Clinical trial NCT01492010: Role of Leucine in the Regulation of Human Myofibrillar Protein Synthesis at Rest and Following Resistance Exercise
Official title: Role of Leucine in the Regulation of Human Myofibrillar Protein Synthesis at Rest and Following Resistance Exercise
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Regulation of Muscle Protein Synthesis
Keywords: skeletal muscle
FSR
resistance exercise
leucine
protein
Lead sponsor: McMaster University
Sponsor class: OTHER
Collaborators: name: University of California, Davis
name: Canadian Institutes of Health Research (CIHR)
name: Natural Sciences and Engineering Research Council, Canada
First posted: 2011-12-14
Enrollment: 24
Sex: MALE
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief 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.


Eligibility 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

Primary outcomes:
measure: Muscle protein synthesis
timeFrame: 5 hours postprandial
Secondary outcomes:
measure: Signaling molecule phosphorylation status
timeFrame: 1, 3, and 5 hours
Other outcomes:
Locations:
city: Hamilton
country: Canada
facility: Exercise Metabolism Research Laboratory, McMaster Univeristy
state: Ontario
Study officials:
affiliation: McMaster University
name: Stuart M Phillips, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Churchward-Venne TA, Burd NA, Mitchell CJ, West DW, Philp A, Marcotte GR, Baker SK, Baar K, Phillips SM. Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. J Physiol. 2012 Jun 1;590(11):2751-65. doi: 10.1113/jphysiol.2012.228833. Epub 2012 Mar 25.