Abstract
Confined space, limited exercise equipment, rotating shift work and reduced sleep may affect cardiometabolic health in submariners. To test this hypothesis, 53 male U.S. Submariners (20–39 years) were studied before and after a 3-month routine submarine patrol. Measures included anthropometrics, dietary and physical activity, biomarkers of cardiometabolic health, energy and appetite regulation, and inflammation. Before deployment, 62% of submariners had a body fat % (BF%) ≥ 25% (obesity), and of this group, 30% met the criteria for metabolic syndrome. In obese volunteers, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), leptin, the leptin/adiponectin ratio, and pro-inflammatory chemokines growth-related oncogene and macrophage-derived chemokine were significantly higher compared to non-obese submariners. Following the patrol, a significant mean reduction in body mass (5%) and fat-mass (11%) occurred in the obese group as a result of reduced energy intake (~2000 kJ) during the patrol; and, independent of group, modest improvements in serum lipids and a mean reduction in interferon γ-induced protein 10 and monocyte chemotactic protein 1 were observed. Since 43% of the submariners remained obese, and 18% continued to meet the criteria for metabolic syndrome following the patrol, the magnitude of weight loss was insufficient to completely abolish metabolic dysfunction. Submergence up to 3-months, however, does not appear to be the cause of obesity, which is similar to that of the general population.
Highlights
The estimated prevalence of overweight and obesity in U.S adults is ~70% and 35%, respectively, rates that have more than doubled since 1976–1980 [1]
Circadian rhythm disruption adversely affects the metabolic responses to feeding, alters leptin secretion patterns favoring energy intake, and leads to dysregulated innate immunity and systemic inflammation [8,9,10,11,12]. These events contribute to the increased risk for metabolic syndrome and cardiovascular disease (CVD) reported in shift workers [12,13]
The primary findings from this work are twofold: First, 62% of crewmembers were obese prior to the patrol; and the cardiometabolic health profile of obese sailors was poor compared to the non-obese sailors, as 30% of this group met the criteria for metabolic syndrome
Summary
The estimated prevalence of overweight and obesity in U.S adults is ~70% and 35%, respectively, rates that have more than doubled since 1976–1980 [1]. Circadian rhythm disruption adversely affects the metabolic responses to feeding (partly due to insulin resistance), alters leptin secretion patterns favoring energy intake, and leads to dysregulated innate immunity and systemic inflammation [8,9,10,11,12] These events contribute to the increased risk for metabolic syndrome and CVD reported in shift workers [12,13]. In the present study we tested the hypothesis that the proportion of submariners classified as overweight and obese would increase following a routine 3-month patrol In contrast to this expectation, we observed a significant mean decrease in submariner body mass and fat mass following the patrol [14]. Physical activity, blood pressure, and serum measures of cardiometabolic health (i.e., glucose, insulin, adiponectin, lipids and inflammatory cytokines) and appetite and energy homeostasis (ghrelin and leptin) were assessed
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