Caffeine has been shown to improve endurance performance Studies showing this date back to the 1970s and the findings have been confirmed over and over. Caffeine is used frequently by athletes in different amounts and in different forms: tablets, gels, drinks, chewing gum etc. However, the most common form in which it is consumed is coffee. Interestingly, however, when coffee was compared to caffeine ingestion in a study in 1988, caffeine improved performance but coffee did not. Several theories were developed and the one that seemed to stick was a theory that coffee must contain other compounds that counteract the effect of caffeine and make coffee less effective.
We set out to test this further. In a study by Dr Adrian Hodgson, one of my students at the University of Birmingham at the time, published in the journal PLOS One in April 2013, caffeine and coffee went head to head in a performance study. Eight trained cyclists and triathletes performed time trials with caffeine taken as a supplement or consumed as coffee. The selected participants reported a low habitual caffeine consumption (under 300mg per day) and undertook 30 minutes of cycling at about 60% of their maximum power output (an intensity that can be sustained for 3-4 hours), followed by a time trial (all-out exercise) lasting 35-40 min. So the total exercise duration was around 65-70 minutes. This exercise was repeated four times, each time coming into the laboratory after an overnight fast (i.e. before breakfast): once taking caffeine dissolved in water; once having drunk instant coffee; once having drunk decaffeinated coffee; and finally having drunk a placebo (See figure 1). All beverages were consumed one hour before cycling, giving caffeine the chance to reach a peak level in the blood.
It was found that time trial performance was significantly faster, and average power significantly higher when caffeine or coffee was consumed, compared with decaffeinated coffee or placebo. But, interestingly, there was no significant difference in performance between coffee and caffeine.
The simple take home message from this study is that both caffeine as a supplement or coffee can result in performance improvements. Since the use of coffee seems to be less controversial than the use of caffeine in the form of a supplement, this may be the preferred option for many. Many will also enjoy the taste and smell of a cup of fresh espresso a lot more than that of a supplement.
Hodgson AB, Randell RK, Jeukendrup AE. (2013) The Metabolic and Performance Effects of Caffeine Compared to Coffee during Endurance Exercise. PLoS ONE 8(4): e59561.
Strength:
Important practical questions addressed in a very controlled way
Blood caffeine levels were measured and they show the same patterns: higher levels, better performance.
Weakness:
Participants in this study consumed 2 very large cups of coffee. Although there were no complaints, this may be more than most athletes normally consume. It would be good to repeat the study with smaller amounts of coffee and caffeine.
In this study to improve control, no breakfast was provided. To mimic a more likely race situation, it would be good to repeat the study after normal race preparation (breakfast).