Changes in Body Composition, Energy Metabolites and Electrolytes During Winter Survival Training in Male Soldiers

Abstract

The aim of this study was to examine changes in body composition, energy metabolites and electrolytes during a 10-day winter survival training period. Two groups of male soldiers were examined: the REC group (n = 26; age 19.7 ± 1.2 years; BMI 23.9 ± 2.7) had recovery period between days 6 and 8 in the survival training, whereas the EXC group (n = 42; age 19.6 ± 0.8 years; BMI 23.1 ± 2.8) did not. The following data were collected: body composition (bioimpedance), energy balance (food diaries, heart rate variability measurements), and biomarkers (blood samples). In survival training, estimated energy balance was highly negative: -4,323 ± 1,515 kcal/d (EXC) and -4,635 ± 1,742 kcal/d (REC). Between days 1 and 10, body mass decreased by 3.9% (EXC) and 3.0% (REC). On day 6, free fatty acid and urea levels increased, whereas leptin, glucose and potassium decreased in all. Recovery period temporarily reversed some of the changes (body mass, leptin, free fatty acids, and urea) toward baseline levels. Survival training caused a severe energy deficit and reductions in body mass. The early stage of military survival training seems to alter energy, hormonal and fluid metabolism, but these effects disappear after an active recovery period.

Keywords: biomarkers; energy deficit; fat mass; military training; recovery.

FIGURE 1

Study protocol. The REC group had 2 days recovery period, whereas the EXC group was in the field all the training. HRV, heart rate variability; EE, estimated energy expenditure, EI, energy intake.

FIGURE 2

Changes in serum (A) leptin and (B) ghrelin concentrations within and between the REC and EXC groups. For leptin, a number of subjects in the REC and EXC groups were daily 26, 22, 22, 20 and 42, 26, 27, 25, respectively. For ghrelin n = 17 (on all days) in the REC group and n = 23, 23, 23, 22 in the EXC group for days 1, 6, 8, 10 respectively. *REC, ^†EXC, and ^‡Between groups. ^**,^††p < 0.01; ^†††,^‡‡‡,^***p < 0.001.

FIGURE 3

Changes in (A) glucose, (B) free fatty acids and (C) urea concentrations within and between the REC and EXC groups. In the REC group, n = 26, 22, 22, 20 and in the EXC group n = 42, 26, 27, 25 for days 1, 6, 8, 10 respectively. *REC, ^†EXC, and ^‡Between groups. *,^†,^‡p < 0.05; ^**,^††,^‡‡p < 0.01; ^***,^†††,^‡‡‡p < 0.001.

FIGURE 4

Changes in (A) sodium (B) potassium and (C) chloride concentration within and between the REC and EXC groups. In the REC group n = 26, 22, 22, 20 and in the EXC group n = 42, 26, 27, 25 for days 1, 6, 8, 10 respectively. *REC, ^†EXC, and ^‡Between groups. ^‡‡p < 0.01; ^***,^†††p < 0.001.