title: Cardiovascular responses to caffeine by gender and pubertal stage.
abstract: BACKGROUND
  Caffeine use is on the rise among children and adolescents. Previous studies from our laboratory reported gender differences in the effects of caffeine in adolescents. The purpose of this study was to test the hypotheses that gender differences in cardiovascular responses to caffeine emerge after puberty and that cardiovascular responses to caffeine differ across the phases of the menstrual cycle.
  
  
  METHODS
  To test these hypotheses, we examined heart rate and blood pressure before and after administration of placebo and 2 doses of caffeine (1 and 2 mg/kg) in prepubertal (8- to 9-year-olds; n = 52) and postpubertal (15- to 17-year-olds; n = 49) boys (n = 54) and girls (n = 47) by using a double-blind, placebo-controlled, dose-response design.
  
  
  RESULTS
  There was an interaction between gender and caffeine dose, with boys having a greater response to caffeine than girls. In addition, we found interactions between pubertal phase, gender, and caffeine dose, with gender differences present in postpubertal, but not in prepubertal, participants. Finally, we found differences in responses to caffeine across the menstrual cycle in post-pubertal girls, with decreases in heart rate greater in the midluteal phase and blood pressure increases greater in the midfollicular phase of the menstrual cycle.
  
  
  CONCLUSIONS
  These data suggest that gender differences in response to caffeine emerge after puberty. Future research will determine the extent to which these gender differences are mediated by physiological factors, such as steroid hormones, or psychosocial factors, such as more autonomy and control over beverage purchases.
authors.affiliation: Department of Exercise and Nutrition Sciences, andCommunity Health and Health Behavior, School of Public Health and Health Professions, University at Buffalo, Buffalo, New York jltemple@buffalo.edu.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Temple
authors.affiliation: Department of Exercise and Nutrition Sciences, and.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Ziegler
authors.affiliation: Department of Exercise and Nutrition Sciences, and.
authors.forename: Adam
authors.initials: A
authors.lastname: Graczyk
authors.affiliation: Department of Exercise and Nutrition Sciences, and.
authors.forename: Ashley
authors.initials: A
authors.lastname: Bendlin
authors.affiliation: Department of Exercise and Nutrition Sciences, and.
authors.forename: Teresa
authors.initials: T
authors.lastname: Sion
authors.affiliation: Department of Exercise and Nutrition Sciences, and.
authors.forename: Karina
authors.initials: K
authors.lastname: Vattana
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001794:Blood Pressure / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology*; D002648:Child; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008597:Menstrual Cycle; D011627:Puberty; D012737:Sex Factors
chemical_list: D002110:Caffeine