Do BCAAs lower muscle breakdown?


Do BCAAs lower muscle breakdown?

Branched-chain amino acids are so-called because they have aliphatic side-chains within the branch – that’s a carbon atom which is connected to another two carbon atoms. There are branched chain amino acids: leucine, isoleucine and valine. BCAAs are actually one of the eight (or nine including glutamine) essential amino acids the human body needs to function properly – in fact, BCAAs should be at 35% of essential amino acids within muscle proteins. They’re also 40% of preformed amino acids as required by mammals. It has been previously suggested that deficiency of BCAAs can increase the degradation of muscles during extended periods of inactivity. One study by Maki T et al at the Kobe University Graduate School of Health Science in Japan sought to research this further. Proposing that protein degradation within muscles could be reduced by the supplementation of BCAAs, the team came up with a reliable model to test and investigate the effects of inactivity on muscles.



Laboratory rats, like in most experiments concerning the effects of BCAAs, were used in this experiment. A group of rats were temporarily disabled by rendering their hind legs unusable, by means of a support which brought their back legs up off the ground. Half of the group were not given supplements, the other half were administered with a daily dosage of 600mg BCAAs per kg of bodyweight. A control group was also used – these rats were not disabled, and half the group was given BCAAs.  


Even though BCAAs did not prevent the decay of muscles in the disabled rats, the breakdown was significantly reduced.  


The supplementation of BCAAs in those who are rendered inactive for periods of time can reduce the rate at which muscle decays, though it cannot stop the process altogether.  

Our take

We’ve already written about how BCAAs can reduce muscle soreness and reduce required recovery time, so it’s no surprise that BCAA has further applications when it comes to limiting muscle breakdown. You may not be a rat but using rat human equivalency ratios and tracking the results of similar studies conducted in humans we can suggest a dose of around 10g of BCAAs around training as being a necessary dose to limit muscle breakdown and accelerate recovery. Trainers such as Nick Mitchell recommend far higher than this amount but we suggest dosing smaller first before going to doses of 20-40g. As an alternative to BCAA supplementation there are other intraworkout supplements we have previously looked at such as Iforce Nutrition’s Compete which employ a wider mix of amino acids to improve recovery, allied to ingredients that can enhance performance.  


  1. Maki T, Yamamoto D, et al Branched-chain amino acids reduce hindlimb suspension-induced muscle atrophy and protein levels of atrogin-1 and MuRF1 in rats. Nutr Res. 2012 Sep;32(9):676-83. doi: 10.1016/j.nutres.2012.07.005. Epub 2012 Sep 17.