overlooks structural causes of inequality. Status characteristics theory posits how socially recognized traits, such as gender, contribute to the formation of informal hierarchies by denoting perceived levels of competence to group members. We investigated gender as a status characteristic in groups in space analog environments. We used data from the Mars Desert Research Station (MDRS) and hypothesized that women crew members are less likely than men to be selected to participate in simulated extravehicular activities during a Mars simulation at the MDRS. We used reports and biographies from 30 randomly selected crews (n = 177) posted on the MDRS website to construct our dataset and multilevel generalized regression models to test our hypothesis. Women crew members were 6% less likely to participate in simulated extravehicular activities than men, controlling for crew role, education, and other factors. Our study shows that gender acts as a status characteristic and influences group decisions in crews in space analogs. These results highlight the need for more studies on interactional inequalities in preparation for a long-term human spaceflight. PubDate: Mon, 24 Jan 2022 07:21:40 PST
Authors:Lucy Joy Wachira et al. Abstract: Background: Outdoor adventure is inevitably linked to risks that lead to injuries, psychological distress, illnesses, and even fatalities. Gathering detailed information on such occurrences and their contributing factors is a valuable component of risk management in outdoor programs. This study investigated the occurrence of injuries, illnesses, evacuation profiles, non-medical concerns, and near-miss events in outdoor adventure practice in Kenya.Methods: A mixed-methods approach involving quantitative and qualitative methods was used to collect data from 136 outdoor adventure practitioners in Kenya. Questionnaires, key informant interviews, focus group discussions, and desk reviews were employed to collect data.Results: The majority of injuries and illnesses occur during mountaineering (39%) and hiking and navigation (25.7%) events. The most reported incidents were mountain sickness (25%) and musculoskeletal injuries consisting of fractures (30%), cuts and wounds (14.7%), blisters (12.5%), sprains and dislocations (12.5%), and muscle strains and pulls (8.8%). Out of the 128 reported evacuation incidences on Mt. Kenya, 95 were due to mountain sickness and10 due to falls. Combined age and sex of the climbers and the location/altitude on the mountain are predictors of the occurrence and the type of injury/illness on the mountain (x2 (10, n = 128) = 63.32, P < 0.001). However, only altitude significantly contributes to the model (P < 0.001). Reported near-miss incidences included flash floods, aggressive encounter with wildlife, getting lost for extended period, near falls and slips, and rolling-rock falls. Non-medical concerns reported included extreme anxiety, intoxication from drug and alcohol use, confrontation and fights, and disorientation.Conclusions: There is evident incidence of injuries and illnesses of varying severity, with age, sex, and altitude reached being key predicting factors. Mitigating efforts and preventive measures should be employed as well as risk assessment and management to promote safety. The findings are vital to advise policy and practice and enhance awareness among practitioners and interested parties in Kenya and also in other destinations with similar conditions, terrains, and challenges. PubDate: Thu, 01 Apr 2021 10:01:20 PDT
Authors:Sarah Chabal Abstract: In the event that submariners become trapped aboard a disabled submarine (DISSUB), they must perform a multitude of cognitively demanding tasks in order to maximize their likelihood of survival. During this time, submariners will also be forced to endure poor living conditions, including drastic changes to their nutrition. These nutritional changes have the potential to impair submariners’ cognitive functioning and affect operational performance, which could jeopardize survival; however, the effects of DISSUB nutrition on cognitive performance are not well understood. This review first describes the unique nutritional conditions that submariners will experience in a DISSUB scenario, including the change to a high-fat/low-calorie diet, restricted water availability, and cessation of caffeine consumption. The known effects of diet (including a high-fat diet and caloric restriction), dehydration, and caffeine withdrawal on cognition are then separately reviewed, with a discussion of how these effects may impact survivability in a DISSUB scenario. PubDate: Thu, 11 Feb 2021 12:11:34 PST
Authors:Sara E. Mahoney et al. Abstract: Ultra-marathon events (i.e., .42.2-km) continue to grow in popularity; however, little is known regarding the sources of nutrition information which inform their beliefs and habits. The objective of this study was to characterize the acquisition of sport-specific nutrition information among ultra-endurance athletes using a mixed methods design. Qualitative data were collected through focus groups and analyzed using thematic analysis. Three primary higher order themes were identified: Optimal Diet for Ultra-Endurance Athletes, Common Sources of Information, and Barriers to Scientific Information. Then, a self-report inventory (Sources of Nutrition Information-SONI questionnaire) was developed to assess common sources of nutrition information and characterize their beliefs about those sources. Likert-type questions were used, and primary sources were scored out of 3, sub-questions out of 5. Differences between sources were assessed using RM-ANOVA. Participants (N = 224) accessed, responded to, and submitted the survey via a secure, study-specific web-based link. Peer reviewed literature was reported as the most frequently used (mean score = 1.64, p < 0.001), credible (3.02, p < 0.001), and interesting (2.62, p < 0.002). Social media was the most accessible (2.81, p < 0.001), but the least credible (1.87, p < 0.001). While social media was perceived less credible than other sources, its accessibility could make it a promising tool to provide evidence-based nutrition information to this population. PubDate: Thu, 11 Feb 2021 12:11:24 PST
Authors:Jennifer Pickett et al. Abstract: We depict the physical and psychological challenges of commercial fishing in Alaska as well as the uplifts, or positive experiences fishermen report. We describe an array of coping methods that are utilized during the fishing season and the contexts in which they occur. Our findings help clarify the link between human behavior, stressors, coping mechanisms employed, and uplifts experienced when working in extreme conditions. By doing this, we provide a better understanding of the effects that severe conditions have on wellbeing, such as working for long periods of time in cramped quarters in remote, extreme environments, and how Alaskan fishermen cope with them. PubDate: Wed, 18 Dec 2019 05:13:04 PST
Authors:Christina N. Angeli et al. Abstract: There has been recent debate on the potential difference in physiological response between exposure to simulated altitude (normobaric hypoxia) and terrestrial altitude (hypobaric hypoxia). Purpose: To determine the difference in the physiological response to normobaric and hypobaric hypoxia during exercise. Methods: Eight recreationally active subjects (27 ± 5 y old, 73.1 ± 7.4 kg body weight, 170.6 ± 6.7 cm height, and 19.3 ± 9.2 % body fat) completed incremental cycling exercise to volitional fatigue in three separate environments: normobaric normoxia (NN; 350 m), normobaric hypoxia (NH; simulated 3094 m), and hypobaric hypoxia (HH; 3094 m). Heart rate, blood oxygen saturation, and muscle tissue oxygenation were measured at rest and continuously throughout the exercise trials. Results: Blood oxygen saturation (SpO2) was ~10% higher in NN compared to the two hypoxic conditions (p < 0.001) at rest and all exercise stages, with no difference between NH and HH (p> 0.05). Heart rate was higher at rest in HH (98 ± 13 bpm) compared to NN (83 ± 15 bpm, p = 0.011) and NH (84 ± 14 bpm, p = 0.001) which persisted until 165 watts at which point no difference was observed (p> 0.05). Muscle tissue oxygenation was 17% higher in HH compared to NN and 19% higher than NH throughout exposure (p < 0.05). Conclusion: This data indicates that the hypoxic stress resulting from normobaric and hypobaric hypoxia are not the sameand that hypobaric hypoxia may not result in hypoxia at the level of the tissue. PubDate: Thu, 12 Dec 2019 04:37:23 PST
Authors:David Bergman Abstract: The present study examined failure in an extreme setting within a military parachute training course used to better prepare individuals for combat. A grounded theory analysis of interviews and observations led to four interdependent reasons for failure, three mediating factors of how failure was perceived, and eight ways of coping in how individuals handled failure. Two overarching master themes were established of decision aversion where individuals tend to avoid making decisions regarding their own failure in order to minimize guilt and shame, and externalization where attribution is made primarily to causes outside the self in order to maintain a positive self-image. In a few cases, active measures were taken to overcome failure, most often by the ones with the strongest reactions of surprise and anger, somewhat counterintuitively indicating that the worst reactions bring out the most successful coping. Suggestions for further research and implementation in extreme military training courses are discussed. PubDate: Wed, 11 Dec 2019 04:52:24 PST
Authors:Paul T. Bartone et al. Abstract: The present qualitative study conducts in-depth interviews with astronauts and other subject matter experts in order to shed light on human adaptability in extreme environments. Deep space travel will entail a range of highly stressful conditions to which astronauts must adapt. Feelings of isolation will be increased, as the space traveler is farther from Earth for longer periods of time. Daily life will take place in small and confined areas, for durations extending into years. The dangers of the extreme environment of space are ever-present, and failure of critical equipment or components can lead to death. Astronauts will need to function more autonomously, with diminished support from Earth. It is thus important to select and train future astronauts who are able to adapt to such extreme and variable conditions and continue to function effectively. Subject matter experts identify the central adaptive challenges faced by crewmembers, and what are the key individual attributes associated with human adaptability. Results also point to organizational factors, as well as several coping and resource strategies that can be applied to improve human adaptability to extreme environments and missions. These results can be used to inform selection and training programs, as well as the design of space vehicles, systems, and habitats in order to enhance astronaut adaptive task performance. PubDate: Wed, 04 Dec 2019 08:47:16 PST
Authors:Nicolas Robin et al. Abstract: This study examined how a tropical climate (TC) influences the cognitive and aiming task performances of young international fencers. The participants performed the tasks in TC and an air-conditioned room. In each session, they completed questionnaires evaluating affective states, fatigue, and comfort and thermal sensations. They also carried out cognitive tasks (simple and choice reaction time, attention, and vigilance tasks) and a motor task testing aiming accuracy with a sword while wearing protective clothing and a mask. TC, which was observed to decrease thermal discomfort, was revealed to decrease aiming accuracy and positive affective states. There was no deleterious effect on cognitive task performance, nor on negative affective states, or fatigue and increased thermal discomfort. These results showed that TC can negatively influence motor performance. PubDate: Mon, 22 Jul 2019 05:25:59 PDT
Authors:Derek Covington et al. Abstract: Technical freediving can be defined as freediving augmented by the use of oxygen-enriched gases or oxygen before, during, or after a freedive. As a result of these techniques, breath-hold divers can visit and enjoy underwater wrecks, reefs, and other diving locations previously located at depths unreachable to apnea divers. By pre-breathing oxygen-enriched gases in conjunction with hyperventilation—which decreases the partial pressure of carbon dioxide (PCO2)—the technical freediver now has additional oxygen to facilitate aerobic respiration during the dive. In addition, pre-breathing oxygen decreases tissue nitrogen tensions, which limits inert gas loading and decreases the risk of decompression sickness (DCS). Finally, this technique decreases PCO2, which diminishes the urge to breathe. Consequently, a diver may be able to dive longer before critical hypoxia or hypercarbia forces an ascent. Technical freediving can also be complemented by the use of a diver propulsion vehicle to increase the speed of descent and ascent and minimize exertion. The techniques of technical freediving may be associated with increased risks in central nervous system oxygen toxicity, DCS, and arterial gas embolism. As the boundaries of apnea diving continue to expand, there will be considerable opportunities to investigate the physiological limits of the human body and to determine the safest methodologies to practice this evolving discipline. PubDate: Wed, 29 May 2019 10:55:12 PDT
Authors:Aude Villemain et al. Abstract: The aim of this research is to understand safety–performance articulation in spearfishing through the study of the global, specific, and temporal organization of an elite free diver’s activity. Three kinds of data were collected: diary reports, ten elicitation interviews on spearfishing, and two self-confrontation interviews on successful and failed apneas. The results indicated (1) the spearfisher’s global organization during the spearfishing set, (2) the alternation of intentions during apnea and periods of stabilization, (3) harmony with the environment, and (4) the strategy of keeping pace with the fish. The article will discuss the specific competence development needed to manage the safety–performance relationship in extreme sports. Drawing on its findings, the article proposes improvements to the safety– performance relationship in risky activity. PubDate: Fri, 05 Apr 2019 15:28:06 PDT
Authors:Cameron M. Smith et al. Abstract: Audiovisual records of a Project Mercury pilot’s activities during an orbital flight indicate that his visor was left open during reentry and descent to the sea surface, phases of flight during which cabin pressure loss was to be mitigated by suit pressurization; however, the suit could not have been pressurized with the visor open. Thus, for a presently unknown reason, a critical safety step—sealing the visor and making a pressure suit integrity test before reentry—was overlooked in this flight. Later, Space Shuttle flights were carried out with visors unsealed for much of the launch and landing phases, with the false assumption that they could be closed if the crew cabin were to lose cabin pressure rapidly. The lessons are clear: first, spaceflight crews should be trained to seal visors for the entire launch and landing phases; and second, procedure checklists will always be important to crewed flight, in both public and private spaceflight. PubDate: Wed, 06 Mar 2019 12:04:02 PST
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