|The stack (ingredients on the right) was ingested twice daily.|
It has been a while since the last study on sodium bicarbonate’s usefulness has found its way to the SuppVersity.
And, technically speaking, the latest RCT by scientists from the Department of Sports Training at the Jerzy Kukuczka Academy of Physical Education in Katowice, Poland, and colleagues from the Miller School of Medicine, at the University of Miami is a “bicar-bonate”, but not a “sodium bicarbonate” study.
How’s that? Well, the scientists did exactly what some of you have already suggested: They combined sodium- and potassium-bicarbonate (the authors write di-carbonate, which is obviously the same) at a dosage of 3g, each, to achieve a balance between the two macro-minerals and topped the bicarbonates up with 1000 mg (600 mg + 400 mg) calcium phosphate and calcium citrate, 1000 mg potassium citrate, and 1000 mg magnesium citrate.
This Na/K-Bicarb + Ca/K/Mg-Citrate super-stack (or placebo) was consumed twice a day by N=26 well-trained soccer players, who compete at the elite Polish league, during an 11-day training camp in Spain. Unfortunately, the exact details about the way the supplement was administered is not adequately described in the FT, where it says:
“The players from the experimental group ingested a single dose of 3000 mg sodium di-carbonate, 3000 mg potassium di-carbonate (6 caps containing 500 mg each), 1000 mg (600 mg + 400 mg) calcium phosphate and calcium citrate, 1000 mg potassium citrate, and 1000 mg magnesium citrate twice a day, 90 min before each practice session. The control group ingested identical capsules containing cornstarch. Supplements were taken with plenty of water (600 mL). The supplementation protocol included an additional dose of di-carbonates and minerals, 90 min before the exercise test protocol and the day before the test” (Chycki 2018).
Only in conjunction with the information from the following “study protocol”-section it becomes clear – or I should say it is my interpretation that …
- …the performance tests [Running-Based Anaerobic Sprint Test (RAST) protocol which involved 6 × 30 m maximal sprint efforts, separated by 10 s of active recovery] were carried out at baseline and after 9 days of supplementation,
- … the supplements were consumed 90 minutes before the regular AM and PM training (or “practice”, as Chycki et al. call it) on day 2-7, i.e. chronically(!),
- … on day 8 the subjects consumed only one serving of the macromineral stack (or cornstarch placebo) and there was either no soccer training at all or, at least, no PM session, so that they would have rested for 24h before the performance test on day 9,
- … on the testing day, the subjects reported to the lab in the AM fasted and consumed another mineral stack 90 minutes before the RAST protocol,
|Table 1: The authors found statistically significant differences between baseline and post-intervention period at rest, post ingestion, and after exercise for the experimental group for all parameters| Note: d, effect size (≥ 0.5 = LARGE effect – found for all parameters); p, statistical significance; F, value of analysis of variance function (Chycki 2018).|
You have to read the captions carefully, though…
because, otherwise, you will miss that the data in Table 1 shows the intra-group change of the given parameters. In other words: After having ingested the macro-mineral-stack the lactate levels, the pH, the HCO3 and Mg2+ content, as well as the performance n the 6x30m sprint test improved compared to baseline. Large effects compared to placebo were observed “only” for:
- lactate immediately after the workout (d = 0.884 |large; p = 0.0001)
- blood pH at rest (d = 0.780 | large; p = 0.0001), and
- the HCO3− content of the subjects’ blood at rest (d = 0.989 | large; p = 0.0001)
Those of you who haven’t read that many SuppVersity articles, yet, must also be aware that “Cohen’s d” as a measure of the effect size does not say that this is “large” = “practically relevant” difference.
I have to emphasize once more While this can be (and often is) the case, it only tells you that the inter-group difference was large even when the standard deviations are considered.
Figure 1: Sprint performance times in seconds before and after the 9-day training + supplementation intervention in the experimental vs. placebo group; left: with a similarly messed up vertical axis scale as in the original from the study / right: with a transparent vertical scale that shows that the statistical “effect size” is large, the relative improvement, on the other hand, rather low [†Note: I cannot guarantee that the data is 100% accurate, because the plotted and discussed data in the stud at hand contradict each other and I had to extrapolate the non-reported absolutes for the placebo group].
I guess I’ll simply show you the subjects’ actual sprinting performance, …because the graph illustrates that very nicely. While you’re looking at Figure 1, there are yet two things you should be aware of:
- Since the scientists’ plot of the data is totally messed up (click here to see it), I had to redo the graph for the sprint times based on the values given in the text, i.e. the 6 × 30 m running test improved from by 2.3% 25.09 s to 24.53 s (p = 0.00001) in the experimental group and by only non-significant 1% in the control group (I extrapolated the absolute values in the control group, which were not reported from inter-group difference in the scientists’ own IMHO wrongly labeled graph).
- Furthermore, I decided to give you both, the equivalent of the scientists’ own plot which uses a scale that totally exaggerates the improvement (Note: the original captions cannot be correct, because then, the sprint times would have improved by ~50% – that’s unrealistic and not in line with any of the other data reported in the text) and my “fair” plot, from which you can see that the real-world effect is not exactly as large as a misinterpretation of “large effect sizes” would suggest.
- Chycki, Jakub, et al. “Chronic Ingestion of Sodium and Potassium Bicarbonate, with Potassium, Magnesium and Calcium Citrate Improves Anaerobic Performance in Elite Soccer Players.” Nutrients 10.11 (2018): 1610.
- Luft, Friedrich C., et al. “Sodium bicarbonate and sodium chloride: effects on blood pressure and electrolyte homeostasis in normal and hypertensive man.” Journal of hypertension 8.7 (1990): 663-670.