Coffee and training

A cup of coffee before the gym is the habit of millions of people, and in this case the habit has serious scientific support. The editorial team broke down how caffeine affects training, whether coffee equals a caffeine supplement, how much and when to drink it and who should be cautious.

Coffee as a sports supplement

Caffeine is one of the few substances whose ergogenic effect is confirmed by dozens of randomized studies and meta-analyses. The IOC consensus on dietary supplements for athletes (Maughan et al., 2018) places it in the group of supplements with well-proven effectiveness. And for most people the most accessible source of caffeine is ordinary coffee.

Since 2004 caffeine has not been on the WADA Prohibited List, although it remains in the monitoring program. This means that athletes can legally use coffee before training and competitions.

At the same time, there is a difference between a caffeine pill and a cup of coffee. In coffee, caffeine is combined with hundreds of other compounds — chlorogenic acids, diterpenes, antioxidants — and its amount in a cup varies greatly depending on the variety, roast and method of preparation.

The editorial team looked into whether coffee itself works as a pre-workout tool, how much of it is needed, when to drink it and what is wrong with it for certain people.

How caffeine affects training

The main mechanism of caffeine’s action is the blockade of adenosine receptors in the brain. Adenosine accumulates during wakefulness and physical exertion, increasing the feeling of fatigue. Caffeine occupies its receptors and thus reduces the perception of effort and pain, improves concentration and reaction time.

The ISSN position on caffeine (Guest et al., 2021) sums up that caffeine consistently improves endurance performance and can also increase strength endurance, power and performance in many team sports. An umbrella review by Grgic and colleagues (2020), which combined 21 meta-analyses, confirmed the ergogenic effect across a wide spectrum of loads, although its magnitude is usually moderate.

For strength training the effect is less pronounced than for endurance, but it exists: more repetitions to failure, slightly higher power, a lower subjective feeling of fatigue. In practice this means the ability to perform a larger training volume.

Effective doses in studies were usually 3–6 mg of caffeine per kilogram of body weight about 60 minutes before exertion. Some work shows an effect even at lower doses, around 2–3 mg/kg, especially in the context of concentration and endurance.

Coffee or caffeine in capsules

For a long time it was believed that other components of coffee might “dampen” the effect of caffeine. However, a study by Hodgson, Randell and Jeukendrup (2013) showed that coffee and anhydrous caffeine in an equivalent dose (5 mg/kg) equally improved performance in an endurance test compared with placebo. A review by Higgins and colleagues (2016) also concluded that coffee before exertion is able to increase endurance.

The main problem of coffee is the unpredictability of the dose. The amount of caffeine in a cup can differ severalfold depending on the bean, grind, brewing method and portion size.

For an amateur who trains for themselves, a cup or two of coffee 30–60 minutes before training is an entirely adequate solution. An athlete for whom the reproducibility of the dose at competitions matters finds it more convenient to use caffeine in capsules or gels with a known amount.

Coffee also contains water and, often, milk and sugar. A large volume of fluid immediately before running can cause stomach discomfort, so the timing of intake should be chosen individually and tested during training, not on race day.

Practical recommendations

For healthy adults, EFSA (2015) considers it safe to consume up to 400 mg of caffeine per day from all sources and up to 200 mg at one time; for pregnant women — up to 200 mg per day. For an athlete weighing 70 kg a dose of 3 mg/kg is about 210 mg, that is, roughly two standard cups of filter coffee.

• drink coffee about 30–60 minutes before training;
• start with a lower dose (about 2–3 mg/kg) and assess tolerance;
• higher doses do not give a proportionally greater effect but increase side effects;
• do not drink coffee late in the evening if the training is in the evening — caffeine worsens sleep;
• test the strategy during training, not on competition day.

Habituation to caffeine partly reduces but does not cancel its ergogenic effect. Some athletes take a “caffeine break” before competitions, but there is little evidence of its necessity, and abrupt cessation can cause headache and fatigue.

A common myth is that coffee dehydrates. A study by Killer, Blannin and Jeukendrup (2014) showed that moderate daily consumption of coffee in men habituated to it did not lead to dehydration compared with water. That is, coffee can be counted in the daily fluid balance.

Coffee on an empty stomach before a morning workout causes heartburn or nausea in some people. A small snack or a switch to capsules usually solves the problem.

Who should be cautious

The reaction to caffeine is very individual. Partly this is linked to genetic variants of the enzyme CYP1A2, which metabolizes caffeine in the liver: in “slow metabolizers” caffeine stays in the blood longer. Metabolism is also affected by smoking, hormonal contraception, pregnancy and some medications.

The side effects of excess caffeine are anxiety, tremor, tachycardia, stomach upset, insomnia. For athletes it is especially important that worsened sleep can eat up all the benefit of a better workout.

People with arrhythmias, uncontrolled arterial hypertension, anxiety disorders, during pregnancy, as well as those taking medications that interact with caffeine, should discuss coffee consumption with a doctor.

A dangerous combination is coffee plus other sources of caffeine: pre-workout complexes, energy drinks, fat burners. The total dose easily exceeds the safe limit, especially when several stimulants are listed on the labels at once.

Editorial conclusions

Coffee is an accessible and effective source of caffeine, whose ergogenic effect is confirmed for endurance and also, to a lesser extent, for strength and speed-strength loads. Studies show that coffee in an equivalent dose of caffeine works no worse than capsules.

The effective range in studies is 3–6 mg/kg about an hour before exertion, but for many a lower dose is enough. The daily limit for healthy adults per EFSA is up to 400 mg.

The main drawbacks of coffee are the unpredictable dose and the effect on sleep with late intake.

Also read our articles on energy drinks and the heart, pre-workout complexes and the athlete’s breakfast.

References

1. Guest NS, VanDusseldorp TA, Nelson MT, et al. International Society of Sports Nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18(1):1.
2. Grgic J, Grgic I, Pickering C, et al. Wake up and smell the coffee: caffeine supplementation and exercise performance — an umbrella review of 21 published meta-analyses. Br J Sports Med. 2020;54(11):681–688.
3. Hodgson AB, Randell RK, Jeukendrup AE. The metabolic and performance effects of caffeine compared to coffee during endurance exercise. PLoS One. 2013;8(4):e59561.
4. Higgins S, Straight CR, Lewis RD. The effects of preexercise caffeinated coffee ingestion on endurance performance: an evidence-based review. Int J Sport Nutr Exerc Metab. 2016;26(3):221–239.
5. 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;9(1):e84154.
6. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on the safety of caffeine. EFSA J. 2015;13(5):4102.
7. Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439–455.