What Runners Should Know About Oral Contraceptives
Though the science on oral contraceptives and running is slim, there are some issues runners should consider
There has always been a lot of conversation about contraceptives and performance. But there's been little conversation about contraceptives and running performance.
Many runners take an oral contraceptive pill (OCP) every day or have an intrauterine device (IUD) releasing hormones, but fail to ask questions about how these measures may impact running performance. However, it’s not the runners’ fault. The research simply isn’t there yet, and a Google search or doctor’s response can provide only speculation.
There is a reason the research isn’t there yet—everyone’s physiology and hormonal profiles are unique. To complicate matters, everyone’s response to training is unique as well. Plus, our contraceptives are continuously evolving, keeping researchers busy with investigating the basics (such as performance of the non-running variety).
Still, it's worth considering what we do know about OCPs and running. Here's a look at the pros and cons of OCPs from a runner's perspective, as well as a few myths and unresolved controversies.
Reduction of Symptoms: Some runners are plagued by heavy menstrual flow and abdominal cramping. These symptoms can impact running performance (and certainly running enjoyment). OCPs thin the lining of the uterus and lessen these symptoms.
Control Your Periods: Most runners would agree that they would like to schedule their menstrual flow so that it does not happen on the same day as their goal race. Women can opt to skip scheduled bleeding for a cycle on OCPs by discarding the placebo pills and taking back-to-back sets of hormonally active pills. Now wouldn’t it be awesome if we could also control when our race legs showed up?
The Contraceptive Aspect: From singles running meet-ups to Valentine’s Day couples races, there are endless opportunities for runner romance. OCPs have a perfect-use failure rate of 0.1 percent and a typical-use failure rate of 9 percent. Failure is defined as pregnancy (sorry kiddos); the typical-use failure rate is higher due to missed pills.
Concealing Diagnosis of Female Athlete Triad: The female athlete triad, unfortunately a common condition among endurance runners, involves three interrelated issues: menstrual dysfunction, low energy availability (with or without an eating disorder) and decreased bone-mineral density.
Because OCPs cause withdrawal bleeding, a female who would otherwise have amenorrhea (missed periods) due to an energy deficiency may still have menstrual flow from OCP use. Doctors often diagnose the female athlete triad after athletes come to them with amenorrhea; therefore, OCP use could inhibit proper diagnosis and prevent underlying problems from being addressed.
“Breakthrough” or Unexpected Bleeding: Although female trail runners generally refrain from wearing bloomers—the glorified bikini bottoms common in track and road racing—breakthrough bleeding can still be a mid-run disaster. It usually happens in the two to three months after starting an OCP and is the primary reason why women choose to discontinue use. It is more common in women taking extended-cycle and low-estrogen OCPs.
Pesky Progestogen Side Effects: There are currently four different "generations" of progestogens in OCPs. Like your great aunt twice removed at Thanksgiving dinner, some generations can have some pesky side effects. The second-generation progestogens can cause hirsutism, or male-pattern hair growth, and lower HDL (the good cholesterol). In addition, though the research is still controversial, some studies link the third-generation progestogens with an increased risk of blood clots. If you have a reason to be concerned about any of these side effects, check your formulation and talk with your doctor.
Myths and Controversies Surrounding OCPs
Weight Gain (Myth): I would love to be given a pint of ice cream for every time I’ve heard a runner say, “But OCPs make you fat!” Thirty years ago, studies showed that OCPs caused weight gain. However, the more modern OCPs have lower doses of estrogen and studies have shown that they are not associated with statistically significant weight gain.
Changes in Bone Density (Controversy): Google “OCPs and bone density” at your own risk. The scientific studies examining the effect of OCPs on bone-density changes and stress-fracture rates are divided, with some studies showing an increase in bone density, others showing a decrease and some showing no change. The experts unequivocally acknowledge the controversy and urge athletes trying to increase bone density to focus on proven bone-strengthening methods such as calcium and vitamin D supplementation and maintaining a healthy weight.
Effect on VO2 Max (Controversy): In the last 10 years, there has not been a single scientific study that has shown that OCP use decreases VO2 max. A post on a cross-country skiing blog from 2011 provides some anecdotal evidence about OCP use and a perceived decrease in VO2 max, but also acknowledges confounding variables. I personally went off Seasonale (an extended-cycle OCP) due to breakthrough bleeding six months ago and have not noticed an increase in my VO2 max. (However, I also doubled my ice-cream consumption and had to start running at 3 a.m. due to medical-school rotations, to name only a few of my confounding variables.)
Everyone’s physiology is unique. Just as we all respond differently to alcohol, caffeine and even hill repeats, we have different responses to OCPs. Ultimately, you just have to do your own research study. If you are concerned about OCPs' effect on your running performance, you can consider switching contraceptive methods and evaluating how you feel.
Megan Roche is a fourth-year Stanford Medical student, a four-time USATF trail national champion and a member of Nike Trail Elite and Team Clif Bar. Follow Megan’s training on Strava here and follow her on Twitter here.