Saturday, September 17, 2011

High and Low Dose BCAA Supplementation Have Minimal, Non-Significant Effects on Markers of Muscle Damage 24h and 48h Post Heavy Resistance Training

Image 1: Cover of the September issue of the International Journal of Wrestling Science - don't tell me you don't have a subscription, yet!
I don't know about you, but I feel that it's quite interesting to look at the highly heterogeneous dosage suggestions on the labels of the ever-increasing number of BCAA supplements on the market. Interestingly, almost every producer claims in his "non FDA-approved" statements that his supplement contains "scientifically supported" or "clinically validated" amounts of branch-chained amino acids in the "optimal" (whatever that may be) ratio of 2:1:1, 3:1:1, 4:1:1, 8:1:1, ... and all the other variations that appear to be limited only by the patent applications and lawyers of the financially more potent players in the business. From a scientific perspective, however, this "optimal" amount has still to be elucidated - at least to my knowledge, no respectable scientist has yet claimed to have found the "optimal" amount and composition of free form amino acids for a given subgroup of athletes, let alone strength athletes, bodybuilders or figure competitors, in general.
At this point I would like to add that no respectable scientist would ever dare to make the claim that he or she has found the "optimal free form amino acid supplement" for all, or even a significantly large group of athletes, unless he or she would be interested in losing his reputation as a "respectable scientist" ;-)
In a recently published study scientists from the Department of Physical education and Sports Science University of Tabriz in Tabriz, Iran, set out to establish whether there is at least a significant difference between the effects of ~15g (210mg/kg) or 33g (450mg/kg) of branched chain-amino acids taken before and after the completion of an intense resistance training regimen comprised of 7 exercises à 3 sets of 10 repetitions (Amirsasan. 2011). Yet, despite the fact, that even the "low dose" of 15g of BCAAs (in the customary 2:1:1 ratio, i.e. 7.5g of leucine + 3.75g of iso-leucine + 3.7g of valine) was about 1.5x higher than what I have seen as "suggested dosing" or "serving size" on very high-dosed commercial supplements, the effects of this amino acid overkill were "sobering", to say the least.
Figure 1: Effects of "low" (210mg/kg) and "high" (450mg/kg) dose BCAA supplement on enzymatic markers of muscle damage relative to pre-values in the placebo group (data calculated based on Amirsasan. 2011)
As the data in figure 1 goes to show both the "low" as well as the "high" (or should I say "overkill" ;-) dose of pre- and post-workout BCAAs had only marginal, and certainly statistically non-significant effects on creatine kinase (overall - CK; muscle specific - CK MB) and lactate dehydrogenase activity, both established indicators of (exercise-induced) muscle damage.
Comparison of results between groups in mean and amplitude changes of serum indexes of cell damage (CK-LDH-CKMB), 24 and 48 hours after the exercise performance showed no significant difference between the 3 groups. In other words, different amounts of BCAA did not significantly affect the serum cell injury indexes (CK-LDH-CKMB), 24 and 48 hours after the heavy resistance activity.
These results are interesting, because they contradict previous findings by Sharp et al. who reported "significantly reduced" creatine kinase levels with BCAA supplementation in likewise previously strength-trained athletes on a similarly intense (8 exercises; 3x 6-8 repetitions) resistance training protocol (Sharp. 2010), as well as the results of studies in endurance athletes and previously untrained subjects, where the provision of BCAAs decreased creatine kinase and lactate dehydrogenase enzyme expression, across-the-board (Greer. 2007; Koba. 2007; Matsumoto. 2009).
"To supplement or not?" This question may arise if you have a look at the data from this study. Thor, in a comment to this posts poses the question whether his "personal experience" that "having the fast digesting aminos seemed to increase [his] ability to have a more successful work out" is, after all "only in [his] head" and while I cannot say for sure how much of it may be the result a placebo-effect in his case, I can provide you with the results of a 2011 study by Greer et al. who found no increases in exercise performance despite reduced perceived rates of exertion with BCAA supplementation after a 90-minute cycling bout (Greer. 2011). These results seem to confirm the "central fatigue hypothesis" according to which BCAAs exert their beneficial effects agains (perceived) fatigue via modulation of the availability of the serotonin precursor tryptophan. In a 2007 review of the literature, Meeusen and Watson do yet conclude that the "nutritional manipulation of these systems [neurotransmitter] through the provision of amino acids has proven largely unsuccessful" (Meeusen. 2007)... All that does not take away from the established beneficial effects of chronic low-dose BCAA (in particular, leucine) supplementation on endurance performance and strength adaptations to exercise (e.g. Crowe. 2006; Matsumoto. 2009). In the respective studies, dosages in the 1.5-3.0g/day range have yet been sufficient, to elicit these beneficial effects - and that in subject groups that are not particularly well-known for their exorbitantly high protein intakes ;-)
Image 2: When bought in bulk and without the addition of a ton of fancy extras BCAAs have become reasonably priced - whether they are a "necessary" part of your supplement regimen may yet depend on your dietary protein intake.
Probably - this would at least be my first guess - the outcome of these studies was not so much affected by the actual study protocol, but rather by the habitual dietary protein intake of their subjects. With endurance athletes (Koba. 2007; Matsumoto. 2009),  recreationally active (Sharp. 2010) and untrained (Greer. 2007) we usually see much lower dietary protein intake than with professional wrestlers, which prompts me to repeat my previously stated skepticism towards the usefulness of large boluses of additional free form amino acids in a group of athletes whose habitual dietary protein intake is way beyond the 1.5g/kg level, anyway... but hey, that's just the opinion of a brainy physicist; so if your brawny guru says you need those 150g of BCAAs on top of your 5x50g whey protein shakes and your 3 pound of lean meat - go for it!