Strength in Science: Athlete Explores the Impact of Hormones on Performance

A swimmer with a passion for performance optimization, Elaine recently participated in research examining how natural menstrual hormone fluctuations and intrauterine system (IUS) use affect muscular strength and endurance. Her work, supervised by Dr. Derek Kimmerly and conducted alongside research partner Kayla Baker, dives into a largely underexplored area of exercise physiology: the intersection of birth control and athletic performance.

“As an athlete, I’ve always been curious about how to optimize performance.” Says Gentleman. “This project was particularly exciting because it explored a novel, under-researched area and contributed new information to the field.”

The study compared two groups: naturally menstruating individuals and those using an IUS, a hormonal contraceptive that releases progestin locally in the uterus. Participants underwent strength and endurance testing—specifically, a handgrip maximal voluntary contraction and a time-to-fatigue test at 30% of that maximum. The naturally menstruating group was tested during both the early follicular (low-hormone) and mid-luteal (high-hormone) phases, while the IUS group was tested once due to irregular cycles.

While the sample size was small, the findings suggest that IUS use may not negatively impact performance—an encouraging insight for athletes considering contraceptive options.

“Previous research has shown oral contraceptives may reduce muscular strength.” Explains Gentleman. “But our findings suggest IUS use might be less detrimental, possibly because its hormonal effects are more localized.”

The research is ongoing and not yet published, its impact is already being felt. For Gentleman and her teammates, the study has opened important conversations about birth control, performance, and informed decision-making.

“It’s about empowering athletes to understand how their choices might affect their performance,” she says. “There’s no one-size-fits-all answer—everyone should make decisions that align with their goals and well-being.”

Though her involvement in the project has concluded, she hopes the research will inspire further studies in women’s health and exercise science. With IUS users still underrepresented in the literature, she sees this work as a stepping stone toward more inclusive and evidence-based training recommendations.

“My favorite part was being hands-on from start to finish,” she reflects. “Collaborating with Kayla and researching a topic I’m genuinely passionate about made the whole experience incredibly rewarding.”

Whether she’s chasing personal bests in swimming or contributing to scientific discovery, Gentleman is proving that strength comes in many forms—and that curiosity and commitment can be just as powerful as physical endurance.