0.3g/kg Bicarbonate Will Make Trained Cyclists Last 4.5 Min Longer (+9%) During Std. High Intensity Cycling Tests

Don't forget that cyclists are not the only group of athletes who can benefit from bicarbonate supplementation. Strength trainees who spend hours in the gym and train at high intensities will also benefit!

I know that most of you are into resistance not endurance training. So, before I even get into the discussion of the experimental procedures and the results of the latest study from the Institute of Sports and Preventive Medicine at the Saarland University in Saarbrücken, Germany, I would like to point you to an older SuppVersity article which indicates that bicarbonate supplementation is able to Up Your Squat (+27%) & Bench Press (+6%) Within 60 Min" (read more).

Now that you've hopefully put away your prejudices against "that endurance supplement", let's get to the previously mentioned study by Florian Egger, Tim Meyer, Ulf Such, and Anne Hecksteden (thanks to Conrad P. Earnest for bringing this to my attention).
To investigate the effects of BICA supplementation on performance during prolonged, high-intensity cycling to exhaustion in well-trained athletes, the scientists from the Saarland University recruited 6 male and 5 female "well-trained" cyclists (mean ± SD: age 24±8 y, BMI 21.3±1.7, VO2peak 67.3±9.8 ml/kg/min - the VO2peak value tells you that they were fit ;-).

In a double-blind, randomized cross-over design, the subjects underwent two stepwise incremental exercise tests and two constant load tests (with two phases) on an electrically braked cycle ergometer (Excalibur Sport, Lode, Groningen, The Netherlands).

Figure 1: Schematic representation of the general design.Time interval between tests is specified in days (d). Data are presented as means ± standard deviation respectively, with minimum (min) and maximum (max) values (Egger. 2014).

As the overview of the study design in Figure 1 tells you, each test type was completed twice. Once after the ingestion of 0.3 g/kg sodium bicarbonate (yes, that's roughly 24g for someone who weighs 80g and should not be consumed too fast, because otherwise it may trigger diarrhea) or a placebo supplement in form of 4 g sodium chloride that was chosen to make sure that any benefits that were observed were due to the natrium, not the bicarbonate content of sodium bicarbonate.
Both the plain salt and the sodium bicarbonate were solved in 0.7 l water. The outcome measures were simple: Only if the subjects were able to pedal significantly longer until they were exhausted in the standardized constant load test, sodium bicarbonate could be considered to have practically relevant performance enhancing effects (maximum performance in the stepwise incremental exercise test, i.e. maximal workload and VO2peak were used as secondary outcomes).

Figure 2: Blood lactate (BLa) concentrations after ingestion (post drink) and during constant load tests (mean ± SD) for the BICA and placebo trials (Egger. 2014)

The other parameters the scientists measured, i.e. the blood lactate [BLa], pH, and bicarbonate concentration, were merely used determine the mechanisms for the potential improvements in exercise performance.

Speaking of auxiliary measures, if you take a look at Figure 2 you will see that the blood pH dropped significantly right after the ingestion of the bicarbonate supplement and remained "low" throughout the trial and afterwards. An observation that does not come unexpected. Previous trials have after all shown that it's the ability of bicarbonate to blunt the high-intensity exercise related perturbations in both blood and muscle acid-base that keeps the maximal work rate up and leads to performance increases compared to placebo supplements.
These performance decrements are caused by the accumulation of hydrogen ions (H+) in the myoplasm and their detrimental effects on myofilament interaction, glycolytic flux and sarcoplasmatic reticulum function. As Egger et al. point out

"[t]he ability of the body to prevent or delay these force limiting processes is determined by the capacity of its intrinsic buffering systems, which counteract the accumulation of H+ both inside and outside the cell," (Egger. 2014)

which explains why the benefits of both beta alanine (which increases the intra-cellular buffering capacity) and bicarbonate are most pronounced in athletes competing in high intensity sports.

Figure 3: Time to exhaustion and maximal workload (total) and maximal workload at the individual anaerobic threshold (IAT) during the bicarbonate and placebo trials (Egger. 2014).

Apropos ergogenic effects: I already gave it away in the headline. The consumption of the bicarbonate supplement lead to immediate increases in the time to exhaustion with 49.5 ±11.5 min being the maximum in the bicarbonate and 45.0±9.5 min being the maximum in the placebo condition.

The maximal workload in the stepwise incremental tests (BICA: 341±66 W; placebo: 339±67 W) and workload at IAT (BICA: 234±5.5 W; placebo 233±5.7 W), on the other hand, did not differ significantly.
References:

• Egger F, Meyer T, Such U, Hecksteden A. "Effects of Sodium Bicarbonate on High-Intensity Endurance Performance in Cyclists: A Double-Blind, Randomized Cross-Over Trial". PLoS ONE 9.12 (2014): e114729.
• Hobson, Ruth M., et al. "Effects of β-alanine supplementation on exercise performance: a meta-analysis." Amino acids 43.1 (2012): 25-37.