title: Effect of antioxidant supplementation on exercise-induced cardiac troponin release in cyclists: a randomized trial.
abstract: BACKGROUND
  Cardiac troponin is the biochemical gold standard to diagnose acute myocardial infarction. Interestingly however, elevated cardiac troponin concentrations are also frequently observed during and after endurance-type exercise. Oxidative stress associated with prolonged exercise has been proposed to contribute to cardiac troponin release. Therefore, the aim of this study was to assess the effect of 4 week astaxanthin supplementation (a potent cartenoid antioxidant) on antioxidant capacity and exercise-induced cardiac troponin release in cyclists.
  
  
  METHODS
  Thirty-two well-trained male cyclists (age 25±5, weight 73±7 kg, maximum O2 uptake 60±5 mL·kg(-1)·min(-1), Wmax 5.4±0.5 W·kg(-1); mean ± SD) were repeatedly subjected to a laboratory based standardized exercise protocol before and after 4 weeks of astaxanthin (20 mg/day), or placebo supplementation in a double-blind randomized manner. Blood samples were obtained at baseline, at 60 min of cycling and immediately post-exercise (≈ 120 min).
  
  
  RESULTS
  The pre-supplementation cycling trial induced a significant rise of median cardiac troponin T concentrations from 3.2 (IQR 3.0-4.2) to 4.7 ng/L (IQR 3.7-6.7), immediately post-exercise (p<0.001). Four weeks of astaxanthin supplementation significantly increased mean basal plasma astaxanthin concentrations from non-detectable values to 175±86 µg·kg(-1). However, daily astaxanthin supplementation had no effect on exercise-induced cardiac troponin T release (p = 0.24), as measured by the incremental area under the curve. Furthermore, the elevation in basal plasma astaxanthin concentrations was not reflected in changes in antioxidant capacity markers (trolox equivalent antioxidant capacity, uric acid, and malondialdehyde). Markers of inflammation (high-sensitivity C-reactive protein) and exercise-induced skeletal muscle damage (creatine kinase) were equally unaffected by astaxanthin supplementation.
  
  
  CONCLUSIONS
  Despite substantial increases in plasma astaxanthin concentrations, astaxanthin supplementation did not improve antioxidant capacity in well-trained cyclists. Accordingly, exercise-induced cardiac troponin T concentrations were not affected by astaxanthin supplementation.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT01241877.
authors.affiliation: Department of Clinical Chemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center (MUMC), Maastricht, The Netherlands.
authors.forename: Lieke J J
authors.initials: LJ
authors.lastname: Klinkenberg
authors.forename: Peter T
authors.initials: PT
authors.lastname: Res
authors.forename: Guido R
authors.initials: GR
authors.lastname: Haenen
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
authors.forename: Marja P
authors.initials: MP
authors.lastname: van Dieijen-Visser
authors.forename: Steven J R
authors.initials: SJ
authors.lastname: Meex
mesh_terms: D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001642:Bicycling / Q000502:physiology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D020107:Troponin T / Q000097:blood*; D024341:Xanthophylls / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D000975:Antioxidants; D020107:Troponin T; D024341:Xanthophylls; C005948:astaxanthine