Estimation of energy balance and training volume during Army Initial Entry Training

Abstract

Background

Adequate dietary intake is important for promoting adaptation and prevention of musculoskeletal injury in response to large volumes of physical training such as Army Initial Entry Training (IET). The purpose of this study was to evaluate training volume and dietary intake and estimate energy balance in Army IET soldiers.

Methods

Dietary intake was assessed by collecting diet logs for three meals on each of three, non-consecutive days during the first week of IET. Training volume was measured across 13 weeks of training using Actigraph wGT3X accelerometers. Training intensity was classified using Sasaki vector magnitude three cut points. Energy expenditure estimates were calculated during weeks two and three of training using the modified Harris-Benedict equation and by estimation of active energy expenditure using metabolic equivalents for each classification of physical activity. All data is presented as mean ± standard deviation.

Results

A total of 111 male soldiers (ht. = ± 173 ± 5.8 cm, age = 19 ± 2 years, mass = 71.6. ± 12.4 kg) completed diet logs and were monitored with Actigraphs. IET soldiers performed on average 273 ± 62 min low, 107 ± 42 min moderate, 26 ± 22 min vigorous, and 10 ± 21 min of very vigorous intensity physical activity daily across 13 weeks. The estimated total daily energy expenditure was on average 3238 ± 457 kcals/d during weeks two and three of IET. Compared to week one caloric intake, there was a caloric deficit of 595 ± 896 kcals/d on average during weeks two and three of IET. Regression analysis showed that body weight was a significant predictor for negative energy balance (adj. R2 = 0.54, p < 0.001), whereby a 1 kg increase in body mass was associated with a 53 kcal energy deficit.

Conclusions

Based on week one dietary assessment, IET soldiers did not consume adequate calories and nutrients to meet training needs during red phase (weeks one through three). This may directly affect soldier performance and injury frequency. IET soldiers undergo rigorous training, and these data may help direct future guidelines for adequate nourishment to optimize soldier health and performance.

Keywords:

• Soldiers
• Diet
• Energy
• Training
• Volume

Electronic supplementary material

The online version of this article (https://doi.org/10.1186/s12970-018-0262-7) contains supplementary material, which is available to authorized users.

Electronic supplementary material

The online version of this article (https://doi.org/10.1186/s12970-018-0262-7) contains supplementary material, which is available to authorized users.

Acknowledgements

The authors would like to thank all of the participants from Army IET training and their commanders for all of their help and support. We also would like to thank our undergraduate and graduate students who assisted in data collection Sarah Gordon, Alex Brown, Jordan Devine, Josh Ourada, Jessica Nendze, and Bryce Munz.

Ethics approval and consent to participate

Study design was approved by the Auburn University Institutional Review Board (Protocol #15–502 MR 1512) and Army Institutional Review Board. The Director, Research & Analysis Directorate Army Center approved the study procedures for Initial Military Training and that they conformed to the standards set by the latest revision of the Declaration of Helsinki. All subjects provided written and verbal consent prior to study participation.

Funding

Funding to support this study came from the Warrior Research Center, Auburn University Kinesiology.

Availability of data and materials

Availability of data is restricted by Army and Auburn Institutional Review Boards and therefore is not made readily available. Data are however available from the corresponding author upon reasonable request.

Authors’ contributions

All authors read and approved the final manuscript. Contributions of authors are listed below: JSM, primary author, study design, data collection, analysis and interpretation. KDM, data collection, analysis, manuscript review. RLO, data collection, analysis, manuscript review. KCY, study design, data analysis, interpretation, manuscript review. ADF, dietician, data analysis, interpretation, manuscript review. MDR, study design, data collection, analysis, interpretation, manuscript review. JMS, corresponding author, funding, study design, oversight of project, data collection, analysis, interpretation, manuscript review.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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