A review of the physiological and psychological health and wellbeing of naval service personnel and the modalities used for monitoring

Influence of physical characteristics, sport-specific factors, and training participation on mental fatigue in elite Australian Rules Football athletes

This study aimed to monitor subjective mental fatigue (MF) during pre-season in elite male Australian rules football (ARF) athletes and identify factors associated with MF. Thirty-nine elite male ARF athletes (24.6 ± 4.5 y) rated their MF on a visual analogue scale on each training day of a 13-week pre-season (n = 1353 samples, 48 training days). Strength, running measures, sport-specific factors (age, mass, games played, playing years, contract status) and training participation were recorded. Linear models were used to determine the effects between factors and MF. Elevated MF was observed in weeks 2-4 and 7-10 vs practice match week 1 and week 12, and weeks 2-4, 8-10 vs week 11 (all p < 0.05). No strength, running characteristics, sport-specific factors or training participation variables were significantly associated with MF. Mental fatigue changes over an AFL pre-season, being higher in the first 10 weeks, before reducing in the final 3 weeks. Sport-specific factors and physical characteristics were not associated with MF. These findings encourage practitioners to measure MF, particularly in early pre-season, to assess athlete response to training. Practitioners should also look to incorporate adequate mental recovery to optimise the balance between fatigue and performance enhancement during this period.

Circadian rhythm sleep loss impairs motor inhibition more than motor execution in continuous action

Under total sleep deprivation, both inhibitory and motor control are impaired. However, how circadian rhythm sleep loss caused by irregular sleep pattern affects motor inhibition and execution in continuous actions remains unknown. This study utilized a pointing task to investigate the question over 30 days. During regular trials, participants were instructed to tap on a specified location, while in countermanding trials, they were required to countermand their current action. Additionally, there was a control group performed the same task following a normal 24-h rhythm. The results indicated that the decrease in accuracy and the increase in movement time in countermanding trials were more prominent in the shift work group. In contrast, there was no significant difference in reaction time between the two groups. Notably, the shift work group outperformed the control group in terms of movement time in regular trials and radial displacement in countermanding trials. Overall, these results show that circadian rhythm sleep loss predominantly affects inhibitory control, rather than motor control, underscoring the nuanced impacts of sleep disruption on differential aspects of cognitive and motor functions.

Gut microbiome signature and nasal lavage inflammatory markers in young people with asthma

Background

Asthma is a complex disease and a severe global public health problem resulting from interactions between genetic background and environmental exposures. It has been suggested that gut microbiota may be related to asthma development; however, such relationships needs further investigation.

Objective

This study aimed to characterize the gut microbiota as well as the nasal lavage cytokine profile of asthmatic and nonasthmatic individuals.

Methods

Stool and nasal lavage samples were collected from 29 children and adolescents with type 2 asthma and 28 children without asthma in Brazil. Amplicon sequencing of the stool bacterial V4 region of the 16S rRNA gene was performed using Illumina MiSeq. Microbiota analysis was performed by QIIME 2 and PICRUSt2. Type 2 asthma phenotype was characterized by high sputum eosinophil counts and positive skin prick tests for house dust mite, cockroach, and/or cat or dog dander. The nasal immune marker profile was assessed using a customized multiplex panel.

Results

Stool microbiota differed significantly between asthmatic and nonasthmatic participants (P = .001). Bacteroides was more abundant in participants with asthma (P < .05), while Prevotella was more abundant in nonasthmatic individuals (P < .05). In people with asthma, the relative abundance of Bacteroides correlated with IL-4 concentration in nasal lavage samples. Inference of microbiota functional capacity identified differential fatty acid biosynthesis in asthmatic compared to nonasthmatic subjects.

Conclusion

The stool microbiota differed between asthmatic and nonasthmatic young people in Brazil. Asthma was associated with higher Bacteroides levels, which correlated with nasal IL-4 concentration.

Are there differences between officers and ratings on merchant vessels concerning effort-reward imbalance: a cross-sectional maritime field study

PURPOSE

Today, measures to economise in the operation of ships can cause either an effort-reward imbalance or health impairments. The goal of this study was to assess the risk of effort-reward imbalance including overcommitment among officers and ratings on merchant vessels during their assignments and to evaluate lifestyle factors of seafarers as well as the health-promoting conditions on board.

METHODS

A study sample of 308 male seafarers was examined during a total of 20 sea voyages on German container ships (participation rate 91.9%).

RESULTS

Only 11 seafarers were identified as having an increased health risk of an effort-reward imbalance (ER ratio > 1). Officers tended to have a higher risk of an elevated ratio than ratings (4.4% vs. 3.1%) and also showed a significantly higher risk of an ER ratio above the median (58.8% vs. 41.8%; p = 0.022). Compared to land-based populations, the average overcommitment score of seafarers was high (17.9)-particularly among officers (20.3 vs. 16.5; p = 0.031). This corresponded to an elevated risk of overcommitment among officers compared to ratings (OR 2.14; 95% CI 1.78-2.37). This elevated risk remained significant after adjustment for age (OR 2.11; 95% CI 1.76-2.35) and job-related stressors.

CONCLUSION

Although an elevated risk of effort-reward imbalance was only observed in few seafarers, this study revealed a high prevalence of overcommitment particularly among officers. In the course of time, overcommitment can lead to mental exhaustion. Therefore, shipboard health-promoting conditions need to be optimised.

Vitamin D Supplementation in Military Personnel: A Systematic Review of Randomized Controlled Trials

CONTEXT

Vitamin D supplementation is important in military research because of its role in musculoskeletal health.

OBJECTIVE

This systematic review examined the effects of vitamin D supplementation on serum 25-hydroxyvitamin D (25(OH)D) concentrations and musculoskeletal health outcomes in military personnel.

DATA SOURCES

A comprehensive search was conducted using MEDLINE, EMBASE, CINAHL, SportDiscus, and the Cochrane Library databases and the reference lists of existing review articles and relevant studies.

STUDY SELECTION

Reviewers independently screened titles, abstracts, and full texts of the articles using predefined criteria.

STUDY DESIGN

Systematic review of randomized controlled trials (RCTs) using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

Three reviewers independently extracted data and assessed the methodological quality. Mean differences with 95% CI in serum 25(OH)D concentrations between the vitamin D and placebo arms were calculated.

RESULTS

Four RCTs were included in the qualitative analyses. The 25(OH)D concentrations were improved with 2000 IU/d supplementation (mean difference, 3.90 ng/mL; 95% CI, 0.22-7.58). A trial on female Navy recruits showed a significant decrease in stress fractures (risk ratio, 0.77; 95% CI, 0.62-0.95), particularly tibial fractures, from daily supplementation of 800 IU vitamin D and 2000 mg calcium.

CONCLUSION

There was a positive trend in 25(OH)D concentrations from higher doses of supplementary vitamin D in military submariners and a possible benefit to bone health when vitamin D was combined with calcium.

A systematic review of the nutritional implications of military rations

BACKGROUND

The objective of this study was to assess military rations. Military rations must provide military personnel with suitable nutrition, as high-quality nutrition is crucial for promoting health.

AIM

This systematic review provides information regarding the nutritional design of military rations according to energy and protein intake and supplements.

METHODS

A systematic search was conducted for articles published to date regarding the nutritional needs involved in a military diet for an active population of either gender, ranging from 18 to 60 years old, without excluding material by year, type of document, location, or author. The pertinent articles found were published from 1994 to 2017.

RESULTS

Physical activity and environmental factors directly affect calculating energy needs and carbohydrate intake when designing military rations. However, the results showed no influence on protein, fat and/or sodium intake. Furthermore, the search revealed that military populations have a high intake of dietary supplements; it is thus worth considering their incorporation into campaign rations.

CONCLUSION

Military personnel macro- and micro-nutrient needs depend on physical activity and nutrient intake measurement methodologies. The data regarding military personnel dietary supplement consumption indicated that this is a niche worth considering when designing military rations. Research on nutritional needs for military rations could concentrate on optimizing the amount of macro- and micro-nutrients and their biological value, according to physical activity, as well as maintaining their sensory quality, safety and shelf life using different processing technologies.

Stress and Strain among Seafarers Related to the Occupational Groups

The present study analyses whether the stress and strain experienced by seafarers differ between the various occupational groups on board container ships. In a maritime field study, 323 sailors on 22 container ships were asked to complete a questionnaire and were biometrically surveyed. In addition, a survey of energy expenditure and heart rate (variability) was carried out with the SenseWear^® armband monitor and the Polar RS800 watch, respectively. The activity data objectively collected by the armband monitor showed an average sleep duration of 5.0 h per day, with particularly short sleep episodes amongst nautical officers. This occupational group also significantly more frequently reported sleep deficits (67%). The highest work-related energy expenditure per day was among the deck ratings (801 kcal), followed by the engine room personnel (777 kcal), and finally the nautical officers (568 kcal). The last-mentioned group, who were also the most likely to experience mental stress in the workplace, had the lowest heart rate variability compared to the other occupational groups. The average working time was the only stress parameter that correlated significantly negatively with the heart rate variability (r = −0.387; p = 0.002). Overall, job-related stressors of seafarers on board should be objectified in further studies and occupational group-specific health promotion programmes should be developed.