Effects of Branched-Chain Amino Acids (BCAAs) on Muscle Cell Signalling

Effects of Branched-Chain Amino Acids (BCAAs) on Muscle Cell Signalling

Dr. GJohn Mullen Blog, Nutrition/Supplements, Training Leave a Comment

Branched-chain amino acids (BCAA) are a common supplement in sports and resistance training. Their theorized benefit is increasing lean body mass and maximizing strength gains.

BCAA and leucine particularly utilize a signaling route which overlaps with the distal part of the insulin-like growth factor I (IGF-I) signaling pathway, namely the mammalian target of rapamycin (mTOR) cascade (mTORC1).

Haegens et al looked to see if BCAA and leucine increase mTOR signaling, muscle mass, and muscle fibers (myofibrillar) protein content.

What was done

The researchers measured C2C12 skeletal muscle cells using cultures.


Leucine directly induces myofibrillar protein accretion in skeletal muscles. Leucine involved a process leading to mTOR activity.


Leucine appears to be beneficial for stimulating myofibrillar protein rather than generic protein accretion in skeletal muscle. This implies a mTOR dependent and independent regulation.

Practical Implication

Improving in-water strength is essential in swimming. However, many of these gains are with biomechanics and/or neural improvements. Therefore, increasing muscle mass for improving strength in swimming is uncertain, but potentially beneficial.



  1. Haegens A, Schols AM, van Essen AL, van Loon LJ, Langen RC. Leucine induces myofibrillar
    protein accretion in cultured skeletal muscle through mTOR
    dependent and -independent control of myosin heavy chain mRNA levels. Mol Nutr Food
    Res. 2012 May;56(5):741-52.

Originally Posted July 2012 

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