title: Influence of a CYP1A2 polymorphism on post-exercise heart rate variability in response to caffeine intake: a double-blind, placebo-controlled trial.
abstract: BACKGROUND
  Proposed differences in caffeine metabolism due to the CYP1A2*1F polymorphism have been linked to variations in cardiovascular disease risk.
  
  
  OBJECTIVE
  We examined the influence of a CYP1A2*1F polymorphism on post-exercise heart rate variability (HRV) in response to caffeine intake.
  
  
  METHODS
  Volunteers were identified as A/A homozygotes (A/A; 4 females and 7 males; age: 25.3 ± 4.1 years; BMI: 25.9 ± 4.4 kg/m2) or C allele carriers (C allele; 3 females and 6 males; age: 25.5 ± 2.8 years; BMI: 26.6 ± 5.0 kg/m2) for participation in a repeated measures, counterbalanced, double-blind, placebo-controlled trial. Participants chewed three pieces of gum containing either caffeine (CAF) (100 mg/piece) or placebo for 5 min. Thereafter, participants cycled for 15 min at 75 % of their peak oxygen consumption. Eight HRV indices computed during 5 min at baseline (BASE), 0-5 min after exercise (POST1), and 5-10 min after exercise (POST2) were used for analysis.
  
  
  RESULTS
  No significant group differences were detected in HRV indices at BASE, POST1, or POST2 during both trials (p > 0.05). Rate of recovery (POST2-POST1) for the square root of the mean of squared differences between successive RR intervals (RMSSD) was significantly different between A/A (6.0 ± 2.5 ms) and C allele (3.6 ± 2.5 ms) groups during the CAF trial (p = 0.048).
  
  
  CONCLUSIONS
  Rate of RMSSD recovery was the only variable influenced by the CYP1A2*IF polymorphism during post-exercise in response to caffeine intake. Thus, the CYP1A2*1F polymorphism did not overtly influence the effects of caffeine intake on post-exercise HRV.
authors.affiliation: Department of Biology, Chatham University, Pittsburgh, PA, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Thomas
authors.affiliation: Department of Biology, Chatham University, Pittsburgh, PA, USA.
authors.forename: H A
authors.initials: HA
authors.lastname: Algrain
authors.affiliation: Department of Exercise Science, Chatham University, Pittsburgh, PA, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Ryan
authors.affiliation: Department of Biology, Chatham University, Pittsburgh, PA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Popojas
authors.affiliation: Department of Biology, Chatham University, Pittsburgh, PA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Carrigan
authors.affiliation: Department of Biology, Chatham University, Pittsburgh, PA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Abdulrahman
authors.affiliation: Department of Exercise Science, Chatham University, Pittsburgh, PA, USA. acarrillo@chatham.edu.|FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece. acarrillo@chatham.edu.
authors.forename: A E
authors.initials: AE
authors.lastname: Carrillo
mesh_terms: D000328:Adult; D000483:Alleles; D002110:Caffeine / Q000494:pharmacology*; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D055815:Young Adult
chemical_list: D002110:Caffeine; C504573:CYP1A2 protein, human; D019388:Cytochrome P-450 CYP1A2
keywords: Autonomic nervous system; Cardiovascular abnormalities; Cytochrome p 450 CYP1A2; Parasympathetic nervous system; Physical activity; Sympathetic nervous system