Think you know? If so how much caffeine would you say your standard cup of coffee cup has and does it matter?
A 2014 study found that a 200ml cup of regular black drip coffee can have anywhere from 75-150 mg of caffeine, while a six-day analysis of Starbucks' speciality coffee varied between 259 and 564mg caffeine per 473ml cup. So depending on the day, your coffee could be over twice as strong. Hopefully the impact on our daily life is relatively insignificant, however if a strong cup of coffee is part of your pre-race routine it could jeopardise your entire race:
Weak coffee before a short race will deny you of the caffeine boost you’ve come to rely on and the more arduous start could play on your mind and affect your pacing.
Overly strong coffee before a long race will lead to you starting too quickly, increasing your chance of crashing and will diminish the impact of additional caffeine later in the race.
If you are going to drink a coffee pre-race it is therefore vital to understand exactly how strong your coffee is and to learn what determines a coffee's strength.
What Determines The Strength Of Coffee?
From bush to belly nearly every step in a coffee bean's journey impacts on the coffees caffeine strength. The biggest difference though is the bean itself. The Robusta bean is far stronger than the Arabica and has a greater variance in strength. Its caffeine content ranges between 1.2 and 2.4% of dry weight compared to between 0.9 and 1.5% for Arabica, so know which type you're drinking as 0.9 or 2.4% is a huge difference.
Otherwise the main factors in a coffee's caffeine strength is the bean's origin, how coarsely it's ground, the brewing method and the serving size. While roasting time has a minimal impact, during roasting coffee beans expand and lose weight, reducing their density, so if a coffee serving is measured using a scoop, instead of by weight, the stronger the coffee roast, the weaker the coffee.
How a Coffee Bean's Origin Impacts its Strength
The level of light, altitude, soil composition and health of the bush all impact on the caffeine content of the bean, so there is variance even within fields. However most coffees are regional blends, reducing the variation from bag to bag and instead creating broader differences from region to region. Ugandan Robusta coffee has more caffeine that the same species in Vietnam and similarly some Brazilian Arabica subspecies contains more caffeine then Ethiopian, Mexican or Kenyan varieties. There are so many subspecies of coffee varieties though, that the vast majority have not been compared and there is no accurate way of ascertaining a coffees strength by region alone.
How Brewing Impacts a Coffee's Strength
Every step of transforming the roasted coffee bean into a drink directly impacts on its strength - the quantity, tamping, water temperature, water pressure, water/coffee ratio and extraction rate. The biggest differences come from how the coffee is prepared (espresso, drip, French press...) and how finely ground the coffee bean is.
Grinding breaks down the coffee cells, allowing us to dissolve more compounds, creating the flavour. Generally the longer coffee comes into contact with the water, the greater the absorption and greater the strength. Because when you prepare espressos the water passes through the coffee very quickly, the beans need to be ground finely so that the compounds can be absorbed easily.
If the coffee is left with the beans in for too long it becomes bitter, as too many compounds are dissolved (for example chlorogenic acid lactones), so coarsely ground beans are used when making coffee with a French Press, to slow down the absorption process, which will also reduce the caffeine absorption.
So in theory the finer the grind the stronger the coffee, however most baristas will only use finely ground beans with low absorption methods and vice versa, to ensure the balance of flavour and bitterness, which also helps reduce the variation in strength across differing methods. If you do see someone making an espresso with coarsely ground beans or a French press coffee with finely ground, stay clear, as it's likely that it won't be great coffee and the caffeine content could be very off. Please note that there is variation in definitions - coarsely ground coffee in Europe has an average size of 850μm vs 1,130μm in the US and finely ground coffee has an average size of 430μm vs 800μm .
We sadly also cannot use bitterness to estimate caffeine content, as the compounds that create bitterness are different in a light roast to those in a dark roast; caffeine only accounts for at most 15% of a coffee's bitter taste. So once again, there is large variance and estimating the caffeine content is incredibly difficult. The range for different coffee processes are outlined below:
While knowing a coffees origin, its grind and numerous other factors can help you try and understand how strong your coffee is, there is no convenient way of accurately knowing. There's large variation in all coffee styles, even powdered coffee or within the same brand, so if you rely on caffeine before a race, steer clear of percolated, boiled, filtered and French press coffee unless you are making them. Their caffeine variation is between 50-400%, so you could easily consume far more or far less caffeine than you had anticipated, which could have dire consequences for your race.
If you really want to guarantee your caffeine intake, then reach for a Caffeine Bullet with 100mg in every chew, but if you cannot do without your morning coffee, the good news is that it's possible without having to risk throwing your race away. Most coffee chain drinks are a mix of espresso shots with milk and water and use Arabica beans and therefore have a maximum variation of 29%, which is not enough to significantly impact your race.
Good luck with your next race and here's to a new personal best, but whatever you decide, make sure that you have tested your pre-race routine and don't make any significant changes on the day.
About Caffeine Bullet
Caffeine Bullet is a mint chew with 100mg caffeine and 4 types of electrolytes, formulated for athletic performance, to be taken before and during exercise to improve endurance, increase alertness and reduce the perception of pain. Far more convenient and concentrated than a gel, the caffeine is absorbed through your gums, to give you a more pronounced effect up to 4 times faster so that you can train harder and perform better.