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. 2023 Feb 24;20(5):4086.
doi: 10.3390/ijerph20054086.

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

Tarja Nykänen  1 , Tommi Ojanen  2 , Jani P Vaara  3 , Kai Pihlainen  4 , Risto Heikkinen  5 , Heikki Kyröläinen  3   6 , Mikael Fogelholm  7
Affiliations

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

Tarja Nykänen et al. Int J Environ Res Public Health. .

Abstract

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.

Keywords: energy deficit; physical performance; soldier; survival training.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Mean (± SD) energy intake (EI), energy expenditure (EE), and energy balance (EB) during the training in the RECO and FEX groups. RECO = recovery, FEX = field exercise. Statistical significances are presented between the groups.
Figure 2
Figure 2
Mean (±SD) leptin, ghrelin, and testosterone/cortisol ratio concentrations during the training in the recovery (RECO) and field exercise (FEX) groups. Statistical significances are presented between the groups.
See this image and copyright information in PMC

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References

    1. Różański P., Jówko E., Tomczak A. Assessment of the levels of oxidative stress, muscle damage, and psychomotor abilities of special force soldiers during military survival training. Int. J. Environ. Res. Public Health. 2020;17:4886. doi: 10.3390/ijerph17134886. - DOI - PMC - PubMed
    1. Hamarsland H., Paulsen G., Solberg P.A., Slaathaug O.G., Raastad T. Depressed physical performance outlasts hormonal disturbances after military training. Med. Sci. Sports Exerc. 2018;50:2076–2084. doi: 10.1249/MSS.0000000000001681. - DOI - PubMed
    1. Murphy N.E., Carrigan C.T., Philip K.J., Pasiakos S.M., Margolis L.M. Threshold of energy deficit and lower-body performance declines in military personnel: A meta-regression. Sports Med. 2018;48:2169–2178. doi: 10.1007/s40279-018-0945-x. - DOI - PubMed
    1. Margolis L.M., Murphy N.E., Martini S., Spitz M.G., Thrane I., McGraw S.M., Blatny J.M., Castellani J.W., Rood J.C., Young A.J., et al. Effects of winter military training on energy balance, whole-body protein balance, muscle damage, soreness, and physical performance. Appl. Physiol. Nutr. Metab. 2014;39:1395–1401. doi: 10.1139/apnm-2014-0212. - DOI - PubMed
    1. Nindl B.C., Barnes B.R., Alemany J.A., Frykman P.N., Shippee R.L., Friedl K.E. Physiological consequences of U.S. army ranger training. Med. Sci. Sports Exerc. 2007;39:1380–1387. doi: 10.1249/MSS.0b013e318067e2f7. - DOI - PubMed