Also check out Part 1 and Part 2

Caffeine (C8H10N4O2)

As you may know, caffeine is a stimulant that works on the central nervous system, increasing alertness and concentration. It is absorbed by the small intestine within 45 minutes of ingestion and is then distributed throughout all the tissues of the body; it reaches peak blood concentration in about an hour. It has many beneficial effects on the body, but of particular interest to athletes is that it causes the breakdown of fat, which in turn leads to an increase in available glycerol.


Caffeine has been shown to reduce fat and improve cognitive skills and the efficiency of energy expenditure that consequently improves endurance. It has also effected improvements in certain anaerobic activities, such as sprint performances and other short-term, high-intensity events – although, it must be said, far less research has been conducted on its effects on anaerobic exercise.

In general, the many positive research results of caffeine intake for endurance activities have been concluded as significant, but each activity researched was different – often very different – so it is difficult to say any more than that with any confidence. As for the short-term high-intensity events the finish times seem to improve by 0.5 to 1.5 per cent.

Commercial products recommend doses of about 200mg to 400mg a day, which (as we shall see) is on the low side when compared with the doses used in research trials. Caffeine in doses of 3mg, 6mg and 9mg (all per kg of BM) are considered by researchers to be low, moderate and high, respectively.

As it is, most researchers seem to have used doses of 3-9mg per kg of BM before the event, be it endurance or short-term high-intensity; however, for some endurance activities caffeine was instead taken during the event at a reduced rate of 1-2g per kg of BM. Since both intake suggestions have had positive results, both are included here:

– Caffeine: suggested dosage is 3-9mg/kg/BM before the event, or

– Caffeine: suggested dosage of 1-2mg/kg/BM during the event

These recommendations mean that a 50-kg athlete would take between 150mg and 450mg of caffeine before an event, or 50-100mg during the event, and a 100-kg athlete would take 300-900mg before an event and 100-200mg during an event.

Sports supplements guide for beginners part 3 – Caffeine

Most research suggests that caffeine intake should take place 60 minutes before training, which is about the time it takes for it to reach peak blood concentration, but improved performances have still been observed when taken within 15-30 minutes before. Some have suggested that athletes should refrain from caffeine prior to exercise, mostly owing to its reputation as a diuretic, and in such cases it seems that most are referring to caffeinated drinks, such as coffee and energy drinks.

However, whilst this advice seems to be unfounded, it is the anhydrous forms – those without water, such as powders or tablets – that are recommended anyway; they work far better than hydrous forms (with water) and are much easier to measure.

Notwithstanding, tests have consistently shown that caffeine does not act as a diuretic during exercise, increase body temperature or adversely affect performance in hot and/or humid conditions.

Low-to-moderate doses of caffeine (3-6mg/kg/BM) have shown positive results in a variety of activities, and in some cases, high doses (9mg/kg/BM) have shown to be even better; however, doses greater than this have not shown further improvement.

Furthermore, doses above 9mg per kg of BM may show up in urine tests as above doping levels. The common side-effects from caffeine intake are headaches and insomnia, and levels over 1000mg may cause palpitations, though all of these vary considerably according to the individual.

If you do experience side-effects, especially headaches and palpitations, you should stop all forms of caffeine intake immediately and see a physician; if the side-effects are slight, then you might need to review your intake – start by lowing the dosage and the frequency.

Regular caffeine drinkers seem to benefit less from taking caffeine supplements, but this is not a reason to take doses higher than those recommended.

You can find more information about sport nutrition here.

WatchFit Experts change lives!

And they can do the same for you.


Pollyanna Hale Health and Lifestyle coaches
Lost 13 Kg in Total
Mel, 32y Location: London, United Kingdom Working with Pollyanna changed everything. I lost 13kg, got toned and have more energy than ever! Get same results!


Chriz Zaremba Fitness Consultant
Lost 45 Kg in Total
Chris, 50y Location: London, United Kingdom Lost 45kg after the age of 50 and now competes and wins physique competitions and runs marathons Check our weight loss plans