Skeletal Muscle Protein Synthetic Response to Amino Acid and Peptides

Skeletal Muscle Protein Synthetic Response to Amino Acid and Peptides

Skeletal muscle quality is an important determinant of exercise performance and overall health. It is vital for not just movement, but also metabolizing nutrients. Protein from the diet can promote muscle protein synthesis for muscle recovery and growth. More importantly, doing so shifts net protein balance positively (e.g. protein synthesis is greater than protein breakdown) and promotes greater rates of muscle protein turnover. Leucine is an amino acid required to build muscle, but it also acts as a signaling molecule informing the muscle to start protein synthesis. Before reaching skeletal muscle, dietary protein is digested into small peptides and free amino acids. Rate of absorption from the intestine to the blood stream is significantly faster for peptides compared to amino acids. As amino acid availability in the blood is a precursor for muscle protein synthesis, our objective is to determine if the different absorption rates between free amino acid and peptides influence muscle protein synthetic and breakdown rates.

Inclusion Criteria:

• Recreationally-active adults: ≥ 30 min of physical activity at moderate intensity ≥ 3 times per week
• Ages: 18-35 years old
• English fluency

Exclusion Criteria:

• Tobacco, nicotine (patch/gum) use (previous 6 mo)
• Alcohol consumption >10 drinks per week
• Metabolic disorders (e.g., Metabolic Syndrome, Diabetes, thyroid diseases)
• Cardiovascular disease, arrhythmias
• Hypogonadism
• Asthma
• History of uncontrolled hypertension
• Orthopedic injury/surgery (within 1 yr)
• Hepatorenal, musculoskeletal, autoimmune, or neurological disease
• History of neuromuscular problems
• Previous participation in amino acid tracer studies
• Predisposition to hypertrophic scarring or keloid formation
• Consumption of ergogenic-levels of dietary supplements that may affect muscle mass (e.g., creatine, HMB), insulin-like substances, or anabolic/catabolic pro-hormones (e.g., DHEA) within 6 weeks prior to participation
• Consumption of thyroid, androgenic, or other medications known to affect endocrine function
• Consumption of medications known to affect protein metabolism (e.g., prescription-strength corticosteroids, non-steroidal anti-inflammatories, or acne medication)
• Currently pregnant