Food First Approach to Stimulate Muscle Protein Synthesis in Healthy Adults

On both infusion trials, participants will report to the laboratory at 0700 h after an overnight fast. Upon arrival to the lab, the participant will fill out a questionnaire and a baseline breath sample will be collected to determine 13CO2 enrichment by isotope ratio mass spectrometry. A Teflon catheter will be inserted into the antecubital vein for a baseline blood sample (t=-210) and then participants will receive priming doses of NaH13CO2 (2.35 µmol·kg-1), L-[1-13C]leucine (7.6 µmol·kg-1), and L-[ring-2H5]phenylalanine (2.0 µmol·kg-1). Subsequently, a continuous intravenous solution of L-[1-13C]leucine (0.10 µmol·kg-1·min-1) and L-[ring-2H5]phenylalanine (0.05 µmol·kg-1·min-1) will be initiated (t=-210) and maintained over the infusion trials. A second Teflon catheter will be inserted into a heated dorsal vein for repeated arterialized blood sampling and remained patent by a 0.9% saline drip. Breath samples and arterialized blood samples will be collected every 30 to 60 minutes during the postabsorptive and postprandial states. In the post-absorptive state of infusion trial 1, muscle biopsies will be collected at t=-150 and -30 min of infusion to determine basal-state myofibrillar protein synthesis rates, relative skeletal muscle amino acid transporter content, and anabolic-related signaling. In the subsequent cross-over trial only 1 muscle biopsy will be collected at t=-30 for Western blot analysis and postabsorptive myofibrillar protein-bound tracer enrichment. After collection of the resting muscle biopsy at t=-30 for both trials, the participants will perform resistance exercise that consists of 4 sets of 10-12 repetitions or to muscular failure at 65-70% of 1-RM for both leg press and leg extension exercise.

Immediately after the completion of the exercise bout, participants will ingest either 3.5 oz of Salmon fillet or a matched isolated amino acid and fat mixture (t=0). Completion of the meal will mark the start of the postprandial stage and additional muscle biopsies will be collected at t=120 and t=300.

Inclusion criteria

• Age 20-35 years
• Recreationally-active adults: ≥ 30 min of physical activity at moderate intensity ≥ 3 times per week
• English fluency

Exclusion criteria

• Smoking
• Known allergies to fish consumption
• Vegans
• Diagnosed GI tract diseases
• Arthritic conditions
• A history of neuromuscular problems
• Diagnosed cognitive impairments
• Recent (1 year) participation in amino acid tracer studies
• Predisposition to hypertrophic scarring or keloid formation
• Individuals on any medications known to affect protein metabolism (i.e. corticosteroids, non-steroidal anti-inflammatories, or prescription strength acne medications).
• High blood pressure (Systolic > 140 mm HG; Diastolic > 90 mm HG)
• Alcohol consumption >10 drinks per week
• Metabolic disorders (e.g., Metabolic Syndrome, diabetes, thyroid diseases)
• Consumption of thyroid, androgenic or other medications known to affect endocrine function
• Consumption of ergogenic-leves 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
• Currently pregnant
• A suboptimal diet quality score as assessed by ASA24 dietary records
• Asthma
• Hypogonadism
• Cardiovascular disease, arrhythmias