A groundbreaking Fifa-funded study at Kingston University will investigate whether hormonal fluctuations during menstrual cycles could be contributing to an alarming rise in career-threatening knee injuries in women's soccer.
The research comes after players including Arsenal's Beth Mead, Manchester City's Vivianne Miedema and Chelsea's Sam Kerr have all suffered serious injuries to the anterior cruciate ligament (ACL), which runs diagonally in the middle of the knee.
Kerr, who is Australian, has been out for 15 months with a ruptured ACL.
Led by PhD student Blake Rivers alongside a team of sports science experts, the year-long study at Kingston near London will analyse blood samples from elite and grassroots footballers to track hormone concentrations through their menstrual cycles.
"We want to examine whether athletes may be more predisposed to injuries because of the functional changes in terms of their anatomy and physiology during the menstrual cycle," Simon Augustus, Senior Lecturer in Sport Biomechanics, said.
"We know hormones fluctuate during different phases of the cycle but we don't yet know how much of an influence that may have on the risk of injury."
MONITORING HORMONE LEVELS
The research team will specifically monitor oestrogen and progesterone levels -- hormones previously linked to increased ligament laxity and decreased neuromuscular reaction times -- while cross-referencing against physical performance data.
Beginning in June, the study will recruit footballers from London clubs, including Chelsea and Fulham for regular campus visits for blood and physical performance testing.
Researchers will also analyse common ACL injury scenarios, including landing mechanics after heading the ball and rapid directional changes, to identify potential correlations with hormonal states.
"We know some injuries are unavoidable, but we're attempting to help those individuals who injure their ACL outside of impact actions -- those are the ones where we might have more chance to intervene and prevent them from taking place by utilising strength training or tweaking technique," Augustus said.
"There are so many different factors involved with ACL injuries. We are starting to research this from an individual approach and look at an athlete's whole profile and putting protocols in place to reduce risk."
The findings could allow coaches to modify training loads or individual programmes based on menstrual cycle phases.