Glutamine or BCAA, Which is the Better Fatique Buffer? 18g GLU Suprisingly Effective, 9.5g BCAAs (Un-)Surprisingly Useless as Blood Fatigue Factors & Cytokine Buffers

Rowing is an excellent cardio exercise for wanna be bodyuilders, by the way!

I am not really a fan of glutamine, but unlike BCAAs that are still hyped all over the Internet, the conditionally essential amino acid which is the most abundant of all amino acids in human blood is at least not falsely heralded as a potent catabolic, anabolic, weight loss adjuvant and what not, any longer.

Against that background I have to admit that I am not exactly unhappy to tell you that Ga Hee Koo, Jin Hee Woo, Sung Whun Kang, and Ki Ok Sjin who work at the Dong-A University and the Republic of Korea Airforce Academy, have recently observed that BCAAs have absolutely no, glutamine at least a minimal impact on the blood fatigue factor response of juvenile athletes in response to a 2,000 m all out rowing challenge w/ placebo, BCAA or glutamine supps.
In the corresponding experiment, the scientists from the College of Sports Science at the Dong-A University had five male juvenile elite rowing athletes perform the same 2,000m rowing test at maximal intensity after having received a placebo, BCAA, or glutamine for 7 days before
the test. The specific supplementation regimen included:

• BCAA (Spomax, Seoul, Republic of Korea) was given three times a day (25% valine, 50% leucine, 25% isoleucine, 3.15 g/day).
• L-glutamine (Optimum Nutrition, Aurora, IL, USA, 6 g/day) was given three times a day.

Blood samples were collected from the antecubital vein on the day of testing while resting before the test, immediately at the end of test, and 30 min after the test. All tests were conducted with a 1-week interval to eliminate the potential effects from potentially longer-lasting effects of the previously administered supplement.
The actual test was conducted with an indoor rowing machine (Concept², Morrisville, VT, USA) two times each for supplementation with the placebo, BCAA, and glutamine. All the subjects performed a 2,000 m (Olympic single scull race) race at their own individual maximum paces (42–45 pace for 0m~250m, 40 pace for 250m~500m, 36–38 pace for 500m~1,500 m, and over 42 pace for 1,500 m~2,000 m)

Figure 1: Serum markers of fatigue and muscle damage, expressed relative to placebo (Koo. 2014)

There were no significant differences in lactate levels; a significant phopshorus-sparing effect from BCAAs (small effect size) and glutamine (large effect size) of which the scientists believe that it was mediated by the use of the amino acids to maintain adequate muscular ATP levels; and there was a non-significantly elevated level of ammonia in the glutamine group (some arginine could help clear those | learn more) that returned to normal 30 min after the test.
The creatine kinase levels (a marker of muscle damage) and the levels of interleukin-8 and interleukin-15, however, were significantly lower in the glutamine than they were in either the BCAA or placebo group. This is a result of which the authors of the study believe that, it may...

"[...]represent the effects of energy supplementation from glutamine supply, which activated as a fuel in the muscle and as a nitrogen precursor for nucleotide synthesis" (Koo. 2014). 

An alternative explanation would be that glutamine (probably via its connection to glutathione; see Roth. 2002) had a direct protive effect on the skeletal muscle tissue during the workouts.

Figure 2: Serum levels of inflammatory cytokines expressed relative to placebo (Koo. 2014)

This hypothesis would also be supported by the changes in interleukin expression. i.e. the blunted increase of interleukin-8. IL-8 is an inflammatory cytokine that serves as a chemical signal which attracts neutrophils at the site of inflammation. The corresponding increase in IL-15, which was likewise reduced in response to sub-chronic glutamine supplementation, on the other hand, indicates a reduced production (not activity!) of natural killer cells.

Table 1: Intense exercise is not the only condition / disease that's associated  with low blood glutamine levels (Roth. 2002)

In that, it is crucial to understand that the authors (imho reasonably) believe that the increase in IL-8 & IL-15 is a compensatory mechanism which is initiated to counter the reduced immune function that occurs, when the amount of glutamine in the blood and skeletal tissue drops. We do after all know for sure that the this will result in a significant decrease in the cell proliferation rate of lymphocytes, the amount of antioxidants, peptides, amino sugars related to cell resistance against apoptotic processes, purines, as well as the synthesis of key molecules such as pyrimidines which are all involved in redox reactions (Roth. 2002).

Whether supplementation is warranted with low(er) intensity exercise, as well, is however questionable. Previous research by Ostrowski et al. (2001), who had their subjects exercise at significantly lower intensities, did not find comparable increases in IL-8. This difference is probably due to a comparably lower amount of exercise induced stress that corresponds to the reduced intensity. In this context it's also worth mentioning that Fischer et al. (2006) report that the blood chemokine concentrations would increase little or remain stagnant unless a sufficient muscle mass is mobilized and maintained at a certain level of intensity sufficiently... now, everyone who has ever done an all-out rowing time trial will confirm: This is (a) intense and will (b) involve almost every muscle in your body.
References:

• Fischer, Christian P. "Interleukin-6 in acute exercise and training: what is the biological relevance." Exerc Immunol Rev 12.6-33 (2006): 41.
• Koo, Ga Hee, et al. "Effects of Supplementation with BCAA and L-glutamine on Blood Fatigue Factors and Cytokines in Juvenile Athletes Submitted to Maximal Intensity Rowing Performance." Journal of Physical Therapy Science 26.8 (2014): 1241-1246.
• Ostrowski, Kenneth, et al. "Chemokines are elevated in plasma after strenuous exercise in humans." European journal of applied physiology 84.3 (2001): 244-245.
• Roth, Erich, et al. "Regulative potential of glutamine—relation to glutathione metabolism." Nutrition 18.3 (2002): 217-221.