Caffeine and sports performance

WORLDWIDE attention was focused recently on physical performance and endurance at the Olympics in London. Competitive athletes require not only hours of intensive training and practice; specialised diets that are designed to ensure faster recovery, enhance endurance and stimulate athletic performance are also part of the regimen. This supposedly precludes the use of banned performance-enhancing substances, although this didn’t stop athletes from trying or speculation that outstanding performances by certain athletes were spurred by unidentified substances for which the World Anti-Doping Agency (WADA) does not test. But what about caffeine?

Caffeine is not currently listed by the WADA as a banned substance at any concentration in blood or urine samples. Before 2004, WADA did set a specific level over which athletes could be banned, but this restriction was removed as the debate continues as to whether caffeine, whilst regarded as a potent stimulant, really enhances exercise performance.

Muscle power in mice

Ahead of the Olympics, UK scientists showed for the first time that high doses of caffeine directly increase muscle power and endurance during relatively low-intensity activities, which in humans can range from everyday activities to running a marathon.

Muscle activity is divided into maximal, where the muscles are pushed to full capacity such as in sprinting or weight lifting, and sub-maximal, which covers all other activities.

A member of the team, muscle physiologist Jason Tallis, tested the effect of caffeine on both the power output and endurance of soleus muscles (lower leg muscle) in mice, under both maximal and sub-maximal activities. He found that a caffeine dosage of 70 μM enhanced power output by ~6% during both types of activity. This effect in humans is likely to be very similar, according to the researchers.

“70 μM caffeine concentration is the absolute maximum that can normally be achieved in the blood plasma of a human, however concentrations of 20-50 μM are not unusual in people with high caffeine intakes,” explained lead researcher Dr Rob James.

Resultant caffeine in blood plasma may act at receptors on skeletal muscle causing enhanced force production. Scientists already know that ingestion of caffeine can increase athletic performance by stimulaKids Running Shoes