| Autor: |
Kaspy MS; Department of Kinesiology and Physical Education, McGill University, 475 Avenue Des Pins H2W 1S4, Montreal, QC, Canada., Hannaian SJ; Department of Kinesiology and Physical Education, McGill University, 475 Avenue Des Pins H2W 1S4, Montreal, QC, Canada.; Research Institute of the McGill University Health Centre, Glen Site, 1001 Boul. Décarie, H4A 3J1 Montreal, QC, Canada., Bell ZW; Department of Kinesiology and Physical Education, McGill University, 475 Avenue Des Pins H2W 1S4, Montreal, QC, Canada., Churchward-Venne TA; Department of Kinesiology and Physical Education, McGill University, 475 Avenue Des Pins H2W 1S4, Montreal, QC, Canada.; Division of Geriatric Medicine, McGill University, Montreal General Hospital, Room D6 237.F, 1650 Cedar Avenue, H3G 1A4, Montreal, QC, Canada.; Research Institute of the McGill University Health Centre, Glen Site, 1001 Boul. Décarie, H4A 3J1 Montreal, QC, Canada. |
| Abstrakt: |
Branched-chain amino acids (BCAA: leucine, isoleucine and valine) are three of the nine indispensable amino acids, and are frequently consumed as a dietary supplement by athletes and recreationally active individuals alike. The popularity of BCAA supplements is largely predicated on the notion that they can stimulate rates of muscle protein synthesis (MPS) and suppress rates of muscle protein breakdown (MPB), the combination of which promotes a net anabolic response in skeletal muscle. To date, several studies have shown that BCAA (particularly leucine) increase the phosphorylation status of key proteins within the mechanistic target of rapamycin (mTOR) signalling pathway involved in the regulation of translation initiation in human muscle. Early research in humans demonstrated that BCAA provision reduced indices of whole-body protein breakdown and MPB; however, there was no stimulatory effect of BCAA on MPS. In contrast, recent work has demonstrated that BCAA intake can stimulate postprandial MPS rates at rest and can further increase MPS rates during recovery after a bout of resistance exercise. The purpose of this evidence-based narrative review is to critically appraise the available research pertaining to studies examining the effects of BCAA on MPS, MPB and associated molecular signalling responses in humans. Overall, BCAA can activate molecular pathways that regulate translation initiation, reduce indices of whole-body and MPB, and transiently stimulate MPS rates. However, the stimulatory effect of BCAA on MPS rates is less than the response observed following ingestion of a complete protein source providing the full complement of indispensable amino acids. |
