Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military

Abstract

Military personnel experience energy deficit (total energy expenditure higher than energy intake), particularly during combat training and field exercises where exercising energy expenditures are high and energy intake is reduced. Low energy availability (energy intake minus exercising energy expenditure expressed relative to fat free mass) impairs endocrine function and bone health, as recognized in female athletes as the Female Athlete Triad syndrome. More recently, the Relative Energy Deficiency in Sport (RED-S) syndrome encompasses broader health outcomes, physical and cognitive performance, non-athletes, and men. This review summarizes the evidence for the effect of low energy availability and energy deficiency in military training and operations on health and performance outcomes. Energy availability is difficult to measure in free-living individuals but doubly labeled water studies demonstrate high total energy expenditures during military training; studies that have concurrently measured energy intake, or measured body composition changes with DXA, suggest severe and/or prolonged energy deficits. Military training in energy deficit disturbs endocrine and metabolic function, menstrual function, bone health, immune function, gastrointestinal health, iron status, mood, and physical and cognitive performance. There are more data for men than women, and little evidence on the chronic effects of repeated exposures to energy deficit. Military training impairs indices of health and performance, indicative of the Triad and REDS , but the multi-stressor environment makes it difficult to isolate the independent effects of energy deficiency. Studies supplementing with energy to attenuate the energy deficit suggest an independent effect of energy deficiency in the disturbances to metabolic, endocrine and immune function, and physical performance, but randomized controlled trials are lacking.

Comparisons Between Serum Levels of Hepcidin and Leptin in Male College-Level Endurance Runners and Sprinters

“…Since we did not estimate accurate dietary intake (e.g., 3day weighted-food records) and energy expenditure, we did not estimate the energy valance or availability. However, compared to sprinters, a lower body fat amount, BMI, and anemia-related parameters (35,36) in endurance runners may indicate the lower energy availability. In athletes, low energy availability may cause iron deficiency anemia (1)(2)(3)8).…”

Free-Living Dietary Intake in Tactical Personnel and Implications for Nutrition Practice: A Systematic Review

“…An appropriate dietary energy intake is important for tactical populations as their occupational activities can be physically demanding [66][67][68]. Inadequate energy intake can lead to weight loss, decreases in lean muscle mass, and decreases in bone density, which can affect daily performance, increase injury risk, and prolong recovery time [69]. Tactical occupations are renowned for phases of energy deficiency and recovery, and a potential risk for Relative Energy Deficiency in Sport (RED-S) syndrome in military personnel has previously been reported [69].…”

“…Inadequate energy intake can lead to weight loss, decreases in lean muscle mass, and decreases in bone density, which can affect daily performance, increase injury risk, and prolong recovery time [69]. Tactical occupations are renowned for phases of energy deficiency and recovery, and a potential risk for Relative Energy Deficiency in Sport (RED-S) syndrome in military personnel has previously been reported [69]. Therefore, while the reported BMI of tactical personnel did not support a chronic energy deficiency as they were all >25 kg/m 2 (e.g., categorized as normal through to obese), it is unclear whether higher BMI values are reflective of increased lean (muscle) mass or fat mass.…”

“…Large scale studies are also needed to identify the healthy eating barriers as this population face specific occupation-related barriers, such as shift work and working under extreme conditions [20]. Similarly, exploring RED-S or the long-term health effects of military occupations which incorporate phases of energy deficiency and recovery, characteristic of tactical occupations, is warranted [69].…”

Does Protein Supplementation Support Adaptations to Arduous Concurrent Exercise Training? A Systematic Review and Meta-Analysis with Military Based Applications

“…Similarly, recruits undergoing arduous military training routinely engage in concurrent training so as to meet the training and operational demands of military life [7][8][9][10][11][12][13]. Military recruit training programmes are designed to transform civilians into trained soldiers, therefore, physical training is necessarily arduous, involving a combination of aerobic training, strength and conditioning, obstacle courses, swimming, circuit training and loaded marching [14,15]. Despite the requirement of concurrent training in athletic and military recruit populations, and the positive effects protein supplementation may have on training outcomes, the majority of systematic reviews and meta-analyses have focused mainly on the effects of protein supplementation when either resistance or endurance training are studied in isolation with no specific population in particular being studied [16][17][18][19].…”