Caffeine and Training – How It Affects Your Performance (#46)

We Swedes rank among the world's top coffee drinkers, and for many, coffee is a vital part of both daily routines and training. But behind every cup lies caffeine – one of the most researched performance-enhancing substances in sports. The question is, how much impact does it actually have, and what's the best way to use it for optimal results? In this article, we explore what research reveals about how caffeine works in the body and what dosage appears to yield the greatest effect. The picture is clear: caffeine can boost performance in many endurance sports, but the effect depends on dosage, timing, and how your body specifically reacts.

We consume around 9 kg of coffee per person annually, which equals nearly 3.5 cups daily. If you’re not a coffee enthusiast, you might think, “what the heck, that's a lot,” but remember Sweden has a strong coffee culture: coffee is both a social beverage and a part of the morning or energizing routine before work, leisure, and for many, even before or during training.

When it comes to coffee and performance, the active ingredient is caffeine — possibly the most researched legal performance-enhancing substance in recent decades. There's no doubt caffeine boosts performance. Caffeine was even classified as a doping substance and included on the World Anti-Doping Agency's (WADA) list of prohibited substances until 2004, where the doping threshold was 12 micrograms/ml in urine. To reach that level, an athlete had to consume between 10-13 mg of caffeine per kg of body weight, equating to about 800-1,000 mg of caffeine — or 6-7 large cups of coffee — consumed in a short time. The practical relevance of such doses was doubtful, and the substance was removed from the list.

In 2009, a major review was published, which we previously used as a foundation in explanations for Umara Intend and why dosage is crucial. The next review came in 2014, followed by another update in 2016. These reviews are practical – they summarize what we know and provide an overview without delving into excessive detail in each individual study.

The most common explanatory model is that caffeine affects adenosine receptors in the central nervous system (CNS). Adenosine is a neurotransmitter that binds to these receptors and dampens the activity of the nervous system - we wind down, blood pressure drops, and we become tired. Adenosine levels increase during the day and peak in the evening. The amount of adenosine rises even faster if the oxygen level in the blood is low - a safety mechanism to ensure the brain and body don't overexert themselves when oxygen is lacking (for example, during fainting or extreme exertion). Thus, adenosine acts as the brain's rev limiter.

The caffeine molecule resembles the adenosine molecule and can bind to the same receptors. When caffeine attaches to the receptors, it prevents adenosine from doing so, resulting in the rev limiter being disconnected and the fatigue signal decreasing.

Caffeine is absorbed and enters the bloodstream within 10-15 minutes and peaks, that is, reaches its highest effect, somewhere between 40-80 minutes after consumption. Thereafter, caffeine has a half-life of approximately 3-6 hours. If you consume 200 mg of caffeine, after about 4.5 hours, you have about 100 mg left in your blood; after another approximately 4.5 hours, it's down to 50 mg, and so on.

The short answer: 3-6 mg per kg of body weight. The recorded performance-enhancing effect for endurance athletes ranges between 3-24 percent in studies. The range is wide—the higher numbers (up to 24 percent) are often seen in studies measuring time to exhaustion on a bike or treadmill, while smaller percentage improvements (around 3 percent) are common when measuring time improvement over longer distances. However, there is a clear and documented performance-enhancing effect.

The effect starts to appear at around 2 mg/kg, but at that level, the effect is usually not statistically significant—meaning it's so small that chance cannot be ruled out. In the interval of 3-6 mg/kg, we seem to have our “ergogenic window.”

In the latest review, it is concluded that the range of 3-8 mg/kg body weight is a safe range to achieve a performance-enhancing effect in a secure manner.

Researchers have tested doses from 1-13 mg/kg of body weight, and at doses over 6 mg/kg, generally no further performance gain is seen. The hypothesis is that we then saturate the adenosine receptors and block out as much fatigue as possible.

3-6 mg of caffeine per kilo of body weight corresponds to 210-420 mg of caffeine for a 70-kilo person. In Sweden, there is a safety range for caffeine-enriched products where a serving cannot contain more than 300 mg of caffeine before the product is classified as a medicine. This is far below the toxic threshold for adults, who begin to notice toxic symptoms around 20 mg/kg of body weight (equivalent to approximately 1,400 mg for a 70-kg person). The lethal dose is estimated to be approximately 150-250 mg/kg of body weight.

The effect seems to occur regardless of intensity. In a study on 38-year-old cyclists training with and without caffeine at lower intensity, the effects were primarily that the heart rate was 3-4 beats lower and perceived exertion decreased.

Caffeine is typically consumed through beverages such as coffee, tea, soda, energy drinks, pre-workouts like Intend, or as pills/gum and guarana supplements. It's also found in foods where it's used as a flavoring agent, like in dairy products, ice cream, and candy.

Coffee is the largest source of caffeine, providing approximately 80-100 mg per cup, though this can vary significantly. Not all coffee is created equal, which is why we often recommend caffeine supplements for their more controlled and tested doses.

Previously, many researchers believed that something in coffee limited the performance-enhancing effect of caffeine. Nowadays, researchers are not as unanimous, and many argue that coffee works about as well as pure caffeine.

Coffee contains many antioxidants, including chlorogenic acid, which could potentially slow down the performance-enhancing effect of caffeine. It is not entirely certain how significant this is, but dark roast coffee contains less chlorogenic acid than medium roast, which might make dark roast slightly more invigorating.

There is also a significant difference in caffeine content between different coffee varieties—even within the same type, depending on the season and growing conditions. For that reason, we often recommend caffeine pills or another method of controlled caffeine dosage when you want an exact and reproducible effect. If you have tested a setup that works during training, it is unnecessarily risky to change coffee varieties before a competition (for example, due to hotel coffee or another supplier). Train with what you will compete with—natural ingredients are affected by harvest, weather, and storage and are never as precise as controlled supplements.

Recent research suggests considerable variation in the caffeine content (1.2–25.9 mg/g) of individual coffee beans, depending on their variety and specific plant (Mazzafera & Silvarolla, 2010).

For example, one recent analysis reported that variation in caffeine content was more than 15% across 4 or more purchases from different locations, with some brands as high as 30% or more, and 85% of brands had a caffeine content higher than claimed by manufacturers (Desbrow, Henry, et al., 2012).

Moreover, another study found that caffeine content varied from 259–564 mg when the same coffee was purchased from the same major retailer on different days (McCusker et al., 2003)

As a final note, we can say that Arabica beans (common coffee bean on Swedish shelves) contain about half as much caffeine (approximately 1 percent caffeine per bean) as Robusta beans (approximately 2 percent caffeine per bean). Arabica might, therefore, be a sensible choice if you're using coffee as a social "meeting drink" and drink quite often without always wanting to boost performance.

Caffeine peaks in the bloodstream after approximately an hour. Hence, it's recommended to consume caffeine about 45 minutes before you start - this way, you're already active when peak levels occur.

Most likely, yes — abstain for up to 7 days to potentially maximize the effect. However, gradually reduce the intake and don't stop abruptly, especially if it negatively affects your tapering period.

Caffeine can have a diuretic effect, but it's only at doses of at least around 500 mg of caffeine that fluid loss becomes noticeably greater. Caffeine inhibits vasopressin, an antidiuretic hormone that helps the kidneys reabsorb water. However, during activity, ADH (antidiuretic hormone) is regulated up to maintain fluid balance, so during training it's usually not a problem. When sedentary, larger doses of caffeine can make you need to pee more compared to if you'd just drunk water.

Do you find yourself able to down several cups of coffee and still sleep like a log, or perhaps you never notice any caffeine kick although your friend swears by it? This might have to do with genetics.

Almost ten years ago, the gene CYP1A2 was identified—you don't need to memorize the abbreviation—but this gene codes for a step in the breakdown of caffeine. Researchers have discovered that some people exhibit up to 40 times higher activity in this gene compared to others, as noted by scientists.

Your genetic makeup determines whether you are a "fast metabolizer" or a "slow metabolizer" of caffeine. Those who metabolize caffeine quickly tend to experience a greater performance boost from caffeine intake. About 40 percent of us are "slow metabolizers," meaning we break down caffeine more slowly and don't experience the same effects.

In a study, athletes with genotype AA saw a 4.9 percent performance improvement over 40 km cycling, while the group with genotype AC achieved a 1.8 percent improvement.

A larger meta-analysis also revealed that males (not women) with the AA genotype drink more coffee than males with the AC genotype—likely because they metabolize caffeine faster and experience more positive effects. Update August 2018—still the same: the AC genotype doesn't respond to caffeine to the same degree https://www.ncbi.nlm.nih.gov/pubmed/29509641.

We apologize for the long article – there's a lot of useful insights when it comes to caffeine. In short:

• 3–6 mg caffeine/kg body weight 45–60 minutes before start
• The half-life is about 4–5 hours, so after that time, you can boost with a new dose. Another option is a maintenance dose of about 30 mg/hour.
• If you prefer coffee over PWO, caffeine pills, etc., use the same type of coffee and preparation method before both training and competition to avoid large variations in caffeine content.

We're not playing ethics professors here, but want to remind you that caffeine is addictive and, like other substances with effects, can cause side effects. Feel free to train your caffeine strategy before a competition — test, adjust, and learn how you react.

If you thought it was too short, you can listen when we podcast about the topic in episode #046 here.