Influence of Habitual Protein Intake on AA Tracer Oxidation

Study Overview
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Brief Summary
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Protein is an essential nutrient that one's diet to maintain important bodily functions and to recover from exercise. Currently, the Indicator Amino Acid Oxidation method (IAAO) has been used to determine protein requirements in a variety of populations including children, neonates, the elderly and recently, resistance trained populations. This study serves to test the robustness of the IAAO method and to determine if high habitual dietary protein intake, as seen in resistance trained males, has the potential to influence the protein requirements determined by the IAAO method. Further, the current study also aims to determine how the body metabolizes or uses dietary protein and how it might change when consuming a protein intake that is less than what is habitually consumed.

Detailed Description
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This study employed a two-phase randomized crossover design, where participants performed both a High/Habitual protein phase and a moderate protein phase. The Habitual protein phase is designed to model resistance trained individual's habitual protein consumption by providing 2.2g/kg/d in a controlled diet. The Moderate protein phase is designed to investigate the impact of decreasing dietary protein intake to a moderate amount (1.2g/kg/d) over five days on protein metabolism. Both phases used the stable isotope L-[1-13C]Phenylalanine and metabolic trails were modelled after the indicator amino acid oxidation (IAAO) technique. High Protein Phase The high protein phase is three days in length, with diet-controlled throughout, and a metabolic trail on day 3. Participants will perform whole-body resistance exercise on days one and three. Moderate protein phase The Moderate protein phase is seven days in length, with MT on days three, five and seven. Dietary intake will be controlled throughout the whole phase providing either 2.2 g/kg/d of protein (days one and two), or 1.2 g/kg/d (days three through seven). Full body resistance exercise will be performed performed on days one, three, five and seven. This phase will allow measurement of protein metabolism over five days following a decrease in dietary protein intake, and to determine the effect of dietary changes on the IAAO method.

Official Title
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Impact of Habitual Protein Intake on Estimates of Dietary Protein Requirements in Resistance Trained Athletes

Conditions
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Protein/Amino Acid Metabolism, Indicator Amino Acid Oxidation Method

Intervention / Treatment
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* Other: Dietary protein intake reduction
* Other: Three day Controlled Diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy, weight-trained individuals that have trained consistently for > 1 year Habitually dietary protein consumption of 1.9 to 3.0g/kg/d Train each muscle group (i.e. chest, back, legs) at least twice a week Body mass stable in the last month Meets strength relative-to-weight guidelines (adapted from Morton et al., 2016; Chilibeck et -al., 1997) Bench Press: - Bodyweight (kg) * 1.25 Leg Press: - Bodyweight (kg) *4.0 Exclusion Criteria: Inability to meet health and PA guidelines according to the PAR-Q+ Inability to adhere to any of the protocol guidelines (e.g. alcohol and caffeine consumption) Regular tobacco use, screened by questionnaire Illicit drug use (e.g. growth hormone, testosterone, etc.), screened by a survey in training log 1 month sedentary in the last 6 months prior to study participation 30 minutes of continuous cardio per exercise session BMI > or equal to 35 Individual plans to increase or decrease body mass in the next 3 months Use of supplements (excluding whey protein), such as creatine and beta-alanine, in the last 30 days

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

Sexes Eligible for Study
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Male

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: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Randomized crossover trial.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Habitual Protein phase<br>A trial investigating protein oxidation/metabolism that was used to model resistance trained individual's habitual dietary protein intake (2.2g/kg/d). | Other: Three day Controlled Diet<br>* Three days of a controlled diet providing 2.2g/kg/d of dietary protein with protein metabolism measured on day 3. This was used to model the habitual intake of this cohort.<br>|
| Experimental: Moderate Protein Phase<br>A series of three trials over a one week period investigating protein oxidation/metabolism that was used to investigate the metabolic response of decreased protein intake (1.2g/kg/d) over a period of five days (trials on days 1, 3, 5 following reduction in protein intake from 2.2g/kg/d to 1.2g/kg/d) relative to the Habitual protein phase trial. | Other: Dietary protein intake reduction<br>* Following two days of controlled diet at 2.2g/kg/d of dietary protein, intake was reduced to 1.2g/kg/d for five days, and protein metabolism was measured on days 1, 3, and 5.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Phenylalanine excretion (F13CO2) | Expressed as µmol/kg/h; phenylalanine excretion is determined via breath enrichment (F13CO2) of the oral tracer. Breath 13CO2 enrichment was measured by continuous-flow isotope ratio mass spectrometry | Through study completion, an average of 3 months | 
| Phenylalanine oxidation (PheOX) | Expressed as µmol/kg/h; phenylalanine excretion is determined via breath and urine enrichment of the oral tracer. Breath 13CO2 enrichment was measured by continuous-flow isotope ratio mass spectrometry and urinary L-[1-13C] phenylalanine was measured by liquid chromatography tandem mass spectrometry | Through study completion, an average of 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Phenylalanine Rate of Appearance (PheRa/Flux) | In µmol/kg/h; phenylalanine rate of appearance is determined via urinary enrichment of the oral tracer by liquid chromatography tandem mass spectrometry. | Through study completion, an average of 3 months | 
| Net Protein Balance | In µmol/kg/h; calculated as the difference between whole-body protein synthesis and protein breakdown. ). Breath 13CO2 enrichment was measured by continuous-flow isotope ratio mass spectrometry and urinary L-[1-13C] phenylalanine was measured by liquid chromatography tandem mass spectrometry. | Through study completion, an average of 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Amino acids, Protein, metabolism, IAAO, Tracer, Indicator amino acid, Resistance trained