Protein Metabolism
Conditions
Keywords
Metabolism, Amino Acid Peptides, Muscle Protein Synthesis, Muscle Protein Breakdown
Brief summary
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.
Interventions
BEHAVIORALResistance Exercise
Prior to protein consumption participants will perform an acute bout of resistance exercise. They will warm up with two sets of 10 repetitions at 35-75% working load respectively, then perform four working sets of 10-12 repetitions at 65-70% of 1-RM. 1 min, 30 sec rest periods will be implemented between each set.
BEHAVIORALNo Resistance Exercise
Participants allocated to this group will not perform exercise prior to the administration of the nutritional intervention. Participants will remain at rest throughout the trial.
DIETARY_SUPPLEMENTLeucine
Participants will be given 2g of leucine dissolved in 250mL of water. Drink will be consumed immediately after exercise or equivalent time point for non-exercise group.
DIETARY_SUPPLEMENTDileucine
Participants will be given 2g of dileucine dissolved in 250mL of water. Drink will be consumed immediately after exercise or equivalent time point for non-exercise group.
Sponsors
University of Illinois at Urbana-Champaign
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Fractional Synthetic Rate of Mixed Muscle Proteins | Postabsorptive for 3.5 hours, Postprandial for 3 hours. | Mixed muscle protein synthesis rates will be assessed during the 3.5hr Postabsorptive period (e.g. non-fed state) and the 3hr postprandial period (e.g. fed state) for both experimental interventions (e.g. leucine and leucine peptide). This will allow us to assess the change in fractional synthetic rate from the Postabsorptive period to the postprandial period. |
| Fractional Synthetic Rate of Myofibrillar Proteins | Postabsorptive for 3.5 hours, Postprandial for 3 hours. | Myofibrillar muscle protein synthesis rates will be assessed during the 3.5hr Postabsorptive period (e.g. non-fed state) and the 3hr postprandial period (e.g. fed state) for both experimental interventions (e.g. leucine and leucine peptide). This will allow us to assess the change in fractional synthetic rate from the Postabsorptive period to the postprandial period. |
| Fractional Breakdown Rate of Mixed Muscle Proteins | Postprandial for 1 hour | Mixed muscle protein breakdown rates will be assessed during the first hour of the postprandial period (e.g. fed state) for both experimental interventions (e.g. leucine and leucine peptide). This will allow us to assess the change in fractional breakdown rate for each respective experimental intervention. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Phosphorylation of muscle anabolic signaling | Baseline, immediately after ingestion of leucine/leucine peptides, and 3 hours after ingestion of leucine/leucine peptides | Phosphorylation of anabolic signaling pathways will be assessed in the fasted state and after the ingestion of the experimental interventions. |
Countries
United States
Outcome results
None listed