Protein Requirements in Resistance Trained Females
Condition: Healthy
Study type: Interventional

Summary: 
      In this study, the investigators will use the minimally invasive indicator amino acid
      oxidation (IAAO) technique to determine protein requirements in weight-trained males. It is
      hypothesized that the present study will show that protein requirements for weight-trained
      females are i) greater than the current RDA for non-active individual's comparable estimates,
      and ii) greater than existing nitrogen balance-based estimates for weight-training
      individuals
    

Detailed description: 
      Provided that energy needs are met, the adequate ingestion of dietary amino acids is the most
      critical nutritional factor to support the optimal remodeling and deposition of lean body
      mass in individuals of all ages. Current recommendations according to the World Health
      Organization/Food and Agricultural Organization suggest that daily protein requirements in
      healthy, non-active adults are 0.8 g/kg/day. However, of primary interest in the present
      study is the impact that exercise has on the nutritional requirement for dietary amino acids
      in highly active adults - e.g., individuals performing weight training. Protein requirements
      for individuals who participate in strength-based exercise training have been suggested to
      range from 1.2-1.7g protein/kg/day (Rodriguez et al., 2009; Tarnopolsky, 1992; Phillips et
      al., 2007), which equates to a 50-112% increase from the current RDA. The increased
      requirement in this population may reflect the requirement for protein to repair/rebuild lean
      tissues by promoting anabolism (Phillips, 2004). Nutritional requirements for dietary amino
      acids in adults (both active and non-active) have traditionally been determined utilizing the
      antiquated and often erroneous nitrogen balance technique (Costaneda et al., 1995; Campbell
      et al., 1984), which is prone to underestimating protein requirements and therefore provides
      challenges to making accurate nutritional recommendations (Humayun, Elango, Ball, and
      Pencharz, 2007). This observation that nitrogen balance underestimates protein requirements
      in non-active individuals could suggest that protein requirements are much greater than the
      current WHO/FAO recommendation of 0.8 g/kg/day which was evaluated using the nitrogen balance
      technique (Rand, Pellett and Young, 2003). As a result, there is a need to re-evaluate
      recommendations utilizing advanced stable isotope methodology in order to characterize how
      dietary amino acid needs may be modulated by physical activity. Recent studies using the
      minimally invasive indicator amino acid oxidation (IAAO) technique have suggested that
      protein requirements in young men are at least 50% higher than WHO/FAO guidelines based on
      nitrogen balance data (Humayun, Elango, Ball, and Pencharz, 2007). Furthermore, resistance
      training has been reported to increase (according to nitrogen balance methodology) protein
      requirements by up to 75% Tarnopolsky et al., 1992). Therefore, in this study, the
      investigators will use the IAAO technique to determine protein requirements in weight-trained
      males. It is hypothesized that the present study will show that protein requirements for
      weight-trained females are i) greater than the current RDA for non-active individual's
      comparable estimates, and ii) greater than existing nitrogen balance-based estimates for
      weight-training individuals.
    

Intervention name(s): Protein intake (dose)
Intervention type(s): Other
Intervention description(s): Protein intake, in the form of crystalline amino acids, will range between 0.2-3.0 g/kg/d
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science