This blog aims at discussing the considerations and impacts the menstrual cycle can have on exercise performance through an analysis of current literature. It is important to note that the research on this topic is still inconclusive, potentially due to several factors such as hormonal fluctuations, intra and inter individual differences, contraceptive use and menstrual dysfunctions.
Strength and conditioning coaches and fitness professionals working with female population should have a basic understanding of key terminology (see table 1) and how it could potentially impact performance, nutrition and recovery (Pitches, 2019).
Table 1: Redrawn from Pitches, 2019
The menstrual cycle's main purpose is to aid reproduction (Lebrun, 1994). Increasing evidence suggests that hormonal fluctuations during the menstrual cycle can have an impact on exercise performance (Lei, Zheng, Badenhorst & Mündel, 2020). The average age of menarche in the United Kingdom being 13 years old, lasting until the onset menopause, which occurs at approximately 51 years old (Whincup, 2001).
The menses, follicular (first approximately 12 days from menses to ovulation) and luteal (second “half” of the cycle following ovulation) are the three stages which compose the menstrual cycle (Pitchers & Elliott-Sale, 2019). The cycle includes differing levels of two endogenous hormones known as oestrogen and progesterone, which are the hormones that could have the greatest effect on exercise performance (Baltgalvis, Greising, Warren & Lowe, 2010). Oestrogen appears to be low during menstruation, elevated during the follicular period, and mild during the luteal phase. Progesterone appears to be low during menstruation and follicular phase but elevated during the luteal phase (Lei et al., 2020).
Literature on Cardiorespiratory performance
When concerning cardiorespiratory performance, it is believed that some alterations occur in part due to changes in the automatic nervous system functioning. Elevated progesterone levels during the luteal phase can lower the threshold of the medullary respiratory centre, thus enhancing excitability (Janse de Jonge, Thomspson, & Han, (2019). The medullary response centre manages respiration rhythm and is in charge of regulating homeostatic responses to physiological changes stimulated by exercise, heat or emotion (Webster & Karan, 2020). The breathing rate increases when impulses from response centre are quicker, and it reduces when they are slower. Thus, during the luteal phase, increased respiration due to a rise in progesterone may be experienced. With the potential to consequently activate an oestrogen-dependent progesterone receptor triggering increased respiration. Cardiorespiratory function can also be influenced by a rise in core body temperature, which is most prevalent in the mid luteal phase (Constantini, Dubnov & Lebrun, 2005).
Barba-Moreno, Cupeiro, Romero-Parra, Janse de Jonge & Peinado, (2019) investigated the effects of the menstrual cycle on the cardiovascular response to sub maximal exercise. Women in their normal cycle conducted a 40-minute run at 75% max aerobic speed, which saw an increase in heart rate and threshold of ventilation during the mid-luteal phase (in line with previous statements). Researchers speculate that the rise in heart rate and ventilatory threshold are attributed in part to progesterone's thermogenic influence, which may raise core body temperature (though they did not test temperature), so it's difficult to say for sure. Furthermore, these measures showed a low to moderate effect size, making it challenging to justify whether this finding can be applied in a clinical environment. Unexpectedly, VO2 was higher in the mid follicular phase rather than the early follicular phase and there was no affect in the luteal phase. This is particularly surprising because progesterone levels were significantly lower in the mid follicular phase in comparison to the luteal phase. The authors hypothesised that the increase in vo2 occurs as a result of augmented oestrogen levels, thereby influencing the oestrogen and progesterone ratio. Concluding that the primary cause for this was due to the ratio of progesterone and oestrogen, rather than the effect of progesterone alone.
Dokumaci and Hazir, (2019) looked at the effect of the menstrual cycle on running economy in a different study. During two time periods, women were assessed at 75%, 85%, and 95% of their lactic threshold (follicular phase and luteal phase). Running economy was assessed through 3 variables: ml/kg/min, oxygen intake per distance and metabolic calorie cost. Surprisingly, and contrary to their expectations, participants were more effective in the luteal phase than in the follicular phase in all VO2 measures. However, this study possesses some fundamental flaws in relation to its methodology thus influencing its reliability when compared to the previous studies. One flaw which can be highlighted is the fact that tests only occurred during two phases of the menstrual cycle (once in the follicular phase and once in the luteal phase), while the previous study tested in three separate hormonal profiles (early follicular phase, late follicular phase, and mid luteal phase). In addition, testing occurred on days 7-9 after menses, which the phase where oestrogen concentrations rise at the fastest rate, thus influencing more noticeable changes. Therefore, it's crucial that testing takes place across both follicular stages.
Literature on Strength and skeletal muscle characteristics
When discussing strength and skeletal muscle adaptations it is crucial to highlight hormonal factors. Progesterone has been proposed to have a catabolic function; however, its affects are not well known. There is indication that a rise in amino acid oxidation and protein amino acid degradation during the luteal process is elicited (Wohlgemuth et al., 2021), although further research on how progesterone affects skeletal muscle is required.
The role of oestrogen, on the other hand, is better known thanks to studies on peri- and postmenopausal women. Strength levels and skeletal mass has been shown to quickly decline in peri and post-menopausal women (Slemenda, Longcope, Peacock, Hui & Johnston, (1996), though affects can be delayed or even reversed with hormone replacement therapy (Utian & Woods, 2013). Based on this factor, it is believed that a potential increase in muscle mass and strength can be maximised during the menstrual cycle, specifically when there is a high oestrogen concentration (mid-follicular phase). The anabolic affects may also increase the potential for post damage repair due to the proliferation of satellite cells occurring after strength training (Persson, 2015).
Sung et al., (2014) studied the impact of resistance exercise on untrained women during various phases of the menstrual cycle. The study entailed participants training one leg during the luteal phase and the other during the follicular phase. It is important to note that no differences were identified prior to the study. Results showed that both legs significantly improved in strength, however higher values were identified in the leg which was trained through the follicular phase (when oestrogen levels are higher).
Hypertrophy was also measured using ultrasound scans, revealing changes in diameter in both legs, but the leg that was exercised during the follicular process possessed higher increases. The study also indicated that testosterone levels increased during the follicular period, which may contribute to these findings.
Additional training and monitoring considerations through each phase of the cycle
Menses
During this phase women typically experience discharge of blood (25-65ml), however research has shown that this does not have a significant influence on performance. Though it is important to note that a decrease in haemoglobin and iron may be evident (Janse de jonge, 2003). It is suggested that during this phase positive exercise performance is evident due to low hormonal levels and may even aid in reducing the severity of period pains (Sargent & Barker, 2018).
Follicular phase
Pulido & Salazar, (1999) state that there is an increase in pain tolerance and insulin sensitivity during the follicular phase. In addition, research suggests that positive responses to endurance (Fischetto & Sax, 2013) and strength training recovery may be optimised (Priyadharshini, Kavitha, Nirmala & Latha, 2017). However higher levels of ligament and joint laxity have also been reported during this phase due to the increased of oestrogen levels (Enns & Tiidus, 2010). Thus, potentially increasing the risk of injury (Balachandar, 2017).
Luteal phase
One of the main characteristics of this phase is that insulin resistance is higher and glucose absorption is diminished (Oosthuyse & Bosch, 2010). Consequently, enhancing cravings and calorie intake. Due to resistance in the removal of waste products, it is also suggested that recovery between high intensity exercise may be slower (Sargent & Barker, 2018).
Monitoring
Procedures and methods of monitoring and practice may vary depending on the setting a coach operates in. Understanding the process and implications of the menstrual cycle will enable the coach to empathise with the athlete/ client and adapt/manipulate training accordingly if necessary. It's important to stress that the effects of the menstrual cycle and menstrual symptoms varies greatly from person to person and therefore practices should reflect this.
References
Balachandar, V. (2017). Effects of the menstrual cycle on lower-limb biomechanics, neuromuscular control, and anterior cruciate ligament injury risk: a systematic review. Muscle, Ligaments And Tendons Journal, 7(1), 136.
Baltgalvis, K., Greising, S., Warren, G., & Lowe, D. (2010). Estrogen Regulates Estrogen Receptors and Antioxidant Gene Expression in Mouse Skeletal Muscle. Plos ONE, 5(4), e10164.
Barba-Moreno, L., Cupeiro, R., Romero-Parra, N., Janse de Jonge, X., & Peinado, A. (2019). Cardiorespiratory Responses to Endurance Exercise Over the Menstrual Cycle and With Oral Contraceptive Use. Journal Of Strength And Conditioning Research, Publish Ahead of Print.
Constantini, N., Dubnov, G., & Lebrun, C. (2005). The Menstrual Cycle and Sport Performance. Clinics In Sports Medicine, 24(2), 51-82.
Dokumacı, B., & Hazır, T. (2019). Effects of the Menstrual Cycle on Running Economy: Oxygen Cost Versus Caloric Cost. Research Quarterly For Exercise And Sport, 90(3), 318-326.
Enns, D., & Tiidus, P. (2010). The Influence of Estrogen on Skeletal Muscle. Sports Medicine, 40(1), 41-58.
Fischetto & Sax (2013). The menstrual cycle and sport performance. New studies in athletics 28, 57-69.
Janse de Jonge, X. (2003). Effects of the Menstrual Cycle on Exercise Performance. Sports Medicine, 33(11), 833-851.
Janse De Jonge, X., Thompson, B., & Han, A. (2019). Methodological Recommendations for Menstrual Cycle Research in Sports and Exercise. Medicine & Science In Sports & Exercise, 51(12), 2610-2617.
Lebrun, C. (1994). The Effect of the Phase of the Menstrual Cycle and the Birth Control Pill on Athletic Performance. Clinics In Sports Medicine, 13(2), 419-441.
Lei, T., Zheng, H., Badenhorst, C., & Mündel, T. (2020). Comment on: “The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis” and “The Effects of Oral Contraceptives on Exercise Performance in Women: A Systematic Review and Meta-analysis”. Sports Medicine, 51(5), 1107-1109.
Oosthuyse, T., & Bosch, A. (2010). The Effect of the Menstrual Cycle on Exercise Metabolism. Sports Medicine, 40(3), 207-227.
Persson, P. (2015). Skeletal muscle satellite cells as myogenic progenitors for muscle homoeostasis, growth, regeneration and repair. Acta Physiologica, 213(3), 537-538.
Pitches, G. (2019). Training the female athlete. Presentation, UKSCA.
Pitchers, G., & Elliott-Sale, K. (2019). Considerations for coaches training female athletes. Professional Strength & Conditioning, 19-30.
Priyadharshini, Kavitha, Nirmala & Latha (2017). Assessment of Skeletal Muscle Strength, Fatigue and Respiratory Efficiency in Young Healthy Females during Different Phases of Menstrual Cycle. Experimental And Clinical Physiology And Biochemistry, 2017(4), 5-9.
Pulido, J., & Salazar, M. (1999). Changes in Insulin Sensitivity, Secretion and Glucose Effectiveness During Menstrual Cycle. Archives Of Medical Research, 30(1), 19-22.
Sargent, & Barker. (2018). The menstrual cycle, exercise and performance. Strength and Conditioning for Female Athletes (pp. 190- 203). Marlborough: Crawood Press.
Slemenda, C., Longcope, C., Peacock, M., Hui, S., & Johnston, C. (1996). Sex steroids, bone mass, and bone loss. A prospective study of pre-, peri-, and postmenopausal women. Journal Of Clinical Investigation, 97(1), 14-21.
Sung, E., Han, A., Hinrichs, T., Vorgerd, M., Manchado, C., & Platen, P. (2014). Effects of follicular versus luteal phase-based strength training in young women. Springerplus, 3(1), 668.
Utian, W., & Woods, N. (2013). Impact of hormone therapy on quality of life after menopause. Menopause, 20(10), 1098-1105.
Webster, L., & Karan, S. (2020). The Physiology and Maintenance of Respiration: A Narrative Review. Pain And Therapy, 9(2), 467-486.
Whincup, P. (2001). Age of menarche in contemporary British teenagers: survey of girls born between 1982 and 1986. BMJ, 322(7294), 1095-1096.
Wohlgemuth, K., Arieta, L., Brewer, G., Hoselton, A., Gould, L., & Smith-Ryan, A. (2021). Sex differences and considerations for female specific nutritional strategies: a narrative review. Journal Of The International Society Of Sports Nutrition, 18(1).
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