title: The effects of a calcium-rich pre-exercise meal on biomarkers of calcium homeostasis in competitive female cyclists: a randomised crossover trial.
abstract: Cycling is recognised as a sport in which there is a high incidence of poor bone health. Sweat calcium losses may contribute to this.
  
  
  
  To examine whether a calcium-rich pre-exercise meal attenuates exercise-induced perturbations of bone calcium homeostasis caused by maintenance of sweat calcium losses.
  
  
  
  Using a randomized, counterbalanced crossover design, 32 well-trained female cyclists completed two 90 min cycling trials separated by 1 day. Exercise trials were preceded 2 hours by either a calcium-rich (1352 ± 53 mg calcium) dairy based meal (CAL) or a control meal (CON; 46 ± 7 mg calcium). Blood was sampled pre-trial; pre-exercise; and immediately, 40 min, 100 min and 190 min post-exercise. Blood was analysed for ionized calcium and biomarkers of bone resorption (Cross Linked C-Telopeptide of Type I Collagen (CTX-I), Cross Linked C-Telopeptide of Type II Collagen (CTX-II), Parathyroid Hormone (PTH), and bone formation (Procollagen I N-Terminal Propeptide (PINP)) using the established enzyme-linked immunosorbent assay technique.
  
  
  
  PTH and CTX-I increased from pre-exercise to post-exercise in both conditions but was attenuated in CAL (p < 0.001). PTH was 1.55 [1.20, 2.01] times lower in CAL immediately post-exercise and 1.45 [1.12, 1.88] times lower at 40 min post-exercise. CTX-I was 1.40 [1.15, 1.70] times lower in CAL at immediately post-exercise, 1.30 [1.07, 1.57] times lower at 40 min post-exercise and 1.22 [1.00, 1.48] times lower at 190 min post-exercise (p < 0.05). There was no significant interaction between pre-exercise meal condition and time point for CTX-II (p = 0.732) or PINP (p = 0.819).
  
  
  
  This study showed that a calcium-rich pre-exercise breakfast meal containing ~1350 mg of calcium consumed ~90 min before a prolonged and high intensity bout of stationary cycling attenuates the exercise induced rise in markers of bone resorption--PTH and CTX-I.
  
  
  
  Australian New Zealand Clinical Trials Registry ACTRN12614000675628.
authors.affiliation: Sports Nutrition, Australian Institute of Sport, Belconnen, 2616, Australia; Physiology, Australian Institute of Sport, Belconnen, 2616, Australia; Human Movement Studies, University of Queensland, St Lucia, 4072, Australia.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Haakonssen
authors.affiliation: Sports Nutrition, Australian Institute of Sport, Belconnen, 2616, Australia; Physiology, Australian Institute of Sport, Belconnen, 2616, Australia.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Ross
authors.affiliation: Performance Research, Australian Institute of Sport, Belconnen, 2616, Australia.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Knight
authors.affiliation: Sports Nutrition, Australian Institute of Sport, Belconnen, 2616, Australia.
authors.forename: Louise E
authors.initials: LE
authors.lastname: Cato
authors.affiliation: Sports Nutrition, Australian Institute of Sport, Belconnen, 2616, Australia.
authors.forename: Alisa
authors.initials: A
authors.lastname: Nana
authors.affiliation: Department of Epidemiology & Preventive Medicine, School of Public Health & Preventive Medicine, Monash University, Melbourne, 3004, Australia.
authors.forename: Anita E
authors.initials: AE
authors.lastname: Wluka
authors.affiliation: Department of Epidemiology & Preventive Medicine, School of Public Health & Preventive Medicine, Monash University, Melbourne, 3004, Australia.
authors.forename: Flavia M
authors.initials: FM
authors.lastname: Cicuttini
authors.affiliation: Department of Epidemiology & Preventive Medicine, School of Public Health & Preventive Medicine, Monash University, Melbourne, 3004, Australia.
authors.forename: Bing H
authors.initials: BH
authors.lastname: Wang
authors.affiliation: Human Movement Studies, University of Queensland, St Lucia, 4072, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Jenkins
authors.affiliation: Sports Nutrition, Australian Institute of Sport, Belconnen, 2616, Australia; School of Exercise Science, Australian Catholic University, Melbourne, 3065, Australia.
authors.forename: Louise M
authors.initials: LM
authors.lastname: Burke
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D001642:Bicycling; D015415:Biomarkers / Q000097:blood; D001862:Bone Resorption / Q000097:blood / Q000178:diet therapy / Q000517:prevention & control*; D002118:Calcium / Q000097:blood*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002413:Cations, Divalent; D024042:Collagen Type I / Q000097:blood; D024043:Collagen Type II / Q000097:blood; D018592:Cross-Over Studies; D004032:Diet; D015444:Exercise; D005260:Female; D006801:Humans; D010281:Parathyroid Hormone / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000097:blood; D010807:Physical Endurance; D011347:Procollagen / Q000097:blood; D013546:Sweating / Q000502:physiology
chemical_list: D015415:Biomarkers; D002136:Calcium, Dietary; D002413:Cations, Divalent; D024042:Collagen Type I; D024043:Collagen Type II; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; D002118:Calcium