Caffeine and Performance; An Update.
Introduction
Caffeine is the most widely consumed stimulant in the world and the highest studied and used ergogenic aid in sport. As a Methylxanthines it acts as adenosine receptor blocker and a phosphodiesterase inhibitor. By blocking adenosine receptors, caffeine is essentially acting as the ‘brakes’ in the central nervous system. Adenosine promotes our drive to recover and sleep, hence why blocking this channel counteracts this drive, leading to the stimulatory affects we associate with caffeine, such as alertness and wakefulness.
Phosphodiesterase is an enzyme necessary for the breakdown of the 2nd messenger protein cAMP within cells. cAMP helps transfer signals within cells. If this messenger protein is not being broken down (caffeine prevents this breakdown), it will have a better opportunity to cause its stimulatory effects. In simple terms, caffeine prevents the body from slowing things down at a cellular level.
Research has shown caffeine has many benefits for both the general and athletic population. Wakefulness is probably the most common manifestation of caffeine consumption. It has been shown to decrease mental fatigue and increase mental alertness and even relax airways allowing for greater oxygen consumption. Another key performance factor is the ability for caffeine to reduce the perception of fatigue.
However, it is important to note that taking caffeine at the wrong time and using inappropriate doses, may have negative consequences both on health and performance. Common symptoms are restlessness, shakiness, headaches, insomnia, and anxiety. Caffeine’s diuretic effect may also have major implications on exercise performance, causing dehydration and a need for regular toilet breaks. Caffeine consumption can also increase the adverse effects of stimulant drugs such as amphetamines, methylphenidate, and theophylline, causing nervousness, tremor, and insomnia. It can even counteract the anti-anxiety effects of medications like lorazepam. But perhaps my main concern (from a performance perspective) is sleeping disruption, and subsequently poor recovery, increased muscle damage and fatigue. This is perhaps best highlighted in a critical review by Nedelec et al 2015, who provided a comprehensive overview of sleep deprivation in soccer player, concluding disrupted sleep may result in impaired muscle glycogen repletion, impaired muscle damage repair, alterations in cognitive function and an increase in mental fatigue.
Firstly, we are going to cover the scenarios when you will likely benefit from caffeine based on scientific evidence, with a special emphasis on appropriate dosage and timing. Further factors influencing caffeine’s ergogenic effect including habituation and genetic mechanisms will also be discussed.
Appropriate Dosage
Research conducted by Graham and Spriet in 1995, found that the optimum dosage of caffeine to improve both prolonged endurance exercise and shorter bouts of exercise (around 5 minutes) was 3mg/kg. Caffeine ingestion prior to single short duration, very high intense exercise has shown some moderate performance benefits, but these appear modest compared to longer duration and repeated efforts over longer periods that require muscular endurance.
Higher dosages of caffeine (4-6mg/kg) did not appear to further enhance performance. Since then, there has been many studies on caffeine dosage and optimum performance in many different settings using many different exercise modes. However, the conclusion by Graham and Spiet remains well supported in both the recreational and athletic population. For a 70-75kg individual this is approximately 200mg caffeine. The only exception is that there appears to be a clear performance benefit in prolonged exercise (>1 hour duration) with smaller doses of caffeine (1-2mg/kg (Cox et al 2002). It has been hypothesised that this benefit is due to a reduction in perceived exertion.
Careful consideration needs to be made in the potential huge variability of caffeine intake even when it is taken in the same form (coffee). For example, a study found an incredibly large variation in different outlets for a single expresso (25-215mg!!!) (Desbrow et al 2007). Factors affecting the caffeine content include the brewing method, the type of bean and the amount of coffee grounds that is used.
David’s Recommendation
It is my recommendation that dosage should be replicated using as similar method as possible, beginning with approximately 3mg/kg of caffeine before performance and adjusting if necessary. Also note that recommendations are always based on a person’s body weight and not absolute values (i.e., 200mg). Expect better performance gains when doing longer duration workouts than very short duration workouts.
Appropriate Timing
Caffeine is rapidly absorbed, and there has been research to suggest acute intakes towards the end of endurance performance can improve performance (Cox et al 2002). However, the traditional approach to caffeine intake is in the pre-workout period. Since research has suggested that peak concentrations of caffeine are reached within 1 hour after ingestion, (Fredholm et al 1999), it is feasible to use caffeine between 30-60 minutes prior to exercise. This is supported in many studies, showing performance increases between 1-4% increases in sports such as running, cycling, team sports (relying on muscular endurance) when caffeine is taken between 30-60 minutes before exercise. This is a contrary practice to many experiences I regularly see in the fitness/gym environments where individuals would take a pre-workout caffeine drink and initiate exercise immediately.
David’s Recommendation
The perfect window for caffeine intake before exercise is 30-60 minutes.
Caffeine intake in smaller doses has also shown benefits towards the end of endurance events, by reducing the perception of fatigue. This can be taken with carbohydrate, in capsule or liquid form.
Source
Due to the problems in the real world with variability, particularly in commercially available coffee drinks, there has been several studies that have focused attention on alternative sources of caffeine that could be more practical than coffee. So far studies into coffee vs actual caffeine have been equivocal. It has been suggested that there could be other components in coffee that could even reduce performance, however McLellan and Bell 2004, demonstrated no difference in performance between coffee with pure caffeine. Cola and energy drinks have both been regularly used amongst athletes and both have shown performance enhancements. Unfortunately, many of these trials have not distinguished the contribution of caffeine on its own, but in a study by Cox et al 2002, it was found that much of the performance improvement was due to caffeine and not the carbohydrate in the sports drink.
David’s Recommendation
It appears the source of caffeine is not the significant factor in performance enhancement. Dosage and timing of caffeine should take priority.
Habituation
In a meta-analysis including sixty caffeine studies to determine whether habitual caffeine affects the ergogenic effect of caffeine (Carvalho et al 2022), it was found that there were similar improvements, suggesting there is no habitual affect of regular caffeine intake on performance. This is a conflict to some studies, including Beamont et al 2016, who found that chronic ingestion of a low dose of caffeine develops tolerance in low caffeine consumers. From this research, it is justifiable to advise low caffeine consumers to refrain from chronic caffeine supplementation to maximise the positive benefits from acute supplementation prior to exercise.
David’s Recommendation
My advice is to use an individualised approach, with habitual caffeine users still using the 3mg/kg and 30-60 min rule. This may require adjustment with regular high caffeine consumers but should still be trialled first before extrapolated to an important performance bout or competition.
Genetic
It is important to acknowledge we are different, and whilst there appears to be performance enhancing benefits when consuming caffeine, every study shows a large variability within studies. Due to this variability, it is clear there are other mechanisms involved and it has been hypothesised that there must be a genetic component that has not yet been uncovered. Recently, studies have looked at different genotypes that are likely to be responsible, CYP1A2 and ADORA2A. In a study conducted by Glaister et al 2021 with 40 athletes, there was lots of variability but no attributes to genetics were found. More studies need to be conducted with larger sample sizes, but it appears so far, genotype is not playing a significant role in performance, and the mechanisms are perhaps more complex than we understand. However, a study conducted by Rogers 2010 did find the ADORA2A genotype had significantly higher levels of anxiety. It is clear this is an area for further investigation.
David’s Recommendation
From current available research, we are still too early to base caffeine recommendation on genetic factors. However, there is increasing evidence that the TT component of ADORA2A genotype is responsible for higher anxiety in some individuals. For individuals who have symptoms of anxiety, it is my recommendation they should refrain from caffeine.
Final Word
Caffeine is one of the very few ergogenic aids that I regularly advise individuals to use to enhance performance (both in the recreational and athletic populations). However, careful consideration needs to be made on potential mechanisms that may impact its effectiveness. It is ESSENTIAL to use an individualised approach to caffeine intake, not just relying on studies but monitoring real life situations and recognise the potential negative impact it may have on anxiety, sleep and recovery. Further potential benefits of caffeine intake, including its ability to enhance the breakdown of fat will be discussed at a further date.
David Griffin BSc DipIOC
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Cox et al 2002. Effect of different protocols of caffeine intake on metabolism and endurance performance. J Appl Physiol (1985). 2002 Sep;93(3):990-9.
Desbrow et al 2007. An examination of consumer exposure to caffeine from retail coffee outlets. Food Chem Toxicol. 2007 Sep;45(9):1588-92.
Fredholm et al 2009. Actions of caffeine in the brain with special reference to factors that contribute to its widespread use. Pharmacol Rev. 1999 Mar;51(1):83-133.
Meclellon and Bell 2004. The impact of prior coffee consumption on the subsequent ergogenic effect of anhydrous caffeine. Int J Sport Nutr Exerc Metab. 2004 Dec;14(6):698-708.
Carvalho et al 2022. 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.
Beaumont et al 2016. Chronic ingestion of a low dose of caffeine induces tolerance to the performance benefits of caffeine. J Sports Sci. 2017 Oct;35(19):1920-1927.
Glaister et al 2021. Caffeine, exercise physiology, and time-trial performance: no effect of ADORA2A or CYP1A2 genotypes. Appl Physiol Nutr Metab. 2021 Jun;46(6):541-551.
Rogers 2010. Association of the anxiogenic and alerting effects of caffeine with ADORA2A and ADORA1 polymorphisms and habitual level of caffeine consumption. Neuropsychopharmacology. 2010 Aug;35(9):1973-83.
Caffeine and Performance: An Update.
As the worlds most research ergogenic aid, caffeine serves an important role in enhancing our work and athletic performance. But how do we get the most out of it? Here is an update and my recommendations based on the latest available research.
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