Dr. Stacy Sims on What Sparked Her Mission

Emma-Kate Lidbury

July 1, 2025

When you look at the groundbreaking work Dr. Stacy Sims is doing today in the field of female health and performance, it’s easy to be struck by her academic credentials, the books she’s authored, and her global reputation as a fierce advocate for female athletes. But if you want to understand why she does what she does, you have to go back to the beginning—back to a curious little girl with a chemistry set and a deep need to understand why.

How It Started

Dr. Sims grew up as a self-proclaimed “introverted extrovert” with a relentless curiosity and a strong sense of fairness. These two inner drives—seeking answers and standing up for equity—would become the foundation of her career. “Science is about trying to understand why things happen,” she says, and that has always been her compass.

Her path into women’s physiology wasn’t a straight shot. As a teenager in a military family, she once told her father she wanted to become an Army Ranger or Navy SEAL. He shut that down with a simple, "You can't—because you're a girl." That moment hit hard. Stacy realized that the world operated on invisible rules that excluded women not because of capability, but because of systemic assumptions.

Initially planning to study political science and French to work in international policy, Stacy found those classes uninspiring. She pivoted toward exercise physiology—first out of interest, and then out of necessity, as she started noticing something unsettling: the total lack of female representation in sports science research. Her textbooks, journal articles, and case studies all focused on male subjects. She was learning about athletic performance in a world where “the athlete” was always a man.

While training as a collegiate rower at Purdue, Stacy observed even more stark differences between the men’s and women’s teams. Despite identical training regimens, her male teammates peaked at the right moments while the women often felt flat or misaligned with performance goals. Something wasn’t adding up.

The Moment It All Changed

The tipping point came during a lab test on carbohydrate intake and endurance running. Stacy followed every instruction meticulously—thanks to her military upbringing—but her results didn’t match the expected male patterns. The postdoc told her, "We’re throwing your data out. It’s skewing the results." When she pressed further, she was told the truth: women weren’t typically studied because their menstrual cycles made data “messy.”

That was the moment everything changed.

Realizing that female athletes were being sidelined in scientific research—not because they were less capable, but because their physiology was inconvenient—lit a fire in Stacy that has never gone out. She began focusing her academic and athletic life around her now-trademarked phrase and the title of her popular TedX Talk: Women Are Not Small Men.

Women Are Not Small Men

Her master’s research focused on overtraining in female endurance runners across the menstrual cycle, and the findings were clear: women respond differently to training depending on hormonal fluctuations. Yet the standard protocols used by coaches and trainers didn’t account for this. Instead, women were given male-based training programs and blamed when they broke down—through stress fractures, chronic fatigue, or missed menstrual cycles.

As a former elite athlete herself, Stacy knows firsthand how damaging this can be. “If I had known then what I know now,” she says, “I would have trained differently—lifted more, prioritized recovery, fueled better, and protected my body rather than trying to shrink it.”

That lived experience shaped her work not only in the lab, but in the field. She began bridging the gap between science and real-world coaching, helping female athletes and their teams across a wide range of sports understand that hormonal fluctuations aren't barriers to performance—they’re data points to optimize around.

Despite her evidence-based approach, Stacy has faced ongoing resistance. “Why do you want to study women?” she was once asked. “We don’t even know enough about men.” But her response is clear: If we had built the scientific world with women in the room from the start, female physiology would be the standard—not the exception.

More Determined Than Ever

She’s not deterred. In fact, she’s more determined than ever. Because what’s at stake isn’t just athletic performance—it’s health, confidence, and the longevity of women.

Dr. Sims now champions a systemic shift: more funding for female-focused research, better recruitment and language strategies for studies, and a reframing of what success really looks like for women. It’s not about being more like men. It’s about embracing the strength, power, and complexity of the female body—and training it accordingly.

This mission, born from curiosity, frustration, and a fierce sense of justice, is what fuels her every day. And it’s changing the face of women’s health and performance—one study, one team, one woman at a time.