Coffee is a cycling staple, so its likely no coincidence that caffeine is recognised to be effective for improving endurance and overall sporting performance. But how does this occur, and what’s the best way to utilise caffeines effect? How much/what is an effective dose of caffeine for cycling/endurance events and more to the point WHEN should you be taking that caffeine?
Using caffeine in cycling and endurance sports
Looking at caffeine in purely clinical terms, it IS a drug of dependancy – a drug of dependency is defined as one where a person requires it to function normally, and abruptly stopping the substance leads to withdrawal symptoms. As such caffeine is the world greatest drug dependency. Caffeine is also a stimulant and as such is known to promote improvements during sporting events, particularly in high power (read wattage) endurance activities such as cycling.
A study by Eva et al 1998 showed that a caffeine solution of 320mg/l, when consumed at 8ml/kg during a 20min warm up resulted in an impressive time saving compared to placebo. On average placebo riders completed the TT in 62.5mins, vs 58.9mins for the caffeine group.
A difference of +3.6mins during a TT is a significant benefit. Based upon this, it is worth while investigating HOW caffeine has its action, and from that, can the caffeine effect be further enhanced?
How does caffeine have its effect on exercise performance?
There have been many theories about how caffeine produces its performance effects, and currently the actual process remains to be confirmed.
The two latest, complementary theories are:
- Caffeine triggers release of calcium from the sarcoplasmic reticulum within the muscle cell leading to increased contractility of the muscle
- Caffeine blocks adenosine receptors in both muscle and the brain, this increases mental alertness, reduces fatigue, and crucially reduces pain perception – it is thought that blocking adenosine receptors has the greatest effect on an athletes ability to perform, due to the mental and physical stimulation.
Eva et al 1998 demonstrated an additional psychological effect of caffeine, finding that individuals using pre-exercise caffeine reported lower perceived levels of effort compared to the placebo control groups – with caffeine loading groups reported 12 vs 14 on the Rating of Perceived Exertion score
Timing is key
One of the big questions for using caffeine in sports is when is the optimum time to take a caffeine supplement? Cox et al (2002) in the Applied Journal of Physiology performed a experiment using cyclists, who were put through the following exercise protocol – a 2hr steady state cycle, and then a 7kg/J TT. Three groups were used, placebo group, caffeine loading group taking 6mg/kg 1 hour before cycling, and finally 6mg/kg of caffeine supplement provided every 20mins during the exercise
The study showed no difference when caffeine was loaded pre-cycling, or given during the event. However both caffeine groups demonstrated a 3% faster completion of the TT compared to the placebo TT group.
Overall the study showed that timing of caffeine consumption doesn’t appear to matter – this may be due to the large variabilities possible for caffeine half life of caffeine, which will be largely due to rider specific variables. One possible reason for the lack of effect with regard to timing is that Cox et al demonstrated that that maximal concentrations of caffeine in the blood are achieved 2hrs post consumption – thus both groups would have very similar, near maximal concentrations of caffeine by the time the TT began, after the two hour steady state cycle.
Based on this, it may be most effective to take caffeine supplements within 2 hours prior your intention to start exercise.
How much caffeine should I use?
There is no universally agreed optimum dose for caffeine to be used for events – heck some studies have even failed to find a dose-response relationship – however from a competition point of view, caffeine does have some regulation – it was previously banned by the IOC (IOC Athletes Medical Information 2012), but this has now been removed. However the National Collegiate Athletic Association (NCAA) in the USA still considers caffeine to have been used as a doping agent if urine concentrations of >12ug/ml are found, which corresponds to consumption of roughly 500mg. Based on this we have a maximum ceiling, certainly in the USA which corresponds to approximately 4x335ml cans of Red Bull
Interestingly, with regard to “doping” at 500mg caffeine, 6mg/kg of caffeine, such as used in the Cox et al 2002 study, and is the optimum dosing, translates to 432mg of caffeine for myself!
This dose is particularly interesting when you look at the caffeine content of many sports drinks and supplements, as many will not come close to this content – e.g. power bar shots at 75mg.
Results are still seen at lesser doses however, Ivy et al in 2009 demonstrated approximately 5% reduction in time over a 1hr TT, after consumption of 1 can of Red Bull 1 hour before exercise. For me the two interesting points from this study are the improvement with lower caffeine doses, but also that Red Bull appears to have become a standard measure in some journals!!!
Similarly Desbrow in 2012 found a 4% improvement in 60min cycling exercises, when caffeine was ingested 90mins before activity, but didnt show a difference between 3mg/kg and 6mg/kg. Combined with the other studies, suggests that the optimum dose of caffeine, will differ between individuals, and will likely be seen within the 3-6mg/kg region
Do you NEED the caffeine?
From studies looking at different doses of caffeine use and subsequent performance, there appears to be considerable variation between individuals in their bodies ability to benefit from caffeine doses. However it has also been suggested that this may relate to the nature of the exercise, rather than the individual athletes – with optimum response to all caffeine doses seen when the intensity of the workout is >70% Vo2Max. Cox et al put forward the theory that this may be because during higher intensity exercise caffeine able to “spare” or “delay” an athletes muscles from utilising their glycogen muscles stores, which is not such an issue at lesser aerobic workouts.
An analogy here being using Nitros in a car. You can press the Nitros button when your are doing 20mph, but it’s unlikely you’ll notice any major change in performance. You will only see the “Fast and Furious” level response when the car is already going fast.
Higher doses of caffeine, which should really be considered as greater than 3mg/kg body weight, can be associated with side effects, these include mild anxiety, irritability, insomnia, tremor and heart palpitations.
Looking at caffeine from the other perspective, caffeine does have an adult toxic dose, of 10 GRAMS per day, but the sheer volume of energy drinks/supplements consumption required to reach this level would be considerable. You’d need to be drinking 88 cans of Red Bull (335ml), in which case I don’t think anyone would be surprised if you had a problem!
The diuretic effect
One considered issue of using caffeine is dehydration – the reason being when at rest, caffeine, like alcohol, is a recognised diuretic, I.e. Stimulating the production of urine. Which would in turn raise concerns about possible impairment during endurance as the athlete may need to stop to pass urine, or conversely develop dehydration. HOWEVER this effect is not seen during endurance protocol testing, suggesting natural anti-diuretic hormone produced during activity is sufficient to suppress the diuretic effect of the caffeine.
Take home message
Between 3-6mg/kg seems to be the most effective caffeine pre-cycling loading dose (2hrs before) – for myself weighing 72kg, @6mg/kg this equates to 432mg of caffeine…which is quite a lot of caffeine. To put it in a different metric, that’s three Grenade Black Ops capsules – (the box advises two tablets, 295mg of caffeine, for “an explosive workout”)
Caffeine really only appears to benefit high intensity exercise, and a greater effect is seen in aiding endurance, although there may be a small effect on promoting maximum/prolonging greater power outputs. It is not clear if this is related to muscle effects, or the psychological effects of reduced fatigue
Using high doses of caffeine like this should not be an issue with an early morning triathlon for example, but might not be a wise idea prior to starting an evening ZWIFT ZTR session, due to risks of not sleeping – and I’ve already written a post on the importance of sleep for optimum sports performance! Similarly, if you are relatively caffeine naive its certainly going to be worth trying lower doses first, in the 3mg/kg and less range, to reduce to chance of side effects.
Thanks for reading, next time I’m going to take a look at protein supplements and cycling
Other TitaniumGeek Nutrition posts
- Sleep and Sports
- Hydration and Indoor Cycling
- Caffeine in endurance sports
- Omega 3
- Protein Post Workout