Researchers are suggesting that energy drinks loaded with caffeine can change the way the heart beats.

A team from the University of Bonn in Germany said the study shows contractions were more forceful an hour after people had the drink.

Researcher Dr. Jonas Dorner says the amount of caffeine is up to three times higher than in other caffeinated drinks such as coffee or cola.

The researchers told those attending the annual meeting of the Radiological Society of North America that children and people with some health conditions should not use the drinks.