Caffeine is one of the few legal (since 2004) performance enhancing (ergogenic) drugs. It is ergogenic for different components of exercise performance including aerobic endurance, muscle strength, muscle endurance, power, jumping performance and exercise speed.
Most people ingest caffeine via coffee, some via energy drinks, powder, tea or tablets. Caffeine intake can improve your performance by up to 5% and alongside carbohydrate up to 10%. This was observed in events or time trials between 60-90mins duration.
Typically caffeine peaks in the blood stream 1hr after ingestion. It has a half life (time it stays in your body) of approx. 4hrs.
Caffeine Use for Endurance Training
Caffeine use for endurance training needs to be tested by self experimentation. Many factors (gender, age, body size, genetics, food intake etc.) affect the effect it has on your body and therefore performance. Some athletes experience negative side effects of caffeine such as headaches, irritability, increased heart rate, nausea & GI distress. Some can only tolerate small doses, others larger doses.
Try a variety of dosages, different timings and forms (tablet, coffee, in an energy drink) to find what works best for you. Monitor how it affects you including energy levels, sleep and anxiety levels.
A double espresso or two cups of coffee (~ 150-200mg caffeine) 1hr before exercise should illicit performance benefits in most athletes.
It is ok to top up your caffeine levels for later in the race, but you need to ingest it 60mins before you need it.
You do not need to reduce caffeine intake in the days leading into an event etc. to get the benefits. Low, medium and high caffeine consumers all responded in the same way to doses of caffeine.
To be ergogenic, the caffeine dose from coffee likely has to fall within the 3–6mg/kg range. The caffeine dose received from coffee depends on many factors, including bean type, preparation method and size of the cup; there are large differences in caffeine concentrations between different coffee brands and flavours and within the same brand across time.
References / Further Reading