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Women Are Not Small Men—and Here’s the Research to Prove It

In this research digest Dr. Stacy Sims highlights some of the most pertinent female-specific research that every coach needs to know.

Female cyclist riding up a mountain

“Women are not small men” is a phrase coined by Dr. Stacy Sims to highlight the significant differences that exist between the sexes when it comes to endurance sports training and physiology. There has been a remarkable increase in the number of female-specific studies published in the last five to eight years. Dr. Sims has campaigned for more female-specific information, underscoring how detrimental it can be for women and girls to follow protocols and programs that have only been tested and established for men.  

Dr. Sims profiles the most salient research of recent years that is particularly pertinent to topics such as Low Energy Availability (LEA), overtraining, Relative Energy Deficiency in Sport (RED-S), and the loss of muscle mass and strength brought on by aging. Much of this research forms the basis for this video interview, Separating Fact from Fiction for Female Athletes

Research on female-specific nutrition and fueling 

1. Direct and indirect impact of low energy availability on sports performance  

In this article published in the Scandinavian Journal of Medicine and Science in Sports (Mar. 2023), researchers looked at the short, medium, and long-term impact of LEA on sports performance in both lab settings and real-world case studies.  

2. Sex differences and considerations for female specific nutritional strategies: A narrative review 

This review provides a practical overview of key physiological and nutritional considerations for the active female athlete to improve performance, body composition, and overall health. (Journal of the International Society of Sports Nutrition, 2021)  

3. More than a gut feeling: What is the role of the gastrointestinal tract in female athlete health?  

This study, from the European Journal of Sport Science (May 2021), looks at the under-researched differences in female gut function during exercise. It also discusses the differences in GI-related issues experienced by male and female athletes and contributing factors.  

4. Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared pathways, symptoms and complexities  

In this paper, published in Sports Medicine (Jun. 2021), Dr. Trent Stellingwerff et al. look at the many overlaps between overtraining and RED-S in a bid to increase awareness around RED-S and help ensure more accurate diagnoses.  

Research considering the effect of the menstrual cycle on performance 

5. Patterns of endogenous and exogenous ovarian hormone modulation on recovery metrics across the menstrual cycle 

Dr. Sims teams up with researchers at Whoop, Inc. to explore the effects of female hormones (including various types of birth control) on data such as HRV, resting heart rate, sleep duration, and respiratory rate, which is all-important to interpreting data from wearables. (BMJ Open Sport and Exercise Medicine, Jul. 2021) 

6. Menstrual cycle: The importance of both the phases and the transitions between phases on training and performance  

Female sex hormones can change by more than 100% in 24 hours, and it is these day-to-day changes that this paper discusses in depth, as well as best ways of managing symptoms to help female athletes get the most from training and performance. (Sports Medicine, Jul. 2022) 

7. Analysis of the variability in the timing of physiological events in the menstrual cycle 

Similar to the paper above, this research looked at the notable variations in the timing and peak levels of hormones during different phases of the menstrual cycle. (ResearchGate, Mar. 2023) 

8. Aging of the musculoskeletal system: How the loss of estrogen impacts muscle strength  

Both men and women lose muscle mass as they age, and this is worsened in women by the drop in estrogen associated with menopause. This study, published in Bone (Jun. 2019), specifically looks at the loss of strength when estrogen is low.  

9. Immunology of normal and abnormal menstruation 

This paper published in Women’s Health (Jul. 2013) discusses the under-researched topic of the impact of the menstrual cycle on inflammation. Authors Marina Berbic and Ian Fraser identify a need for more information to allow for better management of menstrual and endometrial disorders.  

10. Effects of follicular and luteal phase-based menstrual cycle resistance training on muscle strength and mass  

Current knowledge on the impact of menstrual cycle phase-based resistance training is overviewed in this article in Sports Medicine (Apr. 2022). Researchers highlight why resistance training during the follicular phase is possibly superior to this type of training in the luteal phase.  


You have reached the end of The Craft of Coaching Module 12 // Coaching Female Athletes. Up next is Module 13 // Coaching Elite Athletes.