title: Influence of exercise on the metabolic profile caused by 28 days of bed rest with energy deficit and amino acid supplementation in healthy men.
abstract: OBJECTIVE
  Muscle loss and metabolic changes occur with disuse [i.e. bed rest (BR)]. We hypothesized that BR would lead to a metabolically unhealthy profile defined by: increased circulating tumor necrosis factor (TNF)-α, decreased circulating insulin-like-growth-factor (IGF)-1, decreased HDL-cholesterol, and decreased muscle density (MD; measured by mid-thigh computerized tomography).
  
  
  METHODS
  We investigated the metabolic profile after 28 days of BR with 8 ± 6% energy deficit in male individuals (30-55 years) randomized to resistance exercise with amino acid supplementation (RT, n=24) or amino acid supplementation alone (EAA, n=7). Upper and lower body exercises were performed in the horizontal position. Blood samples were taken at baseline, after 28 days of BR and 14 days of recovery.
  
  
  RESULTS
  We found a shift toward a metabolically unfavourable profile after BR [compared to baseline (BLN)] in both groups as shown by decreased HDL-cholesterol levels (EAA: BLN: 39 ± 4 vs. BR: 32 ± 2 mg/dL, RT: BLN: 39 ± 1 vs. BR: 32 ± 1 mg/dL; p<0.001) and Low MD (EAA: BLN: 27 ± 4 vs. BR: 22 ± 3 cm(2), RT: BLN: 28 ± 2 vs. BR: 23 ± 2 cm(2); p<0.001). A healthier metabolic profile was maintained with exercise, including NormalMD (EAA: BLN: 124 ± 6 vs. BR: 110 ± 5 cm(2), RT: BLN: 132 ± 3 vs. BR: 131 ± 4 cm(2); p<0.001, time-by-group); although, exercise did not completely alleviate the unfavourable metabolic changes seen with BR. Interestingly, both groups had increased plasma IGF-1 levels (EAA: BLN:168 ± 22 vs. BR 213 ± 20 ng/mL, RT: BLN:180 ± 10 vs. BR: 219 ± 13 ng/mL; p<0.001) and neither group showed TNFα changes (p>0.05).
  
  
  CONCLUSIONS
  We conclude that RT can be incorporated to potentially offset the metabolic complications of BR.
authors.affiliation: 1. Health & Exercise Sciences, University of Stirling, Stirling, Scotland UK.
authors.forename: Naomi E
authors.initials: NE
authors.lastname: Brooks
authors.affiliation: 2. Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston MA.
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Cadena
authors.affiliation: 3. Bouve College of Health Sciences, Northeastern University, Boston MA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Cloutier
authors.affiliation: 4. School of Nutrition and Health Promotion, Arizona State University, Phoenix, AZ.
authors.forename: Sonia
authors.initials: S
authors.lastname: Vega-López
authors.affiliation: 5. Friedman School of Nutrition Science and Policy, Tufts University, Boston MA.
authors.forename: Ronenn
authors.initials: R
authors.lastname: Roubenoff
authors.affiliation: 3. Bouve College of Health Sciences, Northeastern University, Boston MA ; 5. Friedman School of Nutrition Science and Policy, Tufts University, Boston MA.
authors.forename: Carmen
authors.initials: C
authors.lastname: Castaneda-Sceppa
mesh_terms: D000328:Adult; D000601:Amino Acids, Essential / Q000008:administration & dosage*; D001510:Bed Rest / Q000009:adverse effects*; D008076:Cholesterol, HDL / Q000097:blood; D019587:Dietary Supplements; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D055442:Metabolome; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology; D055070:Resistance Training / Q000379:methods*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D000601:Amino Acids, Essential; D008076:Cholesterol, HDL; D014409:Tumor Necrosis Factor-alpha; D007334:Insulin-Like Growth Factor I
keywords: energy deficit; essential amino acids; metabolic profile; resistance training