The blood acid base and gastrointestinal response to three different forms of sodium citrate encapsulation

Enterically coated (ENT) or delayed-release (DEL) capsules may lessen gastrointestinal symptoms (GIS) following acute sodium citrate (SC) ingestion, although the effects on blood acid-base balance are undetermined. Fourteen active males ingested 0.4 g.kg-1 body mass (BM) SC, within gelatine (GEL), DEL and ENT capsules or 0.07 g.kg-1 BM sodium chloride control (CON). Blood acid-base balance and GIS were measured for 4 h. Ingestion form had no significant effect on total GIS experienced (GEL: 2 ± 7; DEL: 1 ± 8; ENT: 1 ± 4 AU). Most (7/14) participants experienced zero symptoms throughout. Peak GIS typically emerged ≤100 min post-ingestion, with a similar time to reach peak GIS between ingestion form (GEL: 36 ± 70; DEL: 13 ± 28; ENT: 15 ± 33 AU). Blood [HCO3-] was significantly higher with ENT versus GEL (ENT: 29.0 ± 0.8; GEL: 28.5 ± 1.1 mmol.L-1, P = 0.037). Acute ingestion of a reduced SC dose elicited minimal GIS, producing significant changes in blood [HCO3-] from rest, irrespective of ingestion form (GEL: 6.0 ± 0.9; DEL: 5.1 ± 1.0; ENT: 6.2 ± 0.8 mmol.L-1). The necessity of individualized ingestion strategies is also challenged, with sustained increases in blood [HCO3-] of ≥4 mmol.L-1 for up to 153 min highlighted. If commencing exercise at peak alkalosis augments subsequent performance above starting at a standardized time point where HCO3- is still elevated remains unclear.

The effect of sodium bicarbonate mini-tablets ingested in a carbohydrate hydrogel system on 40 km cycling time trial performance and metabolism in trained male cyclists

INTRODUCTION

Sodium bicarbonate (NaHCO3) ingestion has been found to be ergogenic in high-intensity exercise that ranges from 1 to 10 min; however, limited studies have investigated high-intensity exercise beyond this duration.

PURPOSE

The present study aimed to determine the effect of NaHCO3 ingested using a carbohydrate hydrogel delivery system on 40 km time trial (TT) performance in trained male cyclists.

METHODS

Fourteen trained male cyclists ingested 0.3 g kg-1 BM NaHCO3 (Maurten AB, Sweden) to determine individualised peak alkalosis, which established time of ingestion prior to exercise. Participants completed a 40 km familiarisation TT, and two 40 km experimental TTs after ingestion of either NaHCO3 or placebo in a randomised, double-blind, crossover design.

RESULTS

NaHCO3 supplementation improved performance (mean improvement = 54.14 s ± 18.16 s; p = 0.002, g = 0.22) and increased blood buffering capacity prior to (HCO3- mean increase = 5.6 ± 0.2 mmol L-1, p < 0.001) and throughout exercise (f = 84.82, p < 0.001, pη2 = 0.87) compared to placebo. There were no differences in total gastrointestinal symptoms (GIS) between conditions either pre- (NaHCO3, 22 AU; Placebo, 44 AU; p = 0.088, r = 0.46) or post-exercise (NaHCO3, 76 AU; Placebo, 63 AU; p = 0.606, r = 0.14).

CONCLUSION

The present study suggests that ingesting NaHCO3 mini-tablets in a carbohydrate hydrogel can enhance 40 km TT performance in trained male cyclists, with minimal GIS. This ingestion strategy could therefore be considered by cyclists looking for a performance enhancing ergogenic aid.

Effects of acute and multi-day low-dose sodium bicarbonate intake on high-intensity endurance exercise performance in male recreational cyclists

PURPOSE

This study aimed to compare the effects of acute and multi-day low-dose sodium bicarbonate (SB) intake on high-intensity endurance exercise performance.

METHODS

In a randomized, double-blind, cross-over design, twelve recreational male cyclists (age: 31.17 ± 4.91 years; V ˙ O2peak: 47.98 ± 7.68 ml·kg-1·min-1) completed three endurance performance tests following acute SB (ASB, 0.2 g·kg-1 SB), multi-day SB (MSB, 0.2 g·kg-1·day-1 SB for four days), and placebo (PLA) intake. The high-intensity endurance performance was assessed with a cycling exercise test, wherein participants cycled on a bicycle ergometer at 95% of the predetermined anaerobic threshold for 30 min, followed by a time-to-exhaustion test at 110% of the anaerobic threshold. Data were analyzed using one-way and two-way repeated-measures ANOVA.

RESULTS

Significant main effects of supplementation protocol were evident in pre-exercise bicarbonate concentrations (F = 27.93; p < 0.01; partial eta squared (η2) = 0.72; false discovery rate (FDR)-adjusted p value = 0.001). Prior to performance test, blood bicarbonate concentrations were significantly higher in MSB (25.78 ± 1.63 mmol·L-1 [95% CI 26.55-28.44] (p < 0.001; FDR-adjusted p value = 0.001)) and ASB (27.49 ± 1.49 mmol·L-1 [95% CI 24.75-26.81] (p < 0.001; FDR-adjusted p value = 0.007)) compared to PLA (23.75 ± 1.40 mmol·L-1 [95% CI 22.86 to 24.64]). Time-to-exhaustion increased in MSB (54.27 ± 9.20 min [95% CI 48.43-60.12]) compared to PLA (49.75 ± 10.80 min [95% CI 42.89-56.62]) (p = 0.048); however, this increase in MSB did not reach the significance threshold of 1% FDR (FDR-adjusted p value = 0.040). No significant difference was noted in exhaustion times between ASB (51.15 ± 8.39 min [95% CI 45.82-56.48]) and PLA (p > 0.05).

CONCLUSION

Both acute and multi-day administration of low-dose SB improves buffering system in cyclists; nevertheless, neither intervention demonstrates sufficient efficacy in enhancing high-intensity endurance performance.

Naturally Bicarbonated Water Supplementation Does Not Improve Anaerobic Cycling Performance or Blood Gas Parameters in Active Men and Women

The completion of high-intensity exercise results in robust perturbations to physiologic homeostasis, challenging the body's natural buffering systems to mitigate the accumulation of metabolic by-products. Supplementation with bicarbonate has previously been used to offset metabolic acidosis, leading to improvements in anaerobic exercise performance.

PURPOSE

The purpose of this study was to investigate the presence of ergogenic properties in naturally occurring low-dose bicarbonated water and their effects on anaerobic cycling performance and blood gas kinetics in recreationally active men and women.

METHODS

Thirty-nine healthy, recreationally active men and women (28.1 ± 8.0 years, 169.8 ± 11.7 cm, 68.9 ± 10.8 kg, 20.1 ± 7.9% fat, V˙O2peak: 42.8 ± 7.6 mL/kg/min) completed two separate testing sessions consisting of 15 cycling sprints (10 s sprint, 20 s active rest) against 7.5% of their body mass. Using a randomized, double-blind, placebo-controlled, parallel group study design, study participants consumed a 10 mL/kg dose of either spring water (SW) or bicarbonated mineral water (BMW) (delivering ~3 g/day of bicarbonate) for 7 days. Venous blood was collected before, immediately after, and 5 and 10 min after the sprint protocol and was analyzed for lactate and a series of blood gas components. After the completion of 15 cycling sprints, averages of peak and mean power for bouts 1-5, 6-10, and 11-15, along with total work for the entire cycling protocol, were calculated. All performance and blood gas parameters were analyzed using a mixed-factorial ANOVA.

RESULTS

pH was found to be significantly higher in the BMW group immediately after (7.17 ± 0.09 vs. 7.20 ± 0.11; p = 0.05) and 10 min post exercise (7.21 ± 0.11 vs. 7.24 ± 0.09; p = 0.04). A similar pattern of change was observed 5 min post exercise wherein pH levels in the SW group were lower than those observed in the BMW group; however, this difference did not achieve statistical significance (p = 0.09). A statistical trend (p = 0.06) was observed wherein lactate in the BMW group tended to be lower than in the SW group 5 min post exercise. No significant main effect for time (p > 0.05) or group × time interactions (p > 0.05) for the total work, average values of peak power, or average values of mean power were observed, indicating performance was unchanged.

CONCLUSION

One week of consuming water with increased bicarbonate (10 mL/kg; ~3 g/day bicarbonate) showed no effect on anaerobic cycling performance. BMW decreased blood lactate concentrations 5 min after exercise and increased blood pH immediately and 10 min after exercise.

Sodium Bicarbonate Ingestion in a Fasted State Improves 16.1-km Cycling Time-Trial Performance

PURPOSE

The use of sodium bicarbonate (SB) as a preexercise ergogenic aid has been extensively studied in short-duration high-intensity exercise. Very few studies have considered the effects of SB ingestion before prolonged high-intensity exercise. The aim of the present study was to determine the effects of a 0.3 g·kg -1 body mass dose of SB ingested before the start of a 16.1-km cycling time trial in cyclists.

METHOD

Ten trained male cyclists (age, 31.1 ± 9 yr; height, 1.84 ± 0.05 m; body mass, 82.8 ± 8.5 kg; and V̇O 2peak , 60.4 ± 3.1 mL·kg -1 ·min -1 ) completed this study. Participants ingested 0.3 g·kg -1 in gelatine (SB-G) and enteric capsules (SB-E) 1 wk apart to determine individualized time-to-peak alkalosis for each ingestion form. Using a randomized crossover design, participants then performed simulated 16.1-km time trials after ingestion of SB-G, SB-E, or a placebo.

RESULTS

There were significant differences in performance between the SB and placebo ingestion strategies ( f = 5.50, P = 0.014, p η2 = 0.38). Performance time was significantly improved by SB ingestion (mean improvement: 34.4 ± 42.6 s ( P = 0.031) and 40.4 ± 45.5 s ( P = 0.020) for SB-G and SB-E, respectively) compared with the placebo. Gastrointestinal symptoms were lower after SB-E compared with SB-G (36.3 ± 4.5 vs 5.6 ± 3.1 AU, P < 0.001, g = 7.09).

CONCLUSIONS

This study demonstrates that increased buffering capacity after acute preexercise SB ingestion can improve endurance cycling time-trial performances. The use of SB could be considered for use in 16.1-km cycling time trials, but further work is required to establish these effects after a preexercise meal.

The effects of enteric-coated sodium bicarbonate supplementation on 2 km rowing performance in female CrossFit® athletes

PURPOSE

Sodium bicarbonate (SB) supplementation can improve exercise performance, but few studies consider how effective it is in female athletes. The aim of the study was to establish the effect of individually timed pre-exercise SB ingestion on 2 km rowing time trial (TT) performance in female athletes.

METHODS

Eleven female CrossFit® athletes (mean ± SD age, 29 y ± 4 y, body mass, 64.5 kg ± 7.1 kg, height, 1.7 m ± 0.09 m, peak oxygen uptake [VO_2peak], 53.8 ± 5.7 mL·kg^-1∙min^-1). An initial trial identified individual time-to-peak [HCO₃^-] following enteric-coated 0.3 g·kg^-1 BM SB ingestion_. Participants then completed a 2 km TT familiarisation followed by a placebo (PLA) or SB trial, using a randomised cross-over design.

RESULTS

The ingestion of SB improved rowing performance (514.3 ± 44.6 s) compared to the PLA (529.9 ± 45.4 s) and FAM trials (522.2 ± 43.1 s) (p = 0.001, pη² = 0.53) which represents a 2.24% improvement compared to the PLA. Individual time-to-peak alkalosis occurred 102.3 ± 22.1 min after ingestion (range 75-150 min) and resulted in increased blood [HCO_3-] of 5.5 ± 1.5 mmol⋅L^-1 (range = 3.8-7.9 mmol⋅L^-1). The change in blood [HCO_3-] was significantly correlated with the performance improvement between PLA and SB trials (r = 0.68, p = 0.020).

CONCLUSIONS

Ingesting a 0.3 g·kg^-1 BM dose of enteric-coated SB improves 2 km rowing performance in female athletes. The improvement is directly related to the extracellular buffering capacity even when blood [HCO_3-] does not change ≥ 5.0 mmol⋅L^-1.

The effects of sodium bicarbonate supplementation at individual time-to-peak blood bicarbonate on 4-km cycling time trial performance in the heat

The purpose of this study was to explore the effect of individualised sodium bicarbonate (NaHCO₃) supplementation according to a pre-established individual time-to-peak (TTP) blood bicarbonate (HCO₃^-) on 4-km cycling time trial (TT) performance in the heat. Eleven recreationally trained male cyclists (age: 28 ± 6 years, height: 180 ± 6 cm, body mass: 80.5 ± 8.4 kg) volunteered for this study in a randomised, crossover, triple-blind, placebo-controlled design. An initial visit was conducted to determine TTP HCO₃^- following 0.2 g.kg^-1 body mass (BM) NaHCO₃ ingestion. Subsequently, on three separate occasions, participants completed a 4-km cycling TT in the heat (30 degrees centigrade; °C) (relative humidity ∼40%) following ingestion of either NaHCO₃ (0.2 g.kg^-1 body mass), a sodium chloride placebo (0.2 g.kg^-1 BM; PLA) at the predetermined individual TTP HCO₃^-, or no supplementation (control; CON) . Absolute peak [HCO₃^-] prior to the 4-km cycling TT's was elevated for NaHCO₃ compared to PLA (+2.8 mmol.l^-1; p = 0.002; g = 2.2) and CON (+2.5 mmol.l^-1; p < 0.001; g = 2.1). Completion time following NaHCO₃ was 5.6 ± 3.2 s faster than PLA (1.6%; CI: 2.8, 8.3; p = 0.001; g = 0.2) and 4.7 ± 2.8 s faster than CON (1.3%; CI: 2.3, 7.1; p = 0.001; g = 0.2). These results demonstrate that NaHCO₃ ingestion at a pre-established individual TTP HCO₃^- improves 4-km cycling TT performance in the heat, likely through enhancing buffering capacity.Highlights This is the first time NaHCO₃ ingestion has been shown to improve 4-km cycling TT performance in conditions of high ambient heat.A smaller dose of NaHCO₃ (0.2 g.kg^-1 BM) is ergogenic in the heat, which is smaller than the dose typically ingested for sports performance (0.3 g.kg^-1 BM). This is important, as gastrointestinal discomfort is typically lower as the dose reduces.This study suggests that the individualised time-to-peak HCO₃^- ingestion strategy with lower doses of NaHCO₃ is an ergogenic strategy in conditions of high ambient heat.

Acute enteric-coated sodium bicarbonate has negligible effect on anaerobic performance but affects metabolomics and attenuates the gastrointestinal response

Sodium bicarbonate ingestion before exercise has a performance-enhancing effect on high-intensity exercise. However, gastrointestinal symptoms can be a problematic side-effect. Enteric-coated sodium bicarbonate can attenuate gastrointestinal symptoms following acute bicarbonate loading. In addition, the subsequent effects on exercise performance and metabolomics have not been investigated. The purpose of this study was to investigate the acute effect of enteric-coated sodium bicarbonate supplementation on the anaerobic performance, physiological profile, and symptoms of gastrointestinal discomfort after severe-intensity intermittent exercise. At the same time, targeted metabolomics was used to study the changes in urine metabolism after ingestion of enteric-coated sodium bicarbonate and to explore the characteristics of biological metabolism. In a randomized crossover design, twelve male college students completed four Wingate anaerobic 30-s cycling tests (WACT) after consuming a placebo (PL) and two experimental conditions: 0.2 g/kg body mass in enteric-coated sodium bicarbonate pills (ES) or general sodium bicarbonate pills (GS). Blood lactate (BLA), heart rate (HR), ratings of perceived exertion (RPE), and gastrointestinal–symptoms assessment questionnaire (GSAQ) were measured pre-exercise and post-exercise. In contrast, mean power (MP) and peak power (PP) were recorded immediately post-exercise. Urine samples were collected before formal tests and 50 min after the third WACT. Our findings indicate the following: 1) mean power and peak power showed no significant difference among conditions (MP: F_{2.0, 33} = 0.541, p = 0.587, η² = 0.032; PP: F_{2.0, 33} = 0.526, p = 0.596, η² = 0.031). The PP decline of the ES and GS after the third WACT was lower than that of the PL; 2) There were no significant differences in physiological responses, such as BLA (F_{2.0, 33.0}= 0.191, p = 0.827, η² = 0.011) and heart rate (F_{2, 33} = 0.418, p = 0.662, η² = 0.025), between the three conditions. Although blood lactate concentration after 10 min of the third WACT was lower with ES and GS than with placebo; 3) Fewer participants experienced gastrointestinal symptoms with enteric-coated than with general sodium bicarbonate; 4) The metabolites with differences among the three conditions 50 min after exercise were 3-phospho-d-glycerate, d-Glucose 6-phosphate, pyruvate, cis-aconitate, oxaloacetate, and citrate. ES had higher levels of 3-phospho-d-glycerate, d-Glucose 6-phosphate, pyruvate, and cis-aconitate than GS. The 3-phospho-d-glycerate, d-Glucose 6-phosphate, pyruvate, and cis-aconitate levels in GS were significantly lower than in PL. In contrast, the citrate level in GS was significantly higher than that in other experimental conditions. Compared to PL, the level of oxaloacetate was higher after exercise in ES. This data suggests that supplementation of enteric-coated and general sodium bicarbonate before exercise can alter energy metabolism following anaerobic exercise, involving the metabolism of 3-phospho-d-glycerate, D-Glucose 6-phosphate, pyruvate, cis-aconitate, oxaloacetate, citrate, and lactate. However, they do not affect anaerobic performance and blood lactate. The supplementation of acute enteric-coated sodium bicarbonate and general sodium bicarbonate can enhance some of the weak effects of blood lactate clearance during anaerobic exercise, which may be beneficial for glycolytic energy supply. In addition, enteric-coated sodium bicarbonate intake mitigates gastrointestinal symptoms compared to general sodium bicarbonate.

Effects of serial and acute enteric-coated sodium bicarbonate supplementation on anaerobic performance, physiological profile, and metabolomics in healthy young men

Background

Previous studies have reported that sodium bicarbonate ingestion may enhance high-intensity exercise performance and cause severe gastrointestinal distress. However, enteric-coated sodium bicarbonate may reduce gastrointestinal symptoms of sodium bicarbonate after oral administration. This remains to be confirmed. This study aimed to verify the effects of serial and acute enteric-coated sodium bicarbonate supplementation on anaerobic performance, physiological profile, and metabolomics in healthy young men.

Methods

Healthy young males (n = 12) ingested 0.2 g/kg body mass of enteric-coated sodium bicarbonate (ES) in serial enteric-coated sodium bicarbonate (SES, continuous ES supplementation for 5 days) and acute enteric-coated sodium bicarbonate (AES, acute ES supplementation before exercise) or a placebo (PL) in a randomized crossover design. After each supplement protocol, the participants completed four Wingate anaerobic tests (WAT). The first three Wingate tests (testing anaerobic capacity) were performed with a 5-min passive recovery between each. After the third Wingate test, participants were required to complete a 50-min recovery followed by a fourth WAT test (testing the recovery of anaerobic capacity after 50-min intervals). Blood lactate (BLA), heart rate (HR), and ratings of perceived exertion (RPE) were measured in all conditions during the test, as was the subjective gastrointestinal–symptoms assessment questionnaire (GSAQ). Mean power (MP) and peak power (PP) were recorded after four WATs. Urine samples were collected before the test and 50 min after the 3rd WAT.

Results

Serial enteric-coated sodium bicarbonate supplementation improved anaerobic capacity in the third bout of WATs, as observed based on an increase in mean power (SES vs. PL (613 ± 57 vs. 542 ± 64 W), P = 0.024) and peak power (SES vs. PL (1,071 ± 149 vs. 905 ± 150 W), P = 0.016). Acute ES supplementation did not affect anaerobic capacity. The occurrence of gastrointestinal symptoms after enteric-coated sodium bicarbonate supplementation was minimal and no difference compared to placebo in the current study. In particular, serial enteric-coated sodium bicarbonate supplementation had no gastrointestinal side effects before the test. The AES and SES groups had a trivial effect on blood lactate compared to the PLA group. There was no significant difference in HR and RPE among the three groups. Based on targeted metabolomics analysis, the 50 min after the third WAT, the levels of lactate (P &lt; 0.001), L-Malic acid (P &lt; 0.05), and oxaloacetate (P &lt; 0.05) were significantly higher in the SES group than in the PL group. Compared with the AES group, the levels of lactate and fumarate in the SES group were significantly increased (P &lt; 0.05).

Conclusions

Our study indicates that serial enteric-coated sodium bicarbonate supplementation positively improves anaerobic performance among healthy young men. However, acute ingestion of enteric-coated sodium bicarbonate did not improve anaerobic exercise performance. Either with serial or acute supplementation doses, enteric-coated sodium bicarbonate produced fewer gastrointestinal symptoms and no difference compared to placebo, especially with no gastrointestinal side effects after serial supplementation. Serial and acute supplementation of enteric-coated sodium bicarbonate might tend to promote lactate clearance. Furthermore, serial enteric-coated sodium bicarbonate ingestion may cause changes in the metabolism of lactate, L-Malic acid, oxaloacetate, and fumarate 50 min after exercise, which presumably may promote the tricarboxylic acid cycle and lactate clearance.

Extracellular Buffering Supplements to Improve Exercise Capacity and Performance: A Comprehensive Systematic Review and Meta-analysis

BACKGROUND

Extracellular buffering supplements [sodium bicarbonate (SB), sodium citrate (SC), sodium/calcium lactate (SL/CL)] are ergogenic supplements, although questions remain about factors which may modify their effect.

OBJECTIVE

To quantify the main effect of extracellular buffering agents on exercise outcomes, and to investigate the influence of potential moderators on this effect using a systematic review and meta-analytic approach.

METHODS

This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Three databases were searched for articles that were screened according to inclusion/exclusion criteria. Bayesian hierarchical meta-analysis and meta-regression models were used to investigate pooled effects of supplementation and moderating effects of a range of factors on exercise and biomarker responses.

RESULTS

189 articles with 2019 participants were included, 158 involving SB supplementation, 30 with SC, and seven with CL/SL; four studies provided a combination of buffering supplements together. Supplementation led to a mean estimated increase in blood bicarbonate of + 5.2 mmol L^-1 (95% credible interval (CrI) 4.7-5.7). The meta-analysis models identified a positive overall effect of supplementation on exercise capacity and performance compared to placebo [ES_0.5 = 0.17 (95% CrI 0.12-0.21)] with potential moderating effects of exercise type and duration, training status and when the exercise test was performed following prior exercise. The greatest ergogenic effects were shown for exercise durations of 0.5-10 min [ES_0.5 = 0.18 (0.13-0.24)] and > 10 min [ES_0.5 = 0.22 (0.10-0.33)]. Evidence of greater effects on exercise were obtained when blood bicarbonate increases were medium (4-6 mmol L^-1) and large (> 6 mmol L^-1) compared with small (≤ 4 mmol L^-1) [β_Small:Medium = 0.16 (95% CrI 0.02-0.32), β_Small:Large = 0.13 (95% CrI - 0.03 to 0.29)]. SB (192 outcomes) was more effective for performance compared to SC (39 outcomes) [β_SC:SB = 0.10 (95% CrI - 0.02 to 0.22)].

CONCLUSIONS

Extracellular buffering supplements generate large increases in blood bicarbonate concentration leading to positive overall effects on exercise, with sodium bicarbonate being most effective. Evidence for several group-level moderating factors were identified. These data can guide an athlete's decision as to whether supplementation with buffering agents might be beneficial for their specific aims.

Nutritional optimization for female elite football players-topical review

Women's football is an intermittent sport characterized by frequent intense actions throughout the match. The high number of matches with limited recovery time played across a long competitive season underlines the importance of nutritional strategies to meet these large physical demands. In order to maximize sport performance and maintain good health, energy intake must be optimal. However, a considerable proportion of female elite football players does not have sufficient energy intake to match the energy expenditure, resulting in low energy availability that might have detrimental physiologic consequences and impair performance. Carbohydrates appear to be the primary fuel covering the total energy supply during match-play, and female elite football players should aim to consume sufficient carbohydrates to meet the requirements of their training program and to optimize the replenishment of muscle glycogen stores between training bouts and matches. However, several macro- and micronutrients are important for ensuring sufficient energy and nutrients for performance optimization and for overall health status in female elite football players. The inadequacy of macro-and micronutrients in the diet of these athletes may impair performance and training adaptations, and increase the risk of health disorders, compromising the player's professional career. In this topical review, we present knowledge and relevant nutritional recommendations for elite female football players for the benefit of sports nutritionists, dietitians, sports scientists, healthcare specialists, and applied researchers. We focus on dietary intake and cover the most pertinent topics in sports nutrition for the relevant physical demands in female elite football players as follows: energy intake, macronutrient and micronutrient requirements and optimal composition of the everyday diet, nutritional and hydration strategies to optimize performance and recovery, potential ergogenic effects of authorized relevant supplements, and future research considerations.

International Society of Sports Nutrition position stand: sodium bicarbonate and exercise performance

Based on a comprehensive review and critical analysis of the literature regarding the effects of sodium bicarbonate supplementation on exercise performance, conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society: 1. Supplementation with sodium bicarbonate (doses from 0.2 to 0.5 g/kg) improves performance in muscular endurance activities, various combat sports, including boxing, judo, karate, taekwondo, and wrestling, and in high-intensity cycling, running, swimming, and rowing. The ergogenic effects of sodium bicarbonate are mostly established for exercise tasks of high-intensity that last between 30 s and 12 min. 2. Sodium bicarbonate improves performance in single- and multiple-bout exercise. 3. Sodium bicarbonate improves exercise performance in both men and women. 4. For single-dose supplementation protocols, 0.2 g/kg of sodium bicarbonate seems to be the minimum dose required to experience improvements in exercise performance. The optimal dose of sodium bicarbonate dose for ergogenic effects seems to be 0.3 g/kg. Higher doses (e.g., 0.4 or 0.5 g/kg) may not be required in single-dose supplementation protocols, because they do not provide additional benefits (compared with 0.3 g/kg) and are associated with a higher incidence and severity of adverse side-effects. 5. For single-dose supplementation protocols, the recommended timing of sodium bicarbonate ingestion is between 60 and 180 min before exercise or competition. 6. Multiple-day protocols of sodium bicarbonate supplementation can be effective in improving exercise performance. The duration of these protocols is generally between 3 and 7 days before the exercise test, and a total sodium bicarbonate dose of 0.4 or 0.5 g/kg per day produces ergogenic effects. The total daily dose is commonly divided into smaller doses, ingested at multiple points throughout the day (e.g., 0.1 to 0.2 g/kg of sodium bicarbonate consumed at breakfast, lunch, and dinner). The benefit of multiple-day protocols is that they could help reduce the risk of sodium bicarbonate-induced side-effects on the day of competition. 7. Long-term use of sodium bicarbonate (e.g., before every exercise training session) may enhance training adaptations, such as increased time to fatigue and power output. 8. The most common side-effects of sodium bicarbonate supplementation are bloating, nausea, vomiting, and abdominal pain. The incidence and severity of side-effects vary between and within individuals, but it is generally low. Nonetheless, these side-effects following sodium bicarbonate supplementation may negatively impact exercise performance. Ingesting sodium bicarbonate (i) in smaller doses (e.g., 0.2 g/kg or 0.3 g/kg), (ii) around 180 min before exercise or adjusting the timing according to individual responses to side-effects, (iii) alongside a high-carbohydrate meal, and (iv) in enteric-coated capsules are possible strategies to minimize the likelihood and severity of these side-effects. 9. Combining sodium bicarbonate with creatine or beta-alanine may produce additive effects on exercise performance. It is unclear whether combining sodium bicarbonate with caffeine or nitrates produces additive benefits. 10. Sodium bicarbonate improves exercise performance primarily due to a range of its physiological effects. Still, a portion of the ergogenic effect of sodium bicarbonate seems to be placebo-driven.

Nonplacebo Controls to Determine the Magnitude of Ergogenic Interventions: A Systematic Review and Meta-analysis

INTRODUCTION

Placebos are used as a control treatment that is meant to be indistinguishable from the active intervention. However, where substantive placebo effects may occur, studies that do not include a nonplacebo control arm may underestimate the overall effect of the intervention (active plus placebo components). This study aimed to determine the relative magnitude of the placebo effect associated with nutritional supplements (caffeine and extracellular buffers) by meta-analyzing data from studies containing both placebo and nonplacebo control sessions.

METHODS

Bayesian multilevel meta-analysis models were used to estimate pooled effects and express the placebo effect as a percentage of the overall intervention effect.

RESULTS

Thirty-four studies were included, with the median pooled effect size (ES0.5) indicating a very small (ES0.5 = 0.09 (95% credible interval (CrI), 0.01-0.17)) improvement in the performance of placebo compared with control. There was no moderating effect of exercise type (capacity or performance), exercise duration, or training status. The comparison between active intervention and control indicated a small to medium effect (ES0.5 = 0.37 (95% CrI, 0.20-0.56)). Expressed in relative terms, the placebo effect was equivalent to 25% (75% CrI, 16%-35%) and 59% (75% CrI, 34%-94%) of the total intervention effect for buffers and caffeine.

CONCLUSIONS

These results demonstrate a very small but potentially important placebo effect with nutritional supplementation studies. A substantive proportion of supplement effects may be due to placebo effects, with the relative proportion influenced by the magnitude of the overall ergogenic effect. Where feasible, intervention studies should use nonplacebo control-arm comparators to identify the proportion of the effect estimated to come from placebo effects and avoid underestimating the overall benefits that the physiological plus psychobiological aspects associated with an intervention provide in the real world.

Enteric-Coated Sodium Bicarbonate Attenuates Gastrointestinal Side-Effects

Enteric-formulated capsules can mitigate gastrointestinal (GI) side effects following sodium bicarbonate (NaHCO3) ingestion; however, it remains unclear how encapsulation alters postingestion symptoms and acid-base balance. The current study aimed to identify the optimal ingestion form to mitigate GI distress following NaHCO3 ingestion. Trained males (n = 14) ingested 300 mg/kg body mass of NaHCO3 in gelatin (GEL), delayed-release (DEL), and enteric-coated (ENT) capsules or a placebo in a randomized cross-over design. Blood bicarbonate anion concentration, potential hydrogen, and GI symptoms were measured pre- and postingestion for 3 hr. Fewer GI symptoms were reported with ENT NaHCO3 than with GEL (p = .012), but not with DEL (p = .106) in the postingestion phase. Symptom severity decreased with DEL (4.6 ± 2.8 arbitrary units) compared with GEL (7.0 ± 2.6 arbitrary units; p = .001) and was lower with ENT (2.8 ± 1.9 arbitrary units) compared with both GEL (p < .0005) and DEL (p = .044) NaHCO3. Blood bicarbonate anion concentration increased in all NaHCO3 conditions compared with the placebo (p < .0005), although this was lower with ENT than with GEL (p = .001) and DEL (p < .0005) NaHCO3. Changes in blood potential hydrogen were reduced with ENT compared with GEL (p = .047) and DEL (p = .047) NaHCO3, with no other differences between the conditions. Ingestion of ENT NaHCO3 attenuates GI disturbances for up to 3 hr postingestion. Therefore, ENT ingestion forms may be favorable for those who report GI disturbances with NaHCO3 supplementation or for those who have previously been deterred from its use altogether.

Dietary and Ergogenic Supplementation to Improve Elite Soccer Players' Performance

BACKGROUND

Soccer is an extremely competitive sport, where the most match important moments can be defined in detail. Use of ergogenic supplements can be crucial to improve the performance of a high-performance athlete. Therefore, knowing which ergogenic supplements are important for soccer players can be an interesting strategy to maintain high level in this sport until final and decisive moments of the match. In addition, other supplements, such as dietary supplements, have been studied and increasingly referenced in the scientific literature. But, what if ergogenic supplements were combined with dietary supplements? This review brings some recommendations to improve performance of soccer athletes on the field through dietary and/or ergogenic supplements that can be used simultaneously.

SUMMARY

Soccer is a competitive sport, where the match important moments can be defined in detail. Thus, use of ergogenic supplements covered in this review can improve performance of elite soccer players maintaining high level in the match until final moments, such as creatine 3-5 g day-1, caffeine 3-6 mg kg-1 BW around 60 min before the match, sodium bicarbonate 0.1-0.4 g kg-1 BW starting from 30 to 180 min before the match, β-alanine 3.2 and 6.4 g day-1 provided in the sustained-release tablets divided into 4 times a day, and nitrate-rich beetroot juice 60 g in 200 mL of water (6 mmol of NO3- L) around 120 min before match or training, including a combination possible with taurine 50 mg kg-1 BW day-1, citrulline 1.2-3.4 g day-1, and arginine 1.2-6 g day-1. Key Messages: Soccer athletes can combine ergogenic and dietary supplements to improve their performance on the field. The ergogenic and dietary supplements used in a scientifically recommended dose did not demonstrate relevant side effects. The use of various evidence-based supplements can add up to further improvement in the performance of the elite soccer players.

Post-exercise upside-down recovery does accelerate the heart rate recovery but does not improve subsequent sprint performance

BACKGROUND

Many recreational cyclists believe that lying upside-down after intense physical exertion speeds up physical recovery, enhancing subsequent exercise performance. However, the effectiveness of this technique has not yet been investigated.

METHODS

25 active cyclists (10 females/15 males; age 23.3±3.8 years old) performed a supramaximal 45-sec Wingate test before and after a 7-min recovery period at +45° or -20° of inclination, randomly, in a two-day cross-over protocol. The percentage decline of post- compared to pre-recovery Wingate performance was used to assess the recovery effectiveness. Kinetics of lactate, heart rate (HR), and mean blood pressure (MBP) during recovery were considered as physiological indices of recovery.

RESULTS

7 subjects (5 males) did not complete the +45° protocol due to pre-syncopal symptoms. The upside-down compared to the standing recovery did not change the subsequent Wingate performance, despite faster HR decline and cyclists' perception of better recovery. The upside-down recovery did not change the kinetics of lactate clearance but prevented the MBP fall.

CONCLUSIONS

Among subjects who fully completed the protocol, our data reveal the ineffectiveness of the upside-down recovery to enhance subsequent exercise performance, despite the faster HR decline and personal feeling of greater recovery may suggest that assumption. Such a better psychophysical feeling when upside-down compared to standing recovery may be associated with attenuation of post-exercise hypotension symptoms. This data suggest being cautious in basing the assessment of the athlete's recovery exclusively on the post-exercise kinetics of the HR.

Effect of Warm-Up and Sodium Bicarbonate Ingestion on 4-km Cycling Time-Trial Performance

PURPOSE

To examine whether an ecologically valid, intermittent, sprint-based warm-up strategy impacted the ergogenic capacity of individualized sodium bicarbonate (NaHCO3) ingestion on 4-km cycling time-trial (TT) performance.

METHODS

A total of 8 male cyclists attended 6 laboratory visits for familiarization, determination of time to peak blood bicarbonate, and 4 × 4-km cycling TTs. Experimental beverages were administered doubleblind. Treatments were conducted in a block-randomized, crossover order: intermittent warm-up + NaHCO3 (IWSB), intermittent warm-up + placebo, control warm-up + NaHCO3 (CWSB), and control warm-up + placebo (CWP). The intermittent warm-up comprised exercise corresponding to lactate threshold (5 min at 50%, 2 min at 60%, 2 min at 80%, 1 min at 100%, and 2 min at 50%) and 3 × 10-second maximal sprints. The control warm-up comprised 16.5 minutes cycling at 150 W. Participants ingested 0.3 g·kg body mass-1 NaHCO3 or 0.03 g·kg body mass-1 sodium chloride (placebo) in 5 mL·kg body mass-1 fluid (3:2, water and sugar-free orange squash). Paired t tests were conducted for TT performance. Hematological data (blood bicarbonate and blood lactate) and gastrointestinal discomfort were analyzed using repeated-measures analysis of variance.

RESULTS

Performance was faster for CWSB versus IWSB (5.0 [6.1] s; P = .052) and CWP (5.8 [6.0] s; P = .03). Pre-TT bicarbonate concentration was elevated for CWSB versus IWSB (+9.3 mmol·L-1; P < .001) and CWP (+7.1 mmol·L-1; P < .001). Post-TT blood lactate concentration was elevated for CWSB versus CWP (+2.52 mmol·L-1; P = .022). Belching was exacerbated pre-warm-up for IWSB versus intermittent warm-up +placebo (P = .046) and CWP (P = .027).

CONCLUSION

An intermittent, sprint-based warm-up mitigated the ergogenic benefits of NaHCO3 ingestion on 4-km cycling TT performance.

Extracellular buffer choice influences acid-base responses and gastrointestinal symptoms

To compare the bicarbonate kinetics and gastrointestinal (GI) symptom responses between an equal dose of sodium bicarbonate and sodium citrate using delayed-release capsules. Thirteen active males (age 20.5 ± 2.1 y, height 1.8 ± 0.1 m and body mass [BM] 76.5 ± 9.6 kg) consumed either 0.3 g^.kg^-1 BM sodium bicarbonate, sodium citrate or a placebo, using a double-blind, randomized crossover design. Blood bicarbonate ion (HCO₃^-) concentration, pH and GI symptoms were measured pre-consumption and every 10 min for 180 min post-consumption. Blood HCO₃^- concentration (P < 0.001) and pH (P = 0.040) were significantly higher in the sodium bicarbonate condition compared with sodium citrate condition up to 3 h post-consumption. Peak blood HCO₃^- concentration was significantly higher with the sodium bicarbonate compared with citrate (P < 0.001). Mean GI symptom scores were lower (P = 0.037) for sodium citrate (1.5 ± 1.8 AU) than bicarbonate (2.6 ± 3.1 AU), with considerable inter-individual variability. No GI symptoms were reported following consumption of the placebo. Both substances increase HCO₃^- values significantly, with sodium bicarbonate causing significantly higher pH and HCO₃^- values than the same dose of sodium citrate, but results in slightly more severe GI symptoms.

Capsule Size Alters the Timing of Metabolic Alkalosis Following Sodium Bicarbonate Supplementation

Introduction: Sodium bicarbonate (NaHCO3) is a well-established nutritional ergogenic aid that is typically ingested as a beverage or consumed in gelatine capsules. While capsules may delay the release of NaHCO3 and reduce gastrointestinal (GI) side effects compared with a beverage, it is currently unclear whether the capsule size may influence acid-base responses and GI symptoms following supplementation. Aim: This study aims to determine the effects of NaHCO3 supplementation, administered in capsules of different sizes, on acid-base responses, GI symptoms, and palatability. Methods: Ten healthy male subjects (mean ± SD: age 20 ± 2 years; height 1.80 ± 0.09 m; weight 78.0 ± 11.9 kg) underwent three testing sessions whereby 0.3 g NaHCO3/kg of body mass was consumed in either small (size 3), medium (size 0), or large (size 000) capsules. Capillary blood samples were procured pre-ingestion and every 10 min post-ingestion for 180 min. Blood samples were analyzed using a radiometer (Radiometer ABL800, Denmark) to determine blood bicarbonate concentration ([HCO 3 - ]) and potential hydrogen (pH). GI symptoms were measured using a questionnaire at the same timepoints, whereas palatability was recorded pre-consumption. Results: Capsule size had a significant effect on lag time (the time [HCO 3 - ] changed, T lag) and the timing of peak blood [HCO 3 - ] (T max). Bicarbonate T lag was significantly higher in the large-sized (28 ± 4 min) compared with the small-sized (13 ± 2 min) capsules (P = 0.009). Similarly, T max was significantly lower in the small capsule (94 ± 24 min) compared with both the medium-sized (141 ± 27 min; P < 0.001) and the large-sized (121 ± 29 min; P < 0.001) capsules. The GI symptom scores were similar for small-sized (3 ± 3 AU), medium-sized (5 ± 3 AU), and large-sized (3 ± 3 AU) capsules, with no significant difference between symptom scores (F = 1.3, P = 0.310). Similarly, capsule size had no effect on palatability (F = 0.8, P = 0.409), with similar scores between different capsule sizes. Conclusion: Small capsule sizes led to quicker T lag and T max of blood [HCO 3 - ] concentration compared to medium and large capsules, suggesting that individuals could supplement NaHCO3 in smaller capsules if they aim to increase extracellular buffering capacity more quickly.

Effect of sodium bicarbonate contribution on energy metabolism during exercise: a systematic review and meta-analysis

Background

The effects of sodium bicarbonate (NaHCO₃) on anaerobic and aerobic capacity are commonly acknowledged as unclear due to the contrasting evidence thus, the present study analyzes the contribution of NaHCO₃ to energy metabolism during exercise.

Methods

Following a search through five databases, 17 studies were found to meet the inclusion criteria. Meta-analyses of standardized mean differences (SMDs) were performed using a random-effects model to determine the effects of NaHCO₃ supplementation on energy metabolism. Subgroup meta-analyses were conducted for the anaerobic-based exercise (assessed by changes in pH, bicarbonate ion [HCO₃⁻], base excess [BE] and blood lactate [BLa]) vs. aerobic-based exercise (assessed by changes in oxygen uptake [VO₂], carbon dioxide production [VCO₂], partial pressure of oxygen [PO₂] and partial pressure of carbon dioxide [PCO₂]).

Results

The meta-analysis indicated that NaHCO₃ ingestion improves pH (SMD = 1.38, 95% CI: 0.97 to 1.79, P < 0.001; I² = 69%), HCO₃⁻ (SMD = 1.63, 95% CI: 1.10 to 2.17, P < 0.001; I² = 80%), BE (SMD = 1.67, 95% CI: 1.16 to 2.19, P < 0.001, I² = 77%), BLa (SMD = 0.72, 95% CI: 0.34 to 1.11, P < 0.001, I² = 68%) and PCO₂ (SMD = 0.51, 95% CI: 0.13 to 0.90, P = 0.009, I² = 0%) but there were no differences between VO₂, VCO₂ and PO₂ compared with the placebo condition.

Conclusions

This meta-analysis has found that the anaerobic metabolism system (AnMS), especially the glycolytic but not the oxidative system during exercise is affected by ingestion of NaHCO₃. The ideal way is to ingest it is in a gelatin capsule in the acute mode and to use a dose of 0.3 g•kg^− 1 body mass of NaHCO₃ 90 min before the exercise in which energy is supplied by the glycolytic system.

Is Individualization of Sodium Bicarbonate Ingestion Based on Time to Peak Necessary?

PURPOSE

To describe the reliability of blood bicarbonate pharmacokinetics in response to sodium bicarbonate (SB) supplementation across multiple occasions and assess, using putative thresholds, whether individual variation indicated a need for individualized ingestion timings.

METHODS

Thirteen men (age 27 ± 5 yr; body mass [BM], 77.4 ± 10.5 kg; height, 1.75 ± 0.06 m) ingested 0.3 g·kg BM SB in gelatine capsules on three occasions. One hour after a standardized meal, venous blood was obtained before and every 10 min after ingestion for 3 h, then every 20 min for a further hour. Time to peak (Tmax), absolute peak (Cmax), absolute peak change ([INCREMENT]Cmax), and area under the curve were analyzed using mixed models, intraclass correlation coefficient, coefficient of variation and typical error. Individual variation in pharmacokinetic responses was assessed using Bayesian simulation with multilevel models with random intercepts.

RESULTS

No significant differences between sessions were shown for blood bicarbonate regarding Cmax, [INCREMENT]Cmax or area under the curve (P > 0.05), although Tmax occurred earlier in SB2 (127 ± 36 min) than in SB1 (169 ± 54 min, P = 0.0088) and SB3 (159 ± 42 min, P = 0.05). Intraclass correlation coefficient, coefficient of variation, and typical error showed moderate to poor reliability. Bayesian modeling estimated that >80% of individuals from the population experience elevated blood bicarbonate levels above +5 mmol·L between 75 and 240 min after ingestion, and between 90 and 225 min above +6 mmol·L.

CONCLUSIONS

Assessing SB supplementation using discrete values showed only moderate reliability at the group level, and poor reliability at the individual level, whereas Tmax was not reproducible. However, when analyzed as modeled curves, a 0.3-g·kg BM dose was shown to create a long-lasting window of ergogenic potential, challenging the notion that SB ingestion individualized to time-to-peak is a necessary strategy, at least when SB is ingested in capsules.

Sodium Bicarbonate Ingestion Improves Time-to-Exhaustion Cycling Performance and Alters Estimated Energy System Contribution: A Dose-Response Investigation

This study investigated the effects of two sodium bicarbonate (NaHCO₃) doses on estimated energy system contribution and performance during an intermittent high-intensity cycling test (HICT), and time-to-exhaustion (TTE) exercise. Twelve healthy males (stature: 1.75 ± 0.08 m; body mass: 67.5 ± 6.3 kg; age: 21.0 ± 1.4 years; maximal oxygen consumption: 45.1 ± 7.0 ml.kg.min⁻¹) attended four separate laboratory visits. Maximal aerobic power (MAP) was identified from an incremental exercise test. During the three experimental visits, participants ingested either 0.2 g.kg⁻¹ BM NaHCO₃ (SBC2), 0.3 g.kg⁻¹ BM NaHCO₃ (SBC3), or 0.07 g.kg⁻¹ BM sodium chloride (placebo; PLA) at 60 min pre-exercise. The HICT involved 3 × 60 s cycling bouts (90, 95, 100% MAP) interspersed with 90 s recovery, followed by TTE cycling at 105% MAP. Blood lactate was measured after each cycling bout to calculate estimates for glycolytic contribution to exercise. Gastrointestinal (GI) upset was quantified at baseline, 30 and 60 min post-ingestion, and 5 min post-exercise. Cycling TTE increased for SBC2 (+20.2 s; p = 0.045) and SBC3 (+31.9 s; p = 0.004) compared to PLA. Glycolytic contribution increased, albeit non-significantly, during the TTE protocol for SBC2 (+7.77 kJ; p = 0.10) and SBC3 (+7.95 kJ; p = 0.07) compared to PLA. GI upset was exacerbated post-exercise after SBC3 for nausea compared to SBC2 and PLA (p < 0.05), whilst SBC2 was not significantly different to PLA for any symptom (p > 0.05). Both NaHCO₃ doses enhanced cycling performance and glycolytic contribution, however, higher doses may maximize ergogenic benefits.

Sodium bicarbonate improves sprint performance in endurance cycling

OBJECTIVES

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. Therefore, the present study investigated the effect of stacked NaHCO₃ loading on sprint performance following a 3-h simulated cycling race.

DESIGN

Double-blind randomized placebo-controlled cross-over study.

METHODS

Eleven trained male cyclists (22.3 (18.3-25.3) year; 73.0 (61.5-88) kg; VO₂max: 63.7 (57-72) mlkg^-1min^-1) ingested either 300mgkg^-1 body weight NaHCO₃ (BIC) or NaCl (PL). NaHCO₃ or NaCl was supplemented prior to (150mgkg^-1) and during (150mgkg^-1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end. Capillary blood samples were collected for determination of blood pH, lactate and HCO₃^- concentrations. Analysis of variance (lactate, pH, HCO₃^-) and paired t-test (power) were applied to compare variables across condition (and time).

RESULTS

NaHCO₃ intake improved mean power during 90S by ∼3% (541±59W vs. 524±57W 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±4.1mmoll¹, 184±7bpm) than in PL (12.4±4.2mmoll^-1, 181±5bpm). NaHCO₃ ingestion increased blood [HCO₃^-] (31.5±1.3 vs. 24.4±1.5mmoll^-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.

CONCLUSIONS

NaHCO₃ supplementation prior and during endurance exercise improves short all-out exercise performance at the end of the event. Therefore, sodium bicarbonate intake can be applied as a strategy to increase success rate in endurance competitions.

The Impact of Individualizing Sodium Bicarbonate Supplementation Strategies on World-Class Rowing Performance

Contemporary meta-analyses have generally demonstrated a positive effect of sodium bicarbonate (NaHCO₃) supplementation on exercise performance. However, despite these claims, there is limited data on contrasting individualized and standardized timing of NaHCO₃ ingestion prior to exercise to further enhance performance outcomes.

Purpose: To determine whether NaHCO₃ ingestion timing impacts 2,000-m rowing time-trial (TT) performance in elite-level rowers (Senior National team including Olympic/World Championships level) adhering to their own individualized pre-race strategies (e.g. nutrition, warm-up, etc.).

Methods: Twenty three (n = 23) rowers across two research centers (using the exact same methods/protocols) completed three trials: NaHCO₃ loading profile at rest to determine the individual's time-to-peak bicarbonate concentration [HCO3-], followed by two randomized 0.3 g·kgBM⁻¹ NaHCO₃ supplementation experimental trials conducted at different time points [consensus timing (CON): TT performed 60 min post-NaHCO₃ ingestion; and individualized peak (IP): TT performed at the rower's individual peak [HCO3-] determined from the profiling trial post-NaHCO₃ ingestion].

Results: There was a significant mean difference of +2.9 [± 0.4 mmol·L⁻¹HCO3- for IP vs. CON (95% CI 2.0 to 3.8 mmol·L⁻¹); p = 0.02; d = 1.08] at pre warm-up, but not immediately prior to the TT (post warm-up). Performance times were significantly different between IP (367.0 ± 10.5 s) vs. CON (369.0 ± 10.3 s); p = 0.007; d = 0.15).

Conclusions: The present study demonstrated a small but significant performance effect of an individualized NaHCO₃ ingestion strategy. Similarities after warm-up between pre-TT sHCO3- values (CON ~ + 5.5 mmol·L⁻¹; IP ~ + 6 mmol·L⁻¹), however, would suggest this effect was not a result of any meaningful differences in blood alkalinity.

Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players

Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1 years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90 min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. -0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. -1.45 ± 0.31 mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41 s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64 W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51 cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11 cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.

Enteric-coated sodium bicarbonate supplementation improves high-intensity cycling performance in trained cyclists

Purpose

Enteric-coated sodium bicarbonate (NaHCO₃) can attenuate gastrointestinal (GI) symptoms following acute bicarbonate loading, although the subsequent effects on exercise performance have not been investigated. The purpose of this study was to examine the effects of enteric-coated NaHCO₃ supplementation on high-intensity exercise performance and GI symptoms.

Methods

Eleven trained male cyclists completed three 4 km time trials after consuming; a placebo or 0.3 g∙kg^–1 body mass NaHCO₃ in enteric-coated or gelatin capsules. Exercise trials were timed with individual peak blood bicarbonate ion concentration ([HCO₃^–]). Blood acid–base balance was measured pre-ingestion, pre-exercise, and post-exercise, whereas GI symptoms were recorded pre-ingestion and immediately pre-exercise.

Results

Pre-exercise blood [HCO3⁻] and potential hydrogen (pH) were greater for both NaHCO₃ conditions (P < 0.0005) when compared to placebo. Performance time was faster with enteric-coated (− 8.5 ± 9.6 s, P = 0.044) and gelatin (− 9.6 ± 7.2 s, P = 0.004) NaHCO₃ compared to placebo, with no significant difference between conditions (mean difference = 1.1 ± 5.3 s, P = 1.000). Physiological responses were similar between conditions, although blood lactate ion concentration was higher with gelatin NaHCO₃ (2.4 ± 1.7 mmol∙L^–1, P = 0.003) compared with placebo. Furthermore, fewer participants experienced GI symptoms with enteric-coated (n = 3) compared to gelatin (n = 7) NaHCO₃.

Discussion

Acute enteric-coated NaHCO₃ consumption mitigates GI symptoms at the onset of exercise and improves subsequent 4 km cycling TT performance. Athletes who experience GI side-effects after acute bicarbonate loading may, therefore, benefit from enteric-coated NaHCO₃ supplementation prior to exercise performance.

The gender dependent influence of sodium bicarbonate supplementation on anaerobic power and specific performance in female and male wrestlers

The aim of this study was the assessment of progressive low-dose sodium bicarbonate (NaHCO₃) supplementation on the anaerobic indices in two bouts of Wingate tests (WT) separated by wrestling-specific performance test and assessing the gender differences in response. Fifty-one (18 F) wrestlers completed a randomized trial of either a NaHCO₃ (up to 100 mg·kg⁻¹) or a placebo for 10 days. Before and after treatment, athletes completed an exercise protocol that comprised, in sequence, the first WT₁, dummy throw test (DT), and second WT₂. The number of completed throws increased significantly in males from 19.3 ± 2.6 NaHCO_3pre to 21.7 ± 2.9 NaHCO_3post. ΔWT₂-WT₁ improved particularly in the midsection of 30-s WT on NaHCO₃. However, no significant differences were found in peak power (PP), power drop (PD) and average power (AP) (analyzed separately for each WT), and ΔWT₂-WT₁ in PP and PD. Interaction with gender was significant for AP, PP and PD, every second of WT₁ and WT₂, as well as DT test. In conclusion, our study suggests that the response to NaHCO₃ may be gender-specific and progressive low-dose NaHCO₃ supplementation allows the advantageous strengthening of wrestling-specific performance in males. It can also lead to maintenance of high anaerobic power mainly in the midsection of the 30-s Wingate test.

Supplements and Nutritional Interventions to Augment High-Intensity Interval Training Physiological and Performance Adaptations-A Narrative Review

High-intensity interval training (HIIT) involves short bursts of intense activity interspersed by periods of low-intensity exercise or rest. HIIT is a viable alternative to traditional continuous moderate-intensity endurance training to enhance maximal oxygen uptake and endurance performance. Combining nutritional strategies with HIIT may result in more favorable outcomes. The purpose of this narrative review is to highlight key dietary interventions that may augment adaptations to HIIT, including creatine monohydrate, caffeine, nitrate, sodium bicarbonate, beta-alanine, protein, and essential amino acids, as well as manipulating carbohydrate availability. Nutrient timing and potential sex differences are also discussed. Overall, sodium bicarbonate and nitrates show promise for enhancing HIIT adaptations and performance. Beta-alanine has the potential to increase training volume and intensity and improve HIIT adaptations. Caffeine and creatine have potential benefits, however, longer-term studies are lacking. Presently, there is a lack of evidence supporting high protein diets to augment HIIT. Low carbohydrate training enhances the upregulation of mitochondrial enzymes, however, there does not seem to be a performance advantage, and a periodized approach may be warranted. Lastly, potential sex differences suggest the need for future research to examine sex-specific nutritional strategies in response to HIIT.

Caffeine and sodium bicarbonate supplementation alone or together improve karate performance

Background

The ergogenic properties of acute caffeine (CAF) and sodium bicarbonate (NaHCO₃) ingestion on athletic performance have been previously investigated. However, each sport has unique physiological and technical characteristics which warrants optimizing supplementations strategies for maximizing performance. This study examined the effects of CAF and NaHCO₃ ingestion on physiological responses and rate of perceived exertion during a Karate-specific aerobic test (KSAT) in competitive karatekas.

Methods

In a double-blind, crossover, randomized placebo-controlled trial, eight Karatekas underwent five experimental conditions including control (CON), placebo (PLA), CAF, NaHCO₃, and CAF + NaHCO₃ before completing KSAT. Capsules containing 6 mg/kg BW CAF were consumed 50 min prior to a KSAT whilst 0.3 g/kg BW NaHCO₃ was consumed for 3 days leading to and 120, 90, and 60 min prior to a KSAT. Time to exhaustion (TTE), rate of perceived exertion (RPE), and blood lactate (BL) were measured before, immediately after and 3 min following KSAT.

Results

TTE was significantly greater following CAF, NaHCO₃, and CAF + NaHCO₃ consumption compared to PLA and CON. However, the differences between CAF, NaHCO₃, and CAF + NaHCO₃ were not statistically significant (p > 0.05). BL increased significantly from baseline to immediately after and 3 min following KSAT in all conditions (p < 0.01), while RPE at the end of KSAT was not significantly different between conditions (p = 0.11).

Conclusions

Karate practitioners may benefit from the ergogenic effects of CAF and NaHCO₃ when consumed separately or together.

Isolated ingestion of caffeine and sodium bicarbonate on repeated sprint performance: A systematic review and meta-analysis

OBJECTIVES

This study is a systematic review and meta-analysis aimed at investigating the isolated effects of caffeine and sodium bicarbonate (NaHCO₃) ingestion on repeated sprint ability (RSA).

METHODS

Following a search through PubMed and Scopus, 13 studies (7 with caffeine and 6 with NaHCO₃) were found to meet inclusion criteria. Random-effects of standardized mean difference (SMD) for total work and best sprint performance was examined. Study quality was assessed using QualSyst.

RESULTS

The meta-analysis indicated that caffeine ingestion did not improve the total work done (weighted average effect size Hedges's g = -0.01, 95%CI: -0.32 to 0.31, p = 0.97), best sprint (weighted average effect size Hedges's g = -0.02, 95% CI: -0.32 to 0.27; p = 0.87) or last sprint performance (weighed average effect size Hedge's g = -0.27, 95%CI: -0.68 to 0.14; p = 0.20), when compared with a placebo condition. Similarly, NaHCO₃ ingestion did not improve the total work done (weighted average effect size Hedges's g = 0.43, 95% CI: -0.11 to 0.97, p = 0.12), best sprint (weighted average effect size Hedges's g = 0.02, 95% CI -0.30 to 0.34; p = 0.90) or last sprint performance (weighted average effect size Hedge's g = 0.20, 95%CI: -0.13 to 0.52, p = 0.14), compared with a placebo condition. Quality assessment of selected articles was classified as strong.

CONCLUSION

This meta-analysis provides evidence that repeated sprint ability is not affected by acute ingestion of caffeine or NaHCO₃.

A Novel Ingestion Strategy for Sodium Bicarbonate Supplementation in a Delayed-Release Form: a Randomised Crossover Study in Trained Males

Background

Sodium bicarbonate (NaHCO₃) is a well-established nutritional ergogenic aid, though gastrointestinal (GI) distress is a common side-effect. Delayed-release NaHCO₃ may alleviate GI symptoms and enhance bicarbonate bioavailability following oral ingestion, although this has yet to be confirmed.

Methods

In a randomised crossover design, pharmacokinetic responses and acid-base status were compared following two forms of NaHCO₃, as were GI symptoms. Twelve trained healthy males (mean ± SD age 25.8 ± 4.5 years, maximal oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$\end{document}V˙O2max) 58.9 ± 10.9 mL kg min⁻¹, height 1.8 ± 0.1 m, body mass 82.3 ± 11.1 kg, fat-free mass 72.3 ± 10.0 kg) underwent a control (CON) condition and two experimental conditions: 300 mg kg⁻¹ body mass NaHCO₃ ingested as an aqueous solution (SOL) and encased in delayed-release capsules (CAP). Blood bicarbonate concentration, pH and base excess (BE) were measured in all conditions over 180 min, as were subjective GI symptom scores.

Results

Incidences of GI symptoms and overall severity were significantly lower (mean difference = 45.1%, P < 0.0005 and 47.5%, P < 0.0005 for incidences and severity, respectively) with the CAP than with the SOL. Symptoms displayed increases at 40 to 80 min post-ingestion with the SOL that were negated with CAP (P < 0.05). Time to reach peak bicarbonate concentration, pH and BE were significantly longer with CAP than with the SOL.

Conclusions

In summary, CAP can mitigate GI symptoms induced with SOL and should be ingested earlier to induce similar acid-base changes. Furthermore, CAP may be more ergogenic in those who experience severe GI distress with SOL, although this warrants further investigation.

The Reproducibility of Blood Acid Base Responses in Male Collegiate Athletes Following Individualised Doses of Sodium Bicarbonate: A Randomised Controlled Crossover Study

BACKGROUND

Current evidence suggests sodium bicarbonate (NaHCO₃) should be ingested based upon the individualised alkalotic peak of either blood pH or bicarbonate (HCO₃^-) because of large inter-individual variations (10-180 min). If such a strategy is to be practical, the blood analyte response needs to be reproducible.

OBJECTIVE

This study aimed to evaluate the degree of reproducibility of both time to peak (TTP) and absolute change in blood pH, HCO₃^- and sodium (Na⁺) following acute NaHCO₃ ingestion.

METHODS

Male participants (n = 15) with backgrounds in rugby, football or sprinting completed six randomised treatments entailing ingestion of two doses of 0.2 g·kg^-1 body mass (BM) NaHCO₃ (SBC2a and b), two doses of 0.3 g·kg^-1 BM NaHCO₃ (SBC3a and b) or two control treatments (CON1a and b) on separate days. Blood analysis included pH, HCO₃^- and Na⁺ prior to and at regular time points following NaHCO₃ ingestion over a 3-h period.

RESULTS

HCO₃^- displayed greater reproducibility than pH in intraclass correlation coefficient (ICC) analysis for both TTP (HCO₃^- SBC2 r = 0.77, P = 0.003; SBC3 r = 0.94, P < 0.001; pH SBC2 r = 0.62, P = 0.044; SBC3 r = 0.71, P = 0.016) and absolute change (HCO₃^- SBC2 r = 0.89, P < 0.001; SBC3 r = 0.76, P = 0.008; pH SBC2 r = 0.84, P = 0.001; SBC3 r = 0.62, P = 0.041).

CONCLUSION

Our results indicate that both TTP and absolute change in HCO₃^- is more reliable than pH. As such, these data provide support for an individualised NaHCO₃ ingestion strategy to consistently elicit peak alkalosis before exercise. Future work should utilise an individualised NaHCO₃ ingestion strategy based on HCO₃^- responses and evaluate effects on exercise performance.

Chronic Ingestion of Sodium and Potassium Bicarbonate, with Potassium, Magnesium and Calcium Citrate Improves Anaerobic Performance in Elite Soccer Players

Anaerobic power and anaerobic capacity significantly influence performance in many sport disciplines. These include prolonged sprints in athletics, swimming, or cycling, and other high intensity intermittent sports, such as soccer or basketball. Considering the association of exercise-induced acidosis and fatigue, the ingestion of potential buffering agents such as sodium bicarbonate, has been suggested to attenuate metabolic acidosis and improve anaerobic performance. Since elite soccer players cover from 200 to 350 m while sprinting, performing 40–60 all out sprints during a game, it seems that repeated sprint ability in soccer players is among the key components of success. In our experiment, we evaluated the effectiveness of chronic supplementation with sodium and potassium bicarbonate, fortified with minerals, on speed and speed endurance in elite soccer players. Twenty-six soccer players participated in the study. The subjects were randomly divided into two groups. The experimental group was supplemented with sodium bi-carbonate and potassium di-carbonate fortified with minerals, while the control group received a placebo. The athletes were tested at baseline and after nine days of supplementation. Anaerobic performance was evaluated by the Repeated Anaerobic Sprint Test (RAST) protocol which involved 6 × 30 m max sprints, separated by 10 s of active recovery. Resting, post ingestion and post exercise concentrations of HCO₃⁻ and blood pH were measured as well as lactate concentration. The current investigation demonstrated a significant increase in RAST performance of elite soccer players supplemented with sodium and potassium bicarbonate along with calcium phosphate, potassium citrate, and magnesium citrate ingested twice a day over a nine-day training period. The improvements in anaerobic performance were caused by increased resting blood pH and bicarbonate levels.

Effects of Three-Day Serial Sodium Bicarbonate Loading on Performance and Physiological Parameters During a Simulated Basketball Test in Female University Players

The aim of this study was to investigate the effect of 3-day serial sodium bicarbonate ingestion on repeated sprint and jump performance. Fifteen female university basketball players (23.3 ± 3.4 years; 173.1 ± 5.8 cm; 65.8 ± 6.3 kg; 23.6 ± 4.9% body fat) ingested 0.4 g/kg body mass of sodium bicarbonate or placebo for 3 days (split in three equal daily doses), before completing a simulated basketball exercise. Sprint and circuit times, jump heights, performance decrements, and gastrointestinal side effects were recorded during the test, and blood lactate concentration was measured pre- and posttest. Sodium bicarbonate supplementation led to significant decreases in mean sprint times (1.34 ± 0.23 vs. 1.70 ± 0.41 s, p = .008, 95% confidence intervals [−0.54, −0.10 s]) and mean circuit times (30.6 ± 2.0 vs. 31.3 ± 2.0 s, p = .044) and significantly greater mean jump height (26.8 [range 25.2–34.2] vs. 26.0 [range 25.6–33.6] cm, p = .013) compared with placebo. Performance decrement was significantly less for sprints with sodium bicarbonate compared with placebo (9.9 [range 3.4–37.0]% vs. 24.7 [range 4.1–61.3]%, p = .013), but not different for jumps (13.1 ± 4.5% vs. 12.5 ± 3.1%, p = .321) between conditions. No differences in gastrointestinal side effects were noted between conditions. Significantly greater postexercise blood lactate concentrations were measured in the sodium bicarbonate condition compared with the placebo condition (8.2 ± 2.8 vs. 6.6 ± 2.4 mmol/L, p = .010). This study is the first to show that serial loading of sodium bicarbonate is effective for basketball players to improve repeated sprint and jump performance during competition, or withstand greater training load during practice sessions without any gastrointestinal side effects.

The effect of chronic progressive-dose sodium bicarbonate ingestion on CrossFit-like performance: A double-blind, randomized cross-over trial

Background

Sodium bicarbonate (SB) has been proposed as an ergogenic aid, as it improves high-intensity and resistance exercise performance. However, no studies have yet investigated SB application in CrossFit. This study examined the effects of chronic, progressive-dose SB ingestion on CrossFit-like performance and aerobic capacity.

Methods

In a randomized, double-blind, cross-over trial, 21 CrossFit-trained participants were randomly allocated to 2 groups and underwent 2 trials separated by a 14-day washout period. Participants ingested either up to 150 mg∙kg^-1 of SB in a progressive-dose regimen or placebo for 10 days. Before and after each trial, Fight Gone Bad (FGB) and incremental cycling (ICT) tests were performed. In order to examine biochemical responses, blood samples were obtained prior to and 3 min after completing each exercise test.

Results

No gastrointestinal (GI) side effects were reported during the entire protocol. The overall FGB performance improved under SB by ~6.1% (p<0.001) and it was ~3.1% higher compared to post placebo (PLA_post) (p = 0.040). The number of repetitions completed in each round also improved under SB (mean from baseline: +5.8% to +6.4%). Moreover, in ICT, the time to ventilatory threshold (VT) (~8:25 min SB_post vs. ~8:00 min PLA_post, p = 0.020), workload at VT (~218 W SB_post vs. ~208 W PLA_post, p = 0.037) and heart rate at VT (~165 bpm SB_post vs. ~161 bpm PLA_post, p = 0.030) showed higher SB_post than PLA_post. Furthermore, the maximum carbon dioxide production increased under SB by ~4.8% (from ~3604 mL∙min^-1 to ~3776 mL∙min^-1, p = 0.049). Pyruvate concentration and creatine kinase activity before ICT showed higher SB_post than PLA_post (~0.32 mmol∙L^-1 vs. ~0.26 mmol∙L^-1, p = 0.001; ~275 U∙L^-1 vs. ~250 U∙L^-1, p = 0.010, respectively). However, the small sample size limits the wide-application of our results.

Conclusions

Progressive-dose SB ingestion regimen eliminated GI side effects and improved CrossFit-like performance, as well as delayed ventilatory threshold occurrence.

Time to Optimize Supplementation: Modifying Factors Influencing the Individual Responses to Extracellular Buffering Agents

Blood alkalosis, as indicated by an increased blood bicarbonate concentration and pH, has been shown to be beneficial for exercise performance. Sodium bicarbonate, sodium citrate, and sodium or calcium lactate, can all result in increased circulating bicarbonate and have all independently been shown to improve exercise capacity and performance under various circumstances. Although there is considerable evidence demonstrating the efficacy of these supplements in several sports-specific situations, it is commonly acknowledged that their efficacy is equivocal, due to contrasting evidence. Herein, we discuss the physiological and environmental factors that may modify the effectiveness of these supplements including, (i) absolute changes in circulating bicarbonate; (ii) supplement timing, (iii) the exercise task performed, (iv) monocarboxylate transporter (MCT) activity; (v) training status, and (vi) associated side-effects. The aim of this narrative review is to highlight the factors which may modify the response to these supplements, so that individuals can use this information to attempt to optimize supplementation and allow the greatest possibility of an ergogenic effect.

Sodium bicarbonate ingestion increases glycolytic contribution and improves performance during simulated taekwondo combat

PURPOSE

To investigate the effect of sodium bicarbonate (NaHCO₃) on performance and estimated energy system contribution during simulated taekwondo combat.

METHODS

Nine taekwondo athletes completed two experimental sessions separated by at least 48 h. Athletes consumed 300 mg/kg body mass of NaHCO₃ or placebo (CaCO₃) 90 min before the combat simulation (three rounds of 2 min separated by 1 min passive recovery), in a double-blind, randomized, repeated-measures crossover design. All simulated combat was filmed to quantify the time spent fighting in each round. Lactate concentration [La^-] and rating of perceived exertion (RPE) were measured before and after each round, whereas heart rate (HR) and the estimated contribution of the oxidative (W_OXI), ATP (adenosine triphosphate)-phosphocreatine (PCr) (W_PCR), and glycolytic (W_[La^-]) systems were calculated during the combat simulation.

RESULTS

[La^-] increased significantly after NaHCO₃ ingestion, when compared with the placebo condition (+14%, P = 0.04, d = 3.70). NaHCO₃ ingestion resulted in greater estimated glycolytic energy contribution in the first round when compared with the placebo condition (+31%, P = 0.01, d = 3.48). Total attack time was significantly greater after NaHCO₃ when compared with placebo (+13%, P = 0.05, d = 1.15). W_OXI, W_PCR, VO₂, HR and RPE were not different between conditions (P > 0.05).

CONCLUSION

NaHCO₃ ingestion was able to increase the contribution of glycolytic metabolism and, therefore, improve performance during simulated taekwondo combat.

Sodium bicarbonate supplementation improves severe-intensity intermittent exercise under moderate acute hypoxic conditions

Acute moderate hypoxic exposure can substantially impair exercise performance, which occurs with a concurrent exacerbated rise in hydrogen cation (H⁺) production. The purpose of this study was therefore, to alleviate this acidic stress through sodium bicarbonate (NaHCO₃) supplementation and determine the corresponding effects on severe-intensity intermittent exercise performance. Eleven recreationally active individuals participated in this randomised, double-blind, crossover study performed under acute normobaric hypoxic conditions (FiO₂% = 14.5%). Pre-experimental trials involved the determination of time to attain peak bicarbonate anion concentrations ([HCO₃⁻]) following NaHCO₃ ingestion. The intermittent exercise tests involved repeated 60-s work in their severe-intensity domain and 30-s recovery at 20 W to exhaustion. Participants ingested either 0.3 g kg bm⁻¹ of NaHCO₃ or a matched placebo of 0.21 g kg bm⁻¹ of sodium chloride prior to exercise. Exercise tolerance (+ 110.9 ± 100.6 s; 95% CI 43.3–178 s; g = 1.0) and work performed in the severe-intensity domain (+ 5.8 ± 6.6 kJ; 95% CI 1.3–9.9 kJ; g = 0.8) were enhanced with NaHCO₃ supplementation. Furthermore, a larger post-exercise blood lactate concentration was reported in the experimental group (+ 4 ± 2.4 mmol l⁻¹; 95% CI 2.2–5.9; g = 1.8), while blood [HCO₃⁻] and pH remained elevated in the NaHCO₃ condition throughout experimentation. In conclusion, this study reported a positive effect of NaHCO₃ under acute moderate hypoxic conditions during intermittent exercise and therefore, may offer an ergogenic strategy to mitigate hypoxic induced declines in exercise performance.

Sodium bicarbonate improves 4 km time trial cycling performance when individualised to time to peak blood bicarbonate in trained male cyclists

The aim of this study was to investigate the effects of sodium bicarbonate (NaHCO₃) on 4 km cycling time trial (TT) performance when individualised to a predetermined time to peak blood bicarbonate (HCO₃^-). Eleven male trained cyclists volunteered for this study (height 1.82 ± 0.80 m, body mass (BM) 86.4 ± 12.9 kg, age 32 ± 9 years, peak power output (PPO) 382 ± 22 W). Two trials were initially conducted to identify time to peak HCO₃^- following both 0.2 g^.kg^-1 BM (SBC2) and 0.3 g^.kg^-1 BM (SBC3) NaHCO₃. Thereafter, on three separate occasions using a randomised, double-blind, crossover design, participants completed a 4 km TT following ingestion of either SBC2, SBC3, or a taste-matched placebo (PLA) containing 0.07 g^.kg^-1 BM sodium chloride (NaCl) at the predetermined individual time to peak HCO₃^-. Both SBC2 (-8.3 ± 3.5 s; p < 0.001, d = 0.64) and SBC3 (-8.6 ± 5.4 s; p = 0.003, d = 0.66) reduced the time to complete the 4 km TT, with no difference between SBC conditions (mean difference = 0.2 ± 0.2 s; p = 0.87, d = 0.02). These findings suggest trained cyclists may benefit from individualising NaHCO₃ ingestion to time to peak HCO₃^- to enhance 4 km TT performance.

The Reproducibility of 4-km Time Trial (TT) Performance Following Individualised Sodium Bicarbonate Supplementation: a Randomised Controlled Trial in Trained Cyclists

BACKGROUND

Individual time to peak blood bicarbonate (HCO3-) has demonstrated good to excellent reproducibility following ingestion of both 0.2 g kg-1 body mass (BM) and 0.3 g kg-1 BM sodium bicarbonate (NaHCO3), but the consistency of the time trial (TT) performance response using such an individualised NaHCO3 ingestion strategy remains unknown. This study therefore evaluated the reproducibility of 4-km TT performance following NaHCO3 ingestion individualised to time to peak blood bicarbonate.

METHODS

Eleven trained male cyclists completed five randomised treatments with prior ingestion of 0.2 g kg-1 (SBC2) or 0.3 g kg-1 BM (SBC3) NaHCO3, on two separate occasions each, or a control trial entailing no supplementation. Participants completed a 4-km cycling TT on a Velotron ergometer where time to complete, power and speed were measured, whilst acid-base blood parameters were also recorded (pH and blood bicarbonate concentration HCO3-) and lactate [La-].

RESULTS

Alkalosis was achieved prior to exercise in both SBC2 and SBC3, as pH and HCO3- were greater compared to baseline (p < 0.001), with no differences between treatments (p > 0.05). The reproducibility of the mean absolute change from baseline to peak in HCO3- was good in SBC2 (r = 0.68) and excellent in SBC3 (r = 0.78). The performance responses following both SBC2 and SBC3 displayed excellent reproducibility (r range = 0.97 to 0.99).

CONCLUSIONS

Results demonstrate excellent reproducibility of exercise performance following individualised NaHCO3 ingestion, which is due to the high reproducibility of blood acid-base variables with repeat administration of NaHCO3. Using a time to peak HCO3- strategy seems to cause no dose-dependent effects on performance for exercise of this duration and intensity; therefore, athletes may consider smaller doses of NaHCO3 to mitigate gastrointestinal (GI) discomfort.

The Effect of Buffering High Acid Load Meal with Sodium Bicarbonate on Postprandial Glucose Metabolism in Humans-A Randomized Placebo-Controlled Study

Background: High dietary acid load relates to increased risk of type 2 diabetes in epidemiological studies. We aimed to investigate whether buffering a high acid load meal with an alkalizing treatment changes glucose metabolism post meal. Methods: Non-diabetic participants (n = 32) were randomized to receive either 1680 mg NaHCO₃ or placebo, followed by a high acid load meal in a double-blind placebo-controlled crossover (1–4 weeks apart) study. Thirty (20 men) participants completed the study. Venous blood pH, serum bicarbonate, blood glucose, serum insulin, C-peptide, non-esterified fatty acid (NEFA), and plasma glucagon-like peptide-1 (GLP-1) concentrations were measured at baseline (fasting) and at 15–30 min intervals for 3 h post meal. Results: The treatment was well tolerated. Venous blood pH declined in the first 15 min post meal with the placebo (p = 0.001), but not with NaHCO₃ (p = 0.86) and remained decreased with the placebo for 3 h (p_interaction = 0.04). On average over the 3 h blood pH iAUC was greater with NaHCO₃ compared with placebo (p = 0.02). However, postprandial glucose, insulin, C-peptide, NEFA and GLP-1 were not different between treatments (p_interaction ≥ 0.07). Conclusions: An alkalizing medication administered pre-meal has no acute effect on glycaemia and insulin response in healthy individuals. Long-term interventions in at-risk populations are necessary to investigate the effect of sustained alkalization on glucose metabolism.

Caffeine and Bicarbonate for Speed. A Meta-Analysis of Legal Supplements Potential for Improving Intense Endurance Exercise Performance

A 1% change in average speed is enough to affect medal rankings in intense Olympic endurance events lasting ~45 s to 8 min which for example includes 100 m swimming and 400 m running (~1 min), 1,500 m running and 4000 m track cycling (~4 min) and 2,000 m rowing (~6-8 min). To maximize the likelihood of winning, athletes utilizes legal supplements with or without scientifically documented beneficial effects on performance. Therefore, a continued systematic evidence based evaluation of the possible ergogenic effects is of high importance. A meta-analysis was conducted with a strict focus on closed-end performance tests in humans in the time domain from 45 s to 8 min. These test include time-trials or total work done in a given time. This selection criterion results in a high relevance for athletic performance. Only peer-reviewed placebo controlled studies were included. The often applied and potentially ergogenic supplements beta-alanine, bicarbonate, caffeine and nitrate were selected for analysis. Following a systematic search in Pubmed and SportsDiscuss combined with evaluation of cross references a total of 7 (beta-alanine), 25 (bicarbonate), 9 (caffeine), and 5 (nitrate) studies was included in the meta-analysis. For each study, performance was converted to an average speed (km/h) from which an effect size (ES; Cohens d with 95% confidence intervals) was calculated. A small effect and significant performance improvement relative to placebo was observed for caffeine (ES: 0.41 [0.15–0.68], P = 0.002) and bicarbonate (ES: 0.40 [0.27–0.54], P < 0.001). Trivial and non-significant effects on performance was observed for nitrate (ES: 0.19 [−0.03–0.40], P = 0.09) and beta-alanine (ES: 0.17 [−0.12–0.46], P = 0.24). Thus, caffeine's and bicarbonate's ergogenic effect is clearly documented for intense endurance performance. Importantly, for all supplements an individualized approach may improve the ergogenic effect on performance.

Determinants of curvature constant (W') of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis

Purpose

This study investigated the effect of induced alkalosis on the curvature constant (W’) of the power-duration relationship under normoxic and hypoxic conditions.

Methods

Eleven trained cyclists (mean ± SD) Age: 32 ± 7.2 years; body mass (bm): 77.0 ± 9.2 kg; VO_2peak: 59.2 ± 6.8 ml·kg⁻¹·min⁻¹ completed seven laboratory visits which involved the determination of individual time to peak alkalosis following sodium bicarbonate (NaHCO₃) ingestion, an environment specific ramp test (e.g. normoxia and hypoxia) and four x 3 min critical power (CP) tests under different experimental conditions. Participants completed four trials: alkalosis normoxia (ALN); placebo normoxia (PLN); alkalosis hypoxia (ALH); and placebo hypoxia (PLH). Pre-exercise administration of 0.3 g.kg⁻¹ BM of NaHCO₃ was used to induce alkalosis. Environmental conditions were set at either normobaric hypoxia (FiO₂: 14.5%) or normoxia (FiO₂: 20.93%).

Results

An increase in W’ was observed with pre-exercise alkalosis under both normoxic (PLN: 15.1 ± 6.2 kJ vs. ALN: 17.4 ± 5.1 kJ; P = 0.006) and hypoxic conditions (ALN: 15.2 ± 4.9 kJ vs. ALN: 17.9 ± 5.2 kJ; P < 0.001). Pre-exercise alkalosis resulted in a larger reduction in bicarbonate ion (HCO₃⁻) concentrations during exercise in both environmental conditions (p < 0.001) and a greater blood lactate accumulation under hypoxia (P = 0.012).

Conclusion

Pre-exercise alkalosis substantially increased W’ and, therefore, may determine tolerance to exercise above CP under normoxic and hypoxic conditions. This may be due to NaHCO₃ increasing HCO₃⁻ buffering capacity to delay exercise-induced acidosis, which may, therefore, enhance anaerobic energy contribution.

Sodium bicarbonate ingestion and individual variability in time-to-peak pH

This study determined variability in time-to-peak pH after consumption of 300 mg kg^-1 of sodium bicarbonate. Seventeen participants (mean ± SD: age 21.38 ± 1.5 years; mass 75.8 ± 5.8 kg; height 176.8 ± 7.6 cm) reported to the laboratory where a resting capillary sample was taken. Then, 300 mg kg^-1 of NaHCO₃ in 450 ml of flavoured water was ingested. Participants rested for 90 min and repeated blood samples were procured at 10 min intervals for 60 min and then every 5 min until 90 min. Blood pH concentrations were measured. Results suggested that time-to-peak pH (64.41 ± 18.78 min) was variable with a range of 10-85 min and a coefficient of variation of 29.16%. A bimodal distribution occurred, at 65 and 75 min. In conclusion, athletes, when using NaHCO₃ as an ergogenic aid, should determine their time-to-peak pH to best utilize the added buffering capacity this substance allows.

Mechanistic Insights into the Efficacy of Sodium Bicarbonate Supplementation to Improve Athletic Performance

A large proportion of empirical research and reviews investigating the ergogenic potential of sodium bicarbonate (NaHCO₃) supplementation have focused predominately on performance outcomes and only speculate about underlying mechanisms responsible for any benefit. The aim of this review was to critically evaluate the influence of NaHCO₃ supplementation on mechanisms associated with skeletal muscle fatigue as it translates directly to exercise performance. Mechanistic links between skeletal muscle fatigue, proton accumulation (or metabolic acidosis) and NaHCO₃ supplementation have been identified to provide a more targeted, evidence-based approach to direct future research, as well as provide practitioners with a contemporary perspective on the potential applications and limitations of this supplement. The mechanisms identified have been broadly categorised under the sections ‘Whole-body Metabolism’, ‘Muscle Physiology’ and ‘Motor Pathways’, and when possible, the performance outcomes of these studies contextualized within an integrative framework of whole-body exercise where other factors such as task demand (e.g. large vs. small muscle groups), cardio-pulmonary and neural control mechanisms may outweigh any localised influence of NaHCO₃. Finally, the ‘Performance Applications’ section provides further interpretation for the practitioner founded on the mechanistic evidence provided in this review and other relevant, applied NaHCO₃ performance-related studies.