INTRODUCTION: The aim of this study was the analysis of human musculoskeletal system energy costs of normal walking and walking under reduced weight loading.METHODS: There were 15 subjects who participated in the study. We analyzed the biomechanical parameters of walking under different musculoskeletal system loads. The subjects walked on a treadmill at a pace of 90 steps/min under various loading conditions: 1) 100% bodyweight loading, corresponding to the terrestrial surface; 2) 38% bodyweight loading, corresponding to the surface of Mars; and 3) 17% bodyweight loading, corresponding to the surface of the Moon. Joint angles and angular velocities were recorded from the hip, knee, and ankle.RESULTS: We analyzed changes in joint phase trajectories and the ratio of kinetic extension energy to kinetic flexion energy in the joints. We observed changes in kinetic energy parameters associated with both flexion and extension motions in the joints of the feet while walking under various loads. In terrestrial conditions (walking under 100% bodyweight), flexion kinetic energy in the hip joint prevailed over extension kinetic energy by 90%, with a small variation equal to 22%. If weight loading decreased up to 17% (lunar conditions), the difference between flexion and extension kinetic energies diminished, and eventually reached only 9%. The ratio of flexion energy and extension energy in the ankle joint equalized under lower loading conditions. Thus, 38% bodyweight loading was sufficient for approximation of flexion and extension energy values.DISCUSSION: Our results revealed that phase trajectories shifted toward smaller joint angles and a decreased ratio between extension kinetic energy and flexion kinetic energy in the knee joint of all subjects. However, significant differences in the ratio of flexion and extension kinetic energy in the knee joint under bodyweight support were not found. The methods used for musculoskeletal system assessments that were proposed in our work can be used in clinical practice to evaluate the effectiveness of rehabilitation measures in a patients musculoskeletal system disorders.Shpakov AV, Artamonov AA, Voronov AV, Plotnikov EV, Puchkova AA, Orlov DO. Human locomotion strategies under changed bodyweight support. Aerosp Med Hum Perform. 2021; 92(1):410.

INTRODUCTION: The visual scanning techniques used by helicopter pilots are a critical skill to accomplish safe and correct landing. According to the human information processing theory, visual scanning techniques can be analyzed as a function of fixation location, number, and duration of fixations.METHODS: This study assessed these techniques in expert and novice pilots during an open sea flight simulation in a low-workload condition, consisting of a daylight and good weather simulation, and in a high-workload condition of night-time, low visibility, and adverse weather conditions. Taking part in the study were 12 helicopter pilots. Mental workload was assessed through psychological measures (NASA-TLX). The pilots performance was assessed and eye movements were recorded using an eye-tracker during four phases of the flight simulations.RESULTS: Overall, pilots made more fixations out of the window (OTW; 22.54) than inside the cockpit (ITC; 11.08), Fixations were longer OTW (830.17 ms) than ITC (647.97 ms) and they were shorter in the low-demand condition (626.27 ms). Further, pilots reported higher mental workload (NASA-TLX) in the high-demand condition compared to the low-demand condition, regardless of their expertise, and expert pilots reported a lower mental workload compared to novice pilots.DISCUSSION: Pilots performance and perceived mental workload varied as a function of expertise and flight conditions. Pilots rely on instrument support during the cruise phase and external visual cues during the landing phase. The implications for a new visual landing system design are discussed.Rainieri G, Fraboni F, Russo G, Tul M, Pingitore A, Tessari A, Pietrantoni L. Visual scanning techniques and mental workload of helicopter pilots during simulated flight. Aerosp Med Hum Perform. 2021; 92(1):1119.

INTRODUCTION: Fatigue is an important phenomenon in modern aviation. Despite the progress in research concerning fatigue among civil aviation and military pilots, fatigue in student pilots has remained unexamined. The aim of this study was to examine fatigue among ab-initio pilots. In this study, the fatigue model previously proposed and used in the literature is redesigned for ab-initio pilots.METHOD: A 48-item questionnaire was applied. Factor analysis was performed using SPSS. The data were collected from 114 ab-initio pilots.RESULTS: It was determined that 23% (N 26) of the participants included in the study were women and 77% (N 88) were men. When the license types of the participants were analyzed, it was seen that 11% (N 13) had commercial pilot licenses (CPL; N 80), 70% had private pilot licenses (PPL), and 18% (N 21) had student pilot licenses (SPL). Results showed that seven performance factors (types of flight, training scheduling, crew composition, environment of the aircraft, types of accommodation, flight training-related issues, and biological issues) affect ab-initio pilots fatigue on various levels.DISCUSSION: The findings may help flight training organizations and ab-initio pilots take assertive preventive measures against fatigue.Kilic B. Fatigue among student pilots. Aerosp Med Hum Perform. 2021; 92(1):2024.

INTRODUCTION: Allergic rhinitis (AR) is a global health problem with gradually increasing prevalence. No large-scale, systematic, and comprehensive study on AR among civil aviation aircrew of China has been reported. We aimed to demonstrate the prevalence of and risk factors for self-reported AR among Chinese civil aviation aircrew.METHODS: This study randomly surveyed 4059 civil aviation aircrew members from 12 cities in mainland China. A structured questionnaire was tailored, designed, and electronically delivered to all participants. Based on self-reported results, prevalence of and risk factors for AR were calculated/analyzed.RESULTS: The prevalence of self-reported AR was 23.38%. Among aircrew members, 10.37% presented with ear barotraumas, whereas 9.95% reported symptom aggravation during flight. Of aircrew members, 10.32% had symptoms related to flight duration, whereas 4.43% of symptoms related to flight altitude. Significant differences between rhinorrhea and sneezing, as well as between nasal itching and sneezing, were observed in the Total Nasal Symptoms Scores (TNSS). The Rhino-conjunctivitis Quality of Life Questionnaire (RQLQ) showed significant correlation between each section. TNSS was significantly related to RQLQ. Both TNSS and RQLQ significantly correlated with flight time.CONCLUSIONS: The prevalence of self-reported AR among civil aviation aircrew is higher than the general population in China. The severity of nasal symptoms and complications are significantly associated with quality of life and flying duties.Bai Y, Hu M, Ma F, Liu K, Xu H, Wu X, Wang H. Self-reported allergic rhinitis prevalence and related factors in civil aviation aircrew of China. Aerosp Med Hum Perform. 2021; 92(1):2531.

INTRODUCTION: In-flight medical events (IMEs), although rare, are challenging due to the limited onboard resources and the time needed to reach an airport. Cabin crewmembers (CCMs) are trained to provide first aid, but their effectiveness has not been appropriately studied.METHODS: IMEs occurring in the biggest airline of Greece were prospectively recorded during a 5-yr period (20142018) and categorized according to a symptom-based taxonomy.RESULTS: During the study period 990 IMEs were recorded corresponding to 16 IMEs for each million passengers or 1.8 IMEs for every thousand flights. The most frequent events were loss of consciousness (38.4%) followed by injuries (8.6%), gastrointestinal problems (8.3%), respiratory symptoms (7.3%), anxiety (5.7%), and burns (5.9%). Diversion was decided in 3% of the cases while death on board was rare (0.3% of events). CCMs responded in 33.5% of IMEs without assistance by a volunteer health professional, achieving a 97% success rate.DISCUSSION: IMEs are rare events and the majority can be treated with simple first aid measures. CCMs acting according to a simplified algorithm were very efficient in providing first aid. A standardized symptom-based IME form will assist in creating a reliable registry for further studies.Paxinos O, Savourdos P, Alexelis V, Anastasopoulos A, Karantoni E, Grigoropoulos P, Konstantinou X. In-flight medical events and cabin crew first aid response. Aerosp Med Hum Perform. 2021; 92(1):3238.

INTRODUCTION: In their seminal work, McGuire and colleagues reported an increased incidence of white matter hyperintensities (WMH) in a cohort of U2 pilots and hypobaric chamber personnel. WMH burden was higher in U2 pilots with previous reports of decompression sickness (DCS), and McGuire's reports have raised concerns regarding adverse outcomes in the aftermath of hypobaric exposures. Accordingly, a NATO working group has recently revised its standard recommendations regarding hypobaric exposures, including measures to mitigate the risk of WMH. Mandatory recovery time for up to 72 h between repeated exposures has been suggested on the basis of experimental evidence. However, we argue that the evidence is scarce which supports restricting repeated exposures to mitigate WMH. It is plausible that WMH is correlated with DCS and emphasis should be made on limiting the duration of exposures rather than restricting short and repeated exposures. The profiles in the NATO recommendations are meant to mitigate the risk of DCS. Still, they will potentially expose NATO Air Force and Special Operations personnel to flight profiles that can give rise to DCS incidence above 35%. Awaiting reliable data, we recommend limiting the duration of exposures and allowing for short repeated exposures.Ottestad W, Hansen TA, Ksin JI. Hypobaric decompression and white matter hyperintensities: an evaluation of the NATO standard. Aerosp Med Hum Perform. 2021; 92(1):3942.

INTRODUCTION: Recent epidemiological studies of U.S. Army aviators have suggested higher than anticipated rates of hyperlipidemia and metabolic disorder. The goal of this study was to determine whether this finding has persisted in 20162018 and to subsequently determine whether this trend is genuine and warrants further evaluation.METHODS: Data were requested from the U.S. Army Aeromedical Electronic Resource Office (AERO) and retrieved from the publicly available Defense Medical Surveillance System (DMSS) utilizing similar inclusion/exclusion criteria, where possible, as the earlier studies. For each year 20162018, incidence rates (per 1000 person years) for hyperlipidemia and metabolic syndrome were retrieved from DMSS, while percentages of aviators with these conditions were retrieved from AERO. The DMSS incidence rates were also age stratified. No formal analyses were conducted.RESULTS: Results from DMSS showed overall rates of hyperlipidemia ranging from 3.18 to 6.83 per 1000 person-years and for metabolic syndrome from 0.16 to 0.69 per 1000 person-years. The age stratified rates increased proportionally with age. AERO data showed a range of 0.81.5% of aviators had hyperlipidemia and for metabolic syndrome this ranged from 0.31 to 0.45%. These rates are broadly comparable to the previous studies findings.DISCUSSION: This studys findings suggest no continued increase in hyperlipidemia or metabolic disorder in aviators. While the exact cause is unknown, one could speculate a number of sources such as preferences in testing or encouragement from specific commanders or flight surgeons.Goldie C, McGhee J, Kelley AM. Trends in metabolic disorder in U.S. Army aviators, 20162018. Aerosp Med Hum Perform. 2021; 92(1):4346.

BACKGROUND: While Fairbanks, AK, USA, is a remote location with significant constraints on medical resources and specialty care, a small U.S. Air Force clinic was able to provide a pilot with definitive care for neurological decompression sickness.CASE REPORT: A 31-yr-old female patient presented to her flight surgeon in Anchorage, AK, USA, with migrating polyarthropathy and headaches 48 h after a flight which included planned aircraft decompression for high altitude low opening (HALO) jump operations. In order to get definitive treatment in a hyperbaric chamber, the patient typically would have to be flown to Seattle, WA, USA. This transfer of care would cost the Air Force approximately 150,000 and may have led to more complicated disease. Fortunately, Eielson Air Force Base (AFB) in Fairbanks had previously procured a Hyperlite hyperbaric chamber specifically for this situation. After consultation with a hyperbaric specialist, the team decided that the most appropriate course of action was to transfer her by car 6 h north from Anchorage to Fairbanks. On initiation of the Hart treatment table, she experienced immediate reduction in joint pain with a reversal of neurological symptoms.DISCUSSION: This patients care could not have been done without the procurement of a hyperbaric chamber. This case demonstrates the utility and necessity for these capabilities at more facilities that manage significant flying operations. Military bases should ensure that hyperbaric treatment capabilities are available within a close proximity.Petruso MJ, Philbrick SM. Definitive treatment of neurological decompression sickness in a resource limited location. Aerosp Med Hum Perform. 2021; 92(1):4749.

BACKGROUND: Maxillofacial shields (MFSs) are an available piece of aviation protective equipment designed to integrate into aircrew helmets and protect the face from wind and flying debris. Aviators have anecdotally reported that MFSs have provided blunt impact protection during impact events (i.e., a crash); however, no such cases have been formally documented in the literature.CASE REPORTS: Two cases were identified where aircrew wearing MFSs were involved in mishaps resulting in maxillofacial blunt impacts. In the first case, an OH-58 pilot struck the cyclic with his head/face during a crash. In the second case, a CH-47 crew chief was struck in the face by a maintenance panel dislodged from the aircraft. In both cases the MFS was damaged, but neither service member experienced injuries as a result of impact to the face.DISCUSSION: The cases illustrate the effectiveness of the MFS against blunt impact during aviation mishaps. While MFS use is currently optional for aircrew, it is believed that increased MFS use would result in fewer or less severe facial injuries as well as decrease the associated time and monetary losses due to injury.Weisenbach CA, McGhee JS. Aviation maxillofacial shields and blunt impact protection in U.S. Army helicopter mishaps. Aerosp Med Hum Perform. 2021; 92(1):5053.

BACKGROUND: Nutcracker syndrome is caused by a rare anatomic variant where the left renal vein is trapped between the aorta and the superior mesenteric artery. Posterior nutcracker syndrome is an even rarer entity, characterized by the retro-aortic positioning of the renal vein, causing compression between the aorta and spinal vertebrae. Symptoms include microscopic or frank hematuria, flank pain, varicocele, pelvic congestion syndrome, and abdominal pain. A search of the literature did not reveal prior cases of nutcracker syndrome that became symptomatic and diagnosed secondary to the unique stressors of high gravitational force (G force) in the aviation environment.CASE REPORT: A 25-yr-old man training as an F-16 flight test engineer presented with left scrotal/testicular pain, varicocele, and intermittent gross hematuria. After an extensive workup, he was diagnosed with posterior nutcracker syndrome and underwent a left varicocele ligation with spermatic cord denervation. He was eventually able to be returned to flying duties with limitation to non-high performance aircraft.DISCUSSION: This case is particularly unique as its diagnosis was dependent on exposure to high G force conditions that may have otherwise remained asymptomatic without this environmental stressor. Education on the diagnosis of nutcracker syndrome as a differential in the setting of hematuria and pain is an important lesson learned. This case also illustrates the necessity of considering the effects of the stressful environment of high G force on even overall healthy individuals. Fortunately, due to the collaboration of medical-surgical expertise and familiarity with the requirements for operational readiness, this patient was able to resume his aviation career, albeit in a different capacity compatible with his condition.Chung CY, Lytle ME, Clemente Fuentes RW. A case of posterior nutcracker syndrome revealed in the aerospace environment. Aerosp Med Hum Perform. 2021; 92(1):5456.