Dalle, S., Koppo, K. and Hespel, P.. Journal of Science and Medicine in Sport, 24 (3), 2021.
Oral sodium bicarbonate intake (NaHCO3) may improve performance in short maximal exercise by inducing metabolic alkalosis. However, it remains unknown whether NaHCO3 also enhances all-out performance at the end of an endurance competition.
The present study investigated whether stacked sodium bicarbonate loading in the hours before and during a prolonged endurance exercise bout, can result in a higher HCO3− concentration by the time high anaerobic capacity is needed to be successful in a final all-out exercise bout or sprint. The authors hypothesized that stacked NaHCO3 loading by increasing extracellular buffer capacity can improve performance in a short all-out exercise bout at the end of a 3-h simulated cycling race.
What they did
Eleven trained male cyclists (22.3 (18.3–25.3) years; 73.0 (61.5–88) kg; VO2max: 63.7 (57–72) ml kg−1 min−1) ingested either 300 mg kg−1 body weight NaHCO3 (BIC) or NaCl (PL). NaHCO3 or NaCl was supplemented prior to (150 mg kg−1) and during (150 mg kg−1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end.
The race simulation consisted of six consecutive 30-min blocks during which exercise intensity was varied per 5-min intervals between 60 and 90% of LT taken from the preliminary testing.
Capillary blood samples were collected for determination of blood pH, lactate and HCO3− concentrations.
The design was a double-blind randomized placebo-controlled cross-over study.
What they found
NaHCO3 intake improved mean power during 90S by ∼3% (541 ± 59 W vs. 524 ± 57 W in PL, p = 0.047, Cohen’s D = 0.28, medium). Peak blood lactate concentration and heart rate at the end of 90S were higher (p < 0.05) in BIC (16.2 ± 4.1 mmol l 1, 184 ± 7 bpm) than in PL (12.4 ± 4.2 mmol l−1, 181 ± 5 bpm). NaHCO3 ingestion increased blood [HCO3-] (31.5 ± 1.3 vs. 24.4 ± 1.5 mmol l−1 in PL, p < 0.001) and blood pH (7.50 ± 0.01 vs. 7.41 ± 0.03 in PL, p < 0.05) prior to 90S.
For the first time, it is shown that sodium bicarbonate loading prior to and during a simulated cycling race improves a 90-sec all-out sprint at the end of the race. This provides new opportunities for endurance athletes (e.g. road cyclists) to diversify a nutritional ergogenic aid previously only used in shorter events (prologues, time trials, track racing) to use in a wider range of events.
Stacked sodium bicarbonate loading of 0.3 g/kg body mass prior to and during cycling did not elicit gastrointestinal disturbances. Attention is required to ensure the dosage is kept small but regular in order to avoid GI upset. Combination of NaHCO3 with a high-carbohydrate meal can facilitate the development of blood alkalosis as well as reduce the incidence of GI symptoms.
The authors noted that many of the prior research surrounding sodium bicarbonate effects on short duration exercise performance have failed to show benefits in untrained individuals. Further research is required in endurance type events to elicit whether the performance benefits shown in this study are also reflected in untrained individuals.
Coaches and athletes should test the supplementation protocol on training sessions before its application in competition.
This may prove to be a breakthrough study for the use of bicarbonate supplementation as an ergogenic aid in endurance events. Many sports (road cycling, open water swimming, cross country skiing, running, etc.) are decided by a high intensity anaerobic effort at the completion of a long distance aerobic effort. If a 3% increase in power output for this type of effort can be supported by subsequent studies we could see many athletes adding NaHCO3 to their bidons in the future.
A real bike race often plays out quite differently to the mock race used in the testing protocol of this study design. The regular accelerations well over LT (lactate threshold), typical of a road race, may result in more utilisation of the NaHCO3 buffer prior to the final decisive sprint. Thus the amount of bicarbonate ingested in this study may then not be enough to provide significant performance benefit, more research required!
More Bits on Bicarb here: https://pubmed.ncbi.nlm.nih.gov/27399820/
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Until then, I’ll keep reading the research papers so you can spend more time on the bike.