Effects of Sodium Bicarbonate on High-Intensity Endurance Performance in Cyclists: A Double-Blind, Randomized Cross-Over Trial

PLOS ONE, Dec 2019

Background While the ergogenic effect of sodium bicarbonate (BICA) on short-term, sprint-type performance has been repeatedly demonstrated, little is known about its effectiveness during prolonged high-intensity exercise in well-trained athletes. Therefore, this study aims to examine the influence of BICA on performance during exhaustive, high-intensity endurance cycling. Methods This was a single-center, double-blind, randomized, placebo-controlled cross-over study. Twenty-one well-trained cyclists (mean ± SD: age 24±8 y, BMI 21.3±1.7, VO2peak 67.3±9.8 ml·kg−1·min−1) were randomly allocated to sequences of following interventions: oral ingestion of 0.3 g·kg−1 BICA or 4 g of sodium chloride (placebo), respectively. One h after ingestion subjects exercised for 30 min at 95% of the individual anaerobic threshold (IAT) followed by 110% IAT until exhaustion. Prior to these constant load tests stepwise incremental exercise tests were conducted under both conditions to determine IAT and VO2peak. Analysis of blood gas parameters, blood lactate (BLa) and gas exchange measurements were conducted before, during and after the tests. The main outcome measure was the time to exhaustion in the constant load test. Results Cycling time to exhaustion was improved (p<0.05) under BICA (49.5±11.5 min) compared with placebo (45.0±9.5 min). No differences in maximal or sub-maximal measures of performance were observed during stepwise incremental tests. BICA ingestion resulted in an increased pH, bicarbonate concentration and BLa before, throughout and after both exercise testing modes. Conclusion The results suggest that ingestion of BICA may improve prolonged, high-intensity cycling performance. Trial Registration German Clinical Trials Register (DRKS) DRKS00006198.

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Effects of Sodium Bicarbonate on High-Intensity Endurance Performance in Cyclists: A Double-Blind, Randomized Cross-Over Trial

December Effects of Sodium Bicarbonate on High- Intensity Endurance Performance in Cyclists: A Double-Blind, Randomized Cross-Over Trial Florian Egger * 0 1 Tim Meyer 0 1 Ulf Such 0 1 Anne Hecksteden 0 1 0 Institute of Sports and Preventive Medicine, Saarland University , Saarbru cken , Germany 1 Editor: Conrad P. Earnest, Texas A&M University , United States of America Background: While the ergogenic effect of sodium bicarbonate (BICA) on shortterm, sprint-type performance has been repeatedly demonstrated, little is known about its effectiveness during prolonged high-intensity exercise in well-trained athletes. Therefore, this study aims to examine the influence of BICA on performance during exhaustive, high-intensity endurance cycling. Methods: This was a single-center, double-blind, randomized, placebo-controlled cross-over study. Twenty-one well-trained cyclists (mean SD: age 248 y, BMI 21.31.7, VO2peak 67.39.8 ml?kg21?min21) were randomly allocated to sequences of following interventions: oral ingestion of 0.3 g?kg21 BICA or 4 g of sodium chloride (placebo), respectively. One h after ingestion subjects exercised for 30 min at 95% of the individual anaerobic threshold (IAT) followed by 110% IAT until exhaustion. Prior to these constant load tests stepwise incremental exercise tests were conducted under both conditions to determine IAT and VO2peak. Analysis of blood gas parameters, blood lactate (BLa) and gas exchange measurements were conducted before, during and after the tests. The main outcome measure was the time to exhaustion in the constant load test. Results: Cycling time to exhaustion was improved (p,0.05) under BICA (49.511.5 min) compared with placebo (45.09.5 min). No differences in maximal or sub-maximal measures of performance were observed during stepwise incremental tests. BICA ingestion resulted in an increased pH, bicarbonate concentration and BLa before, throughout and after both exercise testing modes. Conclusion: The results suggest that ingestion of BICA may improve prolonged, high-intensity cycling performance. Trial Registration: German Clinical Trials Register (DRKS) DRKS00006198. - During prolonged cycling the ability to sustain a high power output is limited by the resources of the athlete to resist fatigue. To date, the cause of fatigue is controversial and performance may be limited by numerous factors, including physiological and psychological components [1]. However, for high-intensity exercise perturbations in both blood and muscle acid-base balance are associated with a decline in work rate and performance [24]. Thus, it has been assumed that muscle fatigue occurring in high-intensity exercise is mainly caused by the accumulation of hydrogen ions (H+) in the myoplasm [2, 5]. The cellular mechanisms include detrimental effects on myofilament interaction [6], glycolytic flux [4] and sarcoplasmatic reticulum function [7]. The ability of the body to prevent or delay these force limiting processes is determined by the capacity of its intrinsic buffering systems [5], which counteract the accumulation of H+ both inside and outside the cell [8]. Supplementation of alkalizing agents such as sodium bicarbonate (BICA) indirectly affects intramuscular pH by increasing the H+ concentration gradient across the sarcolemma [9]. As a result, the co-transport of H+ and lactate from the myoplasm is enhanced [10]. These findings suggest that increased extracellular buffering capacity may influence muscle function and potentially improve exercise performance during continuous cycling. Consequently, BICA has been studied as a potential ergogenic substance in several trials, mainly with a focus on short-term, sprint-type exercise. In a recently published meta-analysis it was concluded that BICA can be used as an ergogenic aid in short-term, high-intensity exercise [11]. By contrast, only few studies investigated the ergogenic potential of BICA in prolonged, high-intensity exercise with controversial findings [1216]. These studies are based on small sample sizes and, in part [14, 15], on subjects who are not habituated to the applied exercise mode. This is despite the relevance for typical competition modes (especially in cycling) and the lower variability of performance in trained subjects. Therefore the aim of this study was to investigate the effects of BICA supplementation on performance during prolonged, high-intensity cycling to exhaustion in welltrained athletes. Participants were recruited between May 2011 and October 2011 through email. Twenty-one healthy, well-trained cyclists (16 male, 5 female; mean SD: age 248 y, BMI 21.31.7, VO2peak 67.39.8 ml?kg21?min21) met the following criterion for inclusion in the study: a maximal performance during a stepwise incremental cycle test of at least 4.5 W?kg21 for females and 5.0 W?kg21 for males, respectively. The sample consisted of nine racing bikers, nine mountain bikers and three triathletes. On their first visit to the laboratory ea (...truncated)


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Florian Egger, Tim Meyer, Ulf Such, Anne Hecksteden. Effects of Sodium Bicarbonate on High-Intensity Endurance Performance in Cyclists: A Double-Blind, Randomized Cross-Over Trial, PLOS ONE, 2014, Volume 9, Issue 12, DOI: 10.1371/journal.pone.0114729