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

McMaster University24 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Enrollment

Conditions

Menstrual Cycle Resistance Exercise Muscle Protein Synthesis OCP

Eligibility

Sex: FEMALEMin age: 18 YearsMax age: 30 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Change in Rates of Muscle Protein Synthesis

The investigators will use deuterated water and skeletal muscle biopsies to calculate the synthesis of skeletal muscle proteins.

Time frame: 6 days

Secondary Outcomes

Whole-body proteolysis

The investigators will use 3-methylhistidine in urine to calculate the rate of whole-body myofibrillar protelysis