The purpose of this study is to compare between sprinters and long marathon in menstrual characteristics and serum estradiol level.

Menstrual function and dysfunction conversations have long been stigmatized both in the general population and in sport settings (O'Flynn, 2006). However, Discussions of menstruation in the sport context often focuses on the impact of physical menstrual symptoms and dysfunction on activities such as training and sport performance (Bruinvels et al., 2016; Knowles et al., 2019). In addition, no study had been compare between sprinters and long-marathon runners in menstrual characteristics and estradiol level. Therefore, the purpose of this study to compare between sprinters and long marathon in menstrual characteristics and serum estradiol level.

Inclusion Criteria:

• Virginal females.
• Their age ranged from 16 to 19years.
• All females had the same socio-economic status.

For athletic groups only:

• They have been starting the practice of sport at least one year before the onset of menarche.

Exclusion Criteria:

• Females who had been used oral contraceptives or any hormonal treatment in the previous six months.
• Smoking.
• History of chronic disease.
• Having any psychiatric problems.

For athletic groups only:

• injured females who were absent from training for at least three months.

Participant eligibility is based on self-representation of gender identity.

Egyptian sprinters, long marathon runners, and non-athletic females