High-Intensity Interval Training leads to reduced testosterone and increased estrogen levels in young women

DOI: https://doi.org/10.21203/rs.3.rs-1639546/v1

Abstract

Background: Hormone levels can be determined according the prevalence of a balance between generation metabolism and clearance rates. High-Intensity Interval Training (HIIT) can affect this balance through a variety of mechanisms, including competition-associated stress, diet, body composition, heat production and hypoxia.

Aims: The present study aimed to evaluate the impact of HIIT on the Health hormones of femininity and fertility in young women.

Methods: The study was comprised of Eighteen females aged 18.06 ± 0.128 years old. The participants were subjected to an eight-week training program (3 sessions/week, two hours (h) after lunch). Participants underwent basal pre-and post-exercise intervention tests, such as reproductive and trophic hormones.

Results: The results revealed that 143.16% increased estrogen levels and a 62.12% reduction in testosterone levels . No significant differences were detected in Luteinizing hormone (LH) and Prolactin (PRL) between participants.

Conclusions: HIIT exercise training in young women decreases testosterone levels and increases estrogen levels, with no effect on trophic hormones (LH, PRL).

Introduction

High-intensity interval training (HIIT) includes alternate bouts of high-intensity intensive exercise along with low-intensity recovery periods. It is considered one of the most effective methods to improve cardiorespiratory and metabolic health [1]. Women have avoided resistance training for many years out of fear of being masculinized due to heavyweights. However, researchers have demonstrated that significant female strength could be observed with only minor degrees of muscle hypertrophy [2, 3]. Currently, it is widely accepted that exercise training in young women is very beneficial, as it can lead to reduced adiposity and increased cardiovascular fitness.

Nevertheless, even if the exercise volume exceeds the physiological limit, this causes adverse effects on the skeletal and reproductive system, one of which is primary/secondary amenorrhea, induced by many factors such as inadequate nutrition and low body weight [3]. Primary and secondary amenorrhea are patterns of follicle-stimulating and luteinizing hormone suppression. Additionally, it may involve the hypothalamic-pituitary-adrenal axis and hypothalamic-pituitary-gonadal axis.

Hypoestrogenism may have a negative effect on bone growth in athletes. Amenorrhea, eating disorders, and osteopenia are all symptoms of fatigue in female athletes. Women with delayed menarche demonstrate elevated stress features, osteopenia, and incidence of scoliosis compared with girls with average menarche [4, 5]. The balance of clearance rates, metabolism, and production is essential for maintaining hormonal blood levels. This balance may be affected by intensive physical exercises or through some mechanisms like dieting, production of heat and hypoxia, stress related to competition, and reduction of body fat mass [6]. Women who engage in high-intensity exercise on a regular basis may experience menstrual disturbances such as oligomenorrhea, amenorrhea, or delayed menarche due to hormonal changes. Among the exercise-induced menstrual disturbance is the impaired production of gonadotropins, which may lead to anovulation and luteal phase deficiency [7].

Previous literature illustrated that prolonged and high-intensity training has a disadvantageous effect on female reproductive hormones. The hypothalamus-ovarian axis and the circulation of feminine reproductive hormones are disrupted due to related fatigue associated with low energy, leptin levels, and high-stress hormone concentration following strenuous exercise. This imbalance could lead to miss menstrual cycle regulation associated with the luteal phase and anovulation deficiency. Consequently, this study aims to investigate further the potential interventions of HIIT, which may be beneficial to reduce or prevent the impacts on reproductive health among female athletes by assessing femininity and fertility hormones.

Methods

Participants

The current study assessed eighteen females, as depicted in (Table 1). The participants completed a familiarization session before initiating the measurements, where participants were excluded if suffering from any metabolic disease or renal, pulmonary, or cardiovascular pathological conditions. Before the onset of any testing or training session, it was required to obtain all participants' oral and written informed signed consent. The Institutional Review Board approved the Faculty of Physical Education study, Mansoura University, Egypt. Table (1) illustrates the participants' physical characteristics.

Table 1

The participants' Physical characteristics. Values are represented as mean (± sem)

Variables

Age (years)

Height (m)

Body mass (kg)

BMI (kg/m2)

Mean

18.06

1.65

63.35

21.35

sem

.128

2.74

2.68

0.46

Insert Table 1.

Hormonal Assay:

Trained laboratory technicians performed blood sampling at standardized laboratory conditions. Before obtaining a blood sample, participants were required to fast for at least 4 hours. Subsequently, the venous blood sample was collected on the third day of the spontaneous cycle. The collected samples were allowed to clot at room temperature for one hour and were then subsequently centrifuged at 8000 rpm for 15 minutes at 4 oC. The serum samples were then stored at -20 oC until assayed. Clear non-hemolyzed sera were separated and used for the assay of testosterone, estrogen, follicle-stimulating (FSH), luteinizing hormone (LH), and prolactin (PRL) by solid-phase competitive chemiluminescent enzyme immunoassay through the utilisation of IMMULITE analyser purchased from DPC (Diagnostic Products Corporation, USA).

Training Program

None of the participants had engaged in any form of an exercise training programme for at least two months prior to the study. The group carried out their HIIT exercise training program (3 sessions/week, 2 h after lunch) for eight weeks on alternate days (Sunday, Tuesday, and Thursday). Each participant's repetition maximum (1RM) was measured. Participants completed a warm-up set of 8–10 repetitions at 50% of their estimated 1RM, before moving to a warm-up set of 3–5 repetitions at 85% of their estimated 1RM. To determine squat 1RM, participants performed 1RM attempts over 4–5 trials separated by 3 min rest intervals. 1RM was measured again, and intensity was re-established after four weeks of HIIT training. The detailed exercise training programme is presented in Table 2.

Table 2

High-Intensity Interval Training (HIIT) Program

S

Exercise

Week 1,2

Week 3,4

Week 5,6

Week 7,8

(time× sets) rest

(time× sets) rest

(time× sets) rest

(time× sets) rest

1

High knees

(10×3) 10

(15×4) 30

(20×4) 20

(30×3) 30

Squats

(10×3) 10

(15×4) 30

(20×4) 20

(30×3) 30

Basic burpees

(10×3) 10

(15×4) 30

(20×4) 20

(30×3) 30

Elbow plank

(10×3) 10

(15×4) 30

(20×4) 20

(30×3) 30

Flutter kicks

(10×3) 10

(15×4) 30

(20×4) 20

(30×3) 30

2

Plank

(10×4) 20

(15×3) 30

(20×5) 40

(30×5) 60

Elbow plank

(10×4) 20

(15×3) 30

(20×5) 40

(30×5) 60

Body saw

(10×4) 20

(15×3) 30

(20×5) 40

(30×5) 60

Side bridges

(10×4) 20

(15×3) 30

(20×5) 40

(30×5) 60

Crunches

(10×4) 20

(15×3) 30

(20×5) 40

(30×5) 60

3

Sit-ups

(10×5) 30

(15×5) 45

(20×3) 40

(30×4) 60

Jumping jacks

(10×5) 30

(15×5) 45

(20×3) 40

(30×4) 60

Scissors chops

(10×5) 30

(15×5) 45

(20×3) 40

(30×4) 60

Arm Scissors

(10×5) 30

(15×5) 45

(20×3) 40

(30×4) 60

Climbers

(10×5) 30

(15×5) 45

(20×3) 40

(30×4) 60

Session (S), Time, rest by seconds

Insert Table 2.

Statistical Analysis

Statistical Package for Social Sciences (SPSS) (version 23.0.) and GraphPad Prism (version 8.4.2. GraphPad Software 154 LLC, CA, USA) were used to perform all statistical analyses. Data included the mean ± standard error of the mean (sem) and "T" value. The significance level was set at p < 0.05.

Results

The results of the current experimental procedure are presented as mean ± standard error of the mean (sem) for the given number of participants, as shown below. Table 1 presents the anthropometric and physical characteristics of the participants (age, height, body mass, body mass index).

Figure 13 depicts the primary data of the current study. It was revealed that 8-week training had a significant impact on estrogen, testosterone, and follicle-stimulating hormone (FSH) levels (Fig. 13). In addition, there was a 2-fold increase in estrogen levels post-exercise training compared to the basal measurement prior to the initiation of the exercise intervention (Fig. 1).

Insert Fig. 1.

Furthermore, there was around a 3-fold reduction in testosterone levels after the exercise- regimen (Fig. 2), highlighting the crucial role of chronic exercise regulating testosterone levels in young female participants. In addition, post-exercise training measurements demonstrated a slight reduction (around 15%) in FSH levels (Fig. 2). In contrast, 8-week exercise training had no significant impact on LH and prolactin (Fig. 23).

Insert Fig. 2.

Insert Fig. 3.

Discussion

This study found that high-intensity interval training had a significant effect on estrogen and testosterone hormones in young females. In contrast, no significant changes were detected in the LH, Prolactin, and FSH hormones. However, this could be related to the small sample size of this study. Previous research studies have indicated that exercise has a positive effect on female hormones. Sex hormone levels are considered an objective marker for assessing the level and effectiveness of exposure to physical training and specifying the appropriate physical activity levels and doses, especially in women. In this study, hormonal estrogen levels showed a significant increase. Estrogen plays a crucial role in promoting the development and effectiveness of female reproductive structure and female secondary sex characteristics [8]. Similar results have been reported by Hackney et al. (2020). They assessed seven young women's hormonal responses on a moderate bicycle ergometer training for eight weeks in a fixed relative intensity. The results of their study detected an increase in beta-endorphin, beta lipotropin cortisol, and reproductive hormone levels [9]. Copeland et al. (2002) [10] investigated the female hormonal endurance and resistance training responses. They found a significant increase in estradiol levels in response to both training interventions in their study. In addition, the impact of physical activity on hormonal circulation has been confirmed by previous research findings reporting elevated estradiol circulation after resistance exercise and endurance exercise in female participants [11]. Vicissitudes in females' estrogen levels have been reported to be influenced by exercise duration, intensity, menstrual phase, and status [3, 12].

In addition to the increase of estrogen, the current study reported a significant increase in testosterone levels related to the impact of this study's proposed high-intensity interval training. These results were confirmed by the analysis of Gharahdaghi et al. 2021. They reported that resistance exercise could induce a temporary rise in testosterone in young, healthy females. Additionally, the anthropometrical indications of adiposity have been found to be significantly correlated with testosterone concentrations [13].

A study conducted by Kochańska-Dziurowicz et al. (2001) investigated the effect of a proposed acute exercise intervention on a cycle ergometer on testosterone and prolactin levels in 13 young female runners. Their study results addressed a significant elevation in the testosterone concentration, indicated at the end of the exercise and 90 minutes past the completion of the test. In contrast, the testosterone level had returned to the base levels as pre-exercise [14].

On the contrary, literature results have concluded that exercising had no effect on testosterone concentration in trained young women and was not influenced by their menstrual cycle [9, 15]. In addition, it has been revealed that training status contributes to mediating the hormones' response to physical activities. After a six-month resistance training intervention, changes in testosterone levels have only occurred in women [16].

In a study by Schmitz et al. (2007), other results were reported, as they found that physical activity level was inversely related to estrogen in late transition age. The adjusted means of estrogen reported were 24.6 and 37.9; a relative difference of 54% in estrogen level was detected when comparing highest to lowest activity (P = 0.02). Similarly, it was shown that physical activity was inversely related to testosterone levels (a relative difference of 47% was detected when comparing the highest to lowest activity [17].

The current study illustrated that the increase in estrogen hormone had been linked to a rise in LH and PRL. Despite the significant elevation in estragon levels, no significant changes have been indicated in the study participants' levels of LH and PRL. This finding could be explained by the conclusion of a recent meta-analysis conducted by Ennour-Idrissi et al., 2015, on the effect of physical activity on sex hormones in women. The meta-analysis results addressed that the impact of physical activity on circulating sex hormones is relatively modest and probably not clinically significant. Also, the levels of sex hormones in the blood may not represent their effects on target tissues. Physical activity may continue to affect sex hormone function by modulating target-tissue sensitivity to these hormones [18].

Summary

Regular exercise may induce changes in the levels of reproductive hormones in females, including an increase in estrogen level and a decrease in test level. High-intensity interval training exercise is highly recommended for young women as it leads to increased estrogen levels and reduced testosterone levels, with no effect on trophic hormones (LH and PRL).

Declarations

Ethics approval and consent to participate and publication: 

The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Institutional Review Board approved the Faculty of Physical Education study, Mansoura University, Egypt. Written and oral and informed signed consent was obtained from all participants

Availability of data and materials: 

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Competing interests: The authors declare no conflict of interest.

Funding: No financial support for the current study.

Authors' contributions: 

Wael  Ramadan contributed to Conceptualization, Formal analysis, Methodology, Supervision, Validation, Visualization, Writing-review & editing. Chrysovalantou E.  Xirouchaki contributed to Investigation, data extraction, data analysis and manuscript writing, results discussion. Medhat Abdel Razek and Mariam  Abu Alim contributed to Supervision, Writing-original draft, Writing-review & editing. All authors read and approved the fnal manuscript.

Acknowledgements:

The authors would like to thank all the participants that voluntarily agreed to participate in the current study after signed informed consent. 

References

  1. Weston M, Taylor KL, Batterham AM, Hopkins WG. Effects of low-volume high-intensity interval training (HIT) on fitness in adults: a meta-analysis of controlled and non-controlled trials. Sports medicine. 2014;44(7):1005-17.
  2. Zanker C, Swaine I. Relation between bone turnover, oestradiol, and energy balance in women distance runners. British journal of sports medicine. 1998;32(2):167 − 71.
  3. Piasecki J, Ireland A, Piasecki M, Cameron J, McPhee J, Degens H. The strength of weight-bearing bones is similar in amenorrheic and eumenorrheic elite long‐distance runners. Scandinavian journal of medicine & science in sports. 2018;28(5):1559-68.
  4. Bjørnerem As, Straume B, Midtby M, Fønnebø V, Sundsfjord J, Svartberg J, et al. Endogenous sex hormones in relation to age, sex, lifestyle factors, and chronic diseases in a general population: the Tromsø Study. The Journal of Clinical Endocrinology & Metabolism. 2004;89(12):6039-47.
  5. Hirschberg AL. Female hyperandrogenism and elite sport. Endocrine connections. 2020;9(4):R81-R92.
  6. McTiernan A, Tworoger SS, Rajan KB, Yasui Y, Sorenson B, Ulrich CM, et al. Effect of exercise on serum androgens in postmenopausal women: a 12-month randomized clinical trial. Cancer Epidemiology and Prevention Biomarkers. 2004;13(7):1099 − 105.
  7. Vislocky LM, Gaine PC, Pikosky MA, Martin WF, Rodriguez NR. Gender impacts the post-exercise substrate and endocrine response in trained runners. Journal of the International Society of Sports Nutrition. 2008;5(1):1–10.
  8. Mosavat M, Mohamed M, Mirsanjari MO. Effect of exercise on reproductive hormones in female athletes. International Journal of Sport and Exercise Science. 2013;5(1):7–12.
  9. Hackney AC, Willett HN. Testosterone Responses to Intensive, Prolonged Endurance Exercise in Women. Endocrines. 2020;1(2):119 − 24.
  10. Copeland JL, Consitt LA, Tremblay MS. Hormonal responses to endurance and resistance exercise in females aged 19–69 years. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. 2002;57(4):B158-B65.
  11. Mannerkorpi K, Landin-Wilhelmsen K, Larsson A, Cider Å, Arodell O, Bjersing JL. Acute effects of physical exercise on the serum insulin-like growth factor system in women with fibromyalgia. BMC musculoskeletal disorders. 2017;18(1):1–8.
  12. Lebrun CM, Joyce SM, Constantini NW. Effects of female reproductive hormones on sports performance. Endocrinology of physical activity and sport: Springer; 2013. p. 281–322.
  13. Gharahdaghi N, Phillips BE, Szewczyk NJ, Smith K, Wilkinson DJ, Atherton PJ. Links Between Testosterone, Oestrogen, and the Growth Hormone/Insulin-Like Growth Factor Axis and Resistance Exercise Muscle Adaptations. Frontiers in Physiology. 2021;11:1814.
  14. Kochańska-Dziurowicz A, Gawel-Szostek V, Gabryś T, Kmita D. Changes in prolactin and testosterone levels induced by acute physical exertion in young female athletes. Human Physiology. 2001;27(3):349 − 52.
  15. O’Leary C, Lehman C, Koltun K, Smith-Ryan A, Hackney A. Response of testosterone to prolonged aerobic exercise during different phases of the menstrual cycle. European journal of applied physiology. 2013;113(9):2419-24.
  16. Hakkinen K, Pakarinen A, Kraemer WJ, Newton RU, Alen M. Basal concentrations and acute responses of serum hormones and strength development during heavy resistance training in middle-aged and elderly men and women. Journals of Gerontology-Biological Sciences and Medical Sciences. 2000;55(2):B95.
  17. Schmitz KH, Lin H, Sammel MD, Gracia CR, Nelson DB, Kapoor S, et al. Association of physical activity with reproductive hormones: the Penn Ovarian Aging Study. Cancer Epidemiology and Prevention Biomarkers. 2007;16(10):2042-7.
  18. Ennour-Idrissi K, Maunsell E, Diorio C. Effect of physical activity on sex hormones in women: a systematic review and meta-analysis of randomized controlled trials. Breast Cancer Research. 2015;17(1):1–11.