The goal of this prospective interventional study is to measure the strength of the external and internal rotator muscles of both shoulders (dominant and non-dominant) of Montpellier Hérault Rugby players at different stages of their menstrual cycle. During the menstrual phase (beginning of the follicular phase from D0 to D5) and during the ovulatory/early luteal phase (approximately D13 to D18 of the menstrual cycle). The study is conducted on volunteers.

The main question it aims to answer is : Is there an effect of the menstrual cycle on the maximum strength of the internal and external rotators of the shoulder in female athletes who play rugby?

Inclusion Criteria :

• Montpellier Hérault Rugby player
• Regular menstrual cycle
• Adult who has received informed consent information about the study and signed the non-objection form

Exclusion Criteria :

• Use or intake of contraception
• Presence of a condition associated with the menstrual cycle
• Recent injury or pain in the upper limbs lasting more than two weeks, incompatible with performing a test of maximum voluntary contraction of the shoulder rotators
• Presence of an infectious disease (fever) that could skew temperature readings during menstrual cycle monitoring.