Menstrual Cycle vs. Oral Contraceptives: Effects on Muscle Protein Metabolism After Resistance Exercise
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Protein Beverage, Stable Isotope Tracer [D5]phenylalanine, Stable Isotope Tracer [13C]phenylalanine.
- Who it may be relevant to
- Registry conditions: Female Sex Hormones, Menstrual Cycle, Oral Contraceptives, Protein Metabolism. Basic parameters: 18 years — 40 years · Female.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Canada
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
The Effect of Menstrual Cycle Phase and Oral Contraceptive Use on Muscle Protein Metabolism Post-Resistance Training
Overview
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.
Interventions
- Dietary supplement Protein Beverage
Participants will consume 16 half-hourly (8 hours) isoenergetic, isonitrogenous beverages containing 1.2 g/kg/d protein. - Dietary supplement 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. - Dietary supplement 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.
Primary outcome measures
- Muscle Protein Synthesis (MPS) [Time frame: 8 hours]
Secondary outcome measures (1)
- Whole Body Protein Synthesis (WBPS) [Time frame: 4 hours]
Eligibility criteria
Inclusion criteria
- Age: 18-40 years
- BMI between 18.5-29.9 kg/m2 (non-obese)
- Recreationally active (resistance train minimum twice a week)
- Using monophasic or triphasic oral contraceptives for >1 year (for oral contraceptive users)
- 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)
- Must meet a progesterone sufficiency test (non-oral contraceptive users)
Exclusion criteria
- 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)
- Severe food allergies (e.g. soy, nuts)
- Smoking, use of performance enhancing drugs (growth hormones, testosterone)
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Open label
- Primary purpose
- Basic science
Study locations
Canada · 1 center
- Goldring Center for High Performance Sport — Toronto
Identifiers
NCT: NCT07258576 · MCOC - REB00048059