Open Access Short report

Effects of a 7-day military training exercise on inflammatory biomarkers, serum hepcidin, and iron status

James P McClung1, Svein Martini2, Nancy E Murphy1, Scott J Montain1, Lee M Margolis1, Ingjerd Thrane2, Marissa G Spitz3, Janet-Martha Blatny2, Andrew J Young1, Yngvar Gundersen2 and Stefan M Pasiakos1*

Author affiliations

1 Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA

2 Norwegian Defence Research Establishment, Kjeller, Norway

3 Thermal Mountain and Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA

For all author emails, please log on.

Citation and License

Nutrition Journal 2013, 12:141  doi:10.1186/1475-2891-12-141

Published: 4 November 2013

Abstract

Background

Hepcidin, a peptide that is released into the blood in response to inflammation, prevents cellular iron export and results in declines in iron status. Elevated serum and urinary levels of hepcidin have been observed in athletes following exercise, and declines in iron status have been reported following prolonged periods of training. The objective of this observational study was to characterize the effects of an occupational task, military training, on iron status, inflammation, and serum hepcidin.

Findings

Volunteers (n = 21 males) included Norwegian Soldiers participating in a 7-day winter training exercise that culminated in a 3-day, 54 km ski march. Fasted blood samples were collected at baseline, on day 4 (PRE, prior to the ski march), and again on day 7 (POST, following the ski march). Samples were analyzed for hemoglobin, serum ferritin, soluble transferrin receptor (sTfR), interleukin-6 (IL-6), and serum hepcidin. Military training affected inflammation and serum hepcidin levels, as IL-6 and hepcidin concentrations increased (P < 0.05) from the baseline to POST (mean ± SD, 9.1 ± 4.9 vs. 14.5 ± 8.4 pg/mL and 6.5 ± 3.5 vs. 10.2 ± 6.9 ng/mL, respectively). Iron status was not affected by the training exercise, as sTfR levels did not change over the course of the 7-day study.

Conclusions

Military training resulted in significant elevations in IL-6 and serum hepcidin. Future studies should strive to identify the role of hepcidin in the adaptive response to exercise, as well as countermeasures for the prevention of chronic or repeated elevations in serum hepcidin due to exercise or sustained occupational tasks which may result in longer term decrements in iron status.

Keywords:
Physical activity; Operational stress; Military; Ferritin; Inflammation; Iron absorption; Soluble transferrin receptor