The objectives of this study are to: 1) determine effects of a prototype recovery food product providing supplemental energy on whole-body protein balance, skeletal muscle mass, and biomarkers of physiological status and strain during winter military training, and 2) determine the extent to which varying macronutrient composition (protein-based [PRO] versus carbohydrate-based [CHO]) of the food product modulates the physiological consequences to strenuous military training.

Up to 120 Norwegian Soldiers from the 2nd Battalion, Brigade North, Norwegian Army stationed at Skjold Garrison will be enrolled in a 9-day, randomized controlled study. Using dietary analysis, body composition assessments, stable isotope methodologies, basic biochemical techniques, and measures of physiological strain, the effects of supplemental energy in the form of carbohydrate and protein on indices of muscle mass and physiological status will be assessed.

We hypothesize that consuming supplemental energy will attenuate the effects of severe energy deficit on inflammation, androgenic hormones, and whole-body protein retention, thereby protecting skeletal muscle mass. We expect that consuming PRO will promote a more favorable recovery than consuming CHO, as indicated by measures of increased whole-body protein synthesis and greater conservation of skeletal muscle mass.

Inclusion Criteria:

• Male and female Norwegian Soldiers aged 18 years or older participating in the 4-day training program.

Exclusion Criteria:

• History of skin irritation (e.g., nickel or adhesive allergy), difficulty swallowing large pills, and allergies to dairy products