Although the effect of caffeine on endurance performance is well documented, a recent study by researchers from South Africa investigated the possible mechanisms why. The researchers studied the effect of caffeine in two triathlons held two weeks apart. The study was conducted with male and female triathletes who trained an average of 12.8 hours per week. The triathletes consumed caffeine 60 minutes before their triathlon and time to completion data was measured.
On average, caffeine supplementation reduced swim times by 3.7% and reduced overall times by 1.7 %. Males appeared to have better performance effects from caffeine than females. What makes the study quite interesting is the possible mechanism by which caffeine acts. The ratings of perceived exertion (RPE) did not change. However the improved performance suggested that caffeine had a central effect resulting in greater muscle performance at the same perceived level of exertion.
Higher levels of cortisol seen post exercise and higher peak lactate levels also suggested that caffeine helps you work harder at the same level of perceived exertion. In other words the mental effect of caffeine on endurance performance is an important mechanism of action.
