Menstrual Cycle Phase and Oral Contraceptive Pill (OCP) Use on Muscle Protein Synthesis

Influence of Menstrual Cycle Phase and Oral Contraceptive Pill (OCP) Use on the Muscle Protein Synthetic Response to Exercise in Young, Healthy Women

Skeletal muscle size and function is regulated by various factors, including hormones. While we understand the role of male sex hormones (testosterone), we aren't sure how female sex hormones (estrogen and progesterone) influence muscle mass and strength. Female physiology is unique in that hormones fluctuate throughout the menstrual cycle. In the first phase (follicular phase) following menstruation, estrogen levels are high while progesterone levels are low. In the second phase (luteal phase), progesterone levels are high. Females are often excluded from studies because researchers are concerned that the menstrual cycle might affect the results. The purpose of this study is to investigate the response to resistance exercise in each phase of the menstrual cycle.

Inclusion Criteria:

• Healthy females, between the ages of 18 and 30 y with a regular menstrual cycle
• Body Mass Index between 18.5 and 30.0 kg/m2
• Able and willing to provide informed consent

Exclusion Criteria:

• A history of neuromuscular disorders or muscle/bone wasting diseases
• Any acute or chronic illness, cardiac, pulmonary, liver, or kidney abnormalities, uncontrolled hypertension, insulin-dependent or insulin-independent diabetes, or the presence of any other metabolic disease - all of which will be determined via a medical history screening questionnaire
• The use of any medications known to affect protein metabolism (glucocorticoids, non-steroidal anti-inflammatory medication, or prescription strength acne medication, etc.)
• A (family) history of thrombosis
• The use of anticoagulant medications
• Consumption of tobacco-containing products
• Excessive alcohol consumption (>21 units/wk)
• History of bleeding diathesis, platelet or coagulation disorders
• Currently pregnant
• Irregular menstrual cycle as defined in the study protocol