A handful of women's soccer stars will miss the upcoming Fifa World Cup in New Zealand and Australia. Each is sidelined with anterior cruciate ligament injuries. Just why is this type of injury so prevalent in women's soccer?

Leah Williamson. Vivianne Miedema. Marie-Antoinette Katoto. Beth Mead. These people have much in common.

Some of these similarities include them all being highly-rated women's soccer stars. They will also all not participate in the upcoming Fifa Women's World Cup, owing to suffering serious anterior cruciate ligament (ACL) injuries in the lead-up to the tournament.

This pattern of women's soccer players either rupturing or tearing their ACL, which is located in the knee area, has long been a mystery. A few theories exist as to why the injury is more prevalent in female athletes. Particularly those who play contact sports such as soccer and rugby.

These suppositions range from the lack of transformation in relation to the design of equipment such as playing boots and the fits and cuts of kits, to the physiological changes that women experience during the menstrual cycle, among other things.

When it comes to the theory of ACL injuries being linked to the menstrual cycle, research is still ongoing and is yet to bear any conclusive evidence indicating that this is truly the case.

Hypothesis

The hypothesis is that when the levels of hormones such as oestrogen rise during the menstrual cycle, it can impact the...