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  • Edgar S.

She is the embodiment of grit and grace: The Endurance Female Athlete

(photo credits @huntingpedals at theGOATS offroad ultracycling 2023 of Jana Mascha Lu Wahlig )

The Fascinating Complexity of Female Endurance Athletes, it’s Journey Through Biology, Performance, and Challenges.

In a world obsessed with comparisons between men and women, the female endurance athlete emerges as an intriguing enigma. In this article, I delve into the complex relationship between biology and performance, exploring how sex differences shape the female experience in endurance sports.

Uncovering Challenges and Predispositions

In this post I analyze the biological hurdles that women face, such as lower muscle mass and hormonal fluctuations during the menstrual cycle. I also explore unique characteristics that may confer special predisposition for ultracycling, such as greater fatigue resistance, more efficient body temperature regulation and great metabolic efficiency.

The Female Biological Identity and its Impacts

Three key areas of female biological identity:

Hormonal Component/Menstrual Cycle: Details on the four main hormones of the menstrual cycle (LH, FSH, estrogen, and progesterone), focusing on the impact of estrogen and progesterone on the different phases of the cycle.

Metabolic Component: The changes in energy metabolism in women, during the menstrual cycle.

Psychological Component: Influence of hormonal fluctuations on mood, cognition, and sleep, and how this impacts training and competition.


Hormonal component of the Menstrual Cycle and Training

It is important to emphasize that this is a general overview. Each athlete has individual characteristics that influence their response to training. Factors such as genetics, nutrition, training history, and lifestyle should also be considered for personalized and effective periodization.


Follicular Phase (low hormone phase): Predisposition for high-intensity training, higher volume, and lower recovery needs.

  • More similar to male physiology, increased pain tolerance, maybe shorter recovery time, higher carbohydrate utilization

  • May be a better time to increase intensity, duration, distance

Luteal Phase (high hormone phase): Predisposition for lower-intensity training, and higher recovery needs, specially for longer sessions (low intensity).

  • Decrease in plasma volume (thicker blood) by approximately 8%, which lowers blood delivery to working muscles

  • Core temperature increases by 0.5 degrees Celsius, time to fatigue is shorter and ability to tolerate heat is decreased

And it’s in this second phase, that training and nutrition become more nuanced. Dive deeper with me as we explore the specifics!

The Hormonal Shifts

The menstrual cycle is a fascinating ebb and flow of hormones, and the final act, the luteal phase (lasting 10-16 days), can be a rollercoaster for some women. While the body prepares for a potential pregnancy, a hormonal shift can trigger a collection of unwelcome guests known as premenstrual syndrome (PMS).

Estrogen: A Two-Faced Coin for Exercise

Estrogen, a dominant hormone throughout the menstrual cycle, has a complex relationship with exercise. While it boasts some muscle-building (anabolic) properties on its own, its impact on workouts can be a double-edged sword.

So, high levels of estrogen:

  • Decreases reliance on liver glycogen

  • Increases fatty acid utilization

  • Lowers post-exercise growth hormone release

  • Anabolic by itself but countered by progesterone

  • May lead to poor recovery and muscle protein synthesis

(More detailed)

Here's how estrogen can influence your exercise experience:

Fuel Source Shuffle: Estrogen can decrease the body's reliance on readily available liver glycogen, the primary fuel source for high-intensity exercise. This can lead to a shift towards increased fatty acid utilization, which takes longer for the body to convert into usable energy.

Recovery Roadblock: Estrogen can also play a role in post-exercise recovery by lowering the release of growth hormone. Growth hormone is crucial for muscle repair and regeneration, so a dip in its levels can hinder muscle protein synthesis and delay recovery. This can be particularly noticeable after intense workouts.

The Progesterone Factor: The story doesn't end there. During the luteal phase of the menstrual cycle, progesterone levels rise, further amplifying the effects of estrogen. Progesterone's opposing nature can exacerbate the decrease in glycogen reliance and growth hormone release, potentially leading to feelings of fatigue and hindering athletic performance.

So, Progesteron at a higher rate does:

  • Competes with aldosterone, increasing sodium excretion

  • Increases protein catabolism

  • Increases respiration

  • Decreases GLUT4 receptor on cells (less glycogen storage)

  • May make it harder to recover, increase risk of hyponatremia, may trigger exercise induced asthma

(more detailed)

Hydration Alert (more on this ahead): Progesterone increases urine output, raising the risk of hyponatremia (low sodium). Stay hydrated during exercise and give more attention to sodium intake via an electrolyte drink.

Muscle Matters: Progesterone might increase muscle breakdown and impact energy usage. Consider lower intensity workouts during peak progesterone phases. Don’t neglect protein intake.

Glycogen: Progesterone may hinder glycogen storage, affecting energy availability. Adjust training intensity as needed.

Asthma Concerns: For some, progesterone fluctuations can worsen exercise-induced asthma symptoms. Consult a healthcare professional if needed.

By understanding your cycle and listening to your body, you can adapt your training and conquer workouts throughout the month. Remember, progesterone is essential, but a few tweaks can keep you active!


Menstrual Cycle and Sodium Balance. This topic deserves a more detailed approach.

The menstrual cycle has a fascinating influence on a woman's body, including how it handles sodium and fluids. Here's a simplified breakdown:

Estrogen's Role: High estrogen levels in the follicular phase can:

  • Increase ADH: This hormone constricts blood vessels and promotes water retention, ensuring proper hydration.

Progesterone's Counterpoint:  In the luteal phase, rising progesterone:

  • Reduces Sodium Reabsorption: It competes with aldosterone for binding sites in the kidneys, leading to increased sodium excretion in urine. This could potentially lead to a temporary dip in total body sodium.

Maintaining Balance:  However, the body has built-in mechanisms to maintain homeostasis (stable internal environment). Even if sodium levels dip slightly due to progesterone's influence:

  • Blood Volume Adjustments: The body may compensate by reducing blood plasma volume, but this effect is usually minimal.

  • Cardiovascular and Thermoregulation: While a slight decrease in blood volume could theoretically affect heart rate and core body temperature, these impacts are not typically significant.

Overall Impact:  The menstrual cycle's influence on sodium and fluid balance is:

  • Minimal in the Follicular Phase: High estrogen promotes water retention.

  • Potentially More Challenging in the Luteal Phase: Progesterone increases sodium excretion, but the body's regulatory systems work to maintain balance.

In essence, while hormonal fluctuations occur throughout the cycle, the body has remarkable compensatory mechanisms to ensure a stable internal environment for optimal functioning.

(photo of Steph King in theGOATS offroad ultracycling 2023 )


The Psychological effect

Mind Over Matter: Hormones and the Female Athlete

The menstrual cycle isn't just about physical changes. Hormonal fluctuations can also significantly impact an athlete's mental state. Estrogen and progesterone, the key players, influence mood, cognition, and sleep patterns throughout the cycle.

During the follicular phase (roughly days 1-14), rising estrogen levels can lead to increased focus, motivation, and energy. This "golden window" can be a prime time for high-intensity training and mental focus.

However, as we enter the luteal phase (days 15-28), progesterone takes center stage. This shift can bring about feelings of fatigue, irritability, and even anxiety. Sleep quality may also be disrupted. These changes can affect focus, concentration, and overall training motivation.

So, what can athletes do?

By tracking your and plan your training accordingly, as explained, scheduling high-intensity workouts for the follicular phase and prioritize recovery and lower-intensity training during the luteal phase, you will manage quite better your mood.

Don't push yourself to the limit during days of low energy. Prioritize sleep and adjust your training intensity based on how you feel.

Maintain a balanced diet rich in essential nutrients to support your body's changing needs throughout the cycle, and also escaping the risk of RED-S (Relative Energy Deficiency)- Let’s give to this one another article.

By being mindful of the hormonal rollercoaster, female athletes can harness the power of their cycle and optimize their mental performance for training and competition success.



Optimizing Your Workouts

While estrogen's influence might necessitate adjustments, it doesn't have to derail your fitness goals. Here are some tips:

Fuel Up Strategically (more in this topic ahed): Focus on pre-workout meals rich in complex carbohydrates to replenish glycogen stores.

Listen to Your Body: Don't push through exhaustion. Adjust workout intensity or opt for lower-impact activities during phases with higher estrogen and progesterone levels.

Prioritize Recovery: Schedule adequate rest days to allow your body to fully recover and rebuild muscle.

By understanding how estrogen interacts with your workouts, you can make informed choices to stay active and achieve your fitness goals throughout your menstrual cycle.


Fueling the Female Engine: Nutrition Strategies Across the Menstrual Cycle

For female endurance athletes, the menstrual cycle presents a unique challenge. Hormonal fluctuations throughout the cycle impact not only physical performance but also nutritional needs. Here's a breakdown of how to tailor your nutrition strategy to each menstrual phase:

Follicular Phase

Rising estrogen levels promote energy production and glycogen storage.

Nutritional Needs:

Focus on Carbohydrates: Emphasize readily available carbohydrates like fruits, vegetables, and whole grains to fuel high-intensity training.

Maintain Adequate Protein: Aim for 0.8-1.2 grams of protein per kilogram of body weight to support muscle repair and growth.

Don't Neglect Healthy Fats: Include healthy fats like nuts, seeds, and avocado for satiety and hormone balance.

Luteal Phase

Hormonal Landscape: Rising progesterone levels can lead to increased water retention, fatigue, and cravings.

Nutritional Needs:

Prioritize Complex Carbohydrates: Opt for complex carbs like whole grains and starchy vegetables for sustained energy release and blood sugar control.

Increase Fiber Intake: Focus on fiber-rich foods like fruits, vegetables, and whole grains to aid digestion and manage bloating.

Hydration is Key: Increased water retention doesn't mean you need less water. Aim for adequate hydration to support bodily functions and performance.

Mindful Snacking: Choose nutrient-dense snacks like fruits with nuts or yogurt to manage cravings and maintain energy levels.

Premenstrual Syndrome (PMS) Symptoms (Variable):

Addressing Specific Symptoms:

Cramps: Include anti-inflammatory foods like fruits, vegetables, and fatty fish to potentially reduce cramping.

Mood Swings: Focus on foods rich in B vitamins and magnesium to support mood regulation.

By understanding the hormonal shifts throughout your menstrual cycle and adapting your nutrition strategy, you can optimize your fuel intake to maximize training performance and recovery as a female endurance athlete. Remember, proper nutrition is a powerful tool to support your body's unique needs and achieve your athletic goals.

Other issues related with Female athletes and endurance sports

Beyond Amenorrhea: Challenges Faced by Female Athletes

Amenorrhea, the absence of menstrual periods, is a well-known concern for female athletes. However, it's just one piece of a larger puzzle when it comes to the unique challenges faced by women in sports. Here, we'll explore some additional issues that impact female athletes and potential solutions to promote their well-being:

Relative Energy Deficiency in Sport (RED-S):

This broader term encompasses amenorrhea but recognizes that low energy availability (LEA) can manifest in various ways, including irregular periods, bone health issues, and increased risk of injuries. Understanding the root cause of LEA, often linked to inadequate calorie intake or high training volume, is crucial for addressing the underlying problem.

Iron Deficiency:

Female athletes are particularly susceptible to iron deficiency due to menstruation and increased iron losses through sweat. This deficiency can lead to fatigue, decreased performance, and impaired immune function. Dietary adjustments and iron supplementation might be necessary to maintain optimal iron levels.

By recognizing and addressing these diverse challenges, it's possible to create a more supportive environment for female athletes to thrive. This includes promoting holistic health approaches, encouraging open communication between athletes and coachs.

When designing training as a stimulus for women, it is crucial to consider the hormonal fluctuations of the menstrual cycle. These fluctuations directly impact various physiological, metabolic, and psychological predispositions, influencing performance and recovery.

More than a comparison between sexes, this article is a celebration of the strength, resilience, and passion of female endurance athletes. It is an invitation to acknowledge their achievements and the importance of their participation in the sport.

Throughout my experience with training endurance athletes, and Female Athletes in this case, I have adopted the principles that guide competent and appropriate work as the fundamental basis for excellence.

In ultracycling, I believe we are close to seeing a woman achieve the fastest time in a race. Their biology and resilience minimize the physiological differences between men and women, allowing both to "compete" in a unique and fair context for both.

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