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

This study has been completed.
Sponsor:
Collaborators:
University of California, Davis
Canadian Institutes of Health Research (CIHR)
Natural Sciences and Engineering Research Council, Canada
Information provided by (Responsible Party):
Stuart M. Phillips, McMaster University
ClinicalTrials.gov Identifier:
NCT01492010
First received: December 12, 2011
Last updated: NA
Last verified: December 2011
History: No changes posted
  Purpose

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, we aim 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

Thus, we 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. We hypothesize 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 we are 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.


Condition Intervention
Regulation of Muscle Protein Synthesis
Dietary Supplement: whey protein
Dietary Supplement: whey protein supplemented with leucine
Dietary Supplement: whey protein supplemeted with essential amino acids

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Single Blind (Subject)
Primary Purpose: Treatment
Official Title: Role of Leucine in the Regulation of Human Myofibrillar Protein Synthesis at Rest and Following Resistance Exercise

Resource links provided by NLM:


Further study details as provided by McMaster University:

Primary Outcome Measures:
  • Muscle protein synthesis [ Time Frame: 5 hours postprandial ] [ Designated as safety issue: No ]
    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).


Secondary Outcome Measures:
  • Signaling molecule phosphorylation status [ Time Frame: 1, 3, and 5 hours ] [ Designated as safety issue: No ]
    Western blot will be used to measure the phosphorylation status of signaling molecules involved in protein synthesis ie. mTOR, p70S6k, 4E-BP1.


Enrollment: 24
Study Start Date: June 2010
Study Completion Date: September 2010
Primary Completion Date: August 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 25 g protein
25 g whey protein
Dietary Supplement: whey protein
25 g whey protein
Other Name: whey protein powder
Experimental: 6.25 g protein supplemented with leucine
6.25 g protein supplemented with leucine
Dietary Supplement: whey protein supplemented with leucine
6.25 g whey protein supplemented with free form leucine
Other Name: whey protein powder supplemented with free-form leucine
Experimental: 6.25 g whey protein with EAA
6.25 g protein supplemented with a mixture of essential amino acids devoid of leucine
Dietary Supplement: whey protein supplemeted with essential amino acids
6.25 g whey protein supplemented with essential amino acids devoid of leucine
Other Name: whey protein supplemented with EAA devoid of leucine

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

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
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT01492010

Locations
Canada, Ontario
Exercise Metabolism Research Laboratory, McMaster Univeristy
Hamilton, Ontario, Canada, L8S 4K1
Sponsors and Collaborators
McMaster University
University of California, Davis
Canadian Institutes of Health Research (CIHR)
Natural Sciences and Engineering Research Council, Canada
Investigators
Principal Investigator: Stuart M Phillips, PhD McMaster University
  More Information

No publications provided by McMaster University

Additional publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Stuart M. Phillips, Principal Investigator, McMaster University
ClinicalTrials.gov Identifier: NCT01492010     History of Changes
Other Study ID Numbers: LEU-10-141
Study First Received: December 12, 2011
Last Updated: December 12, 2011
Health Authority: Canada: Ethics Review Committee

Keywords provided by McMaster University:
skeletal muscle
FSR
resistance exercise
leucine
protein

ClinicalTrials.gov processed this record on April 16, 2014