Maximizing Performance: Understanding the Impacts of Your Menstrual Cycle

The female athlete experiences a dynamic interplay of hormones during her reproductive years, influencing various aspects of her physiology. There is a natural ebb and flow of estradiol and progesterone throughout the menstrual cycle years. Understanding these fluctuations is can help for optimizing athletic training and performance.

Understanding the Menstrual Cycle

The menstrual cycle is divided into two main phases: the follicular phase and the luteal phase. A typical menstrual cycle is 28 days, with menstruation marking day 1 of a new cycle. Menstruation can occur on average for 2-7 days. During the follicular phase (~day 1-14) a dominant follicle grows, and it produces increasing amounts of estrogen. Estrogen stimulates the thickening of the uterine lining. The follicular phase concludes with a surge in luteinizing hormone (LH) triggered by rising estrogen levels, triggering ovulation. This marks the beginning of the luteal phase (~day 15-28). At this time the remaining follicle transforms into a structure called the corpus luteum which produces progesterone. This prepares the uterus for a potential pregnancy by further thickening the endometrium and making it more receptive to a fertilized egg. If no pregnancy occurs, the corpus luteum degenerates, leading to a decline in progesterone and estrogen levels. The drop in hormonal levels triggers the onset of menstruation, marking the beginning of a new menstrual cycle.

KEY POINTS: These phases are characterized by fluctuations in estrogen and progesterone levels, with the follicular phase marked by the rise of estrogen, leading up to ovulation, and the luteal phase marked by increased progesterone levels.

Blood loss during menstruation

Blood loss during menstruation can contribute to iron deficiency in women, as the body loses a significant amount of iron-rich blood each month. It is estimated that women lose about 20 to 90 mL (about 1 to 5 tablespoons) of blood in a period. Iron is a vital component of hemoglobin, the protein responsible for transporting oxygen in the blood. When iron levels drop, it can lead to iron deficiency anemia. Symptoms of iron deficiency include fatigue, weakness, pale skin, shortness of breath, and difficulty concentrating. Iron deficiency anemia is very common in menstruating females, with estimates ranging from 17-77% depending on the parameter of iron assessed.

To counteract the iron loss during menstruation, it's essential to include iron-rich foods in the diet. Foods such as lean meats, poultry, fish, beans, lentils, tofu, and dark leafy greens are excellent sources of iron. Consuming vitamin C-rich foods alongside iron-rich foods can enhance iron absorption. Additionally, considering iron supplements under the guidance of a healthcare professional may be beneficial for those who struggle to meet their iron needs through diet alone. Managing iron levels is crucial for overall well-being, especially for women experiencing regular blood loss during their menstrual cycles. Optimizing iron levels during menstruation can help ensure you have enough energy for your athletic training.

Impact of hormone fluctuations on exercise

A retrospective survey study revealed that a 37-63% of female athletes report no performance detriment associated with specific menstrual cycle phases. Surprisingly, 13-29% reported improvements during menstruation. The best performances often occurred in the postmenstrual days, with the worst performances during the premenstrual interval and the first days of menstrual flow.

 Current research suggests that fluctuations in female reproductive hormones do not significantly impact muscle contractile characteristics, maximal oxygen consumption (V̇O2max), or heart rate. During the luteal phase, increases progesterone and estradiol can lead to net fluid retention. Although in studies these effects have no repercussions on athletic performance, bloating due to fluid retention may make exercise uncomfortable or difficult for some.

For prolonged exercise, especially in hot conditions, the menstrual cycle may have an impact. During the luteal phase, increased progesterone causes an elevation in basal body temperature. This elevated body temperature during the mid-luteal phase is associated with decreased exercise time to exhaustion, potentially due to increased cardiovascular strain and reduced exercise efficiency.

Checkout part 2 of this blog post “Maximizing Performance Part 2: Optimizing Training with Your Menstrual Cycle” to learn more about how to

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