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.

Study Overview

• Status: Completed
• Conditions: Muscle Protein Synthesis; Menstrual Cycle; Resistance Exercise; OCP
• Intervention / Treatment: Other: Unilateral Resistance Exercise Leg; Other: Control Leg

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Hamilton, Ontario, Canada, L8S 4K1
      • Exercise Metabolism Research Laboratory, McMaster Univeristy

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 30 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pre-Ovulation Unilateral Resistance Exercise OR Active OCP Phase; One leg will undergo 2 sessions of unilateral resistance exercise during the follicular phase of the menstrual cycle (pre-ovulation) OR during the active phase of taking the OCP	Other: Unilateral Resistance Exercise Leg; One leg will perform unilateral resistance exercise; Other: Control Leg; One leg will serve as a non-exercise control
Experimental: Post-Ovulation Unilateral Resistance Exercise OR Inactive OCP Phase; One leg will undergo 2 sessions of unilateral resistance exercise during the luteal phase of the menstrual cycle (post-ovulation) OR during the inactive phase of taking the OCP	Other: Unilateral Resistance Exercise Leg; One leg will perform unilateral resistance exercise; Other: Control Leg; One leg will serve as a non-exercise control

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	6 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Whole-body proteolysis	The investigators will use 3-methylhistidine in urine to calculate the rate of whole-body myofibrillar protelysis	6 days

Collaborators and Investigators

• Sponsor: McMaster University
• Collaborators: Natural Science and Engineering Research Council of Canada (NSERC)

Publications and helpful links

General Publications

• Colenso-Semple LM, McKendry J, Lim C, Atherton PJ, Wilkinson DJ, Smith K, Phillips SM. Menstrual cycle phase does not influence muscle protein synthesis or whole-body myofibrillar proteolysis in response to resistance exercise. J Physiol. 2025 Mar;603(5):1109-1121. doi: 10.1113/JP287342. Epub 2024 Dec 4.

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2022
• Primary Completion (Actual): March 1, 2023
• Study Completion (Actual): April 30, 2024

Study Registration Dates

• First Submitted: April 21, 2022
• First Submitted That Met QC Criteria: April 21, 2022
• First Posted (Actual): April 26, 2022

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 31, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: 14067

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: All participants will be assigned a unique subject ID, and therefore, other researchers involved with analyses will not have access to identifying participant information.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No