Plain English Summary
Background and study aims
Resistance exercise involves using an external force (such as heavy weights) to cause the muscles to contract. Eating or drinking protein after resistance exercise stimulates the making of new muscle proteins (muscle protein synthesis). Branched chain amino acids (BCAA) are often suggested as the main part of protein responsible for the increased protein synthesis, but no study has directly examined this. The aim of this study is to find out whether consuming BCAA increases muscle protein synthesis after resistance exercise in trained, young adult males.
Who can participate?
Healthy men aged 18-45 who are experienced weight lifters
What does the study involve?
This study consists of two phases. For each phase, participants undertake two 8-hour studies at the School of Sport and Exercise Sciences at the University of Birmingham. Before the studies, participants’ body composition and the maximum weight they can lift with one leg are assessed. Participants complete an intense bout of resistance exercise. Following the exercise, in Phase I participants are randomly allocated to consume either a drink containing BCAA or a placebo (dummy) drink. In Phase II, participants are randomly allocated to consume either a carbohydrate drink or a drink containing both BCAA and carbohydrates. Muscle samples (biopsies) are collected from the quadriceps (thigh) and blood samples are taken from a hand vein to work out the rates of protein synthesis.
What are the possible benefits and risks of participating?
Participants will receive information about how their muscle changes after exercise. Participants may experience discomfort during the blood or tissue sampling.
Where is the study run from?
University of Birmingham (UK)
When is the study starting and how long is it expected to run for?
October 2009 to October 2011
Who is funding the study?
GlaxoSmithKline Nutritional Healthcare (UK)
Who is the main contact?
Dr Sarah Jackman
Dr Sarah Jackman
Sport and Health Sciences
College of Life and Environmental Sciences
University of Exeter
St Luke's Campus
Branched-chain amino acid ingestion stimulates muscle myofibrillar protein synthesis following resistance exercise in humans
Ingestion of only branched-chain amino acids (BCAA) will be sufficient for the stimulation of myofibrillar muscle protein synthesis (MPS) rates after resistance exercise in a fed state in trained, young adult males.
National Research Ethics Service ethics board, 24/09/2009, ref: 09/H1211/77
Crossover double-blind intervention study
Primary study design
Secondary study design
Randomised cross over trial
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
This research project was performed in two phases. The design, all procedures, risks and analyses of each phase were the same between the two phases. The only difference was the substances that were ingested. For each phase, 10 healthy, weight trained males aged 18 - 45 (from gyms in the local area) undertook two ~8 hour trials that took place in the School of Sport and Exercise Sciences at the University of Birmingham. Prior to the experimental trials, the maximum weight that could be lifted with one leg and body composition were assessed. During the experimental trials, participants were infused with metabolic tracers, muscle biopsies were collected and blood samples taken to determine rates of protein synthesis. Each participant completed an intense bout of resistance exercise followed by three muscle biopsies. Muscle and blood samples were analyzed to determine the rates of muscle protein synthesis and the signalling mechanisms inside the muscle that lead to increased synthesis. Following the exercise, participants will be randomised to consume either a BCAA-containing solution or a placebo in Phase I. In Phase II, a carbohydrate control solution will be compared to BCAA plus carbohydrates. Thus, in each phase, the BCAA will be compared with the appropriate control.
Primary outcome measure
Fractional synthetic rate (FSR), measured using gas combustion isotope ratio chromatography mass spectrometry (GCCIRMS) over the 4h period following drink ingestion.
Secondary outcome measures
1. Signalling proteins, measured using western blots
2. Amino acids in blood, measured using gas chromatography mass spectrometry (GCMS)
3. Tracers enrichment in muscle, measured using GCMS
4. Tracers enrichment in plasma, measured using GCMS
5. Insulin in serum, measured using enzyme-linked immunosorbent assay (ELISA)
6. Glucose in plasma, measured using automated analysers
Blood sample timepoints: -240, -145, -85, -25, 0, 15, 30, 45, 60, 75, 90, 120, 150, 180, 240 min
Muscle biopsy timepoints: 0, 60 and 240 min
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Male, aged 18-45 years
2. Healthy (no known metabolic disorder)
3. Experienced weight lifter for more than 6 months (at least 2 leg resistance training sessions per week)
Target number of participants
Total final enrolment
Participant exclusion criteria
Not simultaneously taking part in another scientific/clinical study
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
University of Birmingham
GlaxoSmithKline Nutritional Healthcare
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
The results of the study will be disseminated to the scientific community via publication in scientific journals (that will ideally be open access). Ideally, the results of the study will also be presented at scientific conferences. Furthermore, it is hoped that the results of the study will be disseminated to the public in a lay summary via various media outlets, and also individual data will be made available and communicated to study volunteers upon request.
IPD sharing plan
The datasets generated and/or analysed during the current study are available from Dr Sarah Jackman on reasonable request.
Intention to publish date
Participant level data
Available on request
Basic results (scientific)
2017 results in: https://www.ncbi.nlm.nih.gov/pubmed/28638350 (added 31/10/2019)