Impact of Menstrual Function on Hormonal Response to Repeated Bouts of Intense Exercise

Anna K Melin; Christian Ritz; Jens Faber; Sven Skouby; Jessica Pingel; Jorunn Sundgot-Borgen; Anders Sjödin; Åsa B Tornberg

doi:10.3389/fphys.2019.00942

Impact of Menstrual Function on Hormonal Response to Repeated Bouts of Intense Exercise

Front Physiol. 2019 Jul 31:10:942. doi: 10.3389/fphys.2019.00942. eCollection 2019.

Authors

Anna K Melin^{1

2}, Christian Ritz², Jens Faber^{3

4}, Sven Skouby^{3

5}, Jessica Pingel⁶, Jorunn Sundgot-Borgen⁷, Anders Sjödin², Åsa B Tornberg⁸

Affiliations

¹ Department of Sport Science, Linnaeus University, Kalmar, Sweden.
² Department of Nutrition, Exercise and Sports, University of Copenhagen, Frederiksberg, Denmark.
³ Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
⁴ Department of Endocrinology, Herlev Hospital, Herlev, Denmark.
⁵ Endocrinological and Reproductive Unit, Department of Obstetrics and Gynecology, Herlev Hospital, Herlev, Denmark.
⁶ Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.
⁷ Norwegian School of Sport Sciences, Oslo, Norway.
⁸ Department of Health Sciences, Lund University, Lund, Sweden.

Abstract

Background: Strenous exercise stimulates the hypothalamic-pituitary (HP) axis in order to ensure homeostasis and promote anabolism. Furthermore, exercise stimulates a transient increase in the neurotrophin brain-derived neurotrophic factor (BDNF) suggested to mediate the anxiolytic effects of exercise. Athletes with secondary functional hypothalamic amenorrhea (FHA) have been reported to have lower BDNF, and a blunted HP axis response to exercise as athletes with overtraining syndrome.

Aim: The aim of the study was to investigate the hormonal and BDNF responses to a two-bout maximal exercise protocol with four hours of recovery in between in FHA and eumenorrheic (EUM) athletes.

Methods: Eumenorrheic (n = 16) and FHA (n = 14) endurance athletes were recruited from national teams and competitive clubs. Protocols included gynecological examination; body composition (DXA); 7-day assessment of energy availability; blood sampling pre and post the two exercises tests.

Results: There were no differences between groups in hormonal responses to the first exercise bout. After the second exercise bout IGFBP-3 increased more in FHA compared with EUM athletes (2.1 ± 0.5 vs. 0.6 ± 0.6 μg/L, p = 0.048). There were non-significant trends toward higher increase in IGF-1 (39.3 ± 4.3 vs. 28.0 ± 4.6 μg/L, p = 0.074), BDNF (96.5 ± 22.9 vs. 34.4 ± 23.5 μg/L, p = 0.058), GH to cortisol ratio (0.329 ± 0.010 vs. 0.058 ± 0.010, p = 0.082), and decrease in IGF-1 to IGFBP-3 ratio (-2.04 ± 1.2 vs. 0.92 ± 1.22, p = 0.081) in athletes with FHA compared with EUM athletes. Furthermore, there was a non-significant trend toward a higher increase in prolactin to cortisol ratio in EUM athletes compared with athletes with FHA (0.60 ± 0.15 vs. 0.23 ± 0.15, p = 0.071). No differences in the hormonal or BDNF responses between the two exercise bouts as a result of menstrual function were found.

Conclusion: No major differences in the hormonal or BDNF responses between the two exercise bouts as a result of menstrual function could be detected.

Keywords: amenorrhea; brain derived neuronal factor; energy availability; female athlete; overtraining syndrome.