Effects of the Menstrual Cycle on Daily Blood Glucose Changes During Exercise and in Recovery in Aerobically Fit Athletes

• Author / Creator

  Martens, Janai M

• Background: Glucose monitoring is becoming increasingly popular in athletes who are hoping to
  optimize their nutrition, training and recovery. Glucose regulation is influenced by several factors,
  including the amount and type of exercise performed as well as circulating ovarian hormones in
  female athletes. As such, female athletes with fluctuating ovarian hormones across the menstrual
  cycle, may experience concurrent changes in blood glucose. Therefore, this study examines
  glucose during exercise and in recovery in female athletes in two distinct phases of the menstrual
  cycle.
  Methods: 11 aerobically fit, naturally cycling female athletes were recruited to participate in this
  pilot study. Participants completed two standardized exercise sessions at two different phases of
  the menstrual cycle (i.e., early follicular phase (FP) and mid luteal phase (LP)). Continuous
  glucose monitors (CGM) were worn for the duration of the menstrual cycle and glucose values
  during exercise and in the 24 hours post exercise were analyzed.
  Results: There were no significant differences in capillary glucose concentrations between the FP
  and LP immediately before (5.6 ± 0.7 vs 5.8 ± 0.5 mmol/L, p= 0.28) or after (5.7 ± 1.0 vs 5.9 ±
  1.0 mmol/L, p= 0.28) exercise. Time spent with low interstitial glucose during exercise and in the
  24-hour recovery window was minimal in both menstrual cycle phases, with the percent of time
  below 3.9 mmol/L being only 4 ± 6% and 3 ± 4% in the FP and the LP respectively (p = 0.82).
  Mean CGM glucose during exercise also did not change significantly between menstrual cycle
  phases, with mean values of 5.5 ± 1.2 and 5.8 ± 0.9 mmol/L in the FP and the LP respectively (p
  = 0.44). Despite the lack of change in glucose throughout the menstrual cycle, respiratory exchange
  ratio (RER) during exercise was higher during the LP compared to the FP (p = 0.04), suggesting greater oxidation of carbohydrates at the same relative exercise intensity in the LP compared to
  the FP.
  Conclusion: Overall, female athletes did not experience significant changes in glucose between
  the FP and LP during exercise and in recovery. Furthermore, they did not experience an increased
  amount of time with low glucose during 24 hours of recovery from exercise in the FP compared
  to the LP.

• Subjects / Keywords

  • Menstrual Cycle
  • Blood Glucose
  • Exercise
  • Female Athletes

• Graduation date

  Fall 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-rw7j-qy43

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.