Effect of sodium bicarbonate supplementation on two different performance indicators in sports: a systematic review with meta-analysis

The effect of diminished metabolic acidosis on thermoregulatory response during exercise

It was reported that metabolic acidosis inhibits the activity of warm-sensitive hypothalamic neurons. The present study was designed to test the hypothesis that metabolic alkalosis may improve heat loss during intensive exercise in men. Fifteen male subjects aged 22-24 years were submitted to incremental exercise on two randomized occasions one week apart. During the bicarbonate trial exercise was preceded by ingestion of NaHCO3 at a dose 250 mg/kg whilst during the placebo trial lactose was administered. Exercise load was increased every 3 min by 30 W until volitional exhaustion. Ambient temperature was kept at 23-24°C and humidity 50-60%. Tympanic and skin temperatures were recorded and the rate of sweating was assayed by humidity measurement of nitrogen flowing through a capsule attached to the mid posterior chest. Total sweat loss was determined by the changes in body mass. Venous blood samples were taken before exercise and at the end of each workload for determination of acid-base parameters. The subjects attained similar maximal workload in the two tests (260 ± 6 W) with heart rate 185 ± 6 beats/min. Blood concentration of hydrogen ions was lower (p < 0.001) in the bicarbonate than in the placebo trial throughout the whole exercise period. There were no significant differences between these tests in tympanic and mean skin temperatures, sweating rate and total sweat loss. The present data showed that in men attenuation of metabolic acidosis by bicarbonate ingestion did not influence thermoregulation during incremental exercise performed until volitional exhaustion, possibly due to too short duration of exertional uncompensated metabolic acidosis.

Acute and Chronic Performance Enhancement in Rowing: A Network Meta-analytical Approach on the Effects of Nutrition and Training

INTRODUCTION

This systematic review and network meta-analysis assessed via direct and indirect comparison the occurrence and magnitude of effects following different nutritional supplementation strategies and exercise interventions on acute and chronic rowing performance and its surrogates.

METHODS

PubMed, Web of Science, PsycNET and SPORTDiscus searches were conducted until March 2022 to identify studies  that met the following inclusion criteria: (a) controlled trials, (b) rowing performance and its surrogate parameters as outcomes, and (c) peer-reviewed and published in English. Frequentist network meta-analytical approaches were calculated based on standardized mean differences (SMD) using random effects models.

RESULTS

71 studies with 1229 healthy rowers (aged 21.5 ± 3.0 years) were included and two main networks (acute and chronic) with each two subnetworks for nutrition and exercise have been created. Both networks revealed low heterogeneity and non-significant inconsistency (I² ≤ 35.0% and Q statistics: p ≥ 0.12). Based on P-score rankings, while caffeine (P-score 84%; SMD 0.43) revealed relevantly favorable effects in terms of acute rowing performance enhancement, whilst prior weight reduction (P-score 10%; SMD - 0.48) and extensive preload (P-score 18%; SMD - 0.34) impaired acute rowing performance. Chronic blood flow restriction training (P-score 96%; SMD 1.26) and the combination of β-hydroxy-β-methylbutyrate and creatine (P-score 91%; SMD 1.04) induced remarkably large positive effects, while chronic spirulina (P-score 7%; SMD - 1.05) and black currant (P-score 9%; SMD - 0.88) supplementation revealed impairment effects.

CONCLUSION

Homogeneous and consistent findings from numerous studies indicate that the choice of nutritional supplementation strategy and exercise training regimen are vital for acute and chronic performance enhancement in rowing.

Total Carbon Dioxide (TCO2) Concentrations in Thoroughbred and Quarter Racehorses in Louisiana

The TCO₂ (total carbon dioxide) test is performed on the blood of racehorses as a means of combatting the practice of administering alkalizing agents. This study evaluated serum TCO₂ concentrations and factors influencing concentration of TCO₂ in Thoroughbred and Quarter Horses. The normality of data were evaluated with a Shapiro-Wilk test. Mann-Whitney tests and Kruskal-Wallis tests were used against different effects. When a fixed effect was detected, Dunn's post-hoc comparisons were performed. The median pre-race serum TCO₂ concentration (32.20 mmol/L (interquartile range (IQR): 30.80-33.50)) was higher than that of post-race samples (26.70 mmol/L (IQR: 24.55-29.25)) (P < .0001). The median TCO₂ concentrations in pre-race samples were different between Thoroughbred (32.40 mmol/L (IQR: 30.90-33.60)) and Quarter Horses (31.30 mmol/L (IQR: 30.00-32.50)) (P < .0001). The median pre-race TCO₂ concentrations were 32.75 (IQR: 31.40-33.90), 31.40 (IQR: 29.80-32.80), 32.50 (IQR: 31.20-33.88), and 31.60 (IQR 30.00-32.70) mmol/L in racehorses at Fair Grounds, Louisiana Downs, Delta Downs, and Evangeline Downs racetracks, respectively (P < .0001). The total serum TCO₂ concentrations in Thoroughbred and Quarter Horse racehorses were affected by seasonal temperature variation (P < .0001). A smaller sample size was available for post-race samples (n = 205) and Quarter Horse pre-race samples (n = 351). The results of this study indicated that the breed, seasonal temperature variation, pre-race or post-race sampling, and track location are strongly correlated to total TCO₂ concentrations. It was not clear whether the statistically significant differences in TCO₂ levels among racetracks in Louisiana were due to location of racetracks and/or seasonal temperature variation.

Effects of Combined Creatine and Sodium Bicarbonate Supplementation on Soccer-Specific Performance in Elite Soccer Players: A Randomized Controlled Trial

Creatine and sodium bicarbonate are both ergogenic aids for athletic performance. However, research on the combined creatine and sodium bicarbonate (CSB) supplementation in soccer is limited. This study investigated the changes in soccer-specific performance in elite soccer players after supplementing with CSB. Twenty well-trained elite soccer players participated in the study (age: 20.70 ± 1.08 years; height: 173.95 ± 2.81 cm; body weight: 70.09 ± 3.96 kg; soccer experience: 8 years; average training hours per week: 20 h). The participants were randomly allocated into CSB groups (CSB, n = 10) and placebo groups (PLA, n = 10). The CSB group took creatine (20 g/day) and sodium bicarbonate (0.3 g/kg/day); these two supplements were taken four times a day (morning, afternoon, evening, and before sleep) for seven days. Soccer-specific performance was assessed via 10- and 30-m sprint, coordination, arrowhead agility, and Yo-Yo intermittent recovery level 1 tests. Compared to the PLA group, the CSB group performed better in the 30-m sprint (CSB: −3.6% vs. PLA: −0.6%, p = 0.007, effect size (ES): 2.3) and both right and left arrowhead agility (right: CSB: −7.3% vs. PLA: −0.7%, p < 0.001, ES: 2.8; left: CSB: −5.5% vs. PLA: −1.2%, p = 0.001, ES: 2.1) tests. However, there were no differences in 10 m sprints, coordination, and Yo-Yo intermittent recovery level 1 tests between the two groups (p > 0.05). In conclusion, CSB supplementation improved sprint and agility in elite soccer players. However, it is still unclear whether such effect is synergistic effect of two supplements or the result of either one of them. Therefore, caution should be taken when interpreting the results, and the limitations should be examined further in future studies.