Empowering Female Athletes. Part 1

anemia carbohydrate creatine fueling hydration low energy availability nutrition protein supplements undernourished Aug 04, 2023
Dr Stacy Sims empowering women

A Review of the International Society of Sports Nutrition Female Athlete Position Stand

I am just back from a whirlwind trip in the US, and one of the stops was to present the new Female Athlete Position Stand at the International Society of Sport Nutrition’s (ISSN) annual conference. The ISSN has been a leading authority in providing evidence-based guidelines and recommendations for optimizing nutrition in sports and exercise settings. The ISSN recently released its Female Athlete Position Stand, aiming to address the specific nutritional needs and considerations for female athletes. 

A lot of research has come out over the past few years, which is exciting to see, and made for a very long, comprehensive journal article that was a long time in the making. Creating the ISSN Female Athlete Position Stand involved a collaboration of almost 20 authors, reviewing the literature and the methodology of the papers, and collating the best and newest information as it applies to female athletes; (bear in mind, the research is still lagging significantly behind men, and we discuss this in the paper). In the end, the goal of this document is to provide a comprehensive resource for coaches, nutritionists, and athletes themselves regarding various aspects of female athlete nutrition. Ultimately, the Position Stand is a statement for the Society on which guidelines can be made. 

Because it is a very long, technical document (and it took us a long time to write!), I wanted to boil down some of the key points here. This will be the first part of a two-part blog post series devoted to the Position Stand. (For those who want the full article, here you go!)

Why Do We Need Our Own Position Stand?

The first point of the paper is the significance of focusing on female athlete nutrition in the first place. Historically, sports nutrition research has predominantly centered around male athletes, neglecting the unique physiological and hormonal differences that females possess. It is well known that data was generalized from men to women, without really asking if this generalization was viable. From there, we illustrate that it’s not viable, and it’s time to move forward. 

In making this point, we describe the hormone profile of a naturally cycling woman, the different phases of the menstrual cycle, and how the female sex hormones can alter immunity, autonomic nervous system, glucose regulation and metabolism, appetite, fluid balance, and body composition. 

We then dive into oral contraceptives (which are widely used in the female athlete community), and how these hormone profiles differ from the natural cycle, as well as how these differences may affect women’s physiological systems. Not to leave it there, because women do exist past 40, we dive into peri and post menopause, how the hormones are changing, and how a woman’s physiology is affected. In this document we (the authors) emphasize the importance of tailoring nutrition strategies to meet the distinct demands of female athletes, which is a crucial step towards optimizing performance and overall health.

Information is Power

A key starting point for women as they aim to optimize their training and nutrition is self awareness. Female athletes have unique and unpredictable hormone profiles, which influence their physiology and nutritional needs across their lifespan. We begin by recommending that female athletes of reproductive age track their hormonal status (natural, hormone driven) against training and recovery to determine their individual patterns and needs. Peri and postmenopausal athletes should track against training and recovery metrics to determine their unique patterns.

Once you have established your own patterns and understand how you may be affected (or not) by your hormone profile, you can dial in specifics for your body and your sport.

Let’s Start With Eating Enough

When it comes to nutrition, the VERY FIRST need for all athletes, regardless of age, hormone profile, or sport, is getting enough energy in to meet the demands of life. We are seeing such an uptick in low energy availability (LEA) across all levels of athletes, it is paramount to understand what LEA is, and how it can contribute to Relative Energy Deficiency in Sport (REDs). Remembering that LEA is the exposure, and REDs is the outcome.

There are currently no scientifically established guidelines for optimal energy availability for female athletes, but conceptual models show that energy needs are likely to vary between training days and training blocks, as well as with varying amounts of non-purposeful physical activity expenditure (i.e. everyday movement). It’s also important to assess the training stress and recovery needs at the beginning of a season (lower fitness) and during high travel and competition blocks to gain insight into how to manipulate energy intake to 1) ensure needs are met, and 2) maintain competitive body composition and health.  

Nutrient timing is critical for reducing the discrepancy between training energy expenditure and energy intake and avoiding LEA. By eating in and around the training load, athletes can maximize their adaptive responses while at the same time dropping exercise-induced increases of cortisol and epinephrine (which can reduce acute immunity changes).  

When taking hormonal fluctuations into consideration, naturally cycling women experience a slight increase in energy needs (~150-300 calories/day) and protein requirements (~12%) in the luteal phase due to the increased demand for building blocks for the endometrial lining. Women using hormonal contraceptives need to be diligent regarding their energy intake and knowing the signs of LEA because contraceptive use can mask changes to the menstrual cycle (signs of early LEA) due to the downregulation of ovarian hormones. Peri- and postmenopausal women may have difficulty discerning the difference between LEA and menopausal transition signs and symptoms, thus leaning into nutrient timing and energy needs will reduce the risk of LEA.

Putting Carbohydrates in the Spotlight

Eating sufficient carbohydrates can help athletes avoid LEA, so the paper details the specifics around carbohydrate needs, which is increasingly important as this macronutrient continues to be demonized in many areas of the mainstream media and on social media. 

There are significant sex differences and sex hormone influences on carbohydrate and lipid (aka fat) metabolism. Women are inherently more metabolically flexible (both at rest and during exercise) than men. But that doesn’t mean we don’t need carbohydrates. We need exogenous carbohydrates to maximize fatty acid uptake by the mitochondria (aka fat burning during exercise). So, we recommend that female athletes be sure to meet their carbohydrate needs across all phases of their menstrual cycle according to their training needs. 

Secondly, we recommend tailoring carbohydrate intake to hormonal status, aiming for greater carbohydrate intake and availability during the active pill weeks of oral contraceptive users and during the luteal phase of the menstrual cycle when sex hormones can more notably suppress glycogen breakdown and glucose availability during exercise.  

A realistic starting recommendation is to take in 30 to 60 grams of carbohydrate per hour during exercise lasting 90 minutes or longer to offset menstrual cycle effects on glucose kinetics/exercise metabolism. This will also limit potential gastrointestinal distress, immune disturbances, and protein breakdown.

Speaking of GI distress, female athletes should track their menstrual cycle/hormone status to identify any times of increased GI issues across the cycle and if their carbohydrate intake affects these symptoms. If GI distress is a concern, start at 30 grams of carbohydrate per hour and avoid exceeding the upper limit of carbohydrate ingestion (>60 g·h−1).

When it comes to recovery, replenishing your glycogen stores after high volume and/or multiple sessions in a 24 hour period is essential to optimize performance. By improving your carbohydrate availability, you can promote positive training adaptations and health.

We recommend female athletes focus on rapid consumption of at least 1.2 grams of carbohydrate per kilogram of body weight (0.54 grams of carbohydrate per pound of body weight) following prolonged exercise in order to restore spent muscle glycogen. Given the  increase in insulin resistance associated with peri and post menopause, female athletes in those stages of life should take advantage of the non-insulin dependent first phase of glycogen synthesis, which lasts 30 to 40 minutes after hard and/or prolonged glycogen depleting exercise sessions. 

That covers Part 1. In the next post, I’ll cover protein, supplementation, and the other key points from the Female Athlete Position Stand

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