title: No effect of menstrual cycle phase on glucose and glucoregulatory endocrine responses to prolonged exercise.
abstract: BACKGROUND
  Prolonged exercise requires increased utilization of blood glucose and adjustment of glucoregulatory hormones. Estrogen can reduce hepatic gluconeogenesis which could affect insulin concentrations. Amylin is co-secreted with insulin and controls influx of glucose into the blood.
  
  
  OBJECTIVE
  To determine the effect of menstrual cycle stage on glucose, leptin, and pancreatic hormone responses to prolonged (90 min) exercise.
  
  
  METHODS
  Five healthy, eumenorrheic women (24.6 ± 5.1 years; 67.4 ± 1 kg) were monitored for 3 months to determine menstrual cycle length. Subjects completed a preliminary session to determine exercise workloads and, in a fasted condition, completed two randomized 90-min treadmill exercise trials at 60 % VO2max during the early follicular (EFX) and mid-luteal phase (MLX) of their menstrual cycle. Blood samples were analyzed for glucose, insulin, C-peptide, amylin, glucagon, leptin, and cortisol concentrations at rest (-30 and 0 min), during exercise (18, 36, 54, 72, and 90 min) and after 20 min of recovery.
  
  
  RESULTS
  No changes in amylin, leptin, or cortisol occurred for EFX and MLX trials. A significant (p < 0.05) time effect occurred for glucose, insulin, and glucagon with reduced insulin across the exercise trial and increases in glucose and glucagon later in the trial, but there were no differences between the EFX and MLX trials.
  
  
  CONCLUSIONS
  Menstrual cycle stage does not affect glucose, insulin, C-peptide, amylin, glucagon, cortisol, and leptin responses to prolonged exercise; however, the exercise reduces insulin and increases glucose and glucagon concentrations. This is the first study to determine acute effects of exercise on amylin and other glucoregulatory hormone responses in women.
authors.affiliation: Department of Kinesiology and Health Studies, Southeastern Louisiana University, SLU10845, Hammond, LA 70402, USA. rkraemer@selu.edu
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kraemer
authors.forename: Michelle
authors.initials: M
authors.lastname: Francois
authors.forename: Nancy Dardis
authors.initials: ND
authors.lastname: Webb
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Worley
authors.forename: Sharon N
authors.initials: SN
authors.lastname: Rogers
authors.forename: Reid L
authors.initials: RL
authors.lastname: Norman
authors.forename: Urvi
authors.initials: U
authors.lastname: Shah
authors.forename: V Daniel
authors.initials: VD
authors.lastname: Castracane
authors.forename: V
authors.initials: V
authors.lastname: Daniel Castracane
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000502:physiology*; D002096:C-Peptide / Q000097:blood; D055098:Endocrine Cells / Q000378:metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D006728:Hormones / Q000097:blood / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D058228:Islet Amyloid Polypeptide / Q000097:blood; D020738:Leptin / Q000097:blood; D008597:Menstrual Cycle / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D010179:Pancreas / Q000378:metabolism / Q000502:physiology; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D006728:Hormones; D007328:Insulin; D058228:Islet Amyloid Polypeptide; D020738:Leptin; D005934:Glucagon; D005947:Glucose; D006854:Hydrocortisone