Strength athletes who for whatever reason are unable to train for a couple of weeks can reduce their muscle decay by using BCAAs. An animal study that Japanese researchers at Kobe University published in Nutrition Research suggests that BCAAs inhibit catabolic processes in inactive muscles.
Inactive muscles wither so quickly that space trips take a heavy toll on cosmonauts, and forced bed rest can cause extra problems for patients who are in recovery. For this reason scientists are keen to find nutritional strategies that doctors can use to prevent muscle decay as a result of inactivity. They have had some success in the past with creatine and leucine.
In many of the studies researchers use rats whose hind legs have been temporarily disabled [HS]. There’s a picture of how these animals look at the top of the page. Rats in a control group were able to use their hind legs normally [Control].
Half of the animals in each group were given 600 mg BCAAs per kg bodyweight daily. The BCAAs were produced by Ajinomoto. The human equivalent of the dose used would be 100 mg BCAA per kg bodyweight. So if you weigh 90 kg that would amount to 9 g per day.
The figure below shows that, while BCAAs couldn’t prevent inactivity from leading to decay of the soleus muscle, administration did mitigate the breakdown. The photos below show that BCAA supplementation did reduce the decrease in the muscle cell size.
The figure above reveals how BCAA supplementation works at molecular level. The amino acids reduced the production of catabolic proteins such as atrogin-1 and MuRF1.
“In conclusion, BCAA protected against soleus muscle atrophy induced by hindlimb suspension and decreased atrogin-1 and MuRF1 protein levels, suggesting the possibility that BCAA protects against muscle atrophy, at least in part, via the inhibition of the Ub-proteasome pathway”, the researchers write. “Oral BCAA administration appears to have the potential to protect against immobilization or microgravity-induced muscle atrophy.”
Branched-chain amino acids reduce hindlimb suspension-induced muscle atrophy and protein levels of atrogin-1 and MuRF1 in rats.
Atrogin-1 and MuRF1, muscle-specific ubiquitin ligases, and autophagy play a role in protein degradation in muscles. We hypothesized that branched-chain amino acids (BCAAs) may decrease atrogin-1, MuRF1, and autophagy, and may have a protective effect on disuse muscle atrophy. To test this hypothesis, we selected hindlimb suspension (HS)-induced muscle atrophy as a model of disuse muscle atrophy because it is an established model to investigate the effects of decreased muscle activity. Sprague-Dawley male rats were assigned to 4 groups: control, HS (14 days), oral BCAA administration (600 mg/[kg day], 22.9% L-isoleucine, 45.8% L-leucine, and 27.6% L-valine), and HS and BCAA administration. After 14 days of the treatment, muscle weights and protein concentrations, cross-sectional area (CSA) of the muscle fibers, atrogin-1 and MuRF1 proteins, and microtubule-associated protein 1 light chain 3 II/I (ratio of LC3 II/I) were measured. Hindlimb suspension significantly reduced soleus muscle weight and CSA of the muscle fibers. Branched-chain amino acid administration partly but significantly reversed the HS-induced decrease in CSA. Hindlimb suspension increased atrogin-1 and MuRF1 proteins, which play a pivotal role in various muscle atrophies. Branched-chain amino acid attenuated the increase in atrogin-1 and MuRF1 in soleus muscles. Hindlimb suspension significantly increased the ratio of LC3 II/I, an indicator of autophagy, whereas BCAA did not attenuate the increase in the ratio of LC3 II/I. These results indicate the possibility that BCAA inhibits HS-induced muscle atrophy, at least in part, via the inhibition of the ubiquitin-proteasome pathway. Oral BCAA administration appears to have the potential to prevent disuse muscle atrophy.
PMID: 23084640 [PubMed – indexed for MEDLINE]