How birth control affects running performance

Some days, runners feel like they’re floating through a workout, while other days they can feel like their legs are actively working against them. For some women, their menstrual cycles can play a role in how their workouts feel, but despite this, it remains an under-researched topic. Sports research has long been done on male subjects and applied to women, which is one of the reasons why the menstrual cycle, birth control and their effects on performance are poorly understood. On Monday, Sports Medicine published two meta-analyses on these topics, which featured some insightful findings for female athletes. 

RELATED: Why sports medicine research needs more women

Performance lowered slightly in early follicular phase

The first of the two studies looks at how a woman’s period affects her performance. Researchers found performance could be slightly lowered during the early follicular phase, which begins during menstruation and ends with ovulation. Early in the phase would likely be when a runner’s period is at its worst. The study found that this period slightly reduced exercise performance, but due to the quality of evidence that researchers were working with, they’re not sold that this is the case for everyone.

Birth control could have a small effect on performance as well

In the second of two papers, researchers also found a slight discrepancy in the performance of women who take oral contraceptives when compared to those who take nothing. However, the differences were so small that they couldn’t really make a case against birth control. If runners are looking to get everything they can from their bodies (for example, to make an Olympic or world championship team), getting off birth control could be a discussion worth having with their doctor. However, for most of us, it seems to be a non-issue. 

The study also assessed the differences between women who did strength training versus those who trained for endurance. They found no difference in the effects of birth control between the groups. 

What should women do?

Researchers feel that women’s needs should be assessed on a case-by-case basis. Earlier this year, world champion Dina Asher-Smith spoke out about the issue on Twitter. If women are experiencing pain or discomfort while training, it’ll most likely come during the first few days of their period. They should monitor these symptoms and even consider keeping a log to identify patterns and assess what helps versus what hinders their performance and pain management. 

How Asher-Smith trains through her period

1. Let your coach (and physiotherapist, chiropractor or strength coach) know that you’re on your period.
2. Asher-Smith’s back tends to get sore, so she ensures that her physiotherapist doesn’t do intense work if she’s already in pain.
3. Communication is key. Usually coaches and trainers will know what to do to help, but they can only help if they know what’s going on.
4. Don’t lift heavy if you’re already sore (Asher-Smith adjusts her strength program during her period).
5. Listen to your own body and adjust training accordingly.
6. Remember that it’s not a big deal, half the world deals with the same thing every month.

RELATED: The birth control pill: what runners need to know