Aspartate+NaHCO3 Maintain Muscle Contractility: Plus 14% Rate of Force Development, Minus 37% Ammonia Post HIT

The combination of aspartate + bicarbonate may make an involuntary rest phase on the floor of the gym obsolete. 
It has been while that sodium bicarbonate, aka NaHCO3, or (pure) baking soda has made the SuppVersity news. The ergogenic aid recently made the TOP-list of "supplements with good to strong evidence of achieving benefits to performance when used in specific scenarios" in the published "IOC consensus statement: dietary supplements and the high-performance athlete" (Maughan 2018) - a short list in which bicarbonate is listed next to caffeine, creatine, nitrates, and beta-alanine, and a list which doesn't include aspartate as a putative congenial synergist, yet.  Aspartate, a salt or ester of aspartic acid is a nonessential amino acid that has a central role in hepatic glyconeogenesis as it is the substrate to the aspartate aminotransferase enzyme in the liver, an enzyme of which you know that it is significantly elevated by (intense) training (learn more).
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Aspartate has been mostly ignored by researchers in the past decades - probably because the follow-up studies to the initially promising research from the 1950s-60s (Laborit 1957 \ not available online), which suggested that aspartate supplements can successfully combat the exercise-induced rise in ammonia (a byproduct of protein breakdown the build-up of which in your blood has been implicated as one of triggers of progressive fatigue | Butch 1983; Wilkinson 2010) yielded mixed, often negative results which have been reviewed most recently 10 years ago by François Trudeau (see Table 1).
Table 1: The effect of aspartate on endurance and ammonia (positive results | Trudeau 2018)
Unfortunately, the overview in Table 1 represents only approx. half of the studies - the studies with positive outcomes - in Trudeau's review. The other half of the studies found no effect.
Duration of prolonged exercise to ex-haustion (y-axis) in the 6 test subjects of Ahlborg et al.'s study from the 1960s after administration (x-axis) of placebo (striped area) and after administration of aspartate (black area).
So why could aspartate work (don't confuse with aspartame btw. ;-): Well, while bicarbonate exerts its ergogenic effect by buffering the increase of hydrogen ions in the blood (H+) and thus preventing both direct negative effects of the ensuing acidification of the body and the formation of lactic acid, we don't really know yet, how aspartate works (if it works as in Ahlborg 1968, see Figure on the left).

Scientists have speculated that the main mechanism is, in fact, the previously cited reduction of the putatively fatigue-inducing formation of ammonia (Mutch 1983), which has been observed in both, rats and humans - as Trudeau points out, though, a reduction in ammonia was not observed in all studies. This is why alternative hypotheses to explain the effects are needed.

Pertinent theories come from Ahlborg et al. (1968 | cf Figure above), themselves, and Wesson et al. (1988) both groups have suggested that aspartate may spare muscle glycogen because it can be used as a substrate for glyconeogenesis via the previously [main text] mentioned de-/transamination of aspartate in the liver. This "glycogen hypothesis" does, however, have as many studies that refute its accuracy / significance as the third alternative, the free fatty acid hypothesis (1993), which suggests that aspartate would increase the release of stored free fatty acids (FFAs) into the blood which could then be used by your mitochondria to fuel your workouts.
Figure 1: Overview of the experimental protocol. There were five sessions of a test-exercise-test sequence of quad force pre-testing, HIT, and quad-force post-testing. The first of these sessions served as a familiarization trial that was also used to establish an individual challenging exercise volume for all following sessions - this means: in all subsequent sessions, the subjects had to perform the exact same number of reps they were able to perform in the first session (based on my understanding of Farney 2018).
In this context, it seems to be worth quoting a finding of Trudeau's previously cited 2008 review which found that "[t]he effect of aspartate on endurance seems more plausible in humans and less supported by animal studies" - that's the way we like it, no?

What did the scientists do and what were the outcomes of this new study, then?

I can understand if you're still not very excited. So, let's take a look at the study design and outcomes, before deciding whether aspartate is a supplement that's missing from pre-workout stack or whether you're rightly skeptical and aspartate isn't worth trying.

The authors of the study under review (Farney 2018), scientists from the Texas A&M and the Louisiana State University, recruited 12 trained participants (minimum 6 months of combined cardio + weight training  exp.; age: 21.9 +/- 1.5 years; height: 1.77 m; and body mass: 82.4 kg).
Having digestive issues with bicarbonate? Check out this not 100% series advice from the SuppVersity Facebook page: "Science-Based, but Not(!) Recommended: "If Oral #Bicarbonate Gave You the Runs, You May Want to Mix #NaHCO3 With #Vaseline and Apply the Paste to Your Toilet-Paper-Scratched #Butt to Become More #Alkaline" - Accidental Induction of #MetabolicAlkalosis in 4-Months-Old Suggests This Could Actually Work" | read more.
One of the initially twelve subjects had to be removed from data analysis because of gastrointestinal tract complications (missed the SuppVersity tips to stomach sodium bicarbonate ;-), the others completed all exercise and testing sessions successfully.
Figure 2: Change (%) in relative force development and peak force (calculated as the rel. change in the given treatment minus the relative change in placebo) in std. tests conducted pre- to post-CrossFit-esque HIT protocol (large) | Relative difference (vs. placebo) in time it took to perform the HIT-workout (small inset | calculated based on Farney 2018).
Based on the data from the pre- and post- isometric thigh pull tests as well as the timed, individualized HIT workout (three rounds of barbell thrusters, squat jumps, lunge jumps, and forward jumps), I've calculated the relative pre- vs. post-test changes and plotted them expressed relative to the placebo group in Figure 2. This form of presentation may not be the most common one, but it illustrates the individual treatment effect better than the absolute rel. changes (pre-to-post, not relative to placebo) which were...
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    for the rate of force development, a 10% plus! in the ASP + NaHCO3 group and reductions of -4% in the NaHCO3 as well as the placebo group and a surprising -7% in the ASP group and...
  • for the peak force, a complete amelioration of the (expected) performance decline in the ASP + NaHCO3 trial and reductions of -3% in the NaHCO3 and -5% in the ASP as well as the placebo trial.
So let's recap. Just as my allegedly unconventional presentation of the data in Figure 2 shows, only the ASP + NaHCO3 had a potential relevant effect on the muscle force decline in response to the HIT workout of which the inset in Figure 2 tells you that it was also completed significantly faster by the subjects who had consumed two servings (cf. red box) of a/an...
  • Serial Loading: Stomach NaHCO3 and Benefit from Baking Soda's Performance-Boosting Effect - 3×3g/Meal for 3 Days | more
    ASP + NaHCO2 stack containing 30 g of a Gatorade sports drink powder, 12.5 g of L-aspartate, and 0.3 g/kg body mass NaHCO3 powder, ...
compared to the...
  • ASP stack containing 30 g of a Gatorade sports drink powder plus 12.5 g of L-aspartate powder, the ...
  • NaHCO3 stack containing 30 g of a Gatorade sports drink powder plus 0.3 g/kg body mass NaHCO3 powder, or the control stack, i.e the ...
  • Placebo containing only the 30 g of a Gatorade sports drink powder and nothing else
All powder/powder-mixes were dissolved in ~20oz (=591ml) of water and consumed by the subjects 23h and 1h before the testing + exercise + testing sequence.
A note on dosing & timing: The full-text, which speaks of "2 bags of a powder mixture consisting of one of the following [list of ingredients for the stacks see list above]" (Farney 2018), does not clearly say if my assumption that those are "per serving dosages" is right and the subjects have used 2x30g Gatorade, 2x0.3g/kg NaHCO, and 2x12.5g of L-aspartate, or if the 30g+0.3g/kg+12.5g is the total amount of supplements the subjects consumed in the ASP + NaHCO2 condition. 
All three treatments, i.e. ASP + NaHCO2, ASP, and NaHCO3, ameliorated the increase in ammonia to a similar extent - a synergistic effect of ASP and NaHCO3 couldn't be observed.
Figure 3: Pre- vs. post concentrations of ammonia (mmol/L) in the blood of the subjects (Farney 2018).
Due to high inter-individual variation, the huge difference between the 35-37% increase in ammonia in the treatment vs. 82% in the placebo group/s didn't reach statistical significance. It could, however, be of practical relevance. If not for all, then at least for some athletes.
If you haven't read it yet, I suggest you head back to the year 2012 in the SuppVersity archive and learn how to supercharge 'ur creatine w/ NaHCO3.
The three main take-homes from the study at hand are: Firstly, there are measurable and potentially practically relevant (e.g. for back-to-back CrossFit competitions) beneficial effects on three out of three markers of exercise-induced fatigue: ammonia, rate of force development*, and peak force of the quads (* p < 0.05), and subjects' ability to perform a set/rep standardized high intensity (mostly body weight) strength-endurance workout in a minimal amount of time. Secondly, aspartate and baking soda, together, can maintain your muscle contractile properties more effectively than either of the two agents on its own.

And, thirdly, the study at hand must be considered as preliminary evidence in favor of the ASP + NaHCO3 combi, since (a) the number of subjects was already low before one subject got the runs and dropped out. Hence, it is not really surprising that only one of the measurable effects of the ASP + NaHCO3 reached statistical significance. It should also be considered preliminary evidence, because (b) the subjects were all young, male, trained individuals, which raises the question, if the same results would/could be observed in other subject groups (e.g. women, older, or untrained individuals). And third and final reason why the study must be considered as preliminary evidence in favor of the aspartate + baking soda stack is that (c) the study doesn't provide an answer to the questions "What's the mechanism behind the effects of aspartate and how does it synergize with the acid buffer sodium bicarbonate"? | Comment on Facebook!
  • Ahlboro, Björn, Lars‐Göran Ekelund, and Carl‐Gustaf Nilsson. "Effect of Potassium‐Magnesium‐Aspartate on the Capacity for Prolonged Exercise in Man." Acta Physiologica Scandinavica 74.1‐2 (1968): 238-245.
  • Bucci, Luke R. Nutrients as ergogenic aids for sports and exercise. Vol. 2. Crc Press, 1993.
  • Mutch, B. J. C., and E. W. Banister. "Ammonia metabolism in exercise and fatigue: a review." Medicine and science in sports and exercise 15.1 (1983): 41-50.
  • Farney, Tyler M., et al. "The Effect of Aspartate and Sodium Bicarbonate Supplementation on Muscle Contractile Properties Among Trained Men." Journal of strength and conditioning research (2018).
  • Laborit, H., et al. "Effect of the ionic composition of the extracellular medium and compared effect of aspartic acid, aspartate of potassium and glucose on the swimming test of white rats." Comptes rendus des seances de la Societe de Biologie et de ses Filiales 151.7 (1957): 1383-1386.
  • Maughan, Ronald J., et al. "IOC consensus statement: dietary supplements and the high-performance athlete." International journal of sport nutrition and exercise metabolism 28.2 (2018): 104-125.
  • Mutch, B. J. C., and E. W. Banister. "Ammonia metabolism in exercise and fatigue: a review." Medicine and science in sports and exercise 15.1 (1983): 41-50.
  • Trudeau, François. "Aspartate as an ergogenic supplement." Sports Medicine 38.1 (2008): 9-16.
  • Wesson, Matthew, et al. "Effects of oral administration of aspartic acid salts on the endurance capacity of trained athletes." Research Quarterly for Exercise and Sport 59.3 (1988): 234-239.
  • Wilkinson, Daniel J., Nicholas J. Smeeton, and Peter W. Watt. "Ammonia metabolism, the brain, and fatigue; revisiting the link." Progress in Neurobiology 91.3 (2010): 200-219.
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