Influence of Habitual Protein Intake on AA Tracer Oxidation
Condition: Protein/Amino Acid Metabolism; Indicator Amino Acid Oxidation Method
Study type: Interventional

Summary: 
      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: 
      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.
    

Intervention name(s): Dietary protein intake reduction; Three day Controlled Diet
Intervention type(s): Other; Other
Intervention description(s): 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.; 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.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomized crossover trial.
Masking: None (Open Label)
Primary purpose: Other
Keywords: Amino acids; Protein; metabolism; IAAO; Tracer; Indicator amino acid; Resistance trained