Protein Requirements in Male and Female Endurance Athletes

Study Overview
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Brief Summary
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Protein is an essential macronutrient for post-exercise recovery through its ability to provide the amino acid building blocks that support increased rates of muscle and whole body protein synthesis. Despite the growing understanding of the importance of post-exercise protein in endurance athlete populations, the impact of sex and female menstrual cycle phase on protein metabolism is not fully understood. To date, no studies have examined protein requirements in female endurance trained athletes. The aim of the proposed study is to utilize the well-established IAAO method to determine protein requirements in endurance trained female and male athletes in a real-world and at-home setting.

Official Title
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Estimating Post-exercise Protein Requirements in Male and Female Endurance Athletes

Conditions
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Increased Metabolic Requirement, Healthy

Intervention / Treatment
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* Dietary Supplement: Amino Acid Intake


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy endurance trained runners. Total weekly running distance of greater than 50km/week and perform endurance exercise for more than 5 hours/week. Age 18-35 years old Eumenorrheic over last 3 months (one cycle no longer than 42 days and no shorter than 20 days). Not using hormonal contraceptives (the pill, implants and injections, hormonal intrauterine devices (IUDs), vaginal ring, skin patch). Do not have polycystic ovarian syndrome (PCOS) or other conditions effecting ovarian hormone regularity. Not pregnant within the past year. Must meet the classification of 'superior' aerobic power for their respective age category based on the ACSM criteria; (women age 20-29 years VO2max >50ml/kg/min and women age 30-35 years VO2max >46ml/kg/min) (men age 20-29 years VO2max >56ml/kg/min and men age 30-35 years VO2max >54ml/kg/min). Exclusion Criteria: Inability to meet health and physical activity guidelines according to the CSEP 'Get Active' Questionnaire (Appendix G). Inability to adhere to study protocol requirements relating to diet and exercise (i.e. alcohol and caffeine consumption, training/exercise prior to beginning a study testing day). Regular use of tobacco and/or other recreational drugs/banned substances (i.e. growth hormone, testosterone, marijuana). Self-reported intentional or unintentional weight loss (past 6 months) or plan to lose weight (>5-10kg). Amenorrhea (self-reported) in the past 3 months. Fewer than 6 menstrual cycles per year. Answering yes to any questions asked within the COVID-19 screening questionnaire until 14 days of being symptom free and/or having a negative COVID-19 test

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Eight men and eight women will be provided three different amino acid intakes on three separate occasions (metabolic trials) over 8 hours following a 20km run. All protein intakes have an amino acid composition modelled off of the profile of egg protein.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low Protein<br>0.2 g/kg/day of protein provided as crystalline amino acid made after egg protein. | Dietary Supplement: Amino Acid Intake<br>* Participants will consume hourly (8 hours) isoenergetic, isonitrogenous beverages containing one of the three protein intakes (0.2g/kg/d, 1.2 g/kg/d, 2.0g/kg/d) assigned in a randomized order between the three metabolic trials. Drinks will be enriched with stable isotope [13C]phenylalanine. The use of stable isotope [13C]phenylalanine will allow for the determination of the fate of AA in the body (incorporation into body protein or oxidation) which can be used to determine protein (AA) requirements.<br>|
| Experimental: Moderate Protein<br>1.2g/kg/day of protein provided as crystalline amino acid made after egg protein. | Dietary Supplement: Amino Acid Intake<br>* Participants will consume hourly (8 hours) isoenergetic, isonitrogenous beverages containing one of the three protein intakes (0.2g/kg/d, 1.2 g/kg/d, 2.0g/kg/d) assigned in a randomized order between the three metabolic trials. Drinks will be enriched with stable isotope [13C]phenylalanine. The use of stable isotope [13C]phenylalanine will allow for the determination of the fate of AA in the body (incorporation into body protein or oxidation) which can be used to determine protein (AA) requirements.<br>|
| Experimental: High Protein<br>2.0 g/kg/day of protein provided as crystalline amino acid made after egg protein. | Dietary Supplement: Amino Acid Intake<br>* Participants will consume hourly (8 hours) isoenergetic, isonitrogenous beverages containing one of the three protein intakes (0.2g/kg/d, 1.2 g/kg/d, 2.0g/kg/d) assigned in a randomized order between the three metabolic trials. Drinks will be enriched with stable isotope [13C]phenylalanine. The use of stable isotope [13C]phenylalanine will allow for the determination of the fate of AA in the body (incorporation into body protein or oxidation) which can be used to determine protein (AA) requirements.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Phenylalanine excretion | 13CO2 production in umol/kg/h | 8 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Phenylalanine Oxidation | [13C]phenylalanine oxidation in umol/kg/h | 8 hours | 
| Phenylalanine net balance | Difference between phenylalanine rate of appearance and disappearance | 8 hours |