When the noted physiologist, David Costill, announced in 1978 that a cup of strong black coffee taken before running a marathon could improve performance by as much as 10 minutes, it was common to see runners just before they embarked on their 42 km spin, drinking, not just one cup of strong black coffee, but several.

Costill found that the caffeine in coffee stimulated the sympathetic nervous system to burn fatty acids for fuel preferentially. This would save valuable glycogen until needed later in the race around the 22 mile (35km) mark. Without coffee, only 19 per cent of fatty acids were burnt, but this was doubled after swigging a cup of strong black coffee. Fatty acids may be classed as "the commercial fuel" for the human machine, while glycogen can be considered a high octane premium fuel which is preferentially oxidised for energy.

As with all alleged ergogenic aids, there are plenty of people around who tried it and because they didn’t become champions over night, were quick to criticise Costill’s findings. Some even said that caffeine was a banned substance in sport. It is not. The permitted amount is 12 microgrammes per millilitre in urine. To reach this level, requires a dose of about 1,200mg of pure caffeine and such an amount will cause violent stomach pain.

So, what went wrong? Well, the first thing is that the user must be well-trained. Caffeine will not transform a poorly prepared athlete into a better one. Two-thirds of the studies with trained athletes showed significant benefits of caffeine on performance or physiological responses or both. This was not the case when sedentary subjects were coerced into exercise. The next thing was pretty obvious to the physiologists and not to the majority of runners: if a person is a three to six cups of coffee a day individual, the effect of just one or two cups of strong coffee will be minimal. For any benefit to show it would be necessary to abstain totally from the beverage for at least 14 days before competition and this applies equally to the consumption of tea. In fact, any caffeine-containing drug or herb, such as guarana, should be avoided in the run up to the race.

How much and when?

The next two important considerations are:

1. What amount to take?

2. What time before the competition?

A safe allocation is half the legal limit, which will be 600mg of pure caffeine. However, this should be tried out first in training with runs in excess of one hour’s duration, and noting whether there is increased anxiety, irritability, delirium and hallucinations! With regard to the second question, the oft-quoted time to take it is one hour before competition. This may be effective for some, but studies which concentrated on the fat-burning response to caffeine suggest that this process does not start until 3-4 hours after ingestion. This would suggest that an athlete aiming to run 4 hours for the marathon would need to take it three hours before hand, while one whose target is 2.5 hours would take it around four hours prior to the race.

But, we are not out of the woods yet! Most marathoners greatly decrease their training for a week up to the race and also increase their carbohydrate intake for the final three days. Normal carbohydrate intake for a strenuous trainer is weight in pounds x 4 = grammes of carbohydrate. So an athlete weighing 100lbs (45kg) would ideally ingest 400 grammes a day. That may seem a lot, but if two hours of running are done daily – it isn’t. Carbohydrate boosting may involve 800 grammes a day being consumed, albeit mostly in the form of a carbo-loader (polymer). If this is done, caffeine ingestion will not make the slightest difference! This is because the muscles being primed with glycogen beyond their normal levels the body will always take the easy alternative, the glycogen boosted one.

What does it do?

For the long-distance runner, caffeine has two allegedly detrimental faces to it. The first is that it is a diuretic (makes you lose water) and if the temperature is over 70^oF (21⁰C) that suggests possible dehydration. The second is that it is thermogenic (raises metabolic rate and body temperature). The two together appear to make caffeine a non-starter in warm conditions. But recent research by Dr. Baraket Falk et al at McMaster University, Ontario, throws doubt on these well-aired criticisms.

Runners were given 7.5mg/kg of caffeine to bodyweight (560mg for a 75kg man). The does did not cause water loss, nor did it raise temperature any higher than without it, while running on a treadmill to exhaustion at 70-75 per cent of VO₂ max, about 80-85 per cent maximum pulse rate. It appears that caffeine on the run does not have the same detrimental effects as when taken at rest.

Who benefits?

Experience, so far, tells us that the novice marathoner responds more spectacularly than the experienced athlete. We can class sub 3-hour marathoners as experienced, and the remainder in the not so experienced class, depending on age. However, an improvement of just two minutes by an elite runner may make the difference between winning and losing, gold instead of silver.

But endurance events are not the only activity that have shown improvements with the use of caffeine. Sprint performance and, in particular, the 1,500 metres have responded well to caffeine ingestion. In fact, the evidence suggests that it can bolster explosive performances by up to 7 per cent. Researchers in Montpellier, France asked seven highly trained swimmers who trained at least five times a week, to swim 100 metres freestyle at highest possible speed, rest for 20 minutes and then repeat the maximal 100 metre effort. On one occasion the athletes ingested 250mg of caffeine – about the amount found in three cups of brewed coffee – one hour before the first maximal swim; in another instance, they took a placebo. Compared to the placebo, caffeine boosted swim velocity during the 100 metre bursts by about 3 per cent. When a placebo was ingested, swimming speed fell dramatically during the second 100 metre sprint, but caffeine prevented this drop in velocity. Caffeine also heightened blood lactate levels by 10 to 15 per cent after the first and second 100 metre swims, indicating that more energy was produced anaerobically when caffeine was utilised. But caffeine only benefited well trained swimmers. When a second group of untrained swimmers also tried the 100 metre swims with and without caffeine, caffeine boosted blood-lactate levels but didn’t heighten swimming speed. The researchers speculated that the non-trained swimmers weren’t able to buffer (reduce) the increases in muscle acidity produced by the excess lactic acid.

In a different study carried out by the same French team, caffeine enhanced maximal anaerobic power during cycling by about 7 per cent. Previous research had avoided looking at caffeine’s effects during very intense exercise because it was felt that it had a glycogen-sparing effect which would actually hinder anaerobic performance. Based on the Montpelier investigations, it now appears that 250mg of caffeine can produce dramatic improvements in high-intensity exercise. Since it has been shown to help both swimmers and cyclists, it can probably lift sprint speeds in runners too.

At the University of Calgary in Canada, 11 swimmers (seven men and four women) consumed either caffeine or a placebo about 2.5 hours before a 1,500m time trial. The total quantity ingested was 6 milligrammes per kilogramme of body weight, or 300-400 total milligrammes, about the amount in three to four cups of strong coffee. Athletes were unaware of whether they were taking caffeine or a placebo, and two separate trials were conducted so that each swimmer’s performance could be evaluated with and without caffeine. With no caffeine, the Canadian swimmers averaged 21:22 for their 1,500m trials; with caffeine, their clockings dropped significantly to 20:58, a 2 per cent improvement. The researchers speculated that caffeine may actually increase the rate at which carbohydrate is broken down for energy inside muscles or may improve the way in which muscle cells handle potassium, an important mineral involved in muscle contraction. As mentioned earlier, when the body has a choice of two nutritional aids it will dump one in favour of the other. And, this is the case if creatine phosphate supplement is being taken.

High levels of this substance increase muscles’ capacity for work in three ways:

1. providing an instant source of energy

2. mopping up some of the fatigue-causing acid that builds up during high-intensity exercise

3. directly stimulating muscle proteins to contract

There is evidence that it is more efficient in the presence of a high-carbohydrate diet. This is because carbohydrate stimulates insulin release, which in turn encourages the uptake of creatine into cells.

A team of Belgian researchers recently investigated the effect of taking creatine supplements with caffeine. They expected it to boost creatine’s effect, since caffeine is known to boost the activity of the transport system that shuttles creatine from the bloodstream across in to the muscle cells. They were surprised and disappointed to find the opposite – caffeine actually counteracted creatine’s positive effects!

The last word

In conclusion, the taking of caffeine as an ergogenic aid requires considerable thought. The considerations are:

1. The distance of the event

2. Where fat-burning preferentially is the aim, taking it just before the start of the race will be non productive

3. For explosive events it should be consumed at least one hour prior to the occasion

4. The type and amount of caffeine to be consumed

5. Pre-competition experiment in training

6. Abstinence of all caffeine consumption for at least two weeks before use.

There will always be those who will consider the use of caffeine as being morally wrong. The answer to that is, if it’s all right to do carbohydrate boosting before an endurance event and to consume high-powered athletic drinks during competition, it is all right to drink extra coffee.