Hormonal responses during a prolonged military field exercise with variable exercise intensity

Eur J Appl Physiol. 2008 Mar;102(5):539-46. doi: 10.1007/s00421-007-0619-0. Epub 2007 Nov 27.


The purpose of the present study was to test the hypothesis that the magnitude of hormonal concentration alterations during a prolonged military field exercise with constant energy intake (EI) is influenced by changes in energy deficit (ED) induced by varying the exercise intensity. Basal serum hormone concentrations were measured in a group of healthy young male volunteers (n = 7) during a 20-day field exercise. During the first week of the exercise, the average ED was 4,000 kcal/day (P-I), in the second week only 450 kcal/day (P-II), and in the last week 1,000 kcal/day (P-III). During the first 5 days of the field exercise, significant increases in cortisol (COR, +32%) and growth hormone (GH, +616%) concentrations were observed, while insulin (INS, -70%), total testosterone (TES, -27%), free testosterone (TES(free), -26%) decreased. However, after these initial responses, COR and GH returned to the pre-exercise level by the beginning of P-II. Also TES and TES(free) recovered to the pre-exercise level by the beginning of P-III, and INS by the end of P-III. The concentration of TES (+29%) increased above the pre-exercise level by the beginning of P-III. Serum thyroxin (T(4)) concentration was significantly lesser (-12%) and urine urea concentration significantly higher (+78%) after the field exercise than before it. Therefore, it can be concluded that the lower levels of ED in the second and third phase (ED <1,000 kcal/day) allowed recovery of hormonal changes observed in the first phase with ED much greater than 1,000 kcal/day.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anaerobic Threshold / physiology
  • Blood Glucose / metabolism
  • Blood Volume / physiology
  • Body Weight / physiology
  • Creatine Kinase / blood
  • Energy Intake / physiology
  • Energy Metabolism / physiology
  • Exercise / physiology*
  • Exercise Test
  • Heart Rate / physiology
  • Hormones / blood*
  • Humans
  • Male
  • Military Personnel*


  • Blood Glucose
  • Hormones
  • Creatine Kinase