Intermittent Fasting Diet Plan Example

Alanine is the livers favorite gluconeogenic amino acid and leucine appears to increase its usage.

Being among the first to learn about the "Glucose-Repartitioning Effect of Iso-Leucine" in February 2013 (read up on it), you, as SuppVersity reader, belong to the selected few who know that valine and isoleucine may be more than unnecessary props in the leucine-powered BCAA show. With the recent publication of a rodent study from the University of Sao Paulo in Brazil (Campos-Ferraz. 2013), however, it looks as if you had to revise your perspective on the purportedly auxiliary BCAAs - at least, with respect to their ability to reduce fatigue, and muscle and liver-glycogen degradation, in trained rats and possibly (!) humans.

So what did the Brazilian researchers do?

Basically, the idea Campos-Ferraz et al. had in mind, when they came up with their 8 week exercise + 2 week supplementation protocol (see Table 1) was to ...

Table 1: Exercise progression; suppl. was initiated in w7 after lactate test

"evaluate effects of the use of supplementation with leucine or a mixture of BCAAs in trained rats submitted to an exercise-induced protocol of glycogen depletion.

Furthermore, we attempted to investigate muscle and liver biochemical parameters that were not performed in the previous study in order to elucidate the role of BCAAs in glycogen depletion. " (Campos-Ferraz. 2013)

In other words: The researchers wanted to find out whether or not leucine would exert identical, less or more pronounced effects on muscle glycogen use and endurance performance in rodents that the full spectrum of branch-chained amino acids, i.e. leucine, valine and isoleucine.

Contrary to what bro-science and the shiny ads of the supplement industry are suggesting, the scientists fundamental hypothesis was that the BCAAs supplementation would impair the rodents endurance capacity, because the branched-chain amino acids would be used in muscle to yield acetyl-CoA. This, in turn could reduce the activity of the glucose-alanine cycle, by which the muscles are supplied with alanine-derived glucose from the liver and (once the BCAAs got burne) result in an earlier onset of fatigue.

BCAAs are "glycogen depleters"?!

If you take a look at the data Campos Ferraz et al. gathered in the testing sessions at the end of the supplementation period, in the course of which the rats received an oral gavage of 166mg/kg per day (in human terms this would be ca. 3-3.5g per day) of BCAAs or leucine, it is quite obvious that the  the leucine group had a significantly lower muscle and liver glycogen degradation ratios than the BCAA group.

Figure 1: Liver & mucle glycogen degradation and time to exhaustion (expressed relative to placebo); muscle TCA intermediate content and enzyme activity / concentration (Campos-Ferraz. 2013)

Compared to the placebo group, only the ratios were different.  While the placebo group had the lowest liver glycogen use and a high muscle glycogen use, the supplemental leucine induced a shifted from muscle to liver glycogen and did thus exert muscle specific glycogen sparing effects.

As the researchers point out, these observations stand in line with their original hypothesis: Leucine can spare a significant amount of muscle and liver glycogen and thus produce a highly significant increase in resistance to exhaustion compared to the mixture of BCAAs (P<0.001).
If we compare the endurance performance of the leucine rodents to that of the placebo group, this does yet cast a slight shadow on the overall image of the glorious ergogenic, and, even more so, the purported performance enhancing effects of BCAAs. Despite measurable differences in the time to exhaustion, the actual endurance increase in response to the leucine supplement is relatively small.
 
If you take another look at the data in Figure 1 you will probably notice the significant increase in TCA cycle intermediates (citrate and malate) in the BCAA group. These changes provide further evidence that the provision of all three branch-chain amino acid emphasized the use of glucose as a main substrate to sustain the endurance activity.

"Mouse vs. man": Can we ignore the differences in BCAA metabolism?


At this point, it may however be about time to point out that the activity of the BCAA catabolizing enzyme branched-chain keto acids dehydrogenase complex (BCKD) in humans is quite different from that in rats.

"In the latter [the rat], liver BCKD is almost completely unphosphorylated (activated) in basal state, making it possible to metabolize more rapidly BCKA from the portal blood; in humans, BCKD in liver is normally phosphorylated (inactivated) in order to spare BCAAs for protein synthesis." (Campos-Ferraz. 2013)

In other words: While rodents use BCAAs mostly as an energy source, the human body spares them as a potential protein anabolic.

In view of the fact that the BCAAs are not used to the same degree as an alternative substrate in the human vs. the rodent liver, it is actually not very surprising that the results of the study at hand appear to conflict with data from a previous study by the same laboratory (Gualano. 2011). In the corresponding experiment, Gualano et al observed measurable increases in exercise capacity and lipid oxidation in human subjects during endurance exercise after muscle glycogen depletion in response to the provision of 300mg/kg BCAAs per day.

Reference:

• Campos-Ferraz PL, Bozza T, Nicastro H, Lancha AH Jr. Distinct effects of leucine or a mixture of the branched-chain amino acids (leucine, isoleucine, and valine) supplementation on resistance to fatigue, and muscle and liver-glycogen degradation, in trained rats. Nutrition. 2013 Nov-Dec;29(11-12):1388-94.
• Gualano AB, Bozza T, Lopes De Campos P, Roschel H, Dos Santos Costa A, Luiz Marquezi M, et al. Branched-chain amino acids supplementation enhances exercise capacity and lipid oxidation during endurance exercise after muscle glycogen depletion. J Sports Med Phys Fitness 2011;51:82–8

The study tested only leg exercises, but you can safely expect increased reps on other exercises, as well.

Citrulline? Yes thats the stuff the supplement industry claims to be a better version of arginine. A "super pump supplement", but not necessarily an ergogenic - in spite of the fact that corresponding evidence from rodent and human studies (Briand. 1992; Pérez-Guisado. 2010; Giannesini. 2011) existed years before the study at hand was published (Wax. 2014).

Benjamin Wax and his colleagues from the Mississippi State University and the Auburn University  investigated the effects of citrulline malate supplementation on lower-body resistance exercise performance, blood lactate, heart rate, and blood pressure.

Based on citrulline malate’s chemical composition and a review of the current literature Wax et al. hypothesized that citrulline malate supplementation would mitigate fatigue occurring to the working muscle; therefore, augmenting resistance training performance.
To test their hypothesis the researchers recruited 12 advanced resistance trained male subjects (85kg body weight; <12% body fat; 22.1 ± 1.4 years) and conducted a randomized, counterbalanced, double blind study.

The subjects were randomly assigned to placebo or citrulline malate (8 g; 60 minutes before the workout) groups and then performed repeated bouts of multiple lower body resistance exercise:

"Subjects warmed up on an upright stationary bike (Life Fitness, Brunswick Corporation, Lake Fores, IL) for five minutes, at 60 – 70 revolution/minute with a mass of 3 – 5 kg. Following this warm up, subjects performed two warm up sets (10 repetitions at 90.9 kg and 8 repetitions at 136.4 kg) on the leg press machine. Subjects rested three minutes between sets during the warm up and trial sets.

Next, 60% of each subject’s predetermined 1RM was loaded on the leg press machine and the subject completed as many repetitions as possible until failure occurred. This process was completed for 4 additional sets for a total of 5 sets on the leg press. Next, the subjects performed one warm upset (10 repetitions) on the hack squat machine at a mass of 40.9 kg. This warm up set was followed by 5 sets of 60% of their predetermined 1RM to failure. Finally, following one warm up set (10 repetitions at 36.4 kg) on the leg extension, subjects completed 5 sets of 60% of their 1RM to failure." (Wax. 2014)

The rest periods (recovery periods between sets of exercise), exercise order, and number of sets performed were the same for all subjects in this investigation, for sessions 2 and 3. Blood lactate, heart rate, systolic blood pressure, and diastolic blood pressure were determined pre and post exercise.
The exercise protocol resulted in sequential significant (p < 0.05) decrease in the number of repetitions in all three exercises. However, subjects in the citrulline malate group performed significantly (p < 0.05) higher number of repetitions during all three exercises compared to placebo group.

Figure 1: Wax et al. observed significant increases in maximal leg press, hack squat, and leg extension (not shown) repetitions in response to the ingestion of 8g of citrulline malate 60min before exercise (Wax. 2014)

Blood lactate and heart rate, on the other hand, were significantly increased (p < 0.05) post-exercise in both groups with no significant inter-group differences between citrulline malate and placebo (p > 0.05).
References:

• Briand, Joël, et al. "Use of a microbial model for the determination of drug effects on cell metabolism and energetics: Study of citrulline‐malate." Biopharmaceutics & drug disposition 13.1 (1992): 1-22.
• Hickner, Robert C., et al. "L-citrulline reduces time to exhaustion and insulin response to a graded exercise test." Medicine and science in sports and exercise 38.4 (2006): 660-666.
• Giannesini, Benoît, et al. "Citrulline malate supplementation increases muscle efficiency in rat skeletal muscle." European journal of pharmacology 667.1 (2011): 100-104.
• Pérez-Guisado, Joaquín, and Philip M. Jakeman. "Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness." The Journal of Strength & Conditioning Research 24.5 (2010): 1215-1222.
• Verleye, M., et al. "Effects of citrulline malate on bacterial lipopolysaccharide induced endotoxemia in rats." Arzneimittelforschung 45.6 (1995): E712.
• Wax, Benjamin, et al. "Effects of Supplemental Citrulline Malate Ingestion During Repeated Bouts of Lower-body Exercise in Advanced Weight Lifters." The Journal of Strength & Conditioning Research (2014).