title: Bone formation is suppressed with multi-stressor military training.
abstract: OBJECTIVE
  To determine the effects of US Army Ranger Training, an 8-week, physically demanding program (energy expenditure of 2,500-4,500 kcal/day) with energy restriction (deficit of 1,000-4,000 kcal/day) and sleep deprivation (<4 h sleep/night) on bone metabolism.
  
  
  METHODS
  Blood was collected from 22 men (age 24 ± 4 years) before and after training. Follow-up measurements were made in a subset of 8 subjects between 2 and 6 weeks after training. Serum was analyzed for bone formation biomarkers [bone alkaline phosphatase (BAP) and osteocalcin (OCN)], bone resorption biomarkers [C-telopeptide cross-links of type I collagen (CTX) and tartrate-resistant acid phosphatase (TRAP5b)], calcium, parathyroid hormone (PTH), and vitamin D 25(OH)D increased significantly by 37.3 ± 45.2 % with training [corrected]. A repeated-measures ANOVA with time as the only factor was used to analyze data on the subset of 8 subjects who completed follow-up data collection.
  
  
  RESULTS
  BAP and OCN significantly decreased by 22.8 ± 15.5% (pre 41.9 ± 10.1; post 31.7 ± 7.8 ng/ml) and 21.0 ± 23.3% (pre 15.0 ± 3.5; post 11.3 ± 2.1 ng/ml), respectively, with training, suggesting suppressed bone formation. OCN returned to baseline, while BAP remained suppressed 2-6 weeks post-training. TRAP5b significantly increased by 57.5 ± 51.6% (pre 3.0 ± 0.9; post 4.6 ± 1.4 ng/ml) from pre- to post-training, suggesting increased bone resorption, and returned to baseline 2-6 weeks post-training. PTH Increased significantly by 37.3 ± 45.2% with training. No changes in CTX, calcium, or PTH were detected.
  
  
  CONCLUSIONS
  These data indicate that multi-stressor military training results in increased bone resorption and suppressed bone formation, with recovery of bone metabolism 2-6 weeks after completion of training.
authors.affiliation: Military Performance Division, United States Army Research Institute of Environmental Medicine, 15 Kansas Street, Building 42, Natick, MA, 01760, USA, julie.m.hughes17.ctr@mail.mil.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Hughes
authors.forename: Martha A
authors.initials: MA
authors.lastname: Smith
authors.forename: Paul C
authors.initials: PC
authors.lastname: Henning
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Scofield
authors.forename: Barry A
authors.initials: BA
authors.lastname: Spiering
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Staab
authors.forename: Jay R
authors.initials: JR
authors.lastname: Hydren
authors.forename: Bradley C
authors.initials: BC
authors.lastname: Nindl
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Matheny
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D001862:Bone Resorption / Q000209:etiology; D031204:Caloric Restriction / Q000009:adverse effects; D024042:Collagen Type I / Q000097:blood; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D008889:Military Personnel; D015675:Osteocalcin / Q000097:blood; D010012:Osteogenesis; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood; D055070:Resistance Training / Q000009:adverse effects*; D012892:Sleep Deprivation / Q000150:complications; D013312:Stress, Physiological; D000071681:Tartrate-Resistant Acid Phosphatase; D014807:Vitamin D / Q000097:blood
chemical_list: D024042:Collagen Type I; D007527:Isoenzymes; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D014807:Vitamin D; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase