This month, I want to focus on a topic that affects us, the female athletes, but is often overlooked: how the menstrual cycle influences our performance. As both a female athlete and a researcher, this subject is close to my heart. Despite the increasing number of women participating in sports, there remains limited research focused on how training and competition affect us. This gap in understanding is why I’m conducting a study at the University of Glasgow, in collaboration with my business, Train4 Body&Mind, and the Manual Therapy Clinic in Edinburgh. My research explores how the menstrual cycle impacts ultradistance runners, a field that has been largely unexplored until now.
The aim of this work is not just academic but deeply practical. Both athletes and coaches need to understand how training interacts with female physiology to optimize performance, minimize risk, and support health. High training volumes can affect the menstrual cycle, which in turn influences how we perform, recover, and adapt to exercise. In this article, I’ll explore the hormonal changes women experience during the menstrual cycle, their physiological effects, and the implications for training and competition.
Hormonal Fluctuations Across the Cycle
The menstrual cycle typically lasts between 21 and 35 days and is divided into four phases: menses, the follicular phase, ovulation, and the luteal phase. Each phase is characterized by distinct hormonal changes. During the follicular phase, oestrogen levels rise, peaking just before ovulation. In the luteal phase, progesterone levels increase, accompanied by moderate oestrogen levels. These hormonal fluctuations influence various physiological systems, including energy metabolism, recovery, and performance.
Research has shown that these hormonal shifts can impact athletic performance, but the findings are mixed. A longitudinal study involving 128 elite British female track and field athletes revealed that over three-quarters experienced negative effects on performance during their menstrual cycle [1]. Specifically, 40% reported a decline in performance during the late luteal phase, and 35% during the early follicular phase [1]. This highlights the significant impact these phases can have, especially during high-intensity training or competition.
Another study examining strength and psychological state across athletes at different levels of conditioning found no significant performance differences between menstrual phases [2]. However, highly trained athletes showed a slight decline in performance during menses, which was not observed in less conditioned athletes [2]. This suggests that performance impacts may be more pronounced in elite athletes who operate closer to their physiological limits.
How Hormonal Changes Affect Energy Systems
Hormones like oestrogen and progesterone play a key role in how the body uses energy during exercise. Oestrogen has been shown to stabilise muscle membranes, reducing muscle damage, it can promote fat metabolism and regulate glycogen use making it more economical. Progesterone, on the other hand, increases fat use but reduces carbohydrate metabolism, which can limit high-intensity efforts.
Studies examining endurance performance have shown mixed results. For example, Taipale-Mikkonen et al. (2021) conducted running tests during various phases of the menstrual cycle, measuring VO2 peak, lactate levels, and running time to exhaustion. They found no significant differences in performance across phases [3]. Similarly, Smekal et al. (2007) studied incremental cycling tests in the follicular and luteal phases and found no significant differences in metrics like VO2 max, heart rate, or blood lactate concentration. However, they did observe higher ventilation rates during the luteal phase, which could indicate subtle physiological differences [4].
Interestingly, some research suggests that endurance may improve during the luteal phase due to this greater reliance on fat metabolism. A systematic review of 26 studies found a small but significant increase in resting metabolic rate (RMR) during the luteal phase, likely due to higher progesterone levels [5]. However, this increase in energy expenditure may require athletes to adjust their nutritional intake to avoid deficits during training.
Recovery, Muscle Damage, and Health
The menstrual cycle also affects recovery and muscle repair. Oestrogen has been found to stabilise muscle cell membranes, reducing inflammation and muscle damage [6]. This is reflected in lower levels of creatine kinase (a marker of muscle damage) in women compared to men after intense exercise [7]. In ultramarathons, women exhibit fewer signs of muscle damage than men, a difference partly attributed to oestrogen’s protective effects [7].
In addition, oestrogen and progesterone promote antioxidant enzyme expression, which may reduce exercise-induced muscle damage during the late follicular and mid-luteal phase [8]. This aligns with findings that women recover faster from certain types of muscle damage during these phases , though more research is needed to confirm these effects across different exercise intensities.
However, a critical issue in female health among marathoners and ultrarunners is the prevalence of menstrual irregularities caused by high training volumes. Many female athletes who train extensively experience anovulation (where ovulation does not occur) or a shortened luteal phase [9]. Both conditions are linked to insufficient levels of luteinising hormone, which disrupts the hormonal balance. These changes not only affect performance but also pose risks to long-term health, such as reduced bone density, hormonal imbalances, and compromised energy availability. Coaches and athletes must monitor these risks closely to safeguard both performance and health.
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Implications for Training and Competition
The implications of these findings are significant for female athletes and their coaches. Understanding how the menstrual cycle affects performance can help optimise training schedules and ensure adequate recovery. For example, coaches might adjust training intensity during phases when athletes feel less energetic or recover more slowly. Nutrition also plays a critical role, particularly during the luteal phase when energy demands are higher.
Despite the growing number of women in sports, only 35% of studies in sports and exercise medicine journals include female participants [10]. Historically, researchers focused on male athletes because their hormonal profiles are simpler, but this approach overlooks the unique challenges and needs of female athletes. Closing this research gap is essential to provide better guidance for women in sports.
Conclusions
The menstrual cycle is a natural and powerful part of being a female athlete. While it can pose challenges, it also offers opportunities to better understand our bodies and optimise performance. By continuing to study these hormonal fluctuations and their effects on training and competition, we can empower female athletes to perform at their best while safeguarding their health.
As researchers and athletes, it’s time to embrace these complexities and ensure that female physiology is no longer an afterthought in sports science. My own study on ultradistance runners is a step in this direction, and I look forward to sharing more insights on it soon. This is the menstrual cycle and performance.Â
REFERENCES
- Jones, B.P., et al., Menstrual cycles and the impact upon performance in elite British track and field athletes: a longitudinal study. Frontiers in Sports and Active Living, 2024. 6.
- Isenmann, E., et al., The effect of the menstrual cycle phases on back squat performance, jumping ability and psychological state in women according to their level of performance -a randomized three-arm crossover study. BMC Sports Science, Medicine and Rehabilitation, 2024. 16(1): p. 224.
- Taipale-Mikkonen, R.S., et al., Influence of Menstrual Cycle or Hormonal Contraceptive Phase on Physiological Variables Monitored During Treadmill Testing. Frontiers in Physiology, 2021. 12.
- Smekal, G., et al., Menstrual cycle: no effect on exercise cardiorespiratory variables or blood lactate concentration. Med Sci Sports Exerc, 2007. 39(7): p. 1098-106.
- Benton, M.J., A.M. Hutchins, and J.J. Dawes, Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis. PLoS One, 2020. 15(7): p. e0236025.
- Tiidus, P.M., Influence of Estrogen on Skeletal Muscle Damage, Inflammation, and Repair. Exercise and Sport Sciences Reviews, 2003. 31(1): p. 40-44.
- Kumagai, H., et al., Genetic polymorphisms in CYP19A1 and ESR1 are associated with serum CK activity after prolonged running in men. Journal of Applied Physiology, 2022. 132(4): p. 966-973.
- Oosthuyse, T., J.A. Strauss, and A.C. Hackney, Understanding the female athlete: molecular mechanisms underpinning menstrual phase differences in exercise metabolism. European Journal of Applied Physiology, 2023. 123(3): p. 423-450.
- Prior, J.C., et al., Menstrual cycle changes with marathon training: anovulation and short luteal phase. Can J Appl Sport Sci, 1982. 7(3): p. 173-7.
- Costello, J.T., F. Bieuzen, and C.M. Bleakley, Where are all the female participants in Sports and Exercise Medicine research? European Journal of Sport Science, 2014. 14(8): p. 847-851.
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