Comparing 4 approaches for female sex hormones
Official title: Menstrual Cycle vs. Oral Contraceptives: Effects on Muscle Protein Metabolism After Resistance Exercise
The Effect of Menstrual Cycle Phase and Oral Contraceptive Use on Muscle Protein Metabolism Post-Resistance Training
- 4 groups
- One site, in Toronto
- Recruiting
Interventions
- Other intervention
Protein Beverage
Participants will consume 16 half-hourly (8 hours) isoenergetic, isonitrogenous beverages containing 1.2 g/kg/d protein.
- Other intervention
Stable Isotope Tracer [D5]phenylalanine
Protein beverages will be enriched with the stable isotope \[D5\]phenylalanine. The use of \[D5\]phenylalanine will allow for determination of muscle protein synthesis.
- Other intervention
Stable Isotope Tracer [13C]phenylalanine
Protein beverages will be enriched with the stable isotope tracer \[13C\]phenylalanine. The use of \[13C\]phenylalanine will allow for the determination of the fate of amino acids in the body (incorporation into body protein or oxidation) which can be used to determine protein requirements.
Canadian Sites (1)
1 of 1 recruiting
- Recruiting
Goldring Center for High Performance Sport
Toronto, Ontario
Eligibility Criteria
See who this study is looking for15 criteria
The trial’s own eligibility text, word for word from the registry. Only the trial site can say who takes part.
Inclusion
- +Age: 18-40 years
- +BMI between 18.5-29.9 kg/m2 (non-obese)
- +Have regular menstrual cycles (21-35 days) for the past 3 months and discontinued any hormonal contraceptive use for at least 6 months (non-oral contraceptive users)
- +Recreationally active (resistance train minimum twice a week)
- +Using monophasic or triphasic oral contraceptives for \>1 year (for oral contraceptive users)
- +Must meet a progesterone sufficiency test (non-oral contraceptive users)
Exclusion
- −Severe food allergies (e.g. soy, nuts)
- −Mid-luteal progesterone levels \<16umol
- −Chronic disease diagnosis (cardiovascular, thyroid, diabetes)
- −Current or recent remission of cancer
- −Regular use of non-steroidal anti-inflammatory drugs (NSAIDs; except low-dose aspirin), anticoagulants
- −Use of prescription drugs that would impact muscle protein synthesis, e.g. Statins, Lithium, ADHD medication.
- −Insertion of intrauterine device (IUD) - exception: copper
- −Use of emergency contraception in the last 3 months (e.g. Plan B)
- −Smoking, use of performance enhancing drugs (growth hormones, testosterone)
In plain language
Assembled directly from this trial’s registry record. Every sentence traces to a field below — nothing here is generated or interpreted.
What this study is
This study is investigating how something functions in the body, rather than testing a treatment directly.
This study is not organised into the usual phase numbers — that is common for device, behavioural, and diagnostic research.
From the trial registry
Built from these fields:
- designModule.designInfo.primaryPurpose
- designModule.phases
Who receives what
There are 4 groups in this study.
Groups A, B, C and D receive one or more of: Protein Beverage, Stable Isotope Tracer [D5]phenylalanine and Stable Isotope Tracer [13C]phenylalanine.
Registry label: A: Mid-Luteal Phase · B: Early Follicular Phase · C: Active Pill Phase · D: Placebo Pill Phase
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].label
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
How the study is run
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
This study is open-labelOpen-labelEveryone knows which treatment is being given — nothing is hidden.Read more →: everyone knows which treatment is being given, including you and the study team.
From the trial registry
Built from these fields:
- designModule.designInfo.allocation
- designModule.designInfo.maskingInfo.masking
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
Who the study is looking for
The study lists an age range of 18 years to 40 years.
The study lists female participants only.
The study accepts healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more → as well as people with the condition.
These are the criteria the study lists. Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part.
From the trial registry
Built from these fields:
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How big and how long
The study aims to enrol about 20 people.
The study is currently expected to finish around September 2026.
The main measurement is taken over: 8 hours.
From the trial registry
Built from these fields:
- designModule.enrollmentInfo.count
- statusModule.completionDateStruct.date
- outcomesModule.primaryOutcomes[].timeFrame
What the study measures
Muscle Protein Synthesis (MPS) — measured over 8 hours.
From the trial registry
Built from these fields:
- outcomesModule.primaryOutcomes[].measure
- outcomesModule.primaryOutcomes[].timeFrame
Source: NCT07258576 on ClinicalTrials.gov. The full registry text is further down this page — this summary never replaces it.
Not medical advice. What do these terms mean?
What is being tested — in plain terms
About Protein BeverageDietary supplement
Participants will consume 16 half-hourly (8 hours) isoenergetic, isonitrogenous beverages containing 1.2 g/kg/d protein.
From the trial registry — its own words, unedited.
What a dietary supplement is here: A vitamin, mineral, or other supplement being studied.
Read the full explanation → · in clinical review
About Stable Isotope Tracer [D5]phenylalanineDietary supplement
Protein beverages will be enriched with the stable isotope \[D5\]phenylalanine. The use of \[D5\]phenylalanine will allow for determination of muscle protein synthesis.
From the trial registry — its own words, unedited.
What a dietary supplement is here: A vitamin, mineral, or other supplement being studied.
Read the full explanation → · in clinical review
About Stable Isotope Tracer [13C]phenylalanineDietary supplement
Protein beverages will be enriched with the stable isotope tracer \[13C\]phenylalanine. The use of \[13C\]phenylalanine will allow for the determination of the fate of amino acids in the body (incorporation into body protein or oxidation) which can be used to determine protein requirements.
From the trial registry — its own words, unedited.
What a dietary supplement is here: A vitamin, mineral, or other supplement being studied.
Read the full explanation → · in clinical review
Common questions
Answered from this trial’s registry record. Where the record doesn’t say, these answers say so rather than filling the gap.
Am I eligible for this trial?
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part. Concord cannot make that determination, and neither can any tool that has not examined you.
What the study lists: an age range of 18 years to 40 years.
The full inclusionInclusion criteriaThe things you must have or be for a study to consider you.Read more → and exclusion criteriaExclusion criteriaThe things that would prevent someone from taking part.Read more → are published on this page, exactly as the study team wrote them.
The useful next step is to bring this trial to your doctor. Answering a few questions first gives them something concrete to review.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.eligibilityCriteria
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
- armsInterventionsModule.armGroups[].type
Would I know which treatment I am getting?
This study is open-labelOpen-labelEveryone knows which treatment is being given — nothing is hidden.Read more →: everyone knows which treatment is being given, including you and the study team.
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
From the trial registry
- designModule.designInfo.maskingInfo.masking
- designModule.designInfo.allocation
Who can join?
The study lists an age range of 18 years to 40 years.
It lists female participants only.
It accepts healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more → as well as people with the condition.
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can confirm whether a particular person can take part.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How long would this take?
The study's main measurement is taken over: 8 hours.
The study as a whole is currently expected to finish around 2026-09-01.
How long any one person takes part can differ from the study length. The study team can tell you what the schedule looks like in practice.
From the trial registry
- outcomesModule.primaryOutcomes[].timeFrame
- statusModule.completionDateStruct.date
How many people are taking part?
The study aims to enrol about 20 people.
From the trial registry
- designModule.enrollmentInfo.count
Where is this happening?
This study lists one location: Toronto, Ontario, Canada.
Sites can open and close during a study, so confirm with the team before travelling.
From the trial registry
- trial_locations
About This Trial
The muscles of the body are constantly breaking down old proteins and building new ones. These two processes, protein breakdown and protein synthesis, together are known as protein turnover. Protein turnover is essential for maintaining healthy muscle. Despite its importance, females have historically been underrepresented in protein metabolism research. A long-standing assumption has been that fluctuations in female sex hormones such as estrogen and progesterone, whether across the natural menstrual cycle or in individuals using oral contraceptives (OCs), make metabolism and training responses too variable to study. Because of this, many researchers have excluded female participants for logistical reasons. Resistance exercise, such as weightlifting, is the most effective way to increase muscle size and strength. Each resistance-training session triggers muscle protein synthesis (MPS), the process by which new muscle proteins are built. Consuming dietary protein or individual amino acids further increases the rate at which new proteins are formed. Over time, higher rates of protein synthesis support muscle growth and the maintenance of other lean tissues in the body. The purpose of this study is to examine how menstrual cycle phases and OC use influence the synthesis of proteins in both muscle tissue and the rest of the body. Improving scientific understanding in this area will support more effective, evidence-based training and nutrition recommendations for females.
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See if this trial could fit youThis page is for informational purposes only and does not constitute medical advice. Clinical trial eligibility can only be determined by the trial site after proper screening. Trial information is sourced from ClinicalTrials.gov and may not reflect the most current status. Always consult your healthcare provider before making decisions about clinical trial participation.