There is still no one who has studied how oral contraceptive use affects recovery in trained women after repeated high-intensity workouts. Consequently, a well-controlled study is needed.

The project is designed as a controlled cohort study, where 20 oral contraceptive users will be compared with 20 non-users. After initial preliminary examination and habituation to the test procedures, the subjects will start the intervention in week 2 of their menstrual cycle / active contraceptive pill cycle. Before and 3h, 24h and 48h after 3 intense strength training sessions performed 2 days in a row, blood samples will be taken, muscle soreness measured and performance tests performed. The day before the first training session and over the 4 trial days, the subjects will receive a standardized diet.

Inclusion Criteria:

• BMI 18.5-30
• Regular training minimum. 4 times a week (1≤ times strength training, 1≤ times endurance training / interval training or interval-based sports. If the interest in participation is greater than necessary, we will prioritize people who perform strength training at least twice a week)

Exclusion Criteria:

• Irregular menstruation over the last 6 months (shorter than 24 days or longer than 35 days cycle)
• Used birth control pills for less than 6 months
• Non-birth control pill users must not have used birth control pills, IUDs, birth control pills, or mini- pills for a maximum of 1 month during the last 6 months and not within the last 3 months up to the trial. .
• Injuries / pain in the lower body, which prevents participation in intense strength training
• Medication consumption that may affect protein metabolism and inflammatory parameters.
• Diabetes
• Smoking
• Unstable weight / major weight loss (weight fluctuations of more than 5 kg in the last six months)
• Eating disorder
• Pregnancy
• Cannot read or understand Danish