A molecule of caffeine

In February we wrote a post on how we went about running a faster marathon time. In the article we discussed changes we had made in training, nutrition and kit which we thought had contributed to our improved performances. Here we would like to talk about our latest interest – the use of caffeine.

We realise that not everyone wants to run faster; some runners want to go further, others want a ‘social’ run or just want to run for the physical / mental benefits regardless of time. We ourselves don’t always want to run fast, but sometimes we do. And while nothing is really a substitute for hard work in training, there are some things that you can do (legally) to help this along. 

For example in our previous post we mentioned the shoes we wore (Nike Vapourfly 4%) which we think gave us an advantage because of certain design features. In the last week s these innovations have been the focus of much discussion in the media in association with Eluid Kipchoge’s 1:59 and Brigid Kosgei’s new marathon world record for women. Opinion is split as to how acceptable these modifications are.

There is a precedent for banning such innovations. The LZR swim suit caused controversy in 2008 when many swimming world records were broken by athletes wearing them. Amid claims such as ‘they provided too much buoyancy’ restrictions were put in place surrounding their use leaving the sport with many hard-to-break world records.

This is a difficult area and we’re agreed that we wouldn’t like to be making the case for why one thing is acceptable and another not. Like many things the answers seem clear until you start to look more closely, then things get a bit murky.

On the surface, this post on the effects of caffeine on performance is not dealing with anything particularly controversial. Caffeine is fairly ubiquitous in the sports arena, found in many gels and drinks. In October this year Maurten (the “Fuel of champions”) released a new product containing more caffeine than other gels currently on the market. However as recently as 2004 caffeine was on WADA’s banned substance list.

This is just an acknowledge that the whole area of performance enhancing equipment or substances is a bit of a mine-field and we are thankful that we don’t have to make the decisions for others – only ourselves.

Some Background

One of our favourite training routes involves running from Chiswick along the river to Bishop’s Park in Fulham. Because of the positions of the  bridges, a convenient circular 10k or 10 mile run finds Bishop’s Park perfectly placed at half way. On a warm day the water fountain is very useful and the toilets are often welcome. As too, we recently discovered, is the park’s cafe which serves a very good machiatto. 

A couple of times in the winter months we stopped at the cafe and had a small coffee to warm up for the run home. After doing this we started to notice that the run back seemed much less effort. A similar finding in the summer involved an iced coffee drink.

We have used caffeine previously when running but in a more or less random fashion – caffeine pills, caffeine gels / Shot Bloks and Caffeine Bullets – not consistently, and never really convinced of the benefit. Our recent dabbling with mid-route coffee has renewed our interest and encouraged us to research a bit more about it. This information was originally meant for our own benefit but we thought it might also be of use to others.

Caffeine and its effects

Caffeine is a natural substance found in around 60 plants. Controlled scientific trials have associated it with:

  • Improved mental alertness
  • Improved neuro-muscular co-ordination (more efficient running)
  • Increased time to exhaustion (keep going for longer)
  • Decreased perception of fatigue (lower level of perceived exertion)
  • Increased performance in heat
  • Improved short-distance times

There is also some evidence that caffeine may help in the recovery process. It has been linked with:

  • Significant drop in post-effort (race/training) muscle soreness
  • More rapid replacement of depleted muscle glycogen


How  Caffeine works

How caffeine works is still a matter of debate. It is known to affect a number of different systems in the body and suggestions are that it:

  • Changes levels of neurotransmitters in the brain – the chemicals making you ‘feel’ tired are blocked 
  • Stimulates release of fatty acids into the blood stream, allowing muscles to use fat as a fuel and save glycogen which allows you to exercise for longer
  • Stimulates the central nervous system, increasing the release of endorphins thus reducing perception of effort
  • Helps to fight the inflammatory response in the liver
  • Acts directly on the muscle fibres to cause stronger contractions

Amount needed

The scientific studies varied in the amount of caffeine they used to produce an effect, but it is generally agreed that 5mg per kilogram of body weight is a good dose.

Caffeine is fairly quickly absorbed and stays around in the body for hours. Different products make their own suggestions but again as a general rule, taking 200-400mg of caffeine one hour before required will be sufficient for up to 3-4 hours effort.

To give you an idea of what this involves

  • one caffeine pill (pro-plus) contains 50mg,
  • SIS caffienated gel – 75mg
  • Maurten caffeinated gel – 100mg
  • Caffeine bullet – 100mg
  • A typical 8-oz (237 ml) cup of brewed coffee contains approximately 70-140mg (the caffeine content in coffee varies depending on the origin, processing, and preparation methods).
  • 1oz (30 ml) shot of espresso contains 47–64 mg (coffee such as Americanos use expresso as base so have similar caffeine content)
  • A regular cup of decaf has 2–5 mg of caffeine,

In comparison to coffee, carbonated drinks have a much smaller caffeine content:

  • one can of cola contains approximately 32–42 mg of caffeine. (Diet Coke is the higher end)
  • one 8oz can of Red Bull – 80mg

A few things to keep in mind.

Caffeine is not the same as coffee – coffee is known to contain other bioactive ingredients which might also have an effect.

People have different sensitivity to caffeine and in fact it has been suggested that some people (10%) might not benefit at all from its enhancing effects.  (For more information on this read Alex Hutchinson’s article.)

Caffeine does have some undesirable side effects. It can cause:

  • Sleep disturbance – and not getting sufficient sleep might impair performance
  • Gastro-intestinal upset
  • Dizziness
  • Anxiety
  • Increased heart rate
  • Irritability

Results so far

This is purely anecdotal evidence from our own running, but we found that taking a weight-related dose of caffeine before racing, both half marathon and marathon distance, greatly reduced the perceived effort.  Since writing this post Jacquie ran two half marathons in her best half marathon time for five years, and both of us ran better than we expected (our second fastest marathon times of the year) at Loch Ness after a hard year of running and racing.

We plan to continue to experiment with caffeine – we are keen to try the new caffeinated Maurten gels (when they are back in stock).

We hope that you have found this post useful. If you would like to read more we would recommend articles by Alex Hutchinson and  Runner’s Connect. The Caffeine bullet website also has good information.


Some of the views on our route. Above: Hammersmith Bridge Middle: Obelisk at entrance to Duke’s Meadows Right: Bishop’s Park Lake

Left: Jacquie on a snowy tow path Middle: Cam on Chiswick Mall at sunset Right: The machiatto!