Energy Expenditure and Changes in Body Composition During Submarine Deployment—An Observational Study “DasBoost 2-2017”

Abstract

The present study was designed to objectively assess the effects of 3-months submarine deployment on behavioural and metabolic determinants of metabolic health. In 13 healthy, non-obese volunteers, we using stable isotope dilution, and plasma and urinary biochemistry to characterize metabolic health before and after a 3-month submarine deployment. Volunteers worked in 6-h shifts. After deployment, we observed reduced fat-free mass (mean ± SD, −4.1 ± 3.3 kg, p = 0.003) and increased adiposity (21.9 ± 3.2% fat mass to 24.4 ± 4.7%, p = 0.01). Changes in fat-free mass were positively associated with physical activity (+0.8 kg per 0.1 increase in PAL, p = 0.03). The average physical activity level was 1.64 ± 0.26 and total energy expenditure during deployment was 2937 ± 498 kcal/d, while energy intake was 3158 ± 786 kcal/d. Fasting glucose (p = 0.03), and triglycerides (p = 0.01) declined, whereas fasting free fatty acids increased (p = 0.04). Plasma vitamin D and B12 concentrations decreased (−14%, p = 0.04, and −44%, p = 0.001, respectively), and plasma calcium, and magnesium increased (+51%, p = 0.01, and +5%, p = 0.02). Haemoglobin was unchanged, but haematocrit decreased (−2.2 ± 2.1%, p = 0.005). In conclusion, submarine deployment impairs fat-free mass maintenance and promotes adiposity. High physical activity may prevent the decline in fat-free mass. Our study confirms the need to counteract Vitamin D and B12 deficiencies, and suggests impairments in erythrocyte metabolism.

Vitamin D status in active duty Navy military personnel: a systematic review

“…3 11 22 Submariners, as SM particularly exposed to occupational factors that may adversely affect bone health (eg, relatively high carbon dioxide content in breathed air, lack of sunlight exposure, confined environment that limits physical activity, restricted diet with reduced access to perishable food), deserve the attention of the Navy Occupational Health Department. [2][3][4] Beyond individual and cultural risk factors, merging the occupational risk factors (serum 25(OH)D level decreased in crew members during patrols) and the environmental risk factors (serum 25(OH)D levels lower in winter than in summer) for vitamin D deficiency means that submariners assigned to winter patrols are particularly prone to vitamin D deficiency and should take vitamin D supplementation before boarding. 26 Despite two exceptions, 27 28 previous publications reported a significant reduction in serum 25(OH)D level of 15-47% during submarine patrols that lasted about approximately 1-2 months due to lack of sunlight exposure (ie, ultraviolet B light radiation).…”

“…1 Submariners are even more prone to vitamin D deficiency due to the total absence of sunlight exposure and reduced access to perishable food. [2][3][4] Mainly because of the increasing attention to vitamin D in the popular and medical literature and better availability of assay procedures, a large increase in the incidence of vitamin D deficiency was observed in US Navy active duty military personnel serving between 1997 (1 case in 393 307 service members (SM)) and 2015 (543 cases in 322 784 SM), with a total of 2968 new diagnoses in this time frame. 5 In a previous study including Portuguese Navy active duty military personnel (n=555; 2014-20), the prevalence of vitamin D deficiency was 37.1%.…”

“…Active duty Navy military personnel are particularly at risk of vitamin D deficiency, essentially due to an occupational environment that limits sunlight exposure (eg, protective military clothing, indoor and/or shift work, high latitude field duty) 1. Submariners are even more prone to vitamin D deficiency due to the total absence of sunlight exposure and reduced access to perishable food 2–4…”

Vitamin D status in the active duty Navy military personnel: protocol for a systematic review

“…Merging high physical and psychological demands with inadequate nutrition and/or sleep disruption places the active duty Navy military personnel at high risk for vitamin D deficiency 31. The lack of exposure to the sun when living and working in a warship or a submarine also increases the risk of vitamin D deficiency 32. For these reasons, vitamin D levels should be routinely assessed on all active duty Navy military personnel, especially those in predeployment and postdeployment mobilisation phases 33…”

“… 31 The lack of exposure to the sun when living and working in a warship or a submarine also increases the risk of vitamin D deficiency. 32 For these reasons, vitamin D levels should be routinely assessed on all active duty Navy military personnel, especially those in predeployment and postdeployment mobilisation phases. 33 …”