This longitudinal study will examine the effects of repeated bouts of operational stress and limited recovery on integrated MPS, whole-body protein balance, iron absorption, and aerobic performance. Following baseline characterization measures, active adults (n=24) representative of normal weight phenotype (NW; n=12) and overweight phenotype (OW; n=12) will complete a 48h balance phase preceding two rounds of repeated 72h energy deficit exposure each immediately followed by a 48h recovery phase. NW cutoff will be defined ≤ 22% body fat for males and ≤ 32% body fat for females. OW cutoff will be defined as \>22% body fat for males and \>32% body fat for females. These body composition cutoffs are informed by the maximum allowable percent body fat standards outlined in current Army Regulation 600-9. Additional details for determining % body fat are outlined in the experimental procedures section of the protocol.
Men and women aged 18 - 39 years (17 - 39 years if military personnel)
Weight stable in the past 2 months (± approximately 5 kg)
Healthy without evidence of chronic illness or musculoskeletal injury as determined by the USARIEM Office of Medical Support and Oversight (OMSO) or home duty station medical support (HMS)
Functional exercise (i.e., step ups, box jumps, body mass movements) and/or aerobic exercise trained defined by self-report as performing ≥ 2 sessions/wk for previous 6 months
Musculoskeletal injuries that compromise exercise capability as determined by OMSO or HMS
Metabolic or cardiovascular abnormalities, sleep disorders (i.e., sleep apnea) gastrointestinal disorders (e.g., kidney disease, diabetes, cardiovascular disease, etc.) as determined by OMSO or HMS
Abnormal or problems with blood clotting as determined by OMSO or HMS
History of complications with lidocaine or similar local anesthetic analogue
Parallel
Operational Stressors
Other interventionIntervention consists of a 48 hour energy balance phase preceding two rounds of repeated 72 hour energy deficit exposure each immediately followed by a 48h recovery phase. Balance and recovery phases will meet 100% of baseline energy requirements. Energy deficit phases will include an approximate 60% energy deficit of total daily energy requirements achieved through both a reduction in dietary intake and increased energy expenditure through physical activity.
Integrated muscle protein synthesis
deuterium oxide stable isotope
Whole-body protein balance
15N alanine stable isotope
Iron Absorption
57-Fe dissolved in water
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United States Army Research Institute of Environmental Medicine
Lead sponsor
Pennington Biomedical Research Center
Collaborator
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