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Flattened cola improves high-intensity interval performance in competitive cyclists



Some cyclists consume flattened cola during competitive events, but limited research has investigated if cola beverages elicit ergogenic effects, particularly on high-intensity exercise performance. Whether the potentially beneficial effects of cola are due to the caffeine and/or the carbohydrate content is also unclear. This study assessed the ergogenic effects of different cola beverages on performance during a constant power bout (CPB) and subsequent high-intensity interval efforts in competitive cyclists.


In a randomized, double-blind, cross-over design, competitive cyclists (n = 13; \(\dot{V}\)O2max 65.7 ± 5.9 ml kg−1 min−1) completed a 45-min CPB at 69% of maximum workload (Wmax), followed by four maximal 1-min high-intensity intervals (HII) against a resistance of 0.5 N kg−1. Participants consumed 16 ml kg−1 total (intermittantly at four time points) of flattened decaffinated diet cola (PLA), caffeinated diet cola (CAF) or cola containing caffeine and carbohydrates (CAF + CHO).


During the CPB, ratings of perceived exertion were lower in the CAF + CHO and CAF conditions compared to PLA (both, P < 0.04). Compared to PLA, CAF + CHO and CAF similarly increased (all, P < 0.049) mean power (CAF + CHO: 448 ± 51 W; CAF: 448 ± 50 W; PLA: 434 ± 57 W), minimum power (CAF + CHO: 353 ± 45 W; CAF: 352 ± 51 W; PLA: 324 ± 49 W) and total work (CAF + CHO: 26.9 ± 3.1 kJ; CAF: 26.9 ± 3.0 kJ; PLA: 26.0 ± 3.4 kJ), but not peak power (CAF + CHO: 692 ± 117 W; CAF: 674 ± 114 W; PLA: 670 ± 113 W; all, P > 0.57) during the HII.


Cola containing caffeine with or without carbohydrates favorably influenced perceived effort during the CPB and enhanced mean and minimum power during repeated maximal intervals. We provide evidence supporting the consumption of commercially available cola for high-intensity cycling in competitive cyclists.

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Fig. 1

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Caffeine and carbohydrates




Constant power bout


Heart rate


High-intensity interval




Rating of perceived exertion

\(\dot{V}\)O2max :

Maximum volume of oxygen consumption

W max :

Maximum workload


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The authors would like to thank the local cycling community for participating in this research project.


Acadia University Research Fund.

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Authors and Affiliations



The study was designed by KGC, JRF and HJP; data were collected by KGC and BT; data analysis and data interpretation was carried out by MWO, KGC and JRF; MWO, KGC and JRF drafted the manuscript; All authors edited the manuscript. All authors approved the final version of the paper.

Corresponding author

Correspondence to Jonathon R. Fowles.

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Conflict of interest

KC and HP have been employed by Dietitians of Canada.

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Approved by the Acadia University Research Ethics Board.

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All participants provided written informed consent.

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All participants provided written informed consent. Only unidentifiable, aggregate data is presented.

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Communicated by Philip D. Chilibeck.

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Fowles, J.R., O’Brien, M.W., Comeau, K.G. et al. Flattened cola improves high-intensity interval performance in competitive cyclists. Eur J Appl Physiol 121, 2859–2867 (2021).

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