Sodium bicarbonate and high-intensity-cycling capacity: variability in responses

No Effect of Individualized Sodium Bicarbonate Supplementation on 200-m or 400-m Freestyle-Swimming Time-Trial Performance in Well-Trained Athletes

PURPOSE

This study investigated the effect of an individualized sodium bicarbonate (SB) supplementation-timing strategy on 200-m and 400-m freestyle swimming time-trial (TT) performance.

METHODS

Thirteen well-trained swimmers (8 men and 5 women; mean [SD] 22 [3] y, 1.76 [0.79] m, 73.4 [9.6] kg) had their time-to-peak bicarbonate (HCO3-) determined after ingestion of 0.3 g·kg-1 body mass SB in size 0 vegetarian capsules alongside a carbohydrate-high meal (1.5 g·kg-1 body mass). Following familiarization, participants performed 200-m and 400-m freestyle TTs after individualized timing (160 [36] min) of either SB or a placebo (PL; cornflour) on 4 separate occasions in a randomized, double-blind, crossover design. Completion times, blood lactate, and rating of perceived exertion (6-20 Borg) were measured.

RESULTS

SB did not improve completion times compared with PL during the 200-m (124.5 [7.3] vs 125.1 [6.2] s, P = .219, g = 0.09) or 400-m (263.4 [12.8] vs 264.7 [13.6] s; P = .192, g = 0.10) TTs. Blood lactate was elevated for SB compared with PL following the 200-m (12.99 [1.45] vs 10.98 [2.25] mmol·L-1; P = .042) and 400-m (13.05 [2.29] vs 10.44 [2.40] mmol·L-1; P = .017) TTs. SB reduced rating of perceived exertion after the TTs compared with PL (200 m: -0.9 [1.4] au, P = .033; 400 m: -1.2 [1.4] au, P = .012).

CONCLUSIONS

SB consumed in capsules at individualized time-to-peak [HCO3-] did not improve 200-m or 400-m freestyle-swimming TT performance and might not be a worthwhile SB ingestion strategy for well-trained swimmers.

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.

The Effects of a Novel Sodium Bicarbonate Ingestion System on Repeated 4 km Cycling Time Trial Performance in Well-Trained Male Cyclists

BACKGROUND

A novel sodium bicarbonate (SB) product has come to market named the "Bicarb System" (M-SB; Maurten AB, Gothenburg, Sweden). It claims to minimise gastrointestinal (GI) discomfort whilst still improving exercise performance.

AIM

To investigate the effects of M-SB ingestion on repeated 4 km cycling time trials (TT1 and TT2) in well-trained male cyclists.

METHODS

The study recruited ten well-trained cyclists (maximal oxygen uptake (V ˙ O 2 max ): 67 ± 4 ml kg-1 min-1 BM; peak power output (PPO) atV ˙ O 2 max : 423 ± 21 W) to take part in this randomised, crossover and double-blinded study. Following one visit to determineV ˙ O 2 max , participants completed a second visit to identify individual time to peak blood bicarbonate (HCO3-) (ITTP) in a rested state. Visit three was a familiarisation trial mimicking the experimental procedures. Visits four to seven consisted of completing 2 × 4 km cycling TTs separated by 45 min passive recovery, following one of either: 0.3 g kg-1 BM M-SB, 0.21 g kg-1 BM sodium chloride (placebo; PLA) in vegetarian capsules (size 00), or a control trial (CON). Supplements (M-SB or placebo) were ingested pre-exercise at their respective ITTP.

RESULTS

Performance in TT1 was faster in the M-SB condition compared with TT1 in CON (- 5.1 s; p = 0.004) and PLA (- 3.5 s; p < 0.001). In TT2, performance was also significantly faster in the M-SB condition compared with CON (- 4.4 s; p = 0.018) or PLA (- 4.1 s; p = 0.002). Total aggregated GI symptoms were generally low and not significantly different between PLA and the M-SB conditions for a range of symptoms.

CONCLUSIONS

The ingestion of M-SB improves repeated 4 km cycling TT performance and the recovery of acid-base balance between bouts, whilst causing minimal GI discomfort.

Enhancing exercise performance and recovery through sodium bicarbonate supplementation: introducing the ingestion recovery framework

Sodium bicarbonate (SB) supplementation is an ergogenic strategy for athletes competing in high-intensity exercise, but the efficacy of SB for accelerating recovery from exercise and thus improving performance during repeated bouts of exercise is not fully understood. In a similar fashion to using SB as a pre-exercise buffer, it is possible accelerated restoration of blood pH and bicarbonate following an exercise bout mechanistically underpins the use of SB as a recovery aid. Physiological mechanisms contributing to beneficial effects for SB during repeated bout exercise could be more far-reaching however, as alterations in strong ion difference (SID) and attenuated cellular stress response might also contribute to accelerated recovery from exercise. From inspection of existing literature, ingestion of 0.3 g kg-1 body mass SB ~60-90 min pre-exercise seems to be the most common dosage strategy, but there is evidence emerging for the potential application of post-exercise supplementation timing, gradual SB doses throughout a competition day, or even ingestion during exercise. Based on this review of literature, an SB ingestion recovery framework is proposed to guide athletes and practitioners on the use of SB to enhance performance for multiple bouts of exercise.

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.

Influence of Ingestion of Bicarbonate-Rich Water Combined with an Alkalizing or Acidizing Diet on Acid-Base Balance and Anaerobic Performance

During high-intensity (HI) exercise, metabolic acidosis significantly impairs exercise performance. Increasing the body's buffering capacity through training and exogenous intake of alkalizing supplements may improve high-intensity performance. Manipulating water and diet intake may influence the acid-base balance. The aim of this study was to determine the effects of mineral water rich in bicarbonate ions (STY) or placebo water (PLA) on circulating biomarkers and anaerobic performance and to verify whether alkalizing (ALK) or acidizing (ACI) diet would modulate these effects. Twenty-four athletes, assigned either to ALK (n = 12) or ACI (n = 12) diet for four weeks, completed a 1-min rowing Wingate Test in a double-blind and randomized trial after one week of daily hydration (1.5 to 2L/d) with either STY or PLA. Blood samples were taken before and after each test, and urine samples were collected each week. Chronic consumption of bicarbonate-rich water significantly impacted resting urinary pH irrespective of alkalizing or acidizing dietary intake. STY induced a significant increase in blood pH, lactate, and HCO3 - ion concentration post-exercise compared to PLA. Similar changes were observed when STY was associated with the ALK diet. In contrast, STY combined with the ACI diet only significantly affected urine pH and peak blood lactate compared to PLA (p < 0.05). No effect of bicarbonate-rich water was reported on anaerobic performance (p > 0.05). Our results suggest that consumption of bicarbonate-rich water alters acid-base balance during a warm-up and after HI exercise, could potentiate beneficial effects of an alkalizing diet on the acid-base balance after HI exercise, and reduces the acid load induced by an acidifying diet.

No additive effect of creatine, caffeine, and sodium bicarbonate on intense exercise performance in endurance-trained individuals

BACKGROUND

Athletes commonly use creatine, caffeine, and sodium bicarbonate for performance enhancement. While their isolated effects are well-described, less is known about their potential additive effects.

METHODS

Following a baseline trial, we randomized 12 endurance-trained males (age: 25 ± 5 years, VO2max: 56.7 ± 4.6 mL kg-1 min-1; mean ± SD) and 11 females (age: 25 ± 3 years, VO2max: 50.2 ± 3.4 mL kg-1 min-1) to 5 days of creatine monohydrate (0.3 g kg-1 per day) or placebo loading, followed by a daily maintenance dose (0.04 g kg-1) throughout the study. After the loading period, subjects completed four trials in randomized order where they ingested caffeine (3 mg kg-1), sodium bicarbonate (0.3 g kg-1), placebo, or both caffeine and sodium bicarbonate before a maximal voluntary contraction (MVC), 15-s sprint, and 6-min time trial.

RESULTS

Compared to placebo, mean power output during 15-s sprint was higher following loading with creatine than placebo (+34 W, 95% CI: 10 to 58, p = 0.008), but with no additional effect of caffeine (+10 W, 95% CI: -7 to 24, p = 0.156) or sodium bicarbonate (+5 W, 95% CI: -4 to 13, p = 0.397). Mean power output during 6-min time trial was higher with caffeine (+12 W, 95% CI: 5 to 18, p = 0.001) and caffeine + sodium bicarbonate (+8 W, 95% CI: 0 to 15, p = 0.038), whereas sodium bicarbonate (-1 W, 95% CI: -7 to 6, p = 0.851) and creatine (-6 W, 95% CI: -15 to 4, p = 0.250) had no effects.

CONCLUSION

While creatine and caffeine can enhance sprint- and time trial performance, respectively, these effects do not seem additive. Therefore, supplementing with either creatine or caffeine appears sufficient to enhance sprint or short intense exercise performance.

Effects of Enteric-Coated Formulation of Sodium Bicarbonate on Bicarbonate Absorption and Gastrointestinal Discomfort

Sodium bicarbonate is used as an ergogenic supplement to enhance people's performances in various exercises. This study aimed to evaluate the effects of intestinal delivery of sodium bicarbonate on bicarbonate absorption and associated side effects in an experimental human trial. After preparing and assessing enteric-coated and uncoated sodium bicarbonate tablet formulations, pharmacokinetic analysis and gastrointestinal symptom tests were performed after oral administration in the human body. The dose required to increase blood bicarbonate concentration over 5 mmol∙L-1 for the purpose of improving performance during high-intensity exercise was also determined. Enteric-coated tablet formulation protects sodium bicarbonate under acidic conditions and releases bicarbonate in the intestine. Enteric-coated tablet formulation also reduced the oral dose required to achieve a blood bicarbonate concentration over 5 mmol∙L-1 from 300 mg∙kg-1 of uncoated tablet formulation to 225 mg∙kg-1. Gastrointestinal discomfort was significantly decreased for the group given 225 mg∙kg-1 enteric-coated tablets compared to that given 300 mg∙kg-1 uncoated tablets. These results suggest that enteric-coated tablet formulation could reduce the oral dose required in order to achieve a blood bicarbonate concentration over 5 mmol∙L-1 by 25%, from 300 mg∙kg-1 to 225 mg∙kg-1, along with its ability to reduce gastrointestinal discomfort associated with the dosage.

The Effects of a Carbohydrate Hydrogel System for the Delivery of Bicarbonate Mini-Tablets on Acid-Base Buffering and Gastrointestinal Symptoms in Resting Well-trained Male Cyclists

BACKGROUND

A new commercially available sodium bicarbonate (SB) supplement claims to limit gastrointestinal (GI) discomfort and increase extracellular buffering capacity. To date, no available data exists to substantiate such claims. Therefore, the aim of this study was to measure blood acid-base balance and GI discomfort responses following the ingestion of SB using the novel "Bicarb System" (M-SB). Twelve well-trained male cyclists completed this randomised crossover designed study. Maximal oxygen consumption was determined in visit one, whilst during visits two and three participants ingested 0.3 g∙kg-1 BM SB using M-SB (Maurten, Sweden) or vegetarian capsules (C-SB) in a randomised order. Finger prick capillary blood samples were measured every 30 min for pH, bicarbonate (HCO3-), and electrolytes (potassium, chloride, calcium, and sodium), for 300 min. Visual analogue scales (VAS) were used to assess GI symptoms using the same time intervals.

RESULTS

Peak HCO3- was 0.95 mmol∙L-1 greater following M-SB (p = 0.023, g = 0.61), with time to peak HCO3- achieved 38.2 min earlier (117 ± 37 vs. 156 ± 36 min; p = 0.026, r = 0.67) and remained elevated for longer (p = 0.043, g = 0.51). No differences were observed for any electrolytes between the conditions. Aggregated GI discomfort was reduced by 79 AU following M-SB (p < 0.001, g = 1.11), with M-SB reducing stomach cramps, bowel urgency, diarrhoea, belching, and stomach-ache compared to C-SB.

CONCLUSIONS

This is the first study to report that M-SB can increase buffering capacity and reduce GI discomfort. This presents a major potential benefit for athletes considering SB as an ergogenic supplement as GI discomfort is almost eliminated. Future research should determine if M-SB is performance enhancing.

Use of Buffers in Specific Contexts: Highly Trained Female Athletes, Extreme Environments and Combined Buffering Agents-A Narrative Review

This narrative review evaluated the evidence for buffering agents (sodium bicarbonate, sodium citrate and beta-alanine), with specific consideration of three discrete scenarios: female athletes, extreme environments and combined buffering agents. Studies were screened according to exclusion and inclusion criteria and were analysed on three levels: (1) moderating variables (supplement dose and timing, and exercise test duration and intensity), (2) design factors (e.g., use of crossover or matched group study design, familiarisation trials) and (3) athlete-specific factors (recruitment of highly trained participants, buffering capacity and reported performance improvements). Only 19% of the included studies for the three buffering agents reported a performance benefit, and only 10% recruited highly trained athletes. This low transferability of research findings to athletes' real-world practices may be due to factors including the small number of sodium citrate studies in females (n = 2), no studies controlling for the menstrual cycle (MC) or menstrual status using methods described in recently established frameworks, and the limited number of beta-alanine studies using performance tests replicating real-world performance efforts (n = 3). We recommend further research into buffering agents in highly trained female athletes that control or account for the MC, studies that replicate the demands of athletes' heat and altitude camps, and investigations of highly trained athletes' use of combined buffering agents. In a practical context, we recommend developing evidence-based buffering protocols for individual athletes which feature co-supplementation with other evidence-based products, reduce the likelihood of side-effects, and optimise key moderating factors: supplement dose and timing, and exercise duration and intensity.

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 sodium bicarbonate ingestion on swimming interval performance in trained competitive swimmers

The use of sodium bicarbonate (NaHCO3) supplementation to improve repeated high-intensity performance is recommended; however, most swimming performance studies examine time trial efforts rather than repeated swims with interspersed recovery that are more indicative of training sessions. The aim of this study, therefore, was to investigate the effects of 0.3 g.kg-1 BM NaHCO3 supplementation on sprint interval swimming (8 × 50 m) in regionally trained swimmers. Fourteen regionally competitive male swimmers (body mass (BM): 73 ± 8 kg) volunteered for this double-blind, randomised, crossover designed study. Each participant was asked to swim 8 × 50 m (front crawl) at a maximum intensity from a diving block, interspersed with 50 m active recovery swimming. After one familiarisation trial, this was repeated on two separate occasions whereby participants ingested either 0.3 g.kg-1 BM NaHCO3 or 0.05 g.kg-1 BM sodium chloride (placebo) in solution 60 min prior to exercise. Whilst there were no differences in time to complete between sprints 1-4 (p > 0.05), improvements were observed in sprint 5 (p = 0.011; ES = 0.26), 6 (p = 0.014; ES = 0.39), 7 (p = 0.005; ES = 0.60), and 8 (p = 0.004; ES = 0.79). Following NaHCO3 supplementation, pH was greater at 60 min (p < 0.001; ES = 3.09), whilst HCO3- was greater at 60 min (p < 0.001; ES = 3.23) and post-exercise (p = 0.016; ES = 0.53) compared to placebo. These findings suggest NaHCO3 supplementation can improve the latter stages of sprint interval swimming performance, which is likely due to the augmentation of pH and HCO3- prior to exercise and the subsequent increase in buffering capacity during exercise.

Sodium Bicarbonate and Time-to-Exhaustion Cycling Performance: A Retrospective Analysis Exploring the Mediating Role of Expectation

BACKGROUND

Research has shown that ingesting 0.3 g·kg^-1 body mass sodium bicarbonate (NaHCO₃) can improve time-to-exhaustion (TTE) cycling performance, but the influence of psychophysiological mechanisms on ergogenic effects is not yet understood.

OBJECTIVE

This study retrospectively examined whether changes in TTE cycling performance are mediated by positive expectations of receiving NaHCO₃ and/or the decline in blood bicarbonate during exercise.

METHODS

In a randomised, crossover, counterbalanced, double-blind, placebo-controlled design, 12 recreationally trained cyclists (maximal oxygen consumption, 54.4 ± 5.7 mL·kg·min^-1) performed four TTE cycling tests 90 min after consuming: (1) 0.3 g·kg^-1 body mass NaHCO₃ in 5 mL·kg^-1 body mass solution, (2) 0.03 g·kg^-1 body mass sodium chloride in solution (placebo), (3) 0.3 g·kg^-1 body mass NaHCO₃ in capsules and (4) cornflour in capsules (placebo). Prior to exercise, participants rated on 1-5 Likert type scales how much they expected the treatment they believe had been given would improve performance. Capillary blood samples were measured for acid-base balance at baseline, pre-exercise and post-exercise.

RESULTS

Administering NaHCO₃ in solution and capsules improved TTE compared with their respective placebos (solution: 27.0 ± 21.9 s, p = 0.001; capsules: 23.0 ± 28.1 s, p = 0.016). Compared to capsules, NaHCO₃ administered via solution resulted in a higher expectancy about the benefits on TTE cycling performance (Median: 3.5 vs. 2.5, Z = 2.135, p = 0.033). Decline in blood bicarbonate during exercise was higher for NaHCO₃ given in solution compared to capsules (2.7 ± 2.1 mmol·L^-1, p = 0.001). Mediation analyses showed that improvements in TTE cycling were indirectly related to expectancy and decline in blood bicarbonate when NaHCO₃ was administered in solution but not capsules.

CONCLUSIONS

Participants' higher expectations when NaHCO₃ is administered in solution could result in them exerting themselves harder during TTE cycling, which subsequently leads to a greater decline in blood bicarbonate and larger improvements in performance.

KEY POINTS

Ingesting 0.3 g·kg^-1 body mass sodium bicarbonate in solution and capsules improved time-to-exhaustion cycling performance Positive expectancy about the benefits of sodium bicarbonate and decline in blood bicarbonate were higher when sodium bicarbonate was administered in solution compared with capsules Improvements in time-to-exhaustion cycling performance for sodium bicarbonate administered in solution were related to expectancy and the enhanced extracellular buffering response.

The interplay between bicarbonate kinetics and gastrointestinal upset on ergogenic potential after sodium bicarbonate intake: a randomized double-blind placebo-controlled trial

This double-blind placebo-controlled cross-over study utilized comprehensive monitoring of blood bicarbonate (HCO₃^¯) kinetics and evaluation of gastrointestinal (GI) upset to determine their impact on an ergogenic potential of sodium bicarbonate (SB) co-ingested with carbohydrate (CHO). Nineteen CrossFit athletes performed 6 bouts of 15 s Wingate Anaerobic Test (WAnT) 90 min post-ingestion of 0.4 g·kg^-1 body mass (BM) of SB (SB + CHO treatment) or PLA (PLA + CHO treatment) with 15 g CHO. Blood HCO₃^¯ concentration was evaluated at baseline, 30-, 60-, 75- and 90 min post-ingestion, in between WAnT bouts, and 3 and 45 min post-exercise, while GI upset at 120 min after protocol started. Control (no supplementation; CTRL) procedures were also performed. An effective elevation of extra-cellular buffering capacity was observed 60-90 min post-ingestion of SB + CHO. At mean peak blood HCO₃^¯, or at start of exercise an increase > 6 mmol·L^-1 in HCO₃^¯ was noted in 84% and 52.6% participants, respectively. SB + CHO did not prevent performance decrements in WAnT bouts. There were no significant relationships between changes in blood HCO₃^¯ and WAnTs' performance. Total GI was significantly higher in SB + CHO compared to CTRL, and stomach problems in SB + CHO compared to CTRL and PLA + CHO. There were inverse associations between peak- (p = 0.031; r = - 0.495), average- (p = 0.002; r = - 0.674) and minimum power (p = 0.008; r = - 0.585) and total GI upset, as well as average power and severe GI distress (p = 0.042; r = - 0.471) at SB + CHO. The implemented dose of SB + CHO was effective in improving buffering capacity, but did not prevent decrements in WAnTs' performance. GI side effects were crucial in affecting the ergogenic potential of SB and thus must be insightfully monitored in future studies.

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.

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.

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.

Warm-Up Intensity Does Not Affect the Ergogenic Effect of Sodium Bicarbonate in Adult Men

This study determined the influence of a high- (HI) versus low-intensity (LI) cycling warm-up on blood acid-base responses and exercise capacity following ingestion of sodium bicarbonate (SB; 0.3 g/kg body mass) or a placebo (PLA; maltodextrin) 3 hr prior to warm-up. Twelve men (21 ± 2 years, 79.2 ± 3.6 kg body mass, and maximum power output [Wmax] 318 ± 36 W) completed a familiarization and four double-blind trials in a counterbalanced order: HI warm-up with SB, HI warm-up with PLA, LI warm-up with SB, and LI warm-up with PLA. LI warm-up was 15 min at 60% Wmax, while the HI warm-up (typical of elites) featured LI followed by 2 × 30 s (3-min break) at Wmax, finishing 30 min prior to a cycling capacity test at 110% Wmax. Blood bicarbonate and lactate were measured throughout. SB supplementation increased blood bicarbonate (+6.4 mmol/L; 95% confidence interval, CI [5.7, 7.1]) prior to greater reductions with HI warm-up (-3.8 mmol/L; 95% CI [-5.8, -1.8]). However, during the 30-min recovery, blood bicarbonate rebounded and increased in all conditions, with concentrations ∼5.3 mmol/L greater with SB supplementation (p < .001). Blood bicarbonate significantly declined during the cycling capacity test at 110%Wmax with greater reductions following SB supplementation (-2.4 mmol/L; 95% CI [-3.8, -0.90]). Aligned with these results, SB supplementation increased total work done during the cycling capacity test at 110% Wmax (+8.5 kJ; 95% CI [3.6, 13.4], ∼19% increase) with no significant main effect of warm-up intensity (+0.0 kJ; 95% CI [-5.0, 5.0]). Collectively, the results demonstrate that SB supplementation can improve HI cycling capacity irrespective of prior warm-up intensity, likely due to blood alkalosis.

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.

The effect of multi-ingredient intra- versus extra-cellular buffering supplementation combined with branched-chain amino acids and creatine on exercise-induced ammonia blood concentration and aerobic capacity in taekwondo athletes

Background

This study aimed to investigate the effect of multi-ingredient intra- (BA) versus extra- (ALK) cellular buffering factor supplementation, combined with the customary intake of branched-chain amino acids (BCAA) and creatine malate (TCM), on body composition, exercise variables, and biochemical and hematological parameters in 9 elite taekwondo athletes.

Methods

Eight-week randomized double-blind crossover BA (5.0 g·day⁻¹ of β-alanine) versus ALK (0.07 g·kg_FFM⁻¹·day⁻¹ of sodium bicarbonate) supplementation combined with BCAA (0.2 g·kg_FFM⁻¹·day⁻¹) and TCM (0.05 g·kg_FFM⁻¹·day⁻¹) during a standard 8-week taekwondo training period was implemented. In the course of the experiment, body composition (dual X-ray absorptiometry), aerobic capacity (ergospirometric measurements during an incremental treadmill test until exhaustion), and exercise blood biomarkers concentrations were measured. Data were analyzed using repeated measures within-between interaction analysis of variance with the inclusion of experimental supplementation order.

Results

The maximum post-exercise blood ammonia concentration decreased in both groups after supplementation (from 80.3 ± 10.6 to 72.4 ± 10.2 µmol∙L⁻¹, p = 0.013 in BA; from 81.4 ± 8.7 to 74.2 ± 8.9 µmol∙L⁻¹, p = 0.027 in ALK), indicating reduced exercise-related adenosine triphosphate degradation. However, no differences were found in body composition, aerobic capacity, blood lactate concentration, and hematological parameters after neither BA (combined with BCAA and TCM) nor ALK (combined with BCAA and TCM) supplementation.

Conclusions

In highly trained taekwondo athletes, neither extra- nor intracellular buffering enhancement resulting from BA and ALK supplementation, combined with BCAA and TCM treatment, affects body mass and composition, maximum oxygen uptake, and hematological indices, even though certain advantageous metabolic adaptations can be observed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12970-021-00451-3.

Effects of post-exercise sodium bicarbonate ingestion on acid-base balance recovery and time-to-exhaustion running performance: a randomised crossover trial in recreational athletes

This study investigated the effect of post-exercise sodium bicarbonate (NaHCO₃) ingestion on acid-base balance recovery and time-to-exhaustion (TTE) running performance. Eleven male runners (stature, 1.80 ± 0.05 m; body mass, 74.4 ± 6.5 kg; maximal oxygen consumption, 51.7 ± 5.4 mL·kg^-1·min^-1) participated in this randomised, single-blind, counterbalanced and crossover design study. Maximal running velocity (v-V̇O_2max) was identified from a graded exercise test. During experimental trials, participants repeated 100% v-V̇O_2max TTE protocols (TTE1, TTE2) separated by 40 min following the ingestion of either 0.3 g·kg^-1 body mass NaHCO₃ (SB) or 0.03 g·kg^-1 body mass sodium chloride (PLA) at the start of TTE1 recovery. Acid-base balance (blood pH and bicarbonate, HCO₃^-) data were studied at baseline, post-TTE1, after 35 min recovery and post-TTE2. Blood pH and HCO₃^- concentration were unchanged at 35 min recovery (p > 0.05), but HCO₃^- concentration was elevated post-TTE2 for SB vs. PLA (+2.6 mmol·L^-1; p = 0.005; g = 0.99). No significant differences were observed for TTE2 performance (p > 0.05), although a moderate effect size was present for SB vs. PLA (+14.3 s; g = 0.56). Post-exercise NaHCO₃ ingestion is not an effective strategy for accelerating the restoration of acid-base balance or improving subsequent TTE performance when limited recovery is available. Novelty: Post-exercise sodium bicarbonate ingestion did not accelerate the restoration of blood pH or bicarbonate after 35 min. Performance enhancing effects of sodium bicarbonate ingestion may display a high degree of inter-individual variation. Small-to-moderate changes in performance were likely due to greater up-regulation of glycolytic activation during exercise.

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.

The effect of β-alanine supplementation on high intensity cycling capacity in normoxia and hypoxia

The availability of dietary beta-alanine (BA) is the limiting factor in carnosine synthesis within human muscle due to its low intramuscular concentration and substrate affinity. Carnosine can accept hydrogen ions (H⁺), making it an important intramuscular buffer against exercise-induced acidosis. Metabolite accumulation rate increases when exercising in hypoxic conditions, thus an increased carnosine concentration could attenuate H⁺ build-up when exercising in hypoxic conditions. This study examined the effects of BA supplementation on high intensity cycling capacity in normoxia and hypoxia. In a double-blind design, nineteen males were matched into a BA group (n = 10; 6.4 g·d^-1) or a placebo group (PLA; n = 9) and supplemented for 28 days, carrying out two pre- and two post-supplementation cycling capacity trials at 110% of powermax, one in normoxia and one in hypoxia (15.5% O₂). Hypoxia led to a 9.1% reduction in exercise capacity, but BA supplementation had no significant effect on exercise capacity in normoxia or hypoxia (P > 0.05). Blood lactate accumulation showed a significant trial x time interaction post-supplementation (P = 0.016), although this was not significantly different between groups. BA supplementation did not increase high intensity cycling capacity in normoxia, nor did it improve cycling capacity in hypoxia even though exercise capacity was reduced under hypoxic conditions.

Evidence-based post exercise recovery in combat sports: a narrative review

INTRODUCTION

Some methods such as ergo nutritional aids, cooling or massage among others could improve recovery in combat sports (CS). The effects, doses, duration, and timing of these methods remains unknown. Nowadays, there is no clear consensus regarding the recovery strategies and it is necessary to understand the type of fatigue induced in CS and its underlying mechanisms. The main aim of this article is to review the update literature related to recovery strategies in CS.

EVIDENCE ACQUISITION

A literature search was conducted following preferred reporting items for review statement on the topic of: "combat sports," "recovery," "nutrition," "fatigue," "ergogenic aids," "weight cutting" and "hydration."

EVIDENCE SYNTHESIS

The initial search of the literature detected 369 articles about CS. Later, 307 were excluded after being determined unrelated to recovery or after failure to fulfill the inclusion criteria. Of the 80 included articles, 19 satisfied the final inclusion criteria.

CONCLUSIONS

To optimize CS performance, adequate recovery is required during training and competition processes. Traditional ergo nutritional supplementation of carbohydrates and proteins combined. Besides, the consumption of evidence supported supplementation (green tea, beetroot gels, creatine or alkaline water) improve recovery processes. Further methods of recovery including physical (cold water immersion, massage or photobiomodulation) and physiological (types of active recovery, sleep and rest) therapies have also been shown useful. This narrative review elucidates the important role of recovery techniques in CS.

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.

Effects of Dietary Supplements on Adaptations to Endurance Training

Endurance training leads to a variety of adaptations at the cellular and systemic levels that serve to minimise disruptions in whole-body homeostasis caused by exercise. These adaptations are differentially affected by training volume, training intensity, and training status, as well as by nutritional choices that can enhance or impair the response to training. A variety of supplements have been studied in the context of acute performance enhancement, but the effects of continued supplementation concurrent to endurance training programs are less well characterised. For example, supplements such as sodium bicarbonate and beta-alanine can improve endurance performance and possibly training adaptations during endurance training by affecting buffering capacity and/or allowing an increased training intensity, while antioxidants such as vitamin C and vitamin E may impair training adaptations by blunting cellular signalling but appear to have little effect on performance outcomes. Additionally, limited data suggest the potential for dietary nitrate (in the form of beetroot juice), creatine, and possibly caffeine, to further enhance endurance training adaptation. Therefore, the objective of this review is to examine the impact of dietary supplements on metabolic and physiological adaptations to endurance training.

Topical Sodium Bicarbonate: No Improvement in Blood Buffering Capacity or Exercise Performance

PURPOSE

To assess the efficacy of a topical sodium bicarbonate (0.3 g/kg body weight NaHCO3) application (PR lotion; Amp Human) on blood buffering capacity and performance in recreationally active participants (study A) and moderately trained athletes (study B).

METHODS

In Study A, 10 participants completed 2 experimental trials: oral NaHCO3 (0.3 g/kg body weight + placebo lotion) or PR lotion (0.9036 g/kg body weight + oral placebo) applied 90 minutes prior to a cycling task to exhaustion (30-s sprints at 120% peak power output with 30-s rest). Capillary blood was collected and analyzed for pH, bicarbonate, and lactate every 10 minutes throughout the 90-minute loading period and postexercise at 5, 10, and 15 minutes. In Study B, 10 cyclists/triathletes completed 2 experimental trials, applying either PR or placebo lotion 30 minutes prior to a cycling performance task (3 × 30-s maximal sprints with 90-s recovery). Capillary blood samples were collected at baseline, preexercise, and postexercise and analyzed as per study A.

RESULTS

In Study A, pH and bicarbonate were significantly elevated from baseline after 10 minutes in the oral NaHCO3 condition and throughout recovery compared with no elevation in the PR lotion condition (P < .001). No differences in cycling time occurred between PR lotion (349 [119] s) and oral NaHCO3 (363 [80] s; P = .697). In Study B, no differences in blood parameters, mean power (P = .108), or peak power (P = .448) were observed between conditions.

CONCLUSIONS

PR lotion was ineffective in altering blood buffering capacity or enhancing performance in either trained or untrained individuals.

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.

Nutrition and Altitude: Strategies to Enhance Adaptation, Improve Performance and Maintain Health: A Narrative Review

Training at low to moderate altitudes (~ 1600-2400 m) is a common approach used by endurance athletes to provide a distinctive environmental stressor to augment training stimulus in the anticipation of increasing subsequent altitude- and sea-level-based performance. Despite some scientific progress being made on the impact of various nutrition-related changes in physiology and associated interventions at mountaineering altitudes (> 3000 m), the impact of nutrition and/or supplements on further optimization of these hypoxic adaptations at low-moderate altitudes is only an emerging topic. Within this narrative review we have highlighted six major themes involving nutrition: altered energy availability, iron, carbohydrate, hydration, antioxidant requirements and various performance supplements. Of these issues, emerging data suggest that particular attention be given to the potential risk for poor energy availability and increased iron requirements at the altitudes typical of elite athlete training (~ 1600-2400 m) to interfere with optimal adaptations. Furthermore, the safest way to address the possible increase in oxidative stress associated with altitude exposure is via the consumption of antioxidant-rich foods rather than high-dose antioxidant supplements. Meanwhile, many other important questions regarding nutrition and altitude training remain to be answered. At the elite level of sport where the differences between winning and losing are incredibly small, the strategic use of nutritional interventions to enhance the adaptations to altitude training provides an important consideration in the search for optimal performance.

The influence of progressive-chronic and acute sodium bicarbonate supplementation on anaerobic power and specific performance in team sports: a randomized, double-blind, placebo-controlled crossover study

Background

The aims of this study were to verify the effect of progressive-chronic and acute sodium bicarbonate (SB) supplementation on the anaerobic capacity, blood acid-base balance, and discipline-specific performance in team sports disciplines.

Methods

Twenty-four trained male field hockey players completed a randomized, placebo-controlled, crossover trial of either progressive-chronic (increments from 0.05 up to 0.2 g/kg) or an acute one-off dose (0.2 g/kg) supplementation protocol. Before and after treatments, athletes completed an exercise protocol that comprised of a discipline-specific field performance test conducted between two separate Wingate anaerobic tests (WAnTs).

Results

Progressive-chronic SB supplementation improved anaerobic capacity in the first bout of WAnTs, as observed based on an increase in mean power (MP: 575 ± 71 vs. 602 ± 67 W, p = 0.005, ~ + 4.7%), peak power (PP: 749 ± 94 vs. 777 ± 96 W, p = 0.002, ~ + 3.7%), power carry threshold (P_CT) at 97%_PP (727 ± 91 vs. 753 ± 93 W, p = 0.002, ~ + 3.6%) and average power over P_CT (739 ± 94 vs. 765 ± 95 W, p = 0.001, ~ + 3.5%). Acute SB supplementation had no effect on anaerobic capacity. However, an improvement in time during discipline-specific field performance test was observed after progressive-chronic (919 ± 42 vs. 912 ± 27 s, p = 0.05; ~ - 0.8%) and acute (939 ± 26 vs. 914 ± 22 s, p = 0.006, ~ 2.7%) SB supplementation. Acute SB supplementation also improved post-exercise parameters of acid-base balance (based on blood pH, bicarbonate concentration and base excess) compared to no supplementation or placebo.

Conclusions

Our study indicates that both chronic and acute SB supplementation positively supports discipline-specific performance among field hockey athletes. Moreover, the chronic protocol supported anaerobic power indices before the inset of exercise-induced fatigue but had no significant impact afterwards. However, only the acute protocol significantly affected the buffering capacity, which can be used to determine athlete's performance during high-intensity sporting events. This study design therefore highlighted that future studies focusing on sodium bicarbonate supplementation in team sports should concentrate on the efficiency of chronic and acute supplementation in varying time frames.

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.

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

Background

The present study investigated the effects of chronic sodium bicarbonate (NaHCO₃) ingestion on a single bout of high-intensity exercise and on acid-base balance during 7-day high-altitude exposure.

Methods

Ten recreationally active subjects participated in a pre-test at sea level and a 7-day hiking tour in the Swiss Alps up to 4554 m above sea level. Subjects received either a daily dose of 0.3 g/kg NaHCO₃ solution (n = 5) or water as a placebo (n = 5) for 7 days. Anaerobic high-intensity exercise performance was assessed using the portable tethered sprint running (PTSR) test under normoxic and hypoxic conditions (3585 m). PTSR tests assessed overall peak force, mean force, and fatigue index. Blood lactate levels and blood gas parameters were assessed pre- and post-PTSR. Urinary pH and blood gas parameters were further analyzed daily at rest in early morning samples under normoxic and hypoxic conditions.

Results

There were no significant differences between the bicarbonate and control group in any of the PTSR-related parameters. However, urinary pH (p = 0.003, ηp² = 0.458), early morning blood bicarbonate concentration (p < 0.001, ηp² = 0.457) and base excess (p = 0.002, ηp² = 0.436) were significantly higher in the bicarbonate group compared with the control group under hypoxic conditions.

Conclusions

These results indicate that oral NaHCO₃ ingestion does not ameliorate the hypoxia-induced impairment in anaerobic, high-intensity exercise performance, represented by PTSR-related test parameters, under hypobaric, hypoxic conditions, but the maximal performance measurements may have been negatively affected by other factors, such as poor implementation of PTSR test instructions, pre-acclimatization, the time course of hypoxia-induced renal [HCO₃⁻] compensation, changes in the concentrations of intra- and extracellular ions others than [H⁺] and [HCO₃⁻], or gastrointestinal disturbances caused by NaHCO₃ ingestion. However, chronic NaHCO₃ ingestion improves blood bicarbonate concentration and base excess at altitude, which partially represent the blood buffering capacity.

Effects of an Alkalizing or Acidizing Diet on High-Intensity Exercise Performance under Normoxic and Hypoxic Conditions in Physically Active Adults: A Randomized, Crossover Trial

Pre-alkalization caused by dietary supplements such as sodium bicarbonate improves anaerobic exercise performance. However, the influence of a base-forming nutrition on anaerobic performance in hypoxia remains unknown. Herein, we investigated the effects of an alkalizing or acidizing diet on high-intensity performance and associated metabolic parameters in normoxia and hypoxia. In a randomized crossover design, 15 participants (24.5 ± 3.9 years old) performed two trials following four days of either an alkalizing (BASE) or an acidizing (ACID) diet in normoxia. Subsequently, participants performed two trials (BASE; ACID) after 12 h of normobaric hypoxic exposure. Anaerobic exercise performance was assessed using the portable tethered sprint running (PTSR) test. PTSR assessed overall peak force, mean force, and fatigue index. Blood lactate levels, blood gas parameters, heart rate, and rate of perceived exertion were assessed post-PTSR. Urinary pH was analyzed daily. There were no differences between BASE and ACID conditions for any of the PTSR-related parameters. However, urinary pH, blood pH, blood bicarbonate concentration, and base excess were significantly higher in BASE compared with ACID (p < 0.001). These findings show a diet-induced increase in blood buffer capacity, represented by blood bicarbonate concentration and base excess. However, diet-induced metabolic changes did not improve PTSR-related anaerobic 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.

Post-exercise Supplementation of Sodium Bicarbonate Improves Acid Base Balance Recovery and Subsequent High-Intensity Boxing Specific Performance

The aim of this study was to assess the effects of post-exercise sodium bicarbonate (NaHCO₃) ingestion (0.3 g.kg⁻¹ body mass) on the recovery of acid-base balance (pH, HCO3-, and the SID) and subsequent exercise performance in elite boxers. Seven elite male professional boxers performed an initial bout of exhaustive exercise comprising of a boxing specific high-intensity interval running (HIIR) protocol, followed by a high-intensity run to volitional exhaustion (T_LIM1). A 75 min passive recovery then ensued, whereby after 10 min recovery, participants ingested either 0.3 g.kg⁻¹ body mass NaHCO₃, or 0.1 g.kg⁻¹ body mass sodium chloride (PLA). Solutions were taste matched and administered double-blind. Participants then completed a boxing specific punch combination protocol, followed by a second high-intensity run to volitional exhaustion (T_LIM2). Both initial bouts of T_LIM1 were well matched between PLA and NaHCO₃ (ICC; r = 0.94, p = 0.002). The change in performance from T_LIM1 to T_LIM2 was greater following NaHCO₃ compared to PLA (+164 ± 90 vs. +73 ± 78 sec; p = 0.02, CI = 45.1, 428.8, g = 1.0). Following ingestion of NaHCO₃, pH was greater prior to T_LIM2 by 0.11 ± 0.02 units (1.4%) (p < 0.001, CI = 0.09, 0.13, g = 3.4), whilst HCO3- was greater by 8.8 ± 1.5 mmol.l⁻¹ (26.3%) compared to PLA (p < 0.001, CI = 7.3, 10.2, g = 5.1). The current study suggests that these significant increases in acid base balance during post-exercise recovery facilitated the improvement in the subsequent bout of exercise. Future research should continue to explore the role of NaHCO₃ supplementation as a recovery aid in boxing and other combat sports.

"I put it in my head that the supplement would help me": Open-placebo improves exercise performance in female cyclists

This study investigated the effect of open-placebo on cycling time-trial (TT) performance. Twenty-eight trained female cyclists completed a 1-km cycling TT following a control session or an open-placebo intervention. The intervention consisted of an individual presentation, provided by a medic, in which the concept of open-placebo was explained to the participant, before she ingested two red and white capsules containing flour; 15 min later, they performed the TT. In the control session, the participant sat quietly for 20 min. Heart rate and ratings of perceived exertion (RPE) were monitored throughout exercise, while blood lactate was determined pre- and post-exercise. Post-exercise questionnaires were employed to gain insight into the perceived influence of the supplement on performance. Open-placebo improved time-to-completion (P = 0.039, 103.6±5.0 vs. 104.4±5.1 s, -0.7±1.8 s, -0.7±1.7%) and mean power output (P = 0.01, 244.8±34.7 vs. 239.7±33.2, +5.1±9.5 W) during the TT. Individual data analysis showed that 11 individuals improved, 13 remained unchanged and 4 worsened their performance with open-placebo. Heart rate, RPE and blood lactate were not different between sessions (all P>0.05). Positive expectation did not appear necessary to induce performance improvements, suggesting unconscious processes occurred, although a lack of an improvement appeared to be associated with a lack of belief. Open-placebo improved 1-km cycling TT performance in trained female cyclists. Although the intervention was successful for some individuals, individual variation was high, and some athletes did not respond or even performed worse. Thus, open-placebo interventions should be carefully considered by coaches and practitioners, while further studies are warranted.

The effects of a novel bicarbonate loading protocol on serum bicarbonate concentration: a randomized controlled trial

BACKGROUND

Previous studies have shown that sodium bicarbonate ingestion may enhance intense exercise performance, but may also cause severe gastrointestinal distress. The purpose of this study was to determine whether a modified sodium bicarbonate (SB) ingestion protocol would elevate serum bicarbonate concentration more than previous methods without causing gastrointestinal distress.

METHODS

In randomized order, seven (5 men, 2 women) elite middle-distance runners ingested either placebo, Modified SB (600 mg·kg^- 1 over 19.5 h), or Acute SB (300 mg·kg^- 1) in opaque gelatin capsules. Baseline and post-ingestion blood samples were analyzed for bicarbonate, pH, sodium, hematocrit, and lactate. Repeated measures ANOVA (2 time points × 3 conditions) were analyzed to determine differences in serum bicarbonate, lactate, sodium, blood pH, and hematocrit. Gastrointestinal distress was assessed via self-report on a Likert scale of 1-10. Simple (condition) and repeated (time) within-participant contrasts were used to determine the location of any statistically significant main and interaction effects (p ≤ 0.05).

RESULTS

Both Modified SB (7.6 mmol·L^- 1, p < 0.01) and Acute SB (5.8 mmol·L^- 1, p < 0.01) increased serum bicarbonate concentration compared to the placebo (p ≤ 0.05). Post-ingestion serum bicarbonate concentration was significantly higher for the Modified SB (34.7 ± 2.2 mmol·L^- 1, 28.0% increase) trials than the Acute SB (33.5 ± 2.0 mmol·L^- 1, 20.9% increase) trials (p = 0.05). There was no reported severe GI distress in the Modified SB trials, but two cases in the Acute SB trials.

CONCLUSIONS

Modified SB elevated serum bicarbonate concentration more than Acute SB, without any severe gastrointestinal side effects. Consequently, it is recommended that future experimentation involving SB by researchers and athletes use the novel ingestion protocol described in this study due to its potential for improved effectiveness and reduced gastrointestinal impact.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03813329 . Registered 23 January 2019 - Retrospectively registered.

Sodium citrate supplementation enhances tennis skill performance: a crossover, placebo-controlled, double blind study

Background

The efficacy of sodium citrate supplementation (SC) in exercise performance is unclear. Therefore, the aim of this study was to investigate the effect of SC on skilled tennis performance.

Methods

Ten Brazilian nationally-ranked young male tennis players (age: 17 ± 1 yrs.; stature: 176.7 ± 5.2 cm; body mass: 68.4 ± 7.9 kg) participated in this crossover, placebo-controlled, double-blind study. Upon arrival, at baseline, in both experimental sessions blood was collected, then subjects ingested either sodium citrate (SC - 0.5 g^.kg⁻¹BM in capsules of 500 mg) or a placebo (PLA). Two hours later, pre-match blood was collected then skills tests (skill tennis performance test - STPT, repeated-sprint ability shuttle test - RSA) were performed followed by a 1-h simulated match. Immediately following the match, blood was again collected, and STPT, and RSA were administered.

Results

All metabolic parameters (i.e. base excess, pH, bicarbonate, and blood lactate) increased (p < 0.001) from baseline to pre-match and post-match in SC condition. Each metabolic parameter was greater (p < 0.001) in SC compared to PLA condition at both pre- and post-match. The SC condition elicited a greater (p < 0.01) shot consistency at post-match in the STPT vs. PLA condition (SC: 58.5 ± 14.8% vs. PLA: 40.4 ± 10.4%). A greater (p < 0.001) amount of games won was observed in the simulated match for SC condition vs. PLA condition (SC: 8.0 ± 1.6 vs. PLA: 6.0 ± 1.7). Additionally, the games won during the simulated match in SC condition was positively correlated with percentage shot consistency (r = 0.67, p < 0.001).

Conclusions

The current findings suggest that SC supplementation is an effective ergogenic aid to enhance skilled tennis performance.

Contemporary Nutrition Interventions to Optimize Performance in Middle-Distance Runners

Middle-distance runners utilize the full continuum of energy systems throughout training, and given the infinite competition tactical scenarios, this event group is highly complex from a performance intervention point of view. However, this complexity results in numerous potential periodized nutrition interventions to optimize middle-distance training adaptation and competition performance. Middle-distance race intensity is extreme, with 800- to 5,000-m races being at ∼95% to 130% of VO₂max. Accordingly, elite middle-distance runners have primarily Type IIa/IIx fiber morphology and rely almost exclusively on carbohydrate (primarily muscle glycogen) metabolic pathways for producing adenosine triphosphate. Consequently, the principle nutritional interventions that should be emphasized are those that optimize muscle glycogen contents to support high glycolytic flux (resulting in very high lactate values, of >20 mmol/L in some athletes) with appropriate buffering capabilities, while optimizing power to weight ratios, all in a macro- and microperiodized manner. From youth to elite level, middle-distance athletes have arduous racing schedules (10-25 races/year), coupled with excessive global travel, which can take a physical and emotional toll. Accordingly, proactive and integrated nutrition planning can have a profound recovery effect over a long race season, as well as optimizing recovery during rounds of championship racing. Finally, with evidence-based implementation and an appropriate risk/reward assessment, several ergogenic aids may have an adaptive and/or performance-enhancing effect in the middle-distance athlete. Given that elite middle-distance athletes undertake ∼400 to 800 training sessions with 10-25 races/year, there are countless opportunities to implement various periodized acute and chronic nutrition-based interventions to optimize performance.

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.