Oral 'Breath Test' to Measure Anabolic Sensitivity to a Protein Meal Across the Age and Physical Activity Spectrum

Inclusion Criteria: * Healthy will be defined as screened by the PAR-Q+ (The Physical Activity Readiness Questionnaire for everyone) * Chronological age for Healthy Young (age: 18-35 years) or Older (age: 60-80 years) adults * Chronological age between 8 to 16 years, with maturity offset \< -1 year from age of Peak Height Velocity (aPHV) for children and between -0.5 to +1.5 years from aPHV in adolescent participants * BMI between normal to overweight (18.5 - 29.9 kg/m2) Exclusion Criteria: * Regular use of nonsteroidal anti-inflammatory dugs (with the exception of daily low-dose aspirin) * use of anticoagulants * use of a walker, cane, or assistive walking device * infectious or gastrointestinal disease * inability to comply with study protocol (e.g., unable to track diet) * regular tobacco use * self-reported illicit drug use (e.g., growth hormone, testosterone, etc.) * diagnosed chronic illness (e.g., type 2 diabetes, heart disease, thyroid disease) * pregnant * hormonal replacement therapy