Protein Requirements in Male and Female Endurance Athletes

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

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.

Study Overview

• Status: Completed
• Conditions: Healthy; Increased Metabolic Requirement
• Intervention / Treatment: Dietary supplement: Amino Acid Intake

• Study Type: Interventional
• Enrollment (Actual): 16
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5S2C9
      • Goldring Centre for High Performance Sport

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Low Protein; 0.2 g/kg/day of protein provided as crystalline amino acid made after egg protein.	Dietary supplement: Amino Acid Intake; 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.
Experimental: Moderate Protein; 1.2g/kg/day of protein provided as crystalline amino acid made after egg protein.	Dietary supplement: Amino Acid Intake; 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.
Experimental: High Protein; 2.0 g/kg/day of protein provided as crystalline amino acid made after egg protein.	Dietary supplement: Amino Acid Intake; 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.

What is the study measuring?

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

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urinary 3-methylhistidine	Concentration of urine 3-methylhistidine	8 hours
Protein requirement	Estimated breakpoint of phenylalanine excretion, phenylalanine oxidation, and phenylalanine net balance	8 hours

Collaborators and Investigators

• Sponsor: University of Toronto
• Investigators: Principal Investigator: Daniel Moore, Ph.D, University of Toronto

Study record dates

Study Major Dates

• Study Start (Actual): March 8, 2021
• Primary Completion (Actual): October 31, 2021
• Study Completion (Actual): December 30, 2022

Study Registration Dates

• First Submitted: April 18, 2021
• First Submitted That Met QC Criteria: April 18, 2021
• First Posted (Actual): April 22, 2021

Study Record Updates

• Last Update Posted (Actual): July 13, 2023
• Last Update Submitted That Met QC Criteria: July 11, 2023
• Last Verified: July 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: IAAO-ETFM

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data described in the manuscript will be made available upon request pending application and approval.

Drug and device information, study documents

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