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

Author

Listed:
  • Tarja Nykänen

    (Army Academy, Finnish Defence Forces, 53600 Lappeenranta, Finland)

  • Tommi Ojanen

    (Finnish Defence Research Agency, Finnish Defence Forces, 04310 Tuusula, Finland)

  • Jani P. Vaara

    (Department of Leadership and Military Pedagogy, National Defence University, Finnish Defence Forces, 00861 Helsinki, Finland)

  • Kai Pihlainen

    (Defence Command, Finnish Defence Forces, 00130 Helsinki, Finland)

  • Risto Heikkinen

    (Statistical Analysis Services, Analyysitoimisto Statisti Oy, 40720 Jyväskylä, Finland)

  • Heikki Kyröläinen

    (Department of Leadership and Military Pedagogy, National Defence University, Finnish Defence Forces, 00861 Helsinki, Finland
    Faculty of Sport and Health Sciences, University of Jyväskylä, 40114 Jyväskylä, Finland)

  • Mikael Fogelholm

    (Department of Food and Nutrition, University of Helsinki, 00014 Helsinki, Finland)

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.

Suggested Citation

  • Tarja Nykänen & Tommi Ojanen & Jani P. Vaara & Kai Pihlainen & Risto Heikkinen & Heikki Kyröläinen & Mikael Fogelholm, 2023. "Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training," IJERPH, MDPI, vol. 20(5), pages 1-12, February.
    • Handle: RePEc:gam:jijerp:v:20:y:2023:i:5:p:4086-:d:1079581
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    References listed on IDEAS

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    1. Paweł Różański & Ewa Jówko & Andrzej Tomczak, 2020. "Assessment of the Levels of Oxidative Stress, Muscle Damage, and Psychomotor Abilities of Special Force Soldiers during Military Survival Training," IJERPH, MDPI, vol. 17(13), pages 1-10, July.
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