INTRODUCTION: For future long-duration spaceflight missions, additional methods of loading the skeleton may be required to supplement exercise to minimize bone loss. Neuromuscular electrical stimulation (NMES) can elicit muscular contractions that create strain on bone. However, the potential effectiveness of NMES on the proximal femur during disuse is not known.METHODS: We measured the maximum isometric force of NMES-induced contractions of the rectus femoris and the hamstrings of 10 subjects (5 male, 5 female), sitting with the hips and knees at 90 degrees of flexion. We employed 2-D biomechanical models of the knee and hip to estimate the hip joint reaction forces, applied these forces to a generic femur finite element analysis model, and qualitatively compared the peak principal strains of the proximal femoral neck to the peak strains modeled in previous studies for other forms of exercise.RESULTS: The average peak tensile/compressive strains were 1380 ± 719 µε/-2179 ± 1130 µε and 573 ± 345 µε/-900 ± 543 µε for the male and female subjects, respectively. While results varied between studies, the strains achieved during NMES generally were comparable to those achieved during walking or stairs, with some individuals matching higher intensity activities.DISCUSSION: This study demonstrated that isometric NMES contractions of the thigh muscles can create strain in the proximal femoral neck similar to that achieved during low impact activities. While NMES alone will unlikely create a sufficient daily strain stimulus to prevent bone loss, it will likely improve the current spaceflight countermeasures by adding more frequent loading throughout the day.Abitante TJ, Bouxsein ML, Duda KR, Newman DJ. Potential of neuromuscular electrical stimulation as a bone loss countermeasure in microgravity. Aerosp Med Hum Perform. 2022; 93(11):774–782.

INTRODUCTION: Pararescue personnel (PJs) deploy in high-risk environments and perform extraordinary missions under intense conditions, requiring an unusual combination of physical and psychological abilities. The rigorous nature of PJ training and the superior levels of fitness and cognitive functioning to perform challenging physical feats in high-pressure, high-intensity environments have prompted military commanders and embedded health care providers to compare successful performance in the PJ mission with the characteristics required of elite, Olympic-level athletes.METHODS: In the current study, we tested this assumption by comparing the social, emotional, and behavioral functioning of 160 U.S. PJ training candidate graduates and 73 elite, Olympic-level track and field athletes using scores on the NEO Personality Inventory-3.RESULTS: Results from this study suggest that although there are physical and psychological challenges inherent in both the PJ and elite athlete career fields, the emotional, social, and behavioral performance of PJs differs in functional ways from the elite athlete population, with PJs scoring significantly lower in Neuroticism and higher in Extraversion and Conscientiousness.DISCUSSION: The results of this study can be used to improve the delivery of embedded mental health services geared toward improving training and enhancing health, recovery, and performance within operational units.Shadle A, Waite L, Chappelle W. Personality trait comparison of pararescue personnel and elite athletes. Aerosp Med Hum Perform. 2022; 93(11):783–790.

INTRODUCTION: The present study aimed to explore whether there are changes in the alerting, orienting, and executive network efficiencies of attention function between high altitude immigrants and low altitude residents.METHODS: Event-related potentials (ERP) were acquired during an attention network test (ANT). The high-altitude (HA) group comprised 22 college student immigrants who were born and raised at low altitudes and had lived at a HA (11,975 ft/3650 m) for 26 mo (tests were conducted when they returned to HA for 3 mo). The low-altitude (LA) group comprised 23 college students who had never visited HA areas before.RESULTS: Compared with the LA group, the HA group had a higher pulse rate, lower oxygen saturation level, and decreased alerting and orienting effects in the behavioral results. The ERP results of the HA group showed a smaller P1 in the occipital area, a larger N1 both in the parietal and occipital areas of the alerting network, and a smaller P1 and larger N1 in the orienting network than the LA group. In the executive control network, the N2 amplitude of the HA group was more negative and the P3 amplitude of the HA group decreased in incongruent conditions.DISCUSSION: Together, these findings suggest that high-altitude migrants are less effective at alerting and orienting than low-altitude residents. For executive control function, changes in the P3 amplitudes of incongruent conditions indicated a decrease in conflict inhibition underlying the executive-control network.An X, Tao G, Zhang X, Ma H, Wang Y. Attention network changes of high-altitude migrants. Aerosp Med Hum Perform. 2022; 93(11):791–799.

INTRODUCTION: Dynamic visual acuity (DVA) refers to the ability of the eye to discern detail in a moving object and plays an important role whenever rapid physical responses to environmental changes are required, such as while performing tasks onboard a space shuttle. A significant decrease in DVA has previously been noted after astronauts returned from long-duration spaceflight (0.75 eye chart lines, 24 h after returning from space). As part of a NASA-funded, head-mounted multimodal visual assessment system for monitoring vision changes in spaceflight, we elaborate upon the technical development and engineering of dynamic visual acuity assessments with virtual reality (VR) technology as the first step in assessing astronaut performance when undergoing G-transitional effects. We also report results from an early validation study comparing VR DVA assessment with traditional computer based DVA assessment.METHODS: Various VR/AR headsets have been utilized to implement DVA tests. These headsets include HTC Vive Pro Eye system. Epic’s game engine UnrealEngine 4 Version 4.24 was used to build the framework and SteamVR was used to experience virtual reality content. Eye tracking technology was used to maintain fixation of the participant. An early validation study with five participants was conducted comparing this technology versus traditional DVA with a laptop.RESULTS: The head-mounted technology developed for assessing DVA changes during G-transitions is fully functional. The results from the early validation study demonstrated that the two DVA tests (laptop-based and VR) indicated a strong association between both methods (Pearson correlation coefficient of 0.91). A Bland-Altman plot was employed to assess levels of agreement, with all data points falling within the limits of agreement.DISCUSSION: The results from this early validation study indicate that head-mounted DVA assessment performs similarly to traditional laptop-based methods and is a promising method for assessing DVA during spaceflight, particularly in G-transitions. Future studies are required for further assessment of validation and reliability of this technology. With its ease of use, accessibility, and portable design, VR DVA has the potential in the near-future to replace conventional methods of assessing DVA. The technology will likely be an important aspect to help monitor functionality and safety during interplanetary missions where astronauts are exposed to G-transitions.Waisberg E, Ong J, Zaman N, Kamran Sa, Lee AG, Tavakkoli A. Head-mounted dynamic visual acuity for G-transition effects during interplanetary spaceflight: technology development and results from an early validation study. Aerosp Med Hum Perform. 2022; 93(11):800–805.

INTRODUCTION: Atopic dermatitis (AD) is a skin condition with many genetic risk factors. In this review, we summarize the different genetic variants for AD from the perspective of screening purposes within the U.S. Air Force aviation community. Using a PRISMA-informed systematic review approach, we found 13 papers reporting genetic associations with AD. We report 98 genetic associations with AD, of which 4 had a greater than twofold increased odds of developing the condition when present. These 98 variants were found in 45 associated genes, including LRRC32, OVOL1, and IL13, which were each replicated in 3 studies; as well as RTEL1 and ZNF365, which were each replicated in 2 studies. A polygenic risk model created based upon these variants or genes could contribute to a risk screening protocol for military aviation candidates, potentially helping minimize risk for candidates at increased genetic risk for AD or other atopic diseases (e.g., asthma, allergic rhinitis).Gregory ID, Collie J, Chapleau RR. Genetic markers of atopic dermatitis risk for screening aviation applicants. Aerosp Med Hum Perform. 2022; 93(11):806–810.

INTRODUCTION: Altitude chambers are used for training aircrews in a hypobaric hypoxic environment to better prepare them for pressurization and oxygen malfunction incidents during flights. However, adverse effects may occur during training sessions, with decompression sickness (DCS) being a major concern. The aim of this study was to examine the risks of different adverse effects during altitude chamber trainings (ACT) in the Israeli Air Force (IAF) facility and to compare them to other training facilities.METHODS: We retrospectively reviewed the records of 1627 individuals in the IAF who were trained in the altitude chamber between 2015 and 2019. Data regarding adverse effects and training safety were extracted. Literature review of altitude chamber trainings was performed and adverse effects rates were compared.RESULTS: There were a total of 91 adverse effects cases in the IAF during the study period. The overall risk rate for an adverse effect was 5.59%. The most common adverse effect was middle ear and sinus barotrauma (69.3% of adverse effects cases), followed by breathing problems (14.3%) and DCS cases (9.9%).CONCLUSIONS: Mitigating the risk for DCS should be major concern during ACT. We recommend setting a standard protocol for an ACT which includes a 45-min preoxygenation period, a maximal ascent rate of 3000 ft · min⁻¹ (914 m · min⁻¹), and setting a maximum altitude of 25,000 ft (7620 m) for fixed-wing trainees.Nakdimon I, Ben-Ari O. Mitigating risks of altitude chamber training. Aerosp Med Hum Perform. 2022; 93(11):811–815.

INTRODUCTION: On space missions one must consider the operating cost of the medical system on crew time. Medical Officer Occupied Time (MOOT) may vary significantly depending on provider skill. This pilot study assessed the MOOT Skill Effect (MOOTSkE).METHODS: An expert surgeon (ES), fifth year surgical resident (PGY5), second year surgical resident (PGY2), and an expert Emergency Physician (EP) with only 4 mo direct surgical training each performed two simulated appendectomies. The completion times for endotracheal intubation, appendectomy, and two subprocedures (multilayer tissue repair and single layer tissue repair) were recorded.RESULTS: The ES performed the appendectomy in 410 s, the PGY-5 in 498 s, the PGY-2 in 645 s, and the EP in 973 s on average. The PGY-2 and EP time difference was significant compared to the expert. The PGY-5 was not. The EP’s time was significantly longer for the appendectomy and the multilayer repair than either surgical resident. For the single layer repair, only the EP-ES difference was significant. A single intubation attempt by the PGY-2 took 73 s while the EP averaged 27 s. The average recorded MOOTSkE between novice and expert was 2.5 (SD 0.34).DISCUSSION: This pilot study demonstrates MOOTSkE can be captured using simulated procedures. It showed the magnitude of the MOOTSkE is likely substantial, suggesting that a more highly trained provider may save substantial crew time. Limitations included small sample size, limited number of procedures, a simulation that may not reflect real world conditions, and suboptimal camera angles.Levin DR, Siu M, Kramer K, Kelly E, Alouidor R, Fernandez G, Kamine T. Time cost of provider skill: a pilot study of medical officer occupied time by knowledge, skill, and ability level. Aerosp Med Hum Perform. 2022; 93(11):816–821.

Wingelaar-Jagt YQ, Wingelaar TT, Riedel WJ, Ramaekers JG. Subjective effects of modafinil in military fighter pilots during deployment. Aerosp Med Hum Perform. 2022; 93(10):739–745.