For 40 hours, across 160 kilometres, University of Tasmania researcher Kate Edwards ran up and down steep alps. She hallucinated. She vomited. She had her period.
This is not a unique case for female ultra-endurance athletes, however the impact of menstruation on athletic performance is largely unknown.
Ms Edwards, who has been an ultramarathon runner for 9 years, said, “the right training and nutrition are critical for endurance and ultra-endurance athletes. But for female athletes, current best practice is overwhelmingly based on data from their male peers.”
“Current training models are, ironically, periodised, but make no allowance for the female menstrual cycle. Did it matter that I had my period? That is the question I am trying to answer during my PhD.”
Ms Edwards wowed judges when she presented the ‘so what?’ behind her research at the Tasmanian 3-Minute-Thesis (3MT) competition last month. She came away from the semi-finals with first place.
“In a world where the default athlete is a male, we need data on females… Because for female athletes, ‘blood and guts’ aren’t just a cliché,” she said.
When we exercise – male or female – the supply of blood and oxygen to the gut is reduced because it is redirected to the working muscles. A particularly susceptible organ is the intestine. The intestinal wall is just one cell thick, and once damaged, it can become leaky, causing inflammation in the body. For ultra-endurance athletes like Kate Edwards, that becomes an issue.
“The damage to my gut resulted in vomiting and diarrhoea. It reduced my ability to absorb nutrients during the race and impaired my recovery,” Ms Edwards explained.
There are two reasons why female athletes might respond differently to this damage, compared with males.
One reason is the hormone oestrogen which helps protect and strengthen our gut barrier. However, during the menstrual cycle, oestrogen concentrations fluctuate.
The second reason is the gut microbiome: the genetic material of the community of micro-organisms that live in our intestines. These may influence immunity, nutrient uptake and hormone production, among other functions.
Ms Edwards said the higher estrogen levels in women means they may tolerate gut damage more effectively than men.
“The issue is that current training methods don’t take women’s monthly oestrogen fluctuations into account, nor their microbiome, which can also influence their oestrogen levels.”
Ms Edwards’ research will be the first to characterise gut damage from exercise during the entire menstrual cycle.