Ergogenic effects of caffeine and sodium bicarbonate supplementation on intermittent exercise performance preceded by intense arm cranking exercise

Marriott et al. Journal of the International Society of Sports Nutrition (2015) 12:13 DOI 10.1186/s12970-015-0075-x RESEARCH ARTICLE Open Access Ergogenic effects of caffeine and sodium bicarbonate supplementation on intermittent exercise performance preceded by intense arm cranking exercise Matthaus Marriott1, Peter Krustrup1,2 and Magni Mohr3,4* Abstract Background: Caffeine and sodium bicarbonate ingestion have been suggested to improve high-intensity intermittent exercise, but it is unclear if these ergogenic substances affect performance under provoked metabolic acidification. To study the effects of caffeine and sodium bicarbonate on intense intermittent exercise performance and metabolic markers under exercise-induced acidification, intense arm-cranking exercise was performed prior to intense intermittent running after intake of placebo, caffeine and sodium bicarbonate. Methods: Male team-sports athletes (n = 12) ingested sodium bicarbonate (NaHCO3; 0.4 g.kg−1 b.w.), caffeine (CAF; 6 mg.kg−1 b.w.) or placebo (PLA) on three different occasions. Thereafter, participants engaged in intense arm exercise prior to the Yo-Yo intermittent recovery test level-2 (Yo-Yo IR2). Heart rate, blood lactate and glucose as well as rating of perceived exertion (RPE) were determined during the protocol. Results: CAF and NaHCO3 elicited a 14 and 23% improvement (P < 0.05), respectively, in Yo-Yo IR2 performance, post arm exercise compared to PLA. The NaHCO3 trial displayed higher [blood lactate] (P < 0.05) compared to CAF and PLA (10.5 ± 1.9 vs. 8.8 ± 1.7 and 7.7 ± 2.0 mmol.L−1, respectively) after the Yo-Yo IR2. At exhaustion CAF demonstrated higher (P < 0.05) [blood glucose] compared to PLA and NaHCO3 (5.5 ± 0.7 vs. 4.2 ± 0.9 vs. 4.1 ± 0.9 mmol.L−1, respectively). RPE was lower (P < 0.05) during the Yo-Yo IR2 test in the NaHCO3 trial in comparison to CAF and PLA, while no difference in heart rate was observed between trials. Conclusions: Caffeine and sodium bicarbonate administration improved Yo-Yo IR2 performance and lowered perceived exertion after intense arm cranking exercise, with greater overall effects of sodium bicarbonate intake. Keywords: Yo-Yo IR2 test performance, Fatigue, Blood lactate, Rating of perceived exertion, Team sport athletes Introduction Fatigue during high-intensity intermittent exercise is complex and multifaceted. Early speculation regarding the aetiology of fatigue commends that high rate of lactic acid production and a concomitant fall in blood and muscle pH [1], which may have multiple indirect and direct impairing effects on centrally and peripherally mediated fatigue-resistance. Caffeine and sodium bicarbonate * Correspondence: 3 Faculty of Natural and Health Sciences, University of the Faroe Islands, Jónas Broncks gøta 25. 3rd floor, Tórshavn, Faroe Islands 4 Center of Health and Human Performance, Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden Full list of author information is available at the end of the article (NaHCO3) are two supplements frequently consumed to elicit ergogenic effects on high-intensity exercise performance [2]. Effects of caffeine on intense intermittent exercise performance have for example been studied by Stuart et al. [3] demonstrating improved repeated sprint performance during a simulated rugby game trial. Moreover, team-sport athletes improved both total work and mean power output during an intermittent cycle sprint protocol [4] and Yo-Yo IR2 performance by 16% after caffeine intake [5]. However, Glaister et al. [6] showed that although the fastest sprint time in a repeated sprint test was observed with caffeine intake, the magnitude of © 2015 Marriott et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Marriott et al. Journal of the International Society of Sports Nutrition (2015) 12:13 fatigue in the caffeine condition appeared to be greater compared to a placebo trial. Furthermore, no ergogenic effect has been found on sprint performance during the Loughborough intermittent shuttle test [7]. Thus, the effects of caffeine intake on intense intermittent exercise protocols are equivocal. NaHCO3 ingested 90–150 min prior exercise has been used as an ergogenic aid for athletic events highly dependent on anaerobic glycolysis, since the ergogenic potential that NaHCO3 might elicit is suggested to depend upon the demands of the activity being sufficient to induce performance inhibiting levels of metabolic acidosis [8]. NaHCO3 ingestion has been reported to improve competitive and laboratory-based protocols lasting 1–7 min including swimming, middle distance running, rowing and repeated sprinting [9]. In addition, improvement in performance during a repeated sprint protocol is reported [10]. However, other studies are less affirmative and demonstrating no performance enhancing effects on high-intensity intermittent cycling [11]. Further discrepancies have been illustrated by Cameron et al. [12] whereby no benefits were observed during a highintensity rugby-specific training session followed by a repeated-sprint test. The absence of effects within the aforementioned studies is potentially due to insufficient metabolic taxation. The Yo-Yo Intermittent Recovery test level 2 (Yo-Yo IR2) consists of 20-m shuttle runs at progressive running speed and has a high anaerobic energy turnover [13]. Thus, in order to examine the effect of caffeine and NaHCO3 intake on high-intensity intermittent exercise the Yo-Yo IR2 test can be utilized. Moreover, engaging in intense arm exercise prior to repeated high-intensity running elevates the levels of leg muscle and blood [lactate] and [H+] [14], as well as increasing the accumulation rate in muscle interstitial [K+] resulting in decreased knee extensor exercise performance [15]. Therefore, intense upper-body exercise prior to running exercise can be applied to induce pre-exercise muscle acidosis and high metabolic disturbance without exercising the legs. Thus, the aim of the present study was therefore to compare the effects of caffeine and NaHCO3 supplementation 70–90 min prior to exercise, respectively, on Yo-Yo IR2 performance and physiological response to intense intermittent exercise with prior metabolic acidosis induced by intense arm cranking exercise. Methods Participants Twelve healthy male participants involved in sub-elite team-sports (age: 20.8 ± 1.4 (±SD) yrs.; height: 183 ± 7 cm; body mass: 78.9 ± 5.4 kg) volunteered to participate in this study. Participants gave their written Page 2 o (...truncated)