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| Caffeine | Does it work? |
| Caffeine is a common part of many athletes' diets as it is found naturally in coffee, tea, and chocolate and is added to some soft drinks. Although caffeine is found in food, it is not a nutrient. It is sometimes used by athletes in an attempt to improve their sport's performance and is therefore thought as an ergogenic aid. | When not exercising, caffeine has a diuretic effect, promoting dehydration - known to be harmful to performance. When exercising however, this diuretic effect disappears and the ergogenic effects of improved endurance (often measured as being able to perform for longer until exhaustion rather than perform faster), nervous stimulation and improvement in power/strength may become apparent in isolated muscle. |
| But .... | Is it safe and legal? |
| Studies have been limited to swimming, cycling and some treadmill running. The effects of caffeine may be sport or exercise specific. Most studies have been done in laboratories and not in the field setting and results may therefore be different under 'real race' conditions. 3-6mg caffeine per kg bodyweight taken 1 hour prior to exercise may improve your ability to run for longer before exhaustion in a laboratory setting; other performance effects have been less convincing. |
Problem is, the effects are variable between individuals and if taken in excess, may produce a level of caffeine during competition above the International Olympic Committee (IOC) upper limit of >12mg per litre of urine (or >12µg per ml of urine). Caffeine is therefore a 'controlled or restricted drug'. |
| Excretion | |
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Getting rid of caffeine, via urine, depends on many factors including age, weight, sex, hormonal status and use of contraceptive pill. However, the evidence suggests that daily amounts between 300-400mg will not result in urinary concentrations above the IOC limit, but levels of 9mg caffeine per kg bodyweight will.  |
However, there are huge individual variations with caffeine excretion rates, such that even 6mg per kg bodyweight has produced a positive urine (360mg caffeine a day if you weigh 60kg). Side effects such as headache, upset stomach, insomnia appear to be rare at or below 6mg per kg, but that is not to say that certain individuals may experience side effects from a much smaller dose. These values are also only 'reliable' for men only as few studies have been done on women.
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| The bottom-line? | |
| Look for clues on labels for words and ingredients suggesting that the food or drink may contain caffeine: |
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If you choose to use caffeine as an aid to performance e.g coffee and tea, do so with care. Used incorrectly it may harm your performance due to dehydration, over stimulation or may even get you banned if you fail IOC guidelines during competition. If your usual morning cuppa makes early training bearable - there may be a good scientific reason!
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Do not re-hydrate with caffeine-containing
fluids. Caffeine is a diuretic when you are not exercising and
therefore encourages dehydration. This is particular important
during extreme weather conditions. For hydration, choose plain
water, dilute fruit juices and non-caffeinated squashes or the
specially formulated hydration drinks. Remember the not-so-obvious sources of caffeine when totting up your daily intake |
| What's my intake? | |
| Soft drinks & sports drinks | Caffeine content of food & drinks |
| Cola Drinks | 30-110mg/l 10-35mg per 330ml can |
| Dr Pepper | 111mg/l |
| Dr Pepper Diet | 120mg/l |
| Irn-Bru | 114mg/l |
| Isostar (with activator compound) | 150mg/l |
| Lucozade (Original Energy) |
90mg/l or 30mg per can |
| Moutain Dew |
122mg/l or 40mg per can |
| Schizan | 0.7mg/l |
| Energy Drinks | |
| Power Horse | 310mg/l |
| Red Bull |
314mg/l 79mg per can |
| Red Card | 0.5mg/l |
| Red Kick Guarana Action | 349mg/l |
| Virgin Energy |
303mg/l 100mg per can |
| Coffee |
1 cup holds 190-200ml of liquid 1 mug holds 260ml of liquid |
Standard Instant Made from 1.6g coffee rounded spoon in 200mls of water. |
Average of 288mg of caffeine per litre |
| Average cup of instant | 55mg caffeine |
| Average mug of instant | 75mg caffeine |
| Decaffeinated Coffee | |
| Average cup of decaffeinated | 2mg caffeine |
| Average mug of decaffeinated | 3mg caffeine |
| Filter & Percolated | |
| Typically 7.6g in 200 mls of water | |
Typical average cup Typical average mug |
100mg caffeine 135mg caffeine |
| Miscellaneous | |
| Nescafé
Cafe au Chocolate Nescafé instant Cappuccino Nescafé instant espresso Pro Plus tablets |
110mg caffeine per cup 13mg caffeine per cup 106mg caffeine per cup 50mg per tablet |
| Tea - Stir & Squeeze technique | |
| Average
cup Average mug |
31-53mg caffeine 43-73mg caffeine |
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Note. The inclusion of named products in this webpage is for information only and not for endorsement or promotion purposes. It is not the intention of the author to support or reject the use of caffeine, merely to provide athletes with the scientific facts applied in a practical way.
© j.boorman 2001
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