Issue 2 - Caffeine Research

 Nutrition Bites                     Edition 2                                  July 2008

CUTTING EDGE CAFFEINE RESEARCH

Exciting new research soon to be published in the Journal of Applied Physiology has found there may be a new nutritional strategy to increase the amount of carbohydrate re-stored following exercise.  It seems taking caffeine with your favourite recovery carb regime can increase the amount of carbohydrate you can re-store by 66%, compared to just refuelling with carbohydrate. 

HOW WAS THIS TESTED?

The study was done by well known exercise physiologist and researcher Dr John Hawley from RMIT, as well as a host of other leading Australian sports science researchers.  Ingesting carbohydrate and caffeine before and during some sports can increase performance and decrease fatigue.  To test the theory that caffeine might also be useful after sport, the researchers recruited seven well trained endurance cyclists.  Before they took part in the experiment, the cyclists consumed a low carbohydrate diet and exercised to exhaustion to lower glycogen (carbohydrate) stores.  The following day, they were given either a carbohydrate and caffeine solution (4g CHO / kg and 8mg caffeine / kg - very large caffeine dose, equivalent to about six cups of strong coffee) following exhaustive exercise, or just a carbohydrate solution (4g / kg).  Neither the researchers nor cyclists knew what they were being given, and took the opposite solution in an identical trial a week later, making this high quality study a randomised, double-blind crossover experiment.  The cyclists were kept resting in the lab for four hours after they cycled.

WHAT DID THEY FIND?

One hour after exercise, muscle glycogen re-storage rates were the same for both the carbs and carbs plus caffeine groups. But four hours later, there was 66% more glycogen stored when the carbs plus caffeine drink was ingested rather than just the carb drink.  Exactly how this occurs is not yet known, say the researchers, but is likely to be linked to elevated blood glucose concentrations after the co-ingestion of caffeine with carbs (which makes more carbs available for the muscle), and an up-regulation of some of the signaling pathways involved in glucose transport into muscle (such that glucose can more easily get back into the muscle for re-storage).

PRACTICAL APPLICATIONS

Although it is the first study to show the beneficial effect of caffeine ingestion for recovery, it is likely to catch the eye of many keen athletes exercising on a daily basis, to see if it gives them the "recovery edge". Athletes must remember that this is a very high dose of caffeine: some people will not notice this dose, whilst others will be awake all night, or worse still, react due to a pre-exiting medical condition.  Ideally future research will determine if the same beneficial effect on recovery can be found taking in a lower dose of caffeine, lowering potential side effects.

If you, or athletes you work with, are considering trialling caffeine or any other nutritional supplements, it is always advised to see a sports dietitian.  They can provide individualised advice on the correct usage and dosage ofsupplements, as well as any medical conditions which would contra-indicate the use of such supplements.

CAFFEINE LEVELS FOUND IN DIFFERENT PRODUCTS

SDA hope you find this a useful e-resource.  If you have any suggestions of content or sports nutrition information you would like to know about, we will happily take ideas on board. Please email info@sportsdietitians.com.au  

Yours in sports nutrition, Sports Dietitians Australia

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