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

Nykänen, Tarja; Ojanen, Tommi; Heikkinen, Risto; Fogelholm, Mikael; Kyröläinen, Heikki

doi:10.3389/fphys.2022.797268

Cited by 4 publications

(5 citation statements)

References 39 publications

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“…In the RECO group, fat mass first reduced and then stabilized during the recovery period (11.4 ± 5.4, 9.0 ± 5.5, 8.7 ± 4.7 kg; p < 0.001 PRE-MID, MID-POST). More results have been presented in the previous study [10].…”

Section: Resultsmentioning

confidence: 71%

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Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training

Nykänen

Ojanen

Vaara

et al. 2023

IJERPH

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Severe energy deficit may impair hormonal regulation and physical performance in military trainings. The aim of this study was to examine the associations between energy intake, expenditure, and balance, hormones and military performance during a winter survival training. Two groups were studied: the FEX group (n = 46) had 8-day garrison and field training, whereas the RECO group (n = 26) had a 36-h recovery period after the 6-day garrison and field training phase. Energy intake was assessed by food diaries, expenditure via heart rate variability, body composition by bioimpedance, and hormones by blood samples. Strength, endurance and shooting tests were done for evaluating military performance. PRE 0 d, MID 6 d, POST 8 d measurements were carried out. Energy balance was negative in PRE and MID (FEX −1070 ± 866, −4323 ± 1515; RECO −1427 ± 1200, −4635 ± 1742 kcal·d−1). In POST, energy balance differed between the groups (FEX −4222 ± 1815; RECO −608 ± 1107 kcal·d−1 (p < 0.001)), as well as leptin, testosterone/cortisol ratio, and endurance performance (p = 0.003, p < 0.001, p = 0.003, respectively). Changes in energy intake and expenditure were partially associated with changes in leptin and the testosterone/cortisol ratio, but not with physical performance variables. The 36-h recovery restored energy balance and hormonal status after strenuous military training, but these outcomes were not associated with strength or shooting performance.

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Section: Resultsmentioning

confidence: 71%

“…Severe energy deficit impairs hormonal regulation and disturbs homeostasis in harsh environments [10,11]. Appetite-mediating hormones, leptin and ghrelin, react in acute caloric deprivation [12] and in response to loss of body mass [13].…”

Section: Introductionmentioning

confidence: 99%

Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training

Nykänen

Ojanen

Vaara

et al. 2023

IJERPH

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“…Thus, it is possible that while standing shooting performance was more engaging task, requiring maintenance of stance and upper body muscle activity to hold the weapon for both groups, prone position enabled impairment in upregulating arousal and attention in sleep-deprived EXP, explaining weakening of the results as compared to CON. Secondly, drastic continued energy deficit and higher physical demands of CON may have had more detrimental effects on fine motor performance, such as shooting performance [ 17 , 29 , 30 ].…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Previous cold environment military studies have concentrated on energy expenditure and energy balance [ 7 , 16 , 17 ], protective clothing [ 18 ] and cold weather injuries [ 19 ]. Nykänen et al [ 17 ] has recently reported results of the present study population and setting regarding energy balance and changes in body composition. This study showed that winter survival training caused severe energy deficit (more than -4500 kcal/day, as energy expenditure between 5000 to 5500 kcal/day, and energy intake between 500 to 1000 kcal/day) and decreases in body mass and body fat percentage.…”

Section: Introductionmentioning

confidence: 99%

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Effects of 36-hour recovery on marksmanship and hormone concentrations during strenuous winter military survival training

Ojanen,

Pihlainen,

Yli-Renko

et al. 2023

BMC Sports Sci Med Rehabil

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Objectives Survival training can provide a unique setting for scientific examination of human stress responses and physical performance in a realistic operational military context. The aim of the present study was to observe effects of a 36-h recovery period on serum hormone concentrations, salivary cortisol, and marksmanship during 10-day winter military survival training in north of the Arctic Circle. Design and methods Sixty-eight male soldiers were randomly divided into two groups; EXP (n = 26) and CON (n = 42). While CON performed the whole exercise phase in the field, EXP had 36-h recovery period between days 6 and 8. Several hormones were measured during the study to investigate recovery. Results Subjective physical and mental demand as well as catabolic hormone levels increased and anabolic hormones decreased in CON (p < 0.05), whereas in EXP, recovery period attenuated negative effects of survival training. Prone shooting performance decreased (87.5 ± 6.5 vs. 76.3 ± 8.8, points out of 100, p < 0.05) between days 6 and 8 in CON while EXP was able to maintain shooting performance throughout the study. Conclusion A short recovery during a strenuous training can prevent the degradation in psychophysiological state and shooting performance in soldiers, which can be crucial for survival in demanding operational winter environment. In the present study, 36-h rest period during the field training seems to enhance recovery but the duration of the period was inadequate for full recovery from the accumulated operative stress. In conclusion, appropriate recovery periods should be implemented in order to optimize occupational performance during high operative stress.

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Sex differences in body composition and serum metabolome responses to sustained, physical training suggest enhanced fat oxidation in women compared with men

Beckner

Thompson

Radcliffe

et al. 2023

Physiological Genomics

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Sex differences in energy metabolism during acute, sub-maximal exercise are well documented. Whether these sex differences influence metabolic and physiologic responses to sustained, physically demanding activities is not well characterized. This study aimed to identify sex differences within changes in the serum metabolome in relation to changes in body composition, physical performance, and circulating markers of endocrine and metabolic status during a 17-day military training exercise. Blood was collected, and body composition and lower-body power measured before and after training on 72 cadets (18 women). Total daily energy expenditure (TDEE) was assessed using doubly labeled water in a subset. TDEE was greater in men (4,085±482kcal/d) than women (2,982±472kcal/d, p<0.001), but not after adjustment for dry lean mass (DLM). Men tended to lose more DLM than women (-0.2[-0.3,-0.1] vs. -0.0[-0.0,0.0] kg, p=0.063, Cohen's d=0.50) and have greater reductions in lower body power (-244[-314,-174] vs. -130[-209,-51] Watts, p=0.085, d=0.49). Reductions in DLM and lower body power were correlated ( r=0.325, p=0.006). Women demonstrated greater fat oxidation than men (Δfat mass/DLM: -0.20[-0.24,-0.17] vs. -0.15[-0.17,-0.13] kg, p=0.012, d=0.64). Metabolites within pathways of fatty acid, endocannabinoid, lysophospholipid, phosphatidylcholine, phosphatidylethanolamine, and plasmalogen metabolism increased in women relative to men. Independent of sex, changes in metabolites related to lipid metabolism were inversely associated with changes in body mass and positively associated with changes in endocrine and metabolic status. These data suggest that during sustained military training, women preferentially mobilize fat stores compared with men, which may be beneficial for mitigating loss of lean mass and lower body power.

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

Cited by 4 publications

References 39 publications

Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training

Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training

Effects of 36-hour recovery on marksmanship and hormone concentrations during strenuous winter military survival training

Sex differences in body composition and serum metabolome responses to sustained, physical training suggest enhanced fat oxidation in women compared with men

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