Effects of an energy drink upon running time, blood glucose level, heart rate and rate of perceived exertion in elite male endurance runners

In recent years sport-drinks industry has developed extensively and ergogenic beverages are used for increasing performance or reduction of dehydration. The objective of this study was to investigate the effects of an energy drink upon running time, blood glucose level, heart rate (HR) and rate of persceived excertion (RPE) in in elite male endurance runners.

Nine elite male endurance runners participated in 2 treadmill sessions. In session 1 they took an energy drink 15 minutes before (6 ml/kg body weight), and 15, 30, 45 and 60 minutes after (2 ml/kg body weight), start of the activity. In session 2, with the same design, the runners took a placebo. The HR was 70% of the maximum value (HRmax) for the first 60 minutes, followed by 85% until exhaustion.

The distance run when the subjects had taken the energy drink was significantly longer than when they had taken the placebo (p<0.05). In addition, there was a significant difference between the experimental and placebo sessions with regard to the plasma glucose level before and 60 minutes after start of the activity. The data also showed a significant difference in HR (p<0.05) as a function of time: the longer the activity, the higher the HR. The differences between the heartbeat and RPE of the subjects in the 2 sessions were also significant (p<0.05).

It can be concluded that taking an energy drink may be effective only towards the final minutes of a severe activity, increasing performance and decreasing rate of persceived excertion in male elite endurance runners.