Role of Leucine in the Regulation of Human Myofibrillar Protein Synthesis at Rest and Following Resistance Exercise

Regulation of Muscle Protein Synthesis Clinical Trial

Official title:

Role of Leucine in the Regulation of Human Myofibrillar Protein Synthesis at Rest and Following Resistance Exercise

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01492010
• Other study ID #: LEU-10-141
• Status: Completed
• Phase: N/A
• Start date: June 2010
• Est. completion date: September 2010

Study information

• Verified date: February 2020
• Source: McMaster University
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Muscle mass is normally maintained through the regulated balance between the processes of protein synthesis (i.e. making new muscle proteins) and protein breakdown (breaking down old muscle proteins). Proteins are composed of amino acids and we know that amino acids increase muscle protein synthesis. However, not all amino acids are the same. Essential amino acids are ones that must be consumed through food, while non-essential amino acids can be made by our body. Interestingly, the essential amino acids are all that are required to increase the rate of muscle protein synthesis. In addition, the essential amino acid leucine appears to be particularly important in regulating protein synthesis. However, how leucine is able to increase protein synthesis is not entirely understood. Previously, it has been shown that 20-25 g of high-quality protein, such as that found in milk, appears to be the amount of protein that maximizes the rate of muscle protein synthesis after performing a bout of resistance exercise. Thus, the aim is to measure the synthesis of new muscle proteins after ingesting the following:

1. 25g whey protein

2. 6.25g whey protein supplemented with leucine

3. 6.25g whey protein supplemented with essential amino acids but no leucine

The investigators will measure muscle protein synthesis after consumption of the above beverages in a leg that has done no exercise ( ie. a rested leg) and in the other leg that has done resistance exercise. The hypothesis is that 6.25g whey supplemented with leucine will stimulate muscle protein synthesis as effectively as 25g whey, but that 6.25g whey supplemented will all the essential amino acids except whey will be less effective at increasing muscle protein synthesis. Whey protein is a dairy-based protein found in cow's milk, thus when you drink a glass of milk you are consuming some whey protein. However, the investigators will be using an isolated form of whey protein, meaning it has been removed from milk. As mentioned previously, amino acids are 'strung-together' to make protein. The 'essential' amino acids must be consumed through food because our body cannot make them, thus they are consumed when you eat protein-rich foods like milk or chicken.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 24
• Est. completion date: September 2010
• Est. primary completion date: August 2010
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 18 Years to 35 Years

Eligibility

Inclusion Criteria:

• male

• 18-35 years of age

• non-smoker/ non-tobacco product user

Exclusion Criteria:

• heart disease

• vascular disease

• rheumatoid arthritis

• diabetes

• poor lung function

• uncontrolled blood pressure

• dizziness

• thyroid problems

Related Conditions & MeSH terms

• Regulation of Muscle Protein Synthesis

Intervention

Dietary Supplement:
• whey protein
25 g whey protein
• whey protein supplemented with leucine
6.25 g whey protein supplemented with free form leucine
• whey protein supplemented with essential amino acids
6.25 g whey protein supplemented with essential amino acids devoid of leucine

Locations

Country	Name	City	State
Canada	Exercise Metabolism Research Laboratory, McMaster Univeristy	Hamilton	Ontario

Sponsors (4)

Lead Sponsor	Collaborator
McMaster University	Canadian Institutes of Health Research (CIHR), Natural Sciences and Engineering Research Council, Canada, University of California, Davis

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Muscle protein synthesis	Muscle protein synthesis will be expressed as fractional synthetic rate (FSR) by dividing the increment in enrichment in the product, i.e. protein-bound C13phe, by the enrichment of the precursor (= intracellular availability).	5 hours postprandial
Secondary	Signaling molecule phosphorylation status	Western blot will be used to measure the phosphorylation status of signaling molecules involved in protein synthesis ie. mTOR, p70S6k, 4E-BP1.	1, 3, and 5 hours