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Introduction: Strong neck muscles may decrease the risk of flight-induced neck pain and possible disability among fast jet pilots. The purpose of this study was to examine the intra- and interrater reliability of a commercial force gauge attached to a pilot's helmet for measuring isometric force production of the neck muscles., Methods: A total of 41 subjects performed maximal isometric cervical flexion, extension, and lateral flexion in two measurement sessions for intrarater reliability, and 31 of these subjects participated in a third session for measuring interrater reliability. Delayed muscle soreness and neck pain were assessed using the Visual Analog Scale before and after each measurement session. The intraclass correlation coefficient (ICC) was used to compare values between the test and retest assessments., Results: The overall interrater reliability was good (ICC 0.79-0.90), whereas the intrarater reliability varied from moderate to good (ICC 0.58-0.84). In both intra- and interrater reliability, the flexion test had good (ICC 0.84-0.89) reliability, while the lateral flexion test results had moderate to good (ICC 0.73-0.90) reliability. The extension test had the lowest reliability in both intra- (ICC 0.58) and interrater (ICC 0.79) tests. The average visual analog scale score (from 1-100 scale) prior to the second measurement session was 16 ± 18 in delayed muscle soreness and 0 ± 0 in neck pain., Discussion: The present study demonstrated that the helmet-attached force gauge is a reliable, safe, and clinically applicable method to evaluate isometric neck strength in the flexion and lateral flexion directions. Honkanen T, Mattila V, Kinnunen O, Janhunen M, Sovelius R, Vaara JP, Kyröläinen H. Reliability of a flight helmet-attached force gauge in measuring isometric neck muscle strength. Aerosp Med Hum Perform. 2024; 95(10):788-793.

Introduction: Fighter pilots work in a unique environment and are subject to high G-force loads under simultaneous head movements. Neck pain is reported to be a common health problem among fighter pilots leading to time lost flying and flight duty limitations. The present study aimed to find out if differences in early military flight career G-force exposure levels could increase the risk for degenerative changes in the cervical spine., Materials and Methods: The study population consisted of 56 20-year-old Finnish Air Force male fighter pilot cadets, who underwent MRI of the cervical spine at baseline and after 5 years. During follow-up, the G-force exposure was measured using the individual Fatigue Index (FI) recordings. The FI data were collected from each flight with BAE Hawks and is determined by the number of times certain levels of G-forces are exceeded during the flights. The incidence or progression of each degenerative change was compared to individual FI values using Pearson correlation coefficients., Results: The pilots flew on average 220 (±21) hours with high performance aircraft during follow-up, resulting in an average FI of 1.98 (±0.47). A statistically significant progression was found in intervertebral disc (IVD) degeneration sum score with no correlation to corresponding FI values. A statistically significant increase was also found in the prevalence of IVD herniations with a negative correlation with FI values. Other degenerative cervical spine changes did not progress or did not correlate with corresponding FI values., Conclusions: The prevalence of IVD degeneration and IVD herniations increases in the early phases of fighter pilots' career. Only the incidence of IVD herniations correlated with FI values and the correlation was negative. The negative correlation may be attributed to avoidance behavior due to neck pain, which was not measured in our study, or other unmeasured confounding factors. This was the first study to compare individual G-force exposure levels to high-quality MRI data over a follow-up of several years. Finnish fighter pilots are known to report increasing cervical symptoms during the Hawk training phase, but longer follow-up periods are likely needed to determine the association between G-force exposure levels and cervical degenerative changes., (© The Association of Military Surgeons of the United States 2024.)

Background: Musculoskeletal (MSK) disorders represent a significant burden to society and can be unpleasant for the affected individuals. Physical activity (PA) can prevent MSK disorders while conferring other health benefits. The present study aimed to investigate associations between device-measured PA and perceived MSK disorders among young adult men., Methods: PA at different intensity levels, standing, and sedentary behavior were measured with a hip-worn accelerometer in a cohort of 422 young adult Finnish men aged 26 years on average. The incidences of three common MSK disorders (viz., knee pain, lumbar radicular pain, and lumbago pain) during the last month were inquired by a questionnaire. Binary logistic regression was used to examine the associations between the MSK outcomes and explanatory PA variables (PA times at different intensity levels, standing, and sedentary times). The models were controlled for age, education, smoking, BMI, and maximal oxygen uptake., Results: PA, standing, and sedentary times were not significantly associated with the incidence of perceived MSK pain during the last month, except for lumbago pain. Lumbago pain was slightly more probable if the time spent in light PA increased, even after controlling for potential confounding factors, including moderate-to-vigorous PA, with an odds ratio (OR) of 1.07 (95% CI: 1.02-1.14). Sedentary time showed an opposite association, with an OR of 0.98 (95% CI: 0.96-1.00)., Conclusions: There were neither positive nor negative clinically meaningful associations between PA and recent MSK disorders among young adult men. The result is surprising and requires further confirmation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Sipilä, Sievänen, Raitanen, Kyröläinen, Vasankari, Vaara and Honkanen.)

Introduction: Degenerative changes of the cervical spine often cause disability and flight duty limitations among Finnish Air Force (FINAF) fighter pilots. We aimed to study the effect of +Gz exposure on degenerative changes in the cervical spine by comparing cervical MRIs of FINAF fighter pilots and controls., Methods: At baseline, the volunteer study population consisted of 56 20-year-old FINAF male fighter pilots (exposure group) and 56 21-year-old Army and Navy cadets (control group). Both groups underwent MRI of the cervical spine at the baseline and after 5 years. Degenerative changes evaluated using MRI included intervertebral disc (IVD) degeneration (Pfirrmann classification), disc herniations, uncovertebral arthrosis, Schmorl's nodes, Modic changes, spinal canal stenosis, kyphosis and scoliosis., Results: The degree of IVD degeneration in the whole cervical spine increased significantly in both populations with no between-group differences. The prevalence of disc herniations also tended to increase in both populations with no difference in the incidence over the follow-up. However, pilots proved to have more disc herniations at the baseline and at the follow-up. There were virtually no between-group differences in other assessed degenerative changes., Discussion: We found that IVD degeneration and the prevalence of disc herniations increased at a similar rate for fighter pilots and non-flying military students when all cervical levels were summed up. The lack of difference may be explained by the relatively low cumulative +Gz exposure during the first 5 years of a pilots' career., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

INTRODUCTION: Fighter pilots must withstand high G z -forces that can damage the cervical spine. Strength of the cervical musculature is of vital importance when it comes to preventing these G-induced neck injuries. However, there is very little evidence on valid neck muscle strength measurement methods for fighter pilots. The aim of this study was to examine the validity of a commercial force gauge attached to a pilot's helmet for measuring isometric neck muscle strength. METHODS: A total of 10 subjects performed maximal isometric cervical flexion, extension, and lateral flexion with the helmet-attached gauge and with a weight stack machine, which was used as a reference. Electromyography (EMG) activities were recorded from the right and left sternocleidomastoids and cervical erector spinae muscles during all measurements. Paired t -tests, Pearson correlation coefficient, and Wilcoxon's test were used to analyze the data. RESULTS: Difference of mean force values between the devices was statistically significant in all directions. Pearson correlation coefficient varied between 0.73 and 0.89 and it was highest in cervical flexion. EMG activities were significantly different only in the left CES during flexion. DISCUSSION: The helmet-attached gauge is a valid tool for measuring isometric neck muscle strength and is best used as a means to compare individual differences in strength levels or to track the progress of strength development. Nyländen P, Virmavirta M, Sovelius R, Kyröläinen H, Honkanen T. A flight helmet-attached force gauge for measuring isometric neck muscle strength . Aerosp Med Hum Perform. 2023; 94(6):480-484.

Evidence on the relationship between psychosocial well-being and physical activity (PA) is insufficient, especially in young adults between 18 and 29 years. Identifying protective factors for psychosocial well-being as well as factors that may promote PA behaviour in this specific age group is crucial.The aim of the present study was to explore the association between self-reported leisure time physical activity (LTPA) and a number of measures of psychosocial well-being in a large sample of Finnish young men. The sample used for this study is based on registers of the Finnish Defence Forces and consist of questionnaire-based data collected from 159,776 young healthy men (18-29 years, mean age 19 years) who started their military service during the period from 2015 to 2021. Sum scores were calculated for self-esteem and prosocial behaviour. Physical activity, number of friends and the relationship with the parents were each measured with a single question. Unadjusted and adjusted (education, financial situation of the family, family structure) logistic regression models were calculated.A multinominal logistic regression analysis showed that a higher level of LTPA was associated with a higher level of both prosocial behaviour (OR 6.12, 95% CI 5.88-6.36) and self-esteem (OR 4.41 95% CI 4.28-4.54). Further, LTPA had a positive relationship with good social relations, both with peers and parents. The odds ratio for participation in any LTPA weekly was higher (OR 2.74; CI 2.27-3.20) among those who had a close and trustworthy relationship with their parents compared to those men with more challenging relationships with their parents (OR 1.77; CI 1.46-2.14). An inactive lifestyle (PA less than once a week) seemed to be most common among men with no friends. About one third (31%) of men with no friends reported to engage in LTPA less than once a week, while only 10% of men with very many good friends reported to engage in similarly inactive LTPA behaviour.LTPA seems to be positively associated with self-esteem, prosocial behaviour and good social relations among young adult men. Actions aimed at promoting LTPA may have a positive impact on psychosocial well-being among young men, or vice versa. The relationship between PA and psychosocial well-being is complex and interrelated., (© 2023. The Author(s).)

Uric acid has promoted renal fibrosis and inflammation in experimental studies, but some studies have shown nephroprotective effects due to alleviated oxidative stress. We studied the influence of experimental hyperuricaemia in surgically 5/6 nephrectomized rats. Three weeks after subtotal nephrectomy or sham operation, the rats were allocated to control diet or 2.0% oxonic acid (uricase inhibitor) diet for 9 weeks. Then blood, urine and tissue samples were taken, and renal morphology and oxidative stress were examined. Inflammation and fibrosis were evaluated using immunohistochemistry and real-time PCR (RT-PCR). Remnant kidney rats ingesting normal or oxonic acid diet presented with ~60% reduction of creatinine clearance and suppressed plasma renin activity. Oxonic acid diet increased plasma uric acid levels by >80 μmol/L. In remnant kidney rats, moderate hyperuricaemia decreased glomerulosclerosis, tubulointerstitial damage and kidney mast cell count, without influencing the fibrosis marker collagen I messenger RNA (mRNA) content. In both sham-operated and 5/6 nephrectomized rats, the mast cell product 11-epi-prostaglandin-F 2α excretion to the urine and kidney tissue cyclooxygenase-2 (COX-2) levels were decreased. To conclude, hyperuricaemic remnant kidney rats displayed improved kidney morphology and reduced markers of oxidative stress and inflammation. Thus, moderately elevated plasma uric acid had beneficial effects on the kidney in this low-renin model of experimental renal insufficiency., (© 2022 The Authors. Basic & Clinical Pharmacology & Toxicology published by John Wiley & Sons Ltd on behalf of Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

Background: There is limited evidence of how physical activity (PA) associates with low back pain (LBP) and neck pain (NP). Particularly, the association between occupational or commuting PA and LBP/NP is unclear. The aim of the present cross-sectional study was to investigate the association between spinal disorders and different physical activity domains in young and healthy adult men., Methods: Self-reported leisure time, occupational and commuting PA, as well as LBP and NP, were studied using questionnaires among young Finnish males ( n = 1,630). Logistic regression analysis was used to study the associations of PA domains, physical fitness, and spinal disorders. Regression models were adjusted for age, education, smoking, waist circumference, and the other PA domains., Results: There was a positive association between moderate leisure-time PA and both LBP (OR: 1.51, 95% CI: 1.18-1.95) and NP (OR: 1.29, 95% CI: 1.00-1.66) compared to low PA. Furthermore, moderate (OR: 1.31, 95% CI: 1.00-1.71) and high (OR: 1.53, 95% CI: 1.15-2.02) leisure time PA groups had a higher likelihood of lumbago. Moderate (OR: 0.67, 95% CI: 0.51-0.90) and high (OR: 0.68, 95% CI: 0.48-0.95) occupational PA groups had lower likelihood for radiating LBP, while high occupational PA (OR: 0.72, 95% CI: 0.52-0.99) had lower likelihood for lumbago., Conclusions: The associations between physical activity and LBP or NP seem to vary between different domains of physical activity among young healthy men. Commuting and occupation-related PA appear not to be harmfully associated with LPB or NP, whereas moderate-level leisure time PA may be associated with increased LBP and NP, and the respective high level may be associated with an increase in the prevalence of lumbago., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Honkanen, Vaara, Pihlajamäki, Västilä and Kyröläinen.)

BACKGROUND: High +G z exposure is known to cause spinal problems in fighter pilots, but the amount of tolerable cumulative +G z exposure or its intensity is not known. The aims of this study were to assess possible breaking points during a flight career and to evaluate possible determinants affecting pilots' spines. METHODS: Survival analysis was performed on the population who started their jet training in 1995-2015. The endpoint was permanent flight duty restriction due to spinal disorder. Then the quantified G z exposure and possible confounding factors were compared between those pilots with permanent flying restriction and their matched controls. Cumulative G z exposure was measured sortie by sortie with fatigue index (FI) recordings. FI is determined by the number of times certain levels of G z are exceeded during the sorties. RESULTS: The linear trend of the survival curve indicates an annual 0.86% drop out rate due to spinal problems among the fighter pilot population. A conditional logistic regression did not find any difference in the FI between cases and controls (OR 0.96, 95%CI 0.87-1.06). No statistical difference was found for flight hours, a sum of intensive flying periods, fitness tests, or with nicotine product use. Additionally, a maximum +G z limitation without airframe restriction was assessed and is presented as a useful tool to manage loading and developed symptoms. DISCUSSION: No particular breaking point during follow-up or individual factor was found for G z induced spinal disorders. The results of the study outline the multifactorial nature of the problem. Thus, multifactorial countermeasures are also needed to protect pilots' health. Sovelius R, Honkanen T, Janhunen M, Mäntylä M, Huhtala H, Leino T. +Gz exposure and flight duty limitations . Aerosp Med Hum Perform. 2022; 93(4):390-395.

Healthy lifestyle behaviors including physical activity (PA) have been recognized to contribute positively to mental health. Most of the evidence on relationship between PA and mental health relies on self-reported PA results. Device-based measures on PA or sedentary behavior (SB) are less frequently used in mental health research. The present study aimed at examining the relationship between mental health and PA/SB measured by accelerometers in young Finnish men. The sample consisted of 409 men (mean age 28 ± 7 years), who participated in the military refresher training in Finland. Self-rated mental health was measured with Mental Health Inventory (MHI-5) and short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS) measuring mental health both from the perspective of mental health problems and mental well-being. PA was measured with accelerometer from the perspective of light, moderate, vigorous, and total activity, as well as SB. Linear regression models and compositional analysis were applied. Age, education, marital status, employment status, BMI, alcohol use and smoking were used as covariates. Evidence on relationship between total PA (standardized regression coefficient 0.340; 95% CI 0.022-0.657, p = 0.036) and SB (standardized regression coefficient -0.340; 95% CI -0.657 to -0.022, p = 0.036) with symptoms of mental health problems was found after adjusting for age, education, marital and employment status. The relationship was marginally significant ( p = 0.056) after adjusting also for BMI, alcohol use and smoking. No evidence on relationship between PA or SB and mental well-being was found, neither in standard linear regression analysis nor in compositional approach. In our sample of young adult men, PA seemed to have a stronger relationship with symptoms of mental health problems rather than with mental well-being. The findings lead to a conclusion that all PA per se may not be independently associated with mental well-being in young adult males and raise the question whether the domain of PA and its context play a critical role in these relationships., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Appelqvist-Schmidlechner, Raitanen, Vasankari, Kyröläinen, Häkkinen, Honkanen and Vaara.)