Caffeine in Sports: The Most Common Questions and Answers

Whether it’s filter coffee, espresso, or latte, most of us love a cup of coffee! The caffeine it contains is one of the most consumed substances worldwide. As a stimulant, it not only keeps our nervous system active at work but also has a performance-enhancing effect in sports. Therefore, it is also available in the form of special supplements like chewing gum, capsules, and tablets.

The International Society of Sports Nutrition (ISSN) recommends a dosage of 3-6 mg of caffeine per kg of body weight for a performance-enhancing effect [1]. For a person weighing 70 kilos, this would amount to 210 - 420 mg of caffeine, which corresponds to roughly two to four cups of coffee, depending on the caffeine content. But is such an amount of caffeine actually healthy? And when should you limit your coffee consumption? Today, we’ll take a look at the most frequently asked questions about caffeine.

Does caffeine dehydrate the body?

Almost everyone believes that coffee, or the caffeine it contains, dehydrates the body due to its diuretic effect. For people who consume caffeine only occasionally, this may be true. However, studies show that a moderate amount of 3 mg per kg of body weight, or up to 300 mg of caffeine per day, does not negatively affect the fluid balance in regular coffee drinkers [2]. The diuretic effect only kicks in with larger amounts, such as 6 mg/kg (or more than 500 mg of caffeine in total per day). Therefore, there is a clear habituation effect [3].

Does caffeine during training lead to dehydration?

Even when consuming caffeine in a sports context, there is little reason to worry about dehydration. Studies have shown that other factors, such as sweat production and genetic predispositions, have a much stronger impact on a person’s hydration status than caffeine consumption [4]. To ensure adequate hydration, it is simply more practical to consume caffeinated beverages rather than tablets or capsules. The performance-enhancing effect of caffeine outweighs any concerns, especially in endurance sports.

Does caffeine help with weight loss?

We’ve often heard that caffeine supposedly boosts metabolism and helps with weight loss. After all, it is also a common ingredient in "fat burner" capsules and supplements. But is this really true? The scientific evidence is not entirely clear. Effects like increased fat burning and enhanced endurance performance have been observed in some studies, but in others, even a high dose of caffeine made no difference [5]. Individual factors such as caffeine habituation, body weight, and activity level seem to play a significant role in its effectiveness. 

Is there a habituation effect with caffeine in sports?

Science is not 100% in agreement on this either, as most studies on the performance-enhancing effects of caffeine did not ask participants about their daily coffee consumption. A habituation effect at a dose of 3-6 mg of caffeine per kg of body weight cannot be ruled out. Nevertheless, even regular coffee drinkers seem to benefit from a dose of 6 mg/kg of body weight taken about 60 minutes before training [6]. 

Can too much caffeine be deadly?

This may not be the first question that comes to mind, but it’s still interesting. Indeed, an overdose of caffeine and the resulting arrhythmias could lead to death; however, this only occurs with an acute dose of more than 5 grams [7]. It is very unlikely to reach such an amount with caffeinated beverages alone. However, caution should be exercised with concentrated products or pure caffeine.

Are there gender differences in the effects of caffeine?

The scientific evidence is not entirely conclusive, but gender differences in the effects of caffeine have been recorded. Hormonal variations can influence how quickly caffeine is metabolized in the body. Therefore, women may be more sensitive to caffeine intake at certain times compared to men. However, in general, both genders benefit from performance-enhancing effects in the area of muscular endurance [8].

Does caffeine affect everyone the same way?

The answer here is a clear no. In fact, there are significant differences in how people react to caffeine. The performance-enhancing effects also vary in intensity for each person and cannot always be reliably reproduced. However, it is extremely unlikely that someone would not react to caffeine at all. For most, it is an effective means to enhance sports performance [9].

Does caffeine cause heart problems during sports?

In fact, research has shown that regular caffeine consumption in moderate amounts, for example through coffee, can be beneficial for heart health. However, excessive or acutely high consumption can be dangerous, especially for people with pre-existing cardiovascular conditions or those who metabolize caffeine more slowly [10]. Those who want to use higher doses of this substance in sports should know their caffeine tolerance well and adjust their intake accordingly.

Is caffeine in sports considered doping?

Caffeine used to be on the World Anti-Doping Agency (WADA) doping list, but it was removed in 2004 because it was too difficult to distinguish between social use and abuse of caffeine through tests. This means that athletes can legally use caffeine to enhance their performance in sports. However, athletes should still pay attention to dosage, as WADA closely monitors the substance, and extremely high doses of caffeine could still be considered abuse in conjunction with modern testing methods in the future [11]. 

Caffeine and Sports Performance: Conclusion

Caffeine for enhancing sports performance is safe and effective in moderate amounts for athletes without pre-existing conditions. Due to individual reactions to the substance, it is advisable to find the right dosage and consider a potential habituation effect. To avoid overdose and associated cardiovascular problems, it is better to consume caffeine through caffeinated beverages rather than in the form of tablets or capsules.

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Sources

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[2] Killer SC, Blannin AK, Jeukendrup AE. No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population. PLoS One. 2014 Jan 9;9(1):e84154. 

[3] Maughan RJ, Griffin J. Caffeine ingestion and fluid balance: a review. J Hum Nutr Diet. 2003 Dec;16(6):411-20. 

[4] Armstrong LE. Caffeine, body fluid-electrolyte balance, and exercise performance. Int J Sport Nutr Exerc Metab. 2002 Jun;12(2):189-206. 

[5] Tabrizi R, Saneei P, Lankarani KB, Akbari M, Kolahdooz F, Esmaillzadeh A, Nadi-Ravandi S, Mazoochi M, Asemi Z. The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. 2019;59(16):2688-2696.

[6] Carvalho A, Marticorena FM, Grecco BH, Barreto G, Saunders B. Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine. Sports Med. 2022 Sep;52(9):2209-2220.

[7] Cappelletti S, Piacentino D, Fineschi V, Frati P, Cipolloni L, Aromatario M. Caffeine-Related Deaths: Manner of Deaths and Categories at Risk. Nutrients. 2018 May 14;10(5):611. 

[8] Jiménez SL, Díaz-Lara J, Pareja-Galeano H, Del Coso J. Caffeinated Drinks and Physical Performance in Sport: A Systematic Review. Nutrients. 2021 Aug 25;13(9):2944. 

[9] Del Coso J, Lara B, Ruiz-Moreno C, Salinero JJ. Challenging the Myth of Non-Response to the Ergogenic Effects of Caffeine Ingestion on Exercise Performance. Nutrients. 2019 Mar 29;11(4):732.

[10] Temple JL, Bernard C, Lipshultz SE, Czachor JD, Westphal JA, Mestre MA. The Safety of Ingested Caffeine: A Comprehensive Review. Front Psychiatry. 2017 May 26;8:80.