Researchers through a new study have found that the condition known as ‘runner’s high’ in which individual experiences a calm feeling and exhilaration after a long run is not caused by release of endorphins.

The researchers from the University of Heidelberg conducted the experiment on mice. Scientists from the Heidelberg's Central Institute of Mental Health during the study discovered the animals exhibited increased degrees of both endocannabinoids and endorphins after running.

The team also found that mice showed less anxiety and less sensitivity to pain. Researchers said that the animals during the study were calmer after their run. Later when the drugs were introduced to close down the endocannabinoid receptors of the mice, the researchers observed that the mice no longer experienced a relaxing benefit from running.

They noted that the animals showed the same level of anxiety and sensitivity to pain as before the animals made their run.

Introducing opioid receptor blockers did not provide any effects on the tranquility the mice experience after running, they said.

Another study conducted by University of Missouri (MU) researchers, showed that internal opioid receptors had significant impact in motivating individuals to run on pavements or on treadmills.

The MU research suggested that mu-opioid receptors capable of releasing dopamine helped rats raised to enjoy running to become less motivated to carry out their exercise. This shows that an individual’s desire to run is directly influenced by these receptors.

MU researcher Greg Ruegsegger, said, “Exercise and addiction to substances follow this same chemical process in the brain, it stands to reason that activating these receptors in people with dangerous addictions could provide the same rewards they are craving without the use of dangerous drugs or alcohol”.