Menstrual cycle tracking can help individuals’ physiologic health in a variety of ways. One realm of health less commonly thought of when focusing on period tracking is traumatic brain injury. Natalie Hardaker, PhD candidate at the Auckland University of Technology, is focusing her dissertation work on the impact that female sex hormones have on sports-related concussions. By using the daily questionnaires and tracking capabilities of Wild.AI, Natalie aims to understand if and how the menstrual cycle affects concussion symptoms and recovery of female athletes. In addition, Hardacker will look at the opposite relationship: the impact that concussions have on the menstrual cycle. Using both pre- and post-concussion cycle data, Natalie hopes that she will be able to shed light on the relationship between the two.
Mild traumatic brain injuries (mTBI), more commonly known as concussions, represent upwards of 95% of traumatic brain injuries (TBI) worldwide (1). Current evidence suggests that female athletes may take up to 7-days longer to recover from such traumatic injuries (2). However, as Hardaker notes, often these findings follow the use of recovery protocols that were developed based on data from male athletes, not considering the hormonal or physiologic differences of the female athlete.
Central to Hardaker’s dissertation work is the overlap of concussion symptoms with hormone-related symptoms associated with the menstrual cycle. Using daily cycle tracking through the Wild.AI app, daily saliva samples to measure levels of sex hormones, and analysis of salivary mRNAs*, Natalie hopes to shed light on how hormone levels may impact mTBI symptoms. In conjunction with the shortcomings discussed above, Hardaker hopes that the outcomes of her dissertation work will help uncover how the menstrual cycle might influence mTBI recovery. Ultimately, she hopes that her work will inform the development of recovery protocols specifically for female athletes.
In addition to helping clinicians and athletes understand how menstrual cycle patterns can impact recovery, Natalie hopes to emphasize the prevalence of mTBI in female athletes, despite misconceptions that concussions occur in predominantly males. “People expect to see concussion in male collision sports, but no one is looking for it in female sports, so I think we’re actually still missing a lot of concussions in female athletes,” Natalie says. However, in sports where both males and females participate (such as soccer, rugby, etc.) women sustain equal or more concussions than men do (Resch et al., 2017).
Figure taken from Resch et al. 2017. A review of 26 different studies from 1997 to 2015 found that when collision sports with male and female equivalents are taken into consideration, females often have an equivalent, if not higher incidence of mTBI than males.
The connection between the menstrual cycle and concussion is an important stride in closing the gender health gap. Natalie Hardaker’s work aims to bring a better understanding of how female sex hormones may impact recovery for any female, athlete, or not, struggling with an mTBI.
*mRNAs (aka messenger RNA) are a type of RNA used for protein production. mRNAs assist in the transcription process, which helps encode proteins.
 Lefevre-Dognin, C., et al. “Definition and Epidemiology of Mild Traumatic Brain Injury.” Neurochirurgie, vol. 67, no. 3, 2021, pp. 218–21, https://doi.org/10.1016/j.neuchi.2020.02.002.
 Resch, Jacob E., et al. “Sport Concussion and the Female Athlete.” Clinics in Sports Medicine, vol. 36, no. 4, 2017, pp. 717–39, https://doi.org/10.1016/j.csm.2017.05.002.
 Thumbnail photo of Hardaker taken from “Five Ways to Help Your Kids Find Sporting Balance.” ACC, https://www.acc.co.nz/newsroom/stories/five-ways-to-help-your-kids-find-sporting-balance/. Accessed 28 July 2022.