Women may be quicker and make fewer errors during menstruation, according to new research.

The study, published in Neuropsychologia, is the first to assess sport-related cognition during the menstrual cycle. The findings suggest that specific types of cognition fluctuate, which could have implications for injury and other aspects of women’s health.

Previous sports medicine research has shown that women seem to be at greater risk of sport-related injury during the luteal phase, the time between ovulation and menstruation. This increased risk is possibly related to hormonal changes. However, precisely how these changes are linked to an increased likelihood of injury remains unknown.

In the study, researchers collected reaction time and error data from 241 participants who completed a battery of cognitive tests 14 days apart. Participants also completed a mood scale and a symptom questionnaire twice. Period-tracking apps were used to estimate which phase of the cycle the participants were in.

The tests were designed to mimic mental processes typical in team sports. In one test, participants were shown smiling or winking faces and asked to press the space bar only when they saw a smiling face, to test inhibition, attention, reaction time, and accuracy. In another test, they were asked to identify mirror images in a 3D rotation task, which assessed spatial cognition. A task that asked them to click when two moving balls collided on the screen measured spatial timing.

Though participants reported feeling worse during menstruation and perceived this as negatively impacting their performance, their reaction times were faster, and they made fewer errors. For example, timing was, on average, 10 milliseconds (12%) more accurate in the moving balls task, and they pressed the space bar at the wrong time 25% less in the inhibition task. Participants’ reaction times were significantly faster (p < .01), they made fewer errors (p < .05), and exhibited lower intra-individual variability (p < .05) during menstruation compared to other phases.

Reaction times were slower during the luteal phase. They were, on average, 10-20 milliseconds slower (p < .01) compared to any other phase. However, they didn’t make more errors in this phase.

“Given that progesterone has an inhibitory effect on the cerebral cortex and estrogen stimulates it, making us react slower or faster, we wondered if injuries could be a result of a change in athletes’ timing of movements throughout the cycle,” noted Flaminia Ronca, PhD, the study's first author.

The authors said the fluctuation in timing could be the difference between an injury or not. Previous research has shown that a variation of just 10 milliseconds can mean the difference between a concussion and a lesser injury, for example. In the colliding balls task, participants’ timing was, on average, 12 milliseconds slower during the luteal phase compared to every other phase, a difference of 16%.

“Though there’s a lot more research needed in this area, these findings are an important first step towards understanding how women’s cognition affects their athletic performance at different points during their cycle, which will hopefully facilitate positive conversations between coaches and athletes around performance and well-being," said study investigator Dr. Megan Lowery in an accompanying editorial.

Full disclosures can be found in the study.