Skeletal Muscle Protein Synthetic Response to Amino Acid and Peptides

University of Illinois at Urbana-Champaign10 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Enrollment

Conditions

Protein Metabolism

Interventions

Eligibility

Sex: ALLMin age: 18 YearsMax age: 35 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Fractional Synthetic Rate of Mixed Muscle Proteins

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.

Time frame: Postabsorptive for 3.5 hours, Postprandial for 3 hours.

Fractional Synthetic Rate of Myofibrillar Proteins

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.

Time frame: Postabsorptive for 3.5 hours, Postprandial for 3 hours.

Fractional Breakdown Rate of Mixed Muscle Proteins

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.

Time frame: Postprandial for 1 hour

Secondary Outcomes

Phosphorylation of muscle anabolic signaling

Phosphorylation of anabolic signaling pathways will be assessed in the fasted state and after the ingestion of the experimental interventions.

Time frame: Baseline, immediately after ingestion of leucine/leucine peptides, and 3 hours after ingestion of leucine/leucine peptides