Coffee and caffeine

Nervous but excited about my cycling race one evening, I questioned whether I should have a coffee to enhance my performance or whether this would just keep me awake at night, making me tired tomorrow. I decided to research.

Caffeine is part of a group of chemicals called methylxanthines, occurring naturally in plant derived foodstuffs (coffee, tea, cola drinks and cocoa products) or added artificially to sports products or medications. Sensitivity to its physiological effects can vary.

Will it make me perform better in sport?

In both short intense and endurance riding, caffeine can improve performance. It has the ability to stimulate the central nervous system making you feel more alert and reduce fatigue. It has the ability to spare glycogen (sugar) as a fuel in endurance events as it allows the use of fats to be metabolised for fuel. Of course, this does not mean go crazy on drinking coffee or caffeine fuelled sports drinks, but we know something in the region of 60-400mg per day can improve mental alertness.

Will it improve my concentration?

Yes, it has been proven that caffeine can increase mental alertness. However excessive consumption or caffeine at inappropriate times can cause sleep disturbance and anxiety.

Will it make me dehydrated?

Caffeine is a mild diuretic, however the effects of it on dehydration are often over estimated. The amount of caffeine in a single caffeinated drink is insufficient to have a diuretic affect. The amount therefore that will need to be taken in fluid to cause dehydration, will be offset by the amount of fluid you have to drink.

What are the long-term effects?

Long-term effects are difficult to determine as studies often focus on the short term. The general consensus of available studies suggests 4mg/kg per day (230-400mg per day) will not have any adverse effects on adults, however doubt remains with excessive levels reaching over 750mg per day.

In summary, one cup of instant coffee this evening probably did enhance my performance whilst riding. I tend to avoid caffeine in the evening due to sleep disturbance as I seem to have a fairly high sensitivity to caffeine, usually resulting in a disrupted sleep - however it did appear to have positive affects on my performance and energy levels during the ride.

Some common foods containing caffeine include:

  • 250ml mug of tea 40-70mg

  • 250ml mug of instant coffee 52-85mg

  • 250ml mug filtered coffee 76-157mg

  • 150ml cup decaffeinated coffee less than 2mg

  • 330ml can cola 11-70mg

  • 250ml stimulant drink 27-87mg

  • 50g Chocolate bar 5-36mg

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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