Search

ObjectiveTo determine the effect of prolonged exposure to a submarine environment on biomarkers of cardiometabolic risk in Royal Navy (RN) submariners.MethodsSerum lipids (cholesterol (C), triglyceride (TG), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), non-HDL-C), glucose, insulin and anthropometrics were compared within three RN submarine crews before and after submerged patrols of 12 or 6 weeks, and with a crew that remained ashore (SUB-HOME). Dietary intake and activity patterns were self-reported during each patrol. Differences were assessed in crew characteristics using one-way analysis of variance and in serum lipids using paired t-tests.ResultsPostpatrol, the mean body weight of submerged crews decreased (−1.4±4.2 kg, p=0.0001), but increased in SUB-HOME (1.9±1.8 kg, p=0.0001). Modest improvements in serum lipids (mean individual change (mmol/L); C=−0.3±0.7, p=0.0001; TG=−0.3±0.7, p=0.0001; HDL-C=−0.1±0.3, p=0.0001; non-HDL-C=−0.2±0.6, p=0.012), glucose (−0.2±0.5, p=0.0001) and insulin (−1.5±4.6 mU/L, p=0.001) were observed in submerged crews. Changes in serum lipids were positively associated with changes in body weight within crews combined. Energy intake was maintained during submerged patrols but was lower compared with non-submerged (11 139±2792 vs. 9617±2466 kJ, p=0.001; 11 062±2775 vs. 9632±2682 kJ, p=0.003).ConclusionsThe environment of a submerged submarine produced no adverse effects on serum biomarkers of cardiometabolic risk in crew. Conversely, modest improvements in these biomarkers were associated with a decrease in body weight.

Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( − 4·6 (sd3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd2·9) %) between the mid- and post-deployment periods (Psd3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.

Polar expeditions have been associated with changes in the hypothalamic–pituitary–testicular axis consistent with central hypogonadism (i.e., decreased testosterone, luteinising hormone (LH), and follicle stimulating hormone (FSH)). These changes are typically associated with body mass loss. Our aim was to evaluate whether maintenance of body mass during a polar expedition could mitigate against the development of central hypogonadism. Male participants (n = 22) from a 42-day expedition (British Services Antarctic Expedition 2012) volunteered to take part in the study. Body mass, body composition, and strength data were recorded pre- and postexpedition in addition to assessment of serum testosterone, LH, FSH, thyroid hormones, insulin-like growth factor 1 (IGF-1), and trace elements. Energy provision and energy expenditure were assessed at mid- and end-expedition. Daily energy provision was 6335 ± 149 kcal·day−1. Estimated energy expenditure midexpedition was 5783 ± 1690 kcal·day−1. Body mass and percentage body fat did not change between pre- and postexpedition. Total testosterone (nmol·L−1) (14.0 ± 4.9 vs. 17.3 ± 4.0, p = 0.006), calculated free testosterone (pmol·L−1) (288 ± 82 vs. 350 ± 70, p = 0.003), and sex hormone binding globulin (nmol·L−1) (33 ± 12 vs. 36 ± 11, p = 0.023) concentrations increased. LH and FSH remained unchanged. Thyroid stimulating hormone (TSH; IU·L−1) (2.1 ± 0.8 vs. 4.1 ± 2.1, p < 0.001) and free triiodothyronine (FT3; IU·L−1) (5.4 ± 0.4 vs. 6.1 ± 0.8, p < 0.001) increased while free thyroxine, IGF-1, and trace elements remained unchanged. Hand-grip strength was reduced postexpedition but static lift strength was maintained. Maintenance of body mass and nutritional status appeared to negate the central hypogonadism previously reported from polar expeditions. The elevated TSH and free FT3 were consistent with a previously reported “polar T3 syndrome”.