More Conflicting Evidence on Leucine Metabolite: HMB Makes Volleyballers Stronger.

The leucine metabolite HMB, i.e. β-Hydroxy-β-Methylbutyric acid, is unquestionable the comeback kid of the supplement industry. "It works!", "It's useless!", ... every now and then a new study supports one side of the debate. A group of international scientists does now present a study, which would support the use of the expensive, yet readily available amino acid.

Portal et al. (Portal. 2011) investigated the effect of 3g HMB/day "on body composition, muscle strength, anaerobic and aerobic capacity, anabolic/catabolic hormones and inflammatory mediators in elite, national team level adolescent volleyball players (13.5–18 years, 14 males, 14 females, Tanner stage 4–5) during the first 7 weeks of the training season". The results were unequivocal, yet not overtly impressive:

HMB led to a significant greater increase in FFM by skinfold thickness (56.4 ± 10.2 to 56.3 ± 8.6 vs. 59.3 ±  11.3 to 61.6 ± 11.3 kg in the control and HMB group, respectively, p < 0.001). HMB led to a significant greater increase in both dominant and non-dominant knee flexion isokinetic force/FFM, measured at fast (180°/sec) and slow (60°/sec) angle speeds, but had no significant effect on knee extension and elbow flexion and extension. HMB led to a significant greater increase in peak and mean anaerobic power determined by the Wingate anaerobic test (peak power: 15.5 ± 1.6 to 16.2 ± 1.2 vs. 15.4 ± 1.6 to 17.2 ± 1.2 watts/FFM, mean power: 10.6 ± 0.9 to 10.8 ± 1.1 vs. 10.7 ± 0.8 to 11.8 ± 1.0 watts/FFM in control and HMB group, respectively, p < 0.01), with no effect on fatigue index.

With no measurable effect on aerobic fitness, anabolic hormone levels or inflammatory mediators, the use of HMB appears to be advisable only in power and strength athletes.

If you are a bodybuilder on a high protein diet, I would however doubt that you would see any benefits from additional HMB. A diet rich in quality protein (high BCAA and particularly leucine content) should provide you with adequate amounts of leucine to keep endogenous HMB levels elevated.

Glycogen-Depleted Athletes may Benefit from 0.3g/kg BCAA Supplementation: Improved Endurance & Lipid Oxidation

If you have ever read up on the general recommendations concerning "cardio on an empty stomach" you will most likely have encountered the advice to supplement with branched-chained amino acids (BCAA) before or in the course of the workout. I have always considered this to be a solid advice, up to now, I had yet not seen a study underpinning the common sense reasoning behind the suggestion.

Now, Gualano et al. (Gualano. 2011) published a study that investigated the effect of BCAA supplementation on exercise performance and energy metabolism in glycogen-depleted athletes (let's assume by now that an athlete following a low carb diet is in fact glycogen-depleted when he wakes up). In a double-blind placebo controlled fashion the scientists provided their subjects with either 0.3g/kg BCAA or placebo for 3 days...

On the second day, subjects were submitted to an exercise-induced glycogen depletion protocol. They then performed an exhaustive exercise test on the third day, after which time to exhaustion, respiratory exchange ratio (RER), plasma glucose, free fatty acids (FFA), blood ketones and lactate were determined. BCAA supplementation promoted a greater resistance to fatigue when compared to the placebo (+17.2%). Moreover, subjects supplemented with BCAA showed reduced RER and higher plasma glucose levels during the exhaustive exercise test.

For all of you who are now asking themselves, what validates the claim of increased fatty acid oxidation, its the reduced respiratory exchange ratio. Although its arguable how reliable a measure the ratio between O2 in and CO2 out is in terms of fatty acid metabolism, these results support the hypothesis and real world observation that BCAA-supplemented cardio on an empty stomach reliably promotes fat loss.

3g BCAA + Arginine + Carbs Pre-Workout Modulates Hormonal Response to Single Bout of Treadmill Running to Exhaustion

BCAAs + Arginine + Carbohydrates before workout!? Sounds familiar, doesn't it? In fact many of the first generation preworkout products were either formulated like that or consumers were advised to stack them with a branched amino acid (BCAA) product of the same company. Studies which investigated the combined ergogenic effect of these nutrients are yet scarce. So, I thought that it would be worth posting the results of a recent study from China (Hsu. 2011).

Before they started exercising on a treadmill, the subjects, 14 male physical active college students, received a beverage containing either 3g of BCAA (2:1:1) + 0.5g Arginine + 12.1g carbohydrates or placebo. Blood samples of each subject were collected before exercise, 0, 10, 20, 40, 60, 120 min and 24 h after exercise and the procedure was repeated after two weeks (cross-over design). The results were as follows:

No significant differences in the levels of lactate, ammonia, creatine kinase and glycerol between the two groups were observed at any of the time points. However, the levels of glucose and insulin were significantly higher in the BA trial as compared to those in the PL trial at the 40 and 60 min recovery points. Furthermore, the testosterone to cortisol ratio at the 120 min recovery point was significantly higher in the BA trial as compared to that in the PL trial.

While higher glucose and insulin levels are hardly surprising in view of the fact that the placebo contained no calories whatsoever, the improved hormonal recovery (measured as testosterone / cortisol ratio) in the supplemented group appears to be pretty interesting.

A closer look at the exact data does yet reveal that the supplemented group had a higher testosterone / cortisol ratio to begin with. So, if we calculate the relative changes in the T/C ratio 120min after exercising to exhaustion, these are +13.2% in the placebo group and only +6.8% in the supplemented group.
Does that mean that the money you are spending on preworkout products is wasted? From a hormonal perspective, maybe. From a psychological perspective, we do yet still have another result of the study: "Fatigue score increased immediately at exhaustion in both groups, but the decrease in the fatigue score at 120 min recovery point was significant only in BA trial." Consequently, even if it does not improve the hormonal milieu in the early recovery period, supplementation with branched chain amino acids, arginine and carbohydrates could provide the psychological edge you need to drag yourself to the gym regularly ;-)

On a side note: It would have been interesting to see T/C levels measured beyond the 120 minutes post exhaustion. Based on the fact that the recovery of the T/C levels of the supplemented group sped up from T=60min to T=120min, one may well hypothesize that there would be measurable (hormonal) advantages for the BA group at T=180min and beyond.